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Forstner Bit Problems! WHY????

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Forum topic by AnthonyD posted 02-20-2013 04:44 PM 1842 views 0 times favorited 12 replies Add to Favorites Watch
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AnthonyD

20 posts in 583 days


02-20-2013 04:44 PM

Topic tags/keywords: question drill-driver lathe turning milling woodburning shaker

So Im making some salt and pepper shakers and grinders. Theyre coming out nice but when I drill out the center with my forstner on the lathe, they smoke and burn the wood pretty badly. No matter how slow I go, it keeps burning up. I cant figure out why. They arent cheap bits. Theyre not the best but they arent bad. Maybe I need to buy better ones? Doesnt anyone know what I can do or at least why this keeps happening??

PS. I am New to LJ and I just have to say that the people on this site are just amazing. Every forum topic I post is mostly about troubles that I run into and everyone is just soooo helpful. Thank you to everyone who gives me thair advise, and those who comment on my projects.

-- AJ DeSantis


12 replies so far

View RussellAP's profile

RussellAP

2950 posts in 938 days


#1 posted 02-20-2013 04:47 PM

Maybe you need a larger pilot hole.

-- A positive attitude will take you much further than positive thinking ever will.

View RussellAP's profile

RussellAP

2950 posts in 938 days


#2 posted 02-20-2013 04:48 PM

What wood are you using? How fast is the lathe turning? Is it turning the right direction?

-- A positive attitude will take you much further than positive thinking ever will.

View Mosquito's profile

Mosquito

4682 posts in 944 days


#3 posted 02-20-2013 04:49 PM

I don’t have any experiences with the lathe aspect, but I’m not sure slower feed rate is the answer (if that’s what you meant by slower). In fact, it’s probably the opposite when using the lathe.

What’s the RPM of the lathe you’re trying to use, and size of forstner bit?
This can be a useful chart for recommended drilling speed (RPM) for various bits for hard or soft wood.
http://www.fnal.gov/pub/takefive/pdfs/Drill_Press_Speed_Chart.pdf

Hope that can help a little.

-- Mos - Twin Cities, MN -- Stanley #45 Evangelist - www.youtube.com/MosquitoMods

View lew's profile

lew

10027 posts in 2407 days


#4 posted 02-20-2013 05:02 PM

Even new Forstner bits will burn in most hard wood, especially the larger diameter bits. Not sure what your lathe slowest speed setting can be but a couple of hundred RPMs is about as fast as you want to go, if possible.
Also, you are probably boring into end grain- which compounds the problem. Extracting the chips often can help some. The only other thing I can think might be happening is that the wooden blank and the bit are not coplanar. That is the center line of the blank and the center line of the bit may be at a slight angle. This would make one side of the bit rub more as it cuts thru the wood..
On the positive side, it’s on the inside and out of site.

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

View Phil53's profile

Phil53

90 posts in 2274 days


#5 posted 02-20-2013 05:05 PM

I still consider myself a beginner but here are some of the things I have run into.
Make sure your bit is sharp and clean. Just because it is new does not mean that it is sharp.
Looks like you a cutting into end grain and that is tuff on any bit.
Also play with you speed a little that will make a diffrence.

Have fun…

View Cosmicsniper's profile

Cosmicsniper

2199 posts in 1810 days


#6 posted 02-20-2013 05:13 PM

I bored out the end grain in regular 2×4s using a 3/4” forstner bit the other day. It took considerable muscle to do that job, but I didn’t get any tear out. This is a tough task with hardwood. You will need very slow speeds and considerable boring pressure with a larger forstner bit in order to limit the burning. I’m not sure how that works on a lathe (explain please), but I’d also considering pre-boring most of the waste with a conventional bit or even a hole saw. You can then take a finish cut with the forstner bit, requiring less boring pressure to make the cut.

I’d consider drilling out the holes on a drill press.

-- jay, www.allaboutastro.com

View RussellAP's profile

RussellAP

2950 posts in 938 days


#7 posted 02-20-2013 05:15 PM

It might profit you in future projects to use a system of stepping up from a 3/8 hole with progressively larger bits until you get the right diameter. Then you can turn the hole to fit the stopper.

-- A positive attitude will take you much further than positive thinking ever will.

View jeff's profile

jeff

646 posts in 2117 days


#8 posted 02-20-2013 05:46 PM

I agree with RussellAP…I recently attended a class on how to make a peppermill at our local Woodcraft store and i used two forstner bits to drill out the hole for the peppermill and my wood choice was mesquite-which is pretty hard wood…

-- Jeff,Tucson,Az.

View Monte Pittman's profile

Monte Pittman

14124 posts in 990 days


#9 posted 02-20-2013 05:55 PM

When I was drilling mine I was drilling into the end grain. I was amazed how fast it dulled my Forster bits. Then it drilled hard slow and burned. That would be my guess.

-- Mother Nature created it, I just assemble it.

View bondogaposis's profile

bondogaposis

2524 posts in 1003 days


#10 posted 02-20-2013 06:00 PM

Slow down the speed and increase the feed rate. Also back out frequently to clear the chips.

-- Bondo Gaposis

View PurpLev's profile

PurpLev

8476 posts in 2300 days


#11 posted 02-20-2013 06:06 PM

step up to your final hole. since you are on the lathe, the alignment is automatically set for you by the machine, so you don’t need to drill the final size hole with the actual bit using the brad in the center to keep it centered.

1. start with a smaller forstner, and use a larger one in each boring operation until you reach your final size.

2. don’t slow the lathe too much or you’ll get poor cut quality and/or a chance for the bit to snag and split the wood. practice makes perfect.

3. don’t feed too slow or you’ll smoke the wood/bit with too much ongoing friction between the 2. feed in, and pull bit out to clear chips – rinse and repeat.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View RogerInColorado's profile

RogerInColorado

293 posts in 606 days


#12 posted 02-21-2013 12:45 AM

When the bit gets hot to the touch, let it cool before you proceed. Big friction generates lots of head, especially in larger bits. Problem is compounded in end grain.

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