Drill bit question - Woodworking Talk - Woodworkers Forum
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post #1 of 10 Old 05-11-2020, 09:37 PM Thread Starter
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Drill bit question

Iím going to drill 3/4 dog holes (2 sheets clamped together) through 1/2 inch plywood and wondering if