LumberJocks

All Replies on Forstner bit

  • Advertise with us
View Karda's profile

Forstner bit

by Karda
posted 02-03-2018 10:57 PM


29 replies so far

View Rayne's profile

Rayne

1197 posts in 1903 days


#1 posted 02-03-2018 11:17 PM

Found this. I’ll keep this around for myself as well. lol. 500 for softwood and 250 for hardwood.

Drill Press Speed Chart

View msinc's profile

msinc

567 posts in 867 days


#2 posted 02-03-2018 11:23 PM

No, it is my experience that 500 rpm’s is not even close to slow enough. I use Forstner bits for old work plumbing to drill thru studs. I have them both smaller and bigger than what you want to run. Milwaukee makes a heavy duty angled drill motor called a “plumbers hole hawg” just for this. To safely drill holes this size with this type bit it crawls it is so slow. I just checked the published rpm’s of the drill and it is variable speed 0-330 rpm. You can change the little gear box to go up to 750 rpm, but I have never been able to use it full throttle on the low setting. Most of the time I am using it I probably do not exceed 100 rpms or it will hang up and hurt you.
My drill press will go down to 250 rpm and I don’t think that is slow enough.

View Lazyman's profile

Lazyman

3339 posts in 1751 days


#3 posted 02-03-2018 11:44 PM

Not saying it is safe, but what I have done is first drill the hole with the the largest bit that is rated at 500 RPM and then drill the rest with the larger bit and go very slowly, backing out frequently. My logic is that at least it wasn’t doing quite as much work but it might still result in a disaster so try at your own risk. I’ve done this on the lathe using a Jacob’s chuck in the tail stock of my lathe as well. Maybe I’ve just been lucky but no problems yet.

Note that on the drill press, before I drilled with the smaller bit, I use the larger bit first to scribe a ring so that I could easily line up the large bit with the ring since you are losing your center point.

Another option that I haven’t tried is perhaps to mark the 2” circle and drill it out the area with multiple holes to clear out most of the waste and then just use the Forstner to clean it out and get a flat bottom. Again try at your own risk.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View johnstoneb's profile

johnstoneb

3100 posts in 2536 days


#4 posted 02-03-2018 11:50 PM

Clamp everything down tightly and very slow feed. The big danger is the bit grabbing and taking the work for a nasty ride and you with it. clamp it down tightly.

-- Bruce, Boise, ID

View Lazyman's profile

Lazyman

3339 posts in 1751 days


#5 posted 02-03-2018 11:57 PM



Clamp everything down tightly and very slow feed. The big danger is the bit grabbing and taking the work for a nasty ride and you with it. clamp it down tightly.

- johnstoneb

+1. Forgot to mention that.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View Dark_Lightning's profile

Dark_Lightning

3424 posts in 3473 days


#6 posted 02-04-2018 02:01 AM

Depending on how big you want to go, you can use a hole saw and then pry the plug out. It’ll blow out some of the wood below, so you might use some caution with that- just don’t drill too deeply. I guess with a hole saw, you won’t be boring that deeply in one pass, though. This will only work if the wood grain is across the piece. If you are stacking the pieces, you can drill all but the bottom one and use a scroll saw to cut out the “waste”. I bought a plank of mahogany, and made 3 bowls out of it using this method- 14”, 10” and 7” diameter bowls from one bunch of wood. Laid up sections with the grain running perpendicular to the one below. There will still be waste, but a lot less than just hogging it out.

Note- as Bruce said above, just use a slow feed rate. In the machining biz, the concept of “surface feet per minute” applies. There are guidelines on how fast you can cut, based on the amount of surface that is going to be removed, and the difficulty of the material being cut.

-- Random Orbital Nailer

View Karda's profile

Karda

1486 posts in 918 days


#7 posted 02-04-2018 02:21 AM

thanks I won’t be drilling deep, this is for a recess for my chuck, 1/4 – 3/8 deep

View IantheTinker's profile

IantheTinker

282 posts in 491 days


#8 posted 02-04-2018 02:23 AM

I am glad you asked this question, Karda. I for one constantly forget to change the speed of my drill press for different woods. This was a good reminder.

-- opiningminnesotan.com

View Nubsnstubs's profile

Nubsnstubs

1536 posts in 2094 days


#9 posted 02-04-2018 03:44 AM



thanks I won t be drilling deep, this is for a recess for my chuck, 1/4 – 3/8 deep

- Karda


You give up on tenons???.......... Jerry (in Tucson)

-- Jerry (in Tucson) www.woodturnerstools.com

View Karda's profile

Karda

1486 posts in 918 days


#10 posted 02-04-2018 04:02 AM

Tenons are messy. I have developed a liking for footed bowls. They look nice and are east to hold but when I am down to a stub I can’t cut them out with out messing up the foot and a chisel is questionable when the wall is this. I like the look of a well cut recess and the bowl bottom is finished. Also I think a recess is better on something thin where there may not be room for a tenon I wouldn’t say givin up just want to learn new options

View Lazyman's profile

Lazyman

3339 posts in 1751 days


#11 posted 02-04-2018 05:55 AM

If you have a wood worm screw for your chuck, just mount the bowl blank backwards and use a gouge or carbide tool to make your recess.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View Karda's profile

Karda

1486 posts in 918 days


#12 posted 02-04-2018 06:01 AM

but that is not teaching me how to do a recess, besides I have a hard time getting worm screws tight because my lathe doesn’t have a spindle lock. I want the recess for times when I don’t have room for a screw or face plate. I just then in. i thought a bit would be faster.

