Forstner bit problems

[Barry McFadden]

Drill in about 2" and you'll understand what he is talking about. More than once I've locked a bit down inside a turning by not clearing the chips every 1/2" or so.

I regularly use a forstner bit to drill in 4 -6 inches to set the depth of bowls I do and have never had an issue.....

[Paul Haus]

I've been experimenting with boring holes in vessels (including end grain) in the lathe using both HSS and carbide forstner bits. What I've done is turn the outside round using a chuck and live center then set up the steady rest to stabilize the turning. Swap the live center for a drill chuck and set up for drilling. I first bore a starter hole in the the end with the largest bit I plan to use (maybe 1/4" deep). I have a smaller carbide forstner bit set and will start drilling in with something like a 3/4" bit to depth, then switch to a larger one and keep going till I get to the maximum size I plan to drill. Each time I drill maybe 1/4"-1/2" then clear out the chips which also helps keep the bits from overheating. I've drilled holes up to about 6" deep and done it successfully this way.
All my drill bits are sharp so they cut well. About the only thing i can think of is assuming your bit is sharp is you're trying to take too much out at a time. Maybe try coring out the middle first with a smaller bit and see if that helps. Good luck.

[Thomas Canfield]

Thanks for the helpful replies. Lowest speed is 250 rpm. Slower than the lowest speed on my drill press. It was end grain drilling. Lathe did not stall, but I put a lot of force on it and it just didn't bite in. Basically got sawdust instead of shavings. Thomas, I've definitely worked up to larger bits from smaller bits before but not with Forstner bits. What do mean by "facing" with the 2" bit and the 1-1/4" bit -- if they won't bite, won't a just get a very shallow circle with a dimple in the middle?

Yes, you will get a shallow grove with the outside cutter (facing) and center. The center will align the smaller bits to maintain center and they will also make a grove as you progress down to allow centering as you work back up. If you try to use a larger bit without the center, the bit can start slightly off center moving your center for the desired spot as the bit engages and finds its grove. This also works for spade bits that need a center or pilot hole diameter of larger bit to prevent wandering.

[Dan Gaylin]

Okay folks, thanks for all the helpful thoughts. I will try some different bits. I will look into sharpening options.

[Russell Neyman]

What usually causes a Forstener-style bit to “lock up” is the wood expanding due to heat. This is Exacerbated by moisture in the wood.

One solution is to drill the hole just slightly off-center, which causes a gap on one side. This can be done by moving the headstock (if you have one that pivots) or by placing a business card under one side of the tailstock.

Forster bits give a cleaner hole, but spade bits are more efficient. I use a combination of both and make the hole larger in steps.

[Pat Scott]

Dan you asked about carbide forstner bits. The good ones are pricey ($50 or more depending on size. A 1-3/4" is $76) but are well worth it if you drill a lot of holes. I've tried cheap $7 carbide forstners that didn't cut very clean or very well. The Bormax3 by Famag is a good carbide forstner, it's effortless drilling into end grain. I wish they made more sizes. My only complaint is their packaging is kind of cheap, after you open/close the package several times the plastic can tear. Several places sell Bormax3, I get them from CarbideProcessors.com. I tried a Freud carbide bit recently and it was OK, but the Bormax3 did a better job drilling end grain for peppermills.

[Dan Gaylin]

Pat thanks for the Bormax3 recommendation. Much appreciated.

-dan

[Perry Hilbert Jr]

I drill a fair amount of holes with forstner bits. Drilling side grain usually chips up and clears fine. End grain will clog up fast once I get about an inch deep.

[John K Jordan]

I drill a fair amount of holes with forstner bits. Drilling side grain usually chips up and clears fine. End grain will clog up fast once I get about an inch deep.

Have you tried the compressed air method while drilling? Use a nozzle to direct a strong stream of air into the hole behind the bit. I've been using it for years and it keeps the chips clear and prevents binding at least for the bits I use, and as a bonus cools bit. I won't drill deep end-grain holes with Forstners without it.

JKJ

[Dan Gaylin]

Thanks John. No I haven’t tried the compressed air method. That is a good tip. But I am very careful with Fortner bits to constantly back off the cut and clear the chips and shavings.

[Bert McMahan]

This chart recommends about 400 RPM for that size bit:

https://www.google.com/url?sa=t&rct=...Fz0ggEDjDEXQxP

It also has some info on sharpening.

[Kyle Iwamoto]

I use a cheapo spade bit a couple sizes smaller than the Forstner. Spades are cheap, drill fast, easy to sharpen. Yeah they don't go straight and they cut poorly, but they cut fast and I don't have clean out problems. I drill to depth, remember the long pointy part, then follow with the Forstner. Having most of the wood wasted out by the spade, the Forstner now can cut pretty fast, and since there's much less wood being drilled by the Forstner, chip lockup usually is not a problem....

[Pete Staehling]

It never occurred to me to use a spade bit to pre drill the hole in a smaller size. I'll have to try that.

I have done a lot of end grain drilling on the lathe and never had too much trouble other than the fact that it does tend to clog and or heat up if you don't back off and clear it out on deeper boring. Also I second the suggestion that the bits need to be sharp. Oh and it takes quite a lot of pressure to drill end grain. You get a lot more on the drill press than you probably realize.

[Dan Gaylin]

Yeah the spade bit is a good idea. I actually now remember i asked a question like two years ago about using spade bits to save the wear and tear on my Forstners like. The beauty of age -- Kyle's suggestion was "new to me".

[Richard Coers]

I regularly use a forstner bit to drill in 4 -6 inches to set the depth of bowls I do and have never had an issue.....

What I was trying to say is if you drill in 2" without clearing the chips, you can easily bind up the bit. I've drilled deeper than 4-6 with an extension, but you must clear the chips very often.