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3K views 7 replies 4 participants last post by  BuckeyeDennis 
#1 ·
Fixturing an out-of-round bowl

I've been an avid woodworking hobbyist for quite some time, but I'm still a novice when it comes to turning. On my third bowl I ran into a bit of a challenge, and came up with a workholding solution that I haven't seen elsewhere. But I don't know what I don't know, so I'd appreciate any opinions and suggestions from you experienced woodturners.

Window Table Recreation Plant Clock


This particular woodworking adventure started when the rough-turned applewood bowl in the pic below dried a full ½" out of round. The tenon that I had chucked onto for rough turning also turned into an oval, so I wasn't going to get a secure grip on it with my standard chuck jaws. The only way I could think of to true up the tenon was to try turning the bowl between some sort of jam chuck and a live center. Which sounded like a fussy setup to me, and I wasn't looking forward to it.

String instrument Wood Measuring instrument Ruler Tool


As my shop is rather small, I use my Shopsmith Mark V as a lathe, with a speed reducer to drop the speed range to about 100 - 770 RPM when turning bowls. My chuck is a Nova G3, which is Shopsmith's standard chuck offering. Mark V's have a 15-1/2" swing over the way tubes, so you can fit a good-sized bowl on them, but you have to take it slow and easy due to the light weight of the machine.

So on to Plan B. I added a set of Nova JSCOLE Cole jaws for my Nova G3 chuck to my wish list. Per Nova, these jaws are for lathes with a minimum 12" swing. I would have preferred larger jaws, but those are the biggest ones that Nova makes to fit a G3 chuck. And it sounded as if they'd be big enough for this 10-1/2" bowl.

My family bought the Cole jaws for me as a Christmas present in 2019. What didn't know until I opened them was that these jaws have a max outside gripping diameter of only 9.29", when mounted on a G3 chuck. I eventually found that info buried deep in the product manual, but it isn't mentioned on the product pages at either Technatool or Amazon. So my new jaws weren't big enough for the applewood bowl.

Rim Bicycle part Automotive wheel system Auto part Font


The other problem I discovered is that Cole jaws are designed to grip round things. Given that the threaded "buffer" mounting holes in the Cole jaws are spaced about 3/8" apart radially, they can't be adjusted to properly fit an out-of-round bowl (unless perhaps you remove half of the buffers, and then orient the bowl just so). This is pretty obvious from the stock photo above, showing the factory buffers. So I stuck my new Cole jaws in a drawer to await a smaller bowl, and there they languished for the next year or so.

When I finally I pulled the Cole jaws back out of the drawer, I noticed a mention in the instruction manual of making your own wooden extenders (at your own risk, of course). And voila! I realized that my new WoodAnchor™ fixturing system could solve the problem quite nicely.

So I made up a set of simple jaw extender segments from Âľ" Baltic birch plywood. The segments mount to the Cole jaws, and have fixturing slots milled right down their centerlines. They not only increase the bowl-size capacity, but they can be adjusted as necessary to securely grip out-of-round bowls. This makes it dead simple to re-turn a warped bowl. They're also a lot less expensive than commercial jaws with a similar bowl-size capacity, and a whale of a lot less expensive than a whole new chuck that can accept those larger jaws.

(Full disclosure: As the founder of ToolQuest, I have a direct financial interest in the WoodAnchor system. But I've always enjoyed participating in woodworking forums as a hobbyist, and I'll endeavor to keep my posts on LJ both interesting and non-commercial.)

Gas Machine Metal Gun turret Art


And here's that rough turned applewood bowl again, chucked up in the jaw extenders.

I did purchase the NOVA 6030 Cole Jaw Buffer Accessory kit, which comes with eight of the multisided buffers shown in the photos. With slightly canted sides that capture the rim of the bowl, these grip much better than the standard cylindrical buffers that are included with the jaws. I mounted them with WoodAnchor sliding nuts, which are each rated for 500 lb. of clamping force. So you can lock them down hard, and then crank down tightly with the chuck. That bowl is going nowhere.

