Using forstner bits.

[Foghat]

Hi,
I'm drilling some holes for a bench vise in hard wood. What is the best way to use these bits so the wood doesn't start smoking or the bit get super hot? Are these best used at slow speeds, with minimum pressure on the drill?
Also, lacking a home drill press, is there a good way to get perpendicular holes with a hand drill?
Thanks.

 

[Elmar50]

They make jigs for use with hand drills. That said, my experience is that Forstner bits work much better on a drill press.

 

[HarveyWildes]

Forstner bits do tend to get hot, but do better in a drill press than a hand drill.  In a hand drill, I take them out of the hole occasionally and dip them in tepid water.  Not too bad in a place with low humidity.

 

[Birdhunter]

I've found the Festool Forstner bits to be much sharper than even Freud bits and sharpness has a lot to do with how hot the bit gets.

I use a drilling technique I learned from an aircraft machinist. He called it "pecker drilling". It means the drill bit is pushed into the wood and then withdrawn repeatedly. This allows for chips to be cleared and for the bit to cool spinning in air before being reinserted.

I seldom freehand Forstner bits as any rocking causes the hole to be irregular and the bit to get hot. There was recently a thread here on substitutes for a drill press. Others with steadier hands might be successful freehanding Forstner bits.

 

[Holmz]

I've found the Festool Forstner bits to be much sharper than even Freud bits and sharpness has a lot to do with how hot the bit gets.
...

My FT marked Zobos get hot enough to give you a blister if you do not drop it quick.
I have not measured it, so I am going by feel.

 

[bertv]

Some people use Forstners in a kind of wobbly way, eg they rock the drill in a clockwise motion or from side to side. My guess is that this reduces friction and thus the heating up and also gives the chips some space to escape.

I personally think that this would compromise the exactness of the hole & use the dip and retract method.

 

[clark_fork]

Use the old drill block trick to keep the bit straight. Drill twice, once with a bit the width of the Forstner shaft and again with the Forstner bit. Use a block to steady the bit.

Pre-Drill the hole with a bit the width of the Forstner shaft through a block of wood. Best use a drill press, cutting an indented hole the diameter of the Forstner into the bottom on the block. Drill a vent hole horizontally into the pre-drilled hole  on the block to let heat escape. Then install the block on the shaft of the Forstner. The block steadies the drill bit. The pre-drilled hole into the bench reduces the amount of debris build-up and the indented hole at the bottom of the block allows setting the block flush on the work piece.

Cross hairs on both the block on the hole will help center the block for both drilling processes. Belt and suspenders....

 

[Cheese]

What is the best way to use these bits so the wood doesn't start smoking or the bit get super hot?

Also, lacking a home drill press, is there a good way to get perpendicular holes with a hand drill?

Curious what diameter holes you're drilling, if it's to mount a bench vise I'd think they'd be in the 3/8"-5/8" diameter range. Those sized holes could be done with a conventional drill bit, a twist drill with or without spurs.

If you decide to use a Forstner bit, it really depends on the material the bit is manufactured from along with the design of the bit that determines the speed. For instance, take a 1" diameter Forstner bit mfg in China from regular steel try around 400 rpm, a bit mfg in Germany (think Colt, Fisch, Famag) from high speed steel around 700 rpm or a Zobo bit from chromium steel about 1000 rpm. Quite a range... [eek]

As far as perpendicular holes go without using a drill press, I use this Big Gator tool. They're available at Woodcraft or Rockler and come in both imperial and metric sizes. I've used this alignment tool to drill 6mm pilot holes in a 1 3/4" maple bench top and then put a 6mm pilot on a 20mm Zobo bit to get an MFT pattern of 20mm holes.

 

[Svar]

put a 6mm pilot on a 20mm Zobo bit

I did not realize you could put 6mm pilot into Zobo bit, that's great. The one I have is 2 or 3 mm (too flimsy), but those are Centrotec type. You've got regular shank Zobo.

 

[Cheese]

I did not realize you could put 6mm pilot into Zobo bit, that's great. The one I have is 2 or 3 mm (too flimsy), but those are Centrotec type. You've got regular shank Zobo.

Ya, they're available from Timber Tools, you need the System 3 Series. Real slick... [cool]
https://www.timbertools.com/Zobo-Central-Drilling-System-3/

 

[charley1968]

You could use a router for the plunge action and than a drill to finish the job. But if you're drilling through you might as well use a spiral drillbit.
Regarding the cutting speed: generally, the larger the diameter the slower the speed/rpm you should use. A drill of 3mm diameter going at 2000 rpm has the same cutting speed as a 30mm Forstner bit going at 200 rpm.

 

[mouppe]

I actually found a hand brace much faster than an electric drill when I did my dog holes. The problem with the router method for me was that it did not plunge deep enough, but you do get a perpendicular hole.

With a hand brace it's so simple to get perpendicular as well. I use two squares clamped to the bench as sight lines- one in front and one to the side- and you can stop and check you are straight as you drill down.

You stop when you feel the snail coming through the bottom, and then I finished the hole from below with a forstner bit in my Festool drill.

 

[otis04]

I drilled holes with a Forstener bit in plywood, then used a long bushed pattern bit in the router to make the holes in my bench.  The holes are dead on diameter and straight.  I did use a hand held drill to remove most of the material prior to using the router, since it was at a smaller diameter, the straightness did not matter.

 

[Brent Taylor]

LR-32 with a 20 mm bit and follow with a brad point bit, if your needs are for deeper holes.  you did not say the type of hold down you were thinking of using or the needed depth. So this is a shot in the dark.