View MrUnix's profile

MrUnix

7361 posts in 2563 days


#13 posted 02-04-2018 08:02 AM

Just for reference, none of my lathes have a spindle lock, and mounting on a woodworm screw is not an issue in the least. And it doesn’t matter if you don’t get it super snug at first, as it will tighten up by itself as soon as you start turning anyway.

Cheers,
Brad

PS: Never had a time where there wasn’t enough room for a glue block :)

-- Brad in FL - In Dog I trust... everything else is questionable

View Lazyman's profile

Lazyman

3339 posts in 1751 days


#14 posted 02-04-2018 02:17 PM

No spindle lock for me either. Just use the same tool you use to hold the spindle as you remove a chuck or face place and tighten as much as you can by hand. It just need to be snug enough that it doesn’t pivot or wobble on the screw. It is actually harder to get the block off without a lock than on (since it tightens as you turn).

I find it easier to rough and shape the outside, flatten the bottom and also add the tennon or recess with it mounted on a wormwood (quicker than a glue block but that works too). Once the bottom is flat and the blank is round. cut a recess with your tool of choice. In fact if your chuck jaws have a dovetail profile, it is best to make the recess, or a tenon for that matter, dovetailed as well to get a good solid grip on it when you remove it from the wormwood and remount it on the chuck. Another advantage of using the wormwood is that you can drill the hole for the screw to just slightly more shallow than you want to hollow and give yourself a guide to where to stop the roughing phase.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View LeeMills's profile

LeeMills

660 posts in 1665 days


#15 posted 02-04-2018 04:08 PM

As to bits. Look at the chart again and go down to Multi Spur bits 2-1/8 – 4” , 250 rpm. I use a 3-1/4” often to set the area for my 3” faceplate or 50mm or 70mm jaw top with the worm screw. I would do as other suggest and clamp the work to stay centered and start smaller and work up.
That said, if concerned with thin work I would not use a bit as is. You have to remember how deep the point will also cut which may be quite a bit. I have heard of folks regrinding the point but I do not have that skill.
You may be able to start with a small (3/8” forstner) which would have a short point and just grind the point off of the larger bit.

As an alternative, when forming the initial recess I only remove enough for the chuck jaws, usually about 3/8” wide and deep. It doesn’t make one bit of difference if the center of the recess is removed at this time or not. This allows room to cut the recess without the live center getting into the way. You still have your center point for remounting.

Cleaning up the recess at the end is quick but I did spring for Vince’s 1” sanding disc. The nub I leave is usually about 1/4” to remove by cutting/sanding.

-- We cannot solve our problems with the same thinking we used when we created them. Albert Einstein

View Karda's profile

Karda

1486 posts in 918 days


#16 posted 02-04-2018 07:02 PM

My problem with the screw and why I need a lock is my hands are not very strong and on some things I really need 2 hands. The reason I don’t want to screw otherwise is when I want to make a plate a screw is to long. I’ll get things figured out. You have givin me a lot to work with thanks

View LesB's profile

LesB

2075 posts in 3807 days


#17 posted 02-04-2018 07:30 PM

A much safer way is to use a router and dove tail bit with a template guide.
I just posted a Blog on how I mount blanks on my lathe chuck using this method. http://lumberjocks.com/LesB/blog

-- Les B, Oregon

View Karda's profile

Karda

1486 posts in 918 days


#18 posted 02-04-2018 09:33 PM

ok thanks

View LeeMills's profile

LeeMills

660 posts in 1665 days


#19 posted 02-06-2018 03:49 PM


The reason I don t want to screw otherwise is when I want to make a plate a screw is to long.
- Karda

I used to use a worm screw often but now seldom do and use my pin jaws.
This short video shows using a spacer to decrease the depth of the screw for shallow items. Video is < 2 minutes total. I had spacers made 1/4, 3/8, and 1/2 thick. For a plate or platter (maybe 1.5” thick) all you need is about 3/8” of the screw in the wood.
https://www.youtube.com/watch?v=nr_7NjMbq64

-- We cannot solve our problems with the same thinking we used when we created them. Albert Einstein

View Karda's profile

Karda

1486 posts in 918 days


#20 posted 02-06-2018 06:34 PM

thanks for your insight lee. The video relay helped I am frequently having the screw come loose now i know why. I am drilling a 5/16 hole, could that be to small. Do I need the full length of the screw. My turning is usualy light around 8” and under

View LeeMills's profile

LeeMills

660 posts in 1665 days


#21 posted 02-07-2018 12:53 AM

If you have a Nova the screw has flats rather than the small parallel grooves.
The easiert way for me to align is to turn any jaw top center, then hold the wormscrew with a flat up. When installed the end of the jaw slides will seat against the flat.
I only turned dry twice as i remember. I use the 5/16 but I believe Nova gives it a nod of approval to go up 1/32 to 11/32 if you are going into dry wood.
If not doing so, use some oil or a piece of candle to lubricate the screw before installing. I always have a bit of wax at the lathe anyway so I just held it to the wormscrew while running to melt some on.