Saw Wood Machine tool Gas Automotive wheel system


I'll be very interested to hear what you experienced turners out there think of this fixture. It solved my immediate problem, and now I'm wondering what other uses it might have. What about eccentric turning? I'd need a much heavier lathe to turn anything very far out of balance, but what do you guys with big lathes think of the idea?
 

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#2 ·
Fixturing an out-of-round bowl

I've been an avid woodworking hobbyist for quite some time, but I'm still a novice when it comes to turning. On my third bowl I ran into a bit of a challenge, and came up with a workholding solution that I haven't seen elsewhere. But I don't know what I don't know, so I'd appreciate any opinions and suggestions from you experienced woodturners.

Window Table Recreation Plant Clock


This particular woodworking adventure started when the rough-turned applewood bowl in the pic below dried a full ½" out of round. The tenon that I had chucked onto for rough turning also turned into an oval, so I wasn't going to get a secure grip on it with my standard chuck jaws. The only way I could think of to true up the tenon was to try turning the bowl between some sort of jam chuck and a live center. Which sounded like a fussy setup to me, and I wasn't looking forward to it.

String instrument Wood Measuring instrument Ruler Tool


As my shop is rather small, I use my Shopsmith Mark V as a lathe, with a speed reducer to drop the speed range to about 100 - 770 RPM when turning bowls. My chuck is a Nova G3, which is Shopsmith's standard chuck offering. Mark V's have a 15-1/2" swing over the way tubes, so you can fit a good-sized bowl on them, but you have to take it slow and easy due to the light weight of the machine.

So on to Plan B. I added a set of Nova JSCOLE Cole jaws for my Nova G3 chuck to my wish list. Per Nova, these jaws are for lathes with a minimum 12" swing. I would have preferred larger jaws, but those are the biggest ones that Nova makes to fit a G3 chuck. And it sounded as if they'd be big enough for this 10-1/2" bowl.

My family bought the Cole jaws for me as a Christmas present in 2019. What didn't know until I opened them was that these jaws have a max outside gripping diameter of only 9.29", when mounted on a G3 chuck. I eventually found that info buried deep in the product manual, but it isn't mentioned on the product pages at either Technatool or Amazon. So my new jaws weren't big enough for the applewood bowl.

Rim Bicycle part Automotive wheel system Auto part Font


The other problem I discovered is that Cole jaws are designed to grip round things. Given that the threaded "buffer" mounting holes in the Cole jaws are spaced about 3/8" apart radially, they can't be adjusted to properly fit an out-of-round bowl (unless perhaps you remove half of the buffers, and then orient the bowl just so). This is pretty obvious from the stock photo above, showing the factory buffers. So I stuck my new Cole jaws in a drawer to await a smaller bowl, and there they languished for the next year or so.

When I finally I pulled the Cole jaws back out of the drawer, I noticed a mention in the instruction manual of making your own wooden extenders (at your own risk, of course). And voila! I realized that my new WoodAnchor™ fixturing system could solve the problem quite nicely.

So I made up a set of simple jaw extender segments from Âľ" Baltic birch plywood. The segments mount to the Cole jaws, and have fixturing slots milled right down their centerlines. They not only increase the bowl-size capacity, but they can be adjusted as necessary to securely grip out-of-round bowls. This makes it dead simple to re-turn a warped bowl. They're also a lot less expensive than commercial jaws with a similar bowl-size capacity, and a whale of a lot less expensive than a whole new chuck that can accept those larger jaws.

(Full disclosure: As the founder of ToolQuest, I have a direct financial interest in the WoodAnchor system. But I've always enjoyed participating in woodworking forums as a hobbyist, and I'll endeavor to keep my posts on LJ both interesting and non-commercial.)

Gas Machine Metal Gun turret Art


And here's that rough turned applewood bowl again, chucked up in the jaw extenders.

