Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Very impressive…..we will be anxious to see some finished spheres.

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

As though "finding the center" is a challenge. Jeeze, Jim. I don't think you know what difficult is. You're a freakin' genius. You've been keeping secrets.
Now. If you'll look at pictures of Shopsmith Mk5, and pictures of bowl coring devices, I'm sure you could help me figure out a set up I can use. Your brain brain works, evidently, on levels mine hasn't yet reached. PM me with any ideas, if you don't mind.

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Extremely fine work-beautifully done and far above my pay grade.

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Thanks for the nice comments.
Hi Mark, you just gave me another idea. Since this will hollow and cut the outside, If I left the pivot locked in place, I could cut the inside and outside of a bowl with it and get a perfect wall thickness. I would have to do something less than 180 degree so the cutter can come out of the center okay.

cheers, Jim

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Must be satisfying to be able to build a tool like this in your own shop .
Great looking tool Jim but that rusty bolt has to go .

BTW what size of box would it fit into ?

Klaus

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Pretty slick Jim.
I love the way you think and your ability to follow through in the real world.
This is one sweet piece of work.

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Jim

How do you like that design? Do you think it is better then mine?

Is it easy to rotate back and forth? How big a sphere can you make?

I really like how you can whip up something so fast.

That reminds me of a guy here Roger something who did a DVD on what you made. I will try and find it or him for you.

Arlin

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Geez Jim, you never cease to amaze me.
That jig is something to be very proud of.
Congratulations on your skills.
Bob.

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Thanks Klaus, Paul and Arlin.

Hi Klaus. That bolt it is not that rusty, the photo in that light turned everything brownish. It is the bottom bolt that fastens the post to the arm. I'm running short of socket head cap screws so I use everything I have without buying anything. I did have to buy that 1" block of aluminum. This box needs to be 5 1/4×7 1/2×11 1/4 ….......inside dimensions. I drew it up tonight. I'm thinking 6 pieces….. all lock mitered…. and then cut on a curve to open.
Hi Paul. It does work slick too!!
Hi Arlin. I know you have plans to make the cuts over the top with a skew type cutter but I have to say this cuts smooth. I wrote Carter and they said they put that ring insert on an angle for a better cut and they were right. I measured it at 13 degrees from the video with a straight on photo and it worked. It rolls on a bearing and it easy to rotate. I can off set the cutter to either side to get more clearance just like the Carter. I don't have a video, but take a look at theirs. I'll see if I can put it in here. It was not fast. I spent a whole week solid on it and three pages of drawings…modifications all the way.

Cheers, Jim

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Excellent thinking Jim. Great way to keep the mind busy. Wish I had the tools to do some metal work like that.
You say you figured out the possibility of hollowing the inside. I have been making stick bobbers for my son and thought of making a round one for myself as a novelty item. Looks like you may have that figured out.

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Thanks, Dave. I love it when I can get back on the metal lathe again. I got to use a lot of my own tools that I made to make this tool….like the boring head in the mill and the fixture for drilling exactly on center of round pieces up to 2" diameter. It drills within a half thousandth. I spent 40 hours grinding that fixture to get it perfect.

Cheers, Jim

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Looks COOL, Jim…

A short video would be nice to see how it really works though…

Thank you!

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Really cool!

I think I will stick to just eyeballing it though. Or maybe actually buying a couple of balls if i need them perfect.

Amazing jig!

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Very smart work there Jim, must be great to see something and then turn around and make it. Well done.
Using that tool will take all the fun and challenge from turning a sphere by eye and feel but sure will make the task easier.

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Thanks Joe, Ray and Bob.
Hi Joe, here is the Carter video. Mine were like that:

Hi Bob. I have wanted to make one of these for a long time but never had the need. I can see many uses for it now.

Cheers, Jim

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Jim

I am now thinking your set up would be much better for making small spheres so I might have to buy one from you.

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

This is a Carter design so I can't sell it.

Jim

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Excellent work and result on this jig Jim. I can only envy your engineering/metal working skills. Extremely useful for a woodworker.

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Geezee Jim, this is a killer piece of machinery, I feel a real amateur with the one I made, this is super cool Mate.
Top stuff
cheers
pete

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Some serious machining going on there Jim

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Thanks Mike, Pete and Roger. I am just about to do some concave work with it today!!

cheers, Jim

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Jim. that video made it perfectly clear! Thank you!
I didn't visualize how the blade rotated off of the base!
Made good sense!

Thanks again…

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Good, Glad you watched it, Joe. I have it set up again in my lathe and my lathe just quit tonight…. Keeps blowing the breaker. time for a new one!!!!!!!!!!!

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Sorry your Lathe gave up…

 

Sphere Jig

I have a job in the future to make some perfect spheres and I could do it with a template and lathe tools but I have often thought I'd like to have a jig to swing the arc to cut spheres. so I decided to make one that will cut convex spheres and concave pockets. I had some sketched but then started looking at what was commercially available and found the Carter Perfect Sphere jig. I followed that design since they had put in all the engineering and all I had to do was determine the size and workings of the parts of the jig.

I used aluminum for the arm and fitted it with a ball bearing that was laying around the shop.

I made the center post adjustable for a 15" or 16" swing lathe. The top of the post is drilled out to hold the horizontal cutter arm with the center shaft that advances with the turn of the handwheel in the back. I could not see how Carter made their adjusting mechanism so I devised one with a ball on the screw and a hole in the cutter arm that works very well.

I made the base mechanism adjustable for different gaps in the bed similar to the Carter design. I scribed the width lines on the bottom instead of the top.

I made some support rings off center so I had a thicker area for the thread without going to a huge diameter.

All the screws that go against the steel shafts have a brass insert in the end to prevent galling.
The horizontal bar has a flat on top and one at 15 degree to either side for doing a shear scrape cut in either direction ( A Carter idea).

The handle on the swing arm is Rosewood.

I made a sample sphere out of a piece of mesquite just to try it out. It cuts very smooth. The cutter is tipped down at 13 degrees. I measured that from a still shot of the Carter tool on You Tube. I think that idea has merit in hollowers as well. The tip is a round Hunter carbide insert that comes with a 4 mm screw.

Here are some shots of the assembly and the parts layout. The steel round parts are coated with Gun Bluing so as to not add to the diameter and yet protect from rust.

Now I'll need a box for it!!
Also,
I have started on 2 pair of wooden cups (2" and 4") to hold a partial sphere in order to cut the ends round and make it a perfectly round piece. Finding exact center again will be a challenge, I think.

Cheers, Jim

Well I made this jig for a 15 or 16" lathe so the new one will most likely be 16". I'll be taking the lathe apart this weekend to see what the motor looks like inside.. I'd like to put an outboard motor on it, but the way it is set up, the pulley only has space to be only about 1 1/4" unless I carve out the casting from the back which might happen!!