I hate to say what depth you need but you can probably get by with max 1/2” deep with smaller items. Again, I used mine with the initial rough turning on larger items so it didn’t matter how deep I went because it was going to be turned away anyway.
If you keep the tailstock in place until you start to form the tenon/recess there should be almost zero chance losing it. You can try to turn it by hand agyrt removing the tail stock just to make sure it is still tight. Look up some other videos and I think you will see most everyone uses spacer blocks to limit the depth for smaller items.

-- We cannot solve our problems with the same thinking we used when we created them. Albert Einstein

View Karda's profile

Karda

1486 posts in 918 days


#22 posted 02-07-2018 01:24 AM

thanks Lee I will try a larger bit. I wish I had a lock because I don’t have the strength to turn it on with one hand, i thoughtof my wife but her hands are worse than mine. I was thinking she could hold the wheel

View Nubsnstubs's profile

Nubsnstubs

1536 posts in 2094 days


#23 posted 02-07-2018 01:44 AM

Mike, if you had a Chuck Plate, you wouldn’t need to screw anything onto your chuck. But, you would pretty much need to make tenons. recesses can be used, but a nub would be present. ......... Jerry (in Tucson)

-- Jerry (in Tucson) www.woodturnerstools.com

View HapHazzard's profile

HapHazzard

116 posts in 1232 days


#24 posted 02-14-2018 03:48 AM

Is your Forstner bit high-speed steel? If so, then clamp your stock securely, set your drill press to its slowest speed and advance the bit slowly, a little at a time, backing it out to clear the chips. Do not pre-drill with a smaller bit as this will remove wood from the center of the hole and leave nothing to anchor the center point. Forstner bits don’t grab and pull, you have to force them into the work, so you can control the feed rate by how hard you lean on the handle.

Just make sure your bit is good and sharp. I sharpen mine with a diamond nail file and hone them on a hard wheel with emery compound. If you get a lot of smoke when you’re drilling, it probably isn’t sharp enough. Either that or it’s filled up with wood chips. Forstners tend to do that.

If this doesn’t work for you, or if you just don’t like the way it feels, a mellower approach would be to use a hand brace and one of those adjustable wood bits with a threaded pilot. It won’t give you those nice, clean edges like the Forstner, but if you can keep it perpendicular I think it’ll work.

Neither one of these is going to be too easy going into end grain, so you might want to try one of those sawtooth or multispur bits that look superficially like a Forstner but cut more aggressively. Some of these have threaded pilots and tend to be self-feeding, so you might want to avoid that if speed is a concern, but if you only use it for cutting into end grain, it might not be too bad. You will find that the Forstner leaves the sides and bottom of the recess cleaner than these do.

-- Unix programmers never die; they just > /dev/null

View hairy's profile

hairy

2826 posts in 3896 days


#25 posted 02-14-2018 01:46 PM

There’s a forstner bit speed chart on this page.

https://www.woodcraft.com/blog_entries/forstner-bit-selection-use-care

-- My reality check bounced...

View jimintx's profile

jimintx

913 posts in 1948 days


#26 posted 02-14-2018 05:11 PM

IN a thread I started, a similar question was raised and answered. The guidance I got there was to run my forester bit faster, not slower.

I did that, and it worked like a champ! Here is the thread:
http://lumberjocks.com/topics/256625

I moved up to 860 rpm and drilled out several 2” holes with no further issues.
THUS: My advice is to not be afraid to change rotation speed up or down in increments and find the right set up for your bit and your piece of work.

And of course make sure the work piece is very well clamped in place.

-- Jim, Houston, TX

View HapHazzard's profile

HapHazzard

116 posts in 1232 days


#27 posted 02-15-2018 01:21 AM

I’m inclined to agree, Jim.

-- Unix programmers never die; they just > /dev/null

View Karda's profile

Karda

1486 posts in 918 days


#28 posted 02-15-2018 02:25 AM

thanks, I’ll try the higher speed, my understanding has always been don’t know why that real large bits require a slower speed. Thank for the other thread that helped

View Jack Lewis's profile

Jack Lewis

437 posts in 1442 days


#29 posted 02-15-2018 06:56 PM



Hi, I want to use a little larger than 2” Forstner bit to make the recess for my bowl blank but my drill press has a minimum speed of a little over 500 RPMs is that slow enough for that large of a bit thanks Mike

- Karda


Turn it around and use the lathe head to hold the bit.

-- "PLUMBER'S BUTT! Get over it, everybody has one"

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com