I did purchase the NOVA 6030 Cole Jaw Buffer Accessory kit, which comes with eight of the multisided buffers shown in the photos. With slightly canted sides that capture the rim of the bowl, these grip much better than the standard cylindrical buffers that are included with the jaws. I mounted them with WoodAnchor sliding nuts, which are each rated for 500 lb. of clamping force. So you can lock them down hard, and then crank down tightly with the chuck. That bowl is going nowhere.

Saw Wood Machine tool Gas Automotive wheel system


I'll be very interested to hear what you experienced turners out there think of this fixture. It solved my immediate problem, and now I'm wondering what other uses it might have. What about eccentric turning? I'd need a much heavier lathe to turn anything very far out of balance, but what do you guys with big lathes think of the idea?
gotta follow this i have that same cole jaw set with the optional buffers myself,curious as to the opinions you get.
 

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#3 ·
Fixturing an out-of-round bowl

I've been an avid woodworking hobbyist for quite some time, but I'm still a novice when it comes to turning. On my third bowl I ran into a bit of a challenge, and came up with a workholding solution that I haven't seen elsewhere. But I don't know what I don't know, so I'd appreciate any opinions and suggestions from you experienced woodturners.

Window Table Recreation Plant Clock


This particular woodworking adventure started when the rough-turned applewood bowl in the pic below dried a full ½" out of round. The tenon that I had chucked onto for rough turning also turned into an oval, so I wasn't going to get a secure grip on it with my standard chuck jaws. The only way I could think of to true up the tenon was to try turning the bowl between some sort of jam chuck and a live center. Which sounded like a fussy setup to me, and I wasn't looking forward to it.

String instrument Wood Measuring instrument Ruler Tool


As my shop is rather small, I use my Shopsmith Mark V as a lathe, with a speed reducer to drop the speed range to about 100 - 770 RPM when turning bowls. My chuck is a Nova G3, which is Shopsmith's standard chuck offering. Mark V's have a 15-1/2" swing over the way tubes, so you can fit a good-sized bowl on them, but you have to take it slow and easy due to the light weight of the machine.

So on to Plan B. I added a set of Nova JSCOLE Cole jaws for my Nova G3 chuck to my wish list. Per Nova, these jaws are for lathes with a minimum 12" swing. I would have preferred larger jaws, but those are the biggest ones that Nova makes to fit a G3 chuck. And it sounded as if they'd be big enough for this 10-1/2" bowl.

My family bought the Cole jaws for me as a Christmas present in 2019. What didn't know until I opened them was that these jaws have a max outside gripping diameter of only 9.29", when mounted on a G3 chuck. I eventually found that info buried deep in the product manual, but it isn't mentioned on the product pages at either Technatool or Amazon. So my new jaws weren't big enough for the applewood bowl.

Rim Bicycle part Automotive wheel system Auto part Font


The other problem I discovered is that Cole jaws are designed to grip round things. Given that the threaded "buffer" mounting holes in the Cole jaws are spaced about 3/8" apart radially, they can't be adjusted to properly fit an out-of-round bowl (unless perhaps you remove half of the buffers, and then orient the bowl just so). This is pretty obvious from the stock photo above, showing the factory buffers. So I stuck my new Cole jaws in a drawer to await a smaller bowl, and there they languished for the next year or so.

When I finally I pulled the Cole jaws back out of the drawer, I noticed a mention in the instruction manual of making your own wooden extenders (at your own risk, of course). And voila! I realized that my new WoodAnchor™ fixturing system could solve the problem quite nicely.

So I made up a set of simple jaw extender segments from Âľ" Baltic birch plywood. The segments mount to the Cole jaws, and have fixturing slots milled right down their centerlines. They not only increase the bowl-size capacity, but they can be adjusted as necessary to securely grip out-of-round bowls. This makes it dead simple to re-turn a warped bowl. They're also a lot less expensive than commercial jaws with a similar bowl-size capacity, and a whale of a lot less expensive than a whole new chuck that can accept those larger jaws.

(Full disclosure: As the founder of ToolQuest, I have a direct financial interest in the WoodAnchor system. But I've always enjoyed participating in woodworking forums as a hobbyist, and I'll endeavor to keep my posts on LJ both interesting and non-commercial.)

Gas Machine Metal Gun turret Art


And here's that rough turned applewood bowl again, chucked up in the jaw extenders.

I did purchase the NOVA 6030 Cole Jaw Buffer Accessory kit, which comes with eight of the multisided buffers shown in the photos. With slightly canted sides that capture the rim of the bowl, these grip much better than the standard cylindrical buffers that are included with the jaws. I mounted them with WoodAnchor sliding nuts, which are each rated for 500 lb. of clamping force. So you can lock them down hard, and then crank down tightly with the chuck. That bowl is going nowhere.

Saw Wood Machine tool Gas Automotive wheel system


I'll be very interested to hear what you experienced turners out there think of this fixture. It solved my immediate problem, and now I'm wondering what other uses it might have. What about eccentric turning? I'd need a much heavier lathe to turn anything very far out of balance, but what do you guys with big lathes think of the idea?
Very nice and using a Shopsmith. I may have to try it hat on mine.
 

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#4 ·
Fixturing an out-of-round bowl

I've been an avid woodworking hobbyist for quite some time, but I'm still a novice when it comes to turning. On my third bowl I ran into a bit of a challenge, and came up with a workholding solution that I haven't seen elsewhere. But I don't know what I don't know, so I'd appreciate any opinions and suggestions from you experienced woodturners.

Window Table Recreation Plant Clock


This particular woodworking adventure started when the rough-turned applewood bowl in the pic below dried a full ½" out of round. The tenon that I had chucked onto for rough turning also turned into an oval, so I wasn't going to get a secure grip on it with my standard chuck jaws. The only way I could think of to true up the tenon was to try turning the bowl between some sort of jam chuck and a live center. Which sounded like a fussy setup to me, and I wasn't looking forward to it.

String instrument Wood Measuring instrument Ruler Tool


As my shop is rather small, I use my Shopsmith Mark V as a lathe, with a speed reducer to drop the speed range to about 100 - 770 RPM when turning bowls. My chuck is a Nova G3, which is Shopsmith's standard chuck offering. Mark V's have a 15-1/2" swing over the way tubes, so you can fit a good-sized bowl on them, but you have to take it slow and easy due to the light weight of the machine.

So on to Plan B. I added a set of Nova JSCOLE Cole jaws for my Nova G3 chuck to my wish list. Per Nova, these jaws are for lathes with a minimum 12" swing. I would have preferred larger jaws, but those are the biggest ones that Nova makes to fit a G3 chuck. And it sounded as if they'd be big enough for this 10-1/2" bowl.

My family bought the Cole jaws for me as a Christmas present in 2019. What didn't know until I opened them was that these jaws have a max outside gripping diameter of only 9.29", when mounted on a G3 chuck. I eventually found that info buried deep in the product manual, but it isn't mentioned on the product pages at either Technatool or Amazon. So my new jaws weren't big enough for the applewood bowl.

Rim Bicycle part Automotive wheel system Auto part Font


The other problem I discovered is that Cole jaws are designed to grip round things. Given that the threaded "buffer" mounting holes in the Cole jaws are spaced about 3/8" apart radially, they can't be adjusted to properly fit an out-of-round bowl (unless perhaps you remove half of the buffers, and then orient the bowl just so). This is pretty obvious from the stock photo above, showing the factory buffers. So I stuck my new Cole jaws in a drawer to await a smaller bowl, and there they languished for the next year or so.

When I finally I pulled the Cole jaws back out of the drawer, I noticed a mention in the instruction manual of making your own wooden extenders (at your own risk, of course). And voila! I realized that my new WoodAnchor™ fixturing system could solve the problem quite nicely.

So I made up a set of simple jaw extender segments from Âľ" Baltic birch plywood. The segments mount to the Cole jaws, and have fixturing slots milled right down their centerlines. They not only increase the bowl-size capacity, but they can be adjusted as necessary to securely grip out-of-round bowls. This makes it dead simple to re-turn a warped bowl. They're also a lot less expensive than commercial jaws with a similar bowl-size capacity, and a whale of a lot less expensive than a whole new chuck that can accept those larger jaws.

(Full disclosure: As the founder of ToolQuest, I have a direct financial interest in the WoodAnchor system. But I've always enjoyed participating in woodworking forums as a hobbyist, and I'll endeavor to keep my posts on LJ both interesting and non-commercial.)

Gas Machine Metal Gun turret Art


And here's that rough turned applewood bowl again, chucked up in the jaw extenders.

I did purchase the NOVA 6030 Cole Jaw Buffer Accessory kit, which comes with eight of the multisided buffers shown in the photos. With slightly canted sides that capture the rim of the bowl, these grip much better than the standard cylindrical buffers that are included with the jaws. I mounted them with WoodAnchor sliding nuts, which are each rated for 500 lb. of clamping force. So you can lock them down hard, and then crank down tightly with the chuck. That bowl is going nowhere.

Saw Wood Machine tool Gas Automotive wheel system


I'll be very interested to hear what you experienced turners out there think of this fixture. It solved my immediate problem, and now I'm wondering what other uses it might have. What about eccentric turning? I'd need a much heavier lathe to turn anything very far out of balance, but what do you guys with big lathes think of the idea?
Thanks, guys. It dawned on me after I posted this first blog installment that I should be able try turning some decorative offset rings on the bottom of that very bowl when I finish-turn it. I'll report on that in a future installment.
 

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#5 ·
Making the extender segments

These jaw extenders are so easy to make that they hardly need any instructions. I'll let the pictures do most of the talking.

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Cut a square piece of plywood to the desired extension-jaw diameter. This will be the diameter when the jaws are closed. Lay out centerlines, diagonals, and the OD.

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With the jaws fully closed, clamp the chuck and cole-jaw assembly to the workpiece, aligned as shown. Transfer the jaw-extender mounting holes to the workpiece using a transfer punch.

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Now finish the layout (which I should have done originally). The corners have to be notched out as shown, to leave clearance for the T-handle of the chuck wrench. The inner circle is the OD of the cole jaws.

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Route WoodAnchor fixturing slots along both centerlines.

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Trim off the waste at the bandsaw, cutting outside of the lines.

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Separate the jaw-extender segments along the diagonal layout lines. This quick-and-dirty WoodAnchor small-parts sled (constructed of scrap plywood) made that operation very easy.

Window Door Wood Rectangle Floor


Sand each jaw-extender segment to the layout lines (I used a disc sander for this), and drill the mounting holes.

Wood Hardwood Gas Flooring Rectangle


Countersink the holes for the 8 mm flat-head mounting screws, and they're ready to use!

Window Table Recreation Plant Clock
 

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#6 ·
Making the extender segments

These jaw extenders are so easy to make that they hardly need any instructions. I'll let the pictures do most of the talking.

Rectangle Wood Wood stain Flooring Floor


Cut a square piece of plywood to the desired extension-jaw diameter. This will be the diameter when the jaws are closed. Lay out centerlines, diagonals, and the OD.

Wood Floor Flooring Automotive tire Gas


With the jaws fully closed, clamp the chuck and cole-jaw assembly to the workpiece, aligned as shown. Transfer the jaw-extender mounting holes to the workpiece using a transfer punch.

Wood Rectangle Floor Font Flooring


Now finish the layout (which I should have done originally). The corners have to be notched out as shown, to leave clearance for the T-handle of the chuck wrench. The inner circle is the OD of the cole jaws.

Door Rectangle Wood Interior design Flooring


Route WoodAnchor fixturing slots along both centerlines.

Wood Hood Architecture Rectangle Door


Trim off the waste at the bandsaw, cutting outside of the lines.

Wood Art Hardwood Flooring Rectangle


Separate the jaw-extender segments along the diagonal layout lines. This quick-and-dirty WoodAnchor small-parts sled (constructed of scrap plywood) made that operation very easy.

Window Door Wood Rectangle Floor


Sand each jaw-extender segment to the layout lines (I used a disc sander for this), and drill the mounting holes.

Wood Hardwood Gas Flooring Rectangle


Countersink the holes for the 8 mm flat-head mounting screws, and they're ready to use!

Window Table Recreation Plant Clock
Fine work and photos. It would be nice if you could add some photos of it in action.
 

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#8 ·
Finish-turning the bowl

I finally finished up the applewood bowl last December, as a Christmas present for my wife. But first, after getting a little more hands-on experience with the Cole-jaw extenders, I made one final tweak to streamline their setup.

After a bowl is trued up, the "buffers" need to be set to a uniform radius. I found that the easiest technique was to set them all relative to the outside radii of the extender segments. So to true up those surfaces, I fully closed the chuck jaws and turned the OD of the entire assembly round. I experimented with using a sharp scraper to do this, but found that the plywood was too prone to chipping out on the trailing edges of the extender segments. So I switched over to "abrasive turning", meaning that I propped a sanding block atop the lathe tool rest and sanded the OD round while the assembly was spinning.

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Now I can use an ordinary combination square as a depth gauge, measuring to the backside of the buffer. To position the buffers, I like to place them outboard of their final positions and tighten the mounting screws just enough to provide a small amount of sliding resistance. Then I use the combination square blade to push them into their final positions. When the head contacts the extender segments, the buffers are properly positioned, and ready to lock down.

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At maximum buffer radius, that big washer can stick out past the end of extender segment and interfere with the head of the combo square. In that case, I simply reference off the backside of the WoodAnchor sliding nut instead of the buffer, and the combo square fits nicely beneath the washer. The buffer and washer are normally in place when I do this, but I removed them for the pic below just so that the nut is visible.

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Now to finish up that bowl! The first order of business was to finish-turn the bottom of the bowl, and true up the tenon. The thickness variation of the unturned "rim" shows just how out of round the bowl was after drying.

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Now, with the tenon trued up, I can flip the bowl around and chuck up on the tenon. The pic below was taken after finish-turning the inside of the bowl, refining the bottom curves a bit, and applying a few coats of satin wipe-on poly. Instead of just putting a flat on a roundish bowl bottom, I decided to leave a small "pedestal" for visual interest.

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Now it's time to get rid of the tenon, so back into the Cole-jaw extenders the bowl goes. When I see turners removing tenons from large bowls on YouTube videos, they usually cut it off with a hand saw, and then flatten and smooth the bowl base with a sander. But the Cole-jaw extenders enabled me to simply turn it off, which is a much nicer process.

Before:

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And after:

Wood Toy Art Personal protective equipment Stuffed toy


Having seen my lame attempt at using a Sharpie to sign the base of a bowl that I turned for my daughter, my wife had taken pity on me the previous Christmas and bought me a personalized branding iron. I hadn't used it yet, but this was definitely the time to do so! After playing with the head temperature and contact time, I finally managed a couple of decent practice brands in a row. So I held my breath and proceeded to brand the pedestal base. Then back the bowl went into the Cole jaws, where I turned an accent groove around the brand, and applied finish to the base.

Wood Art Machine Personal protective equipment Toy


I'll close this story with a couple of beauty pics of the finished bowl. My daughter found a great bowl arrangement photo on the internet, and we shamelessly stole their staging idea. After all, who could argue with putting apples in an applewood bowl? My daughter did the fruit arrangement, and I did the photography.

Food Tableware Dishware Fruit Ingredient


Brown Wood Eyelash Circle Wood stain


Thanks for reading!
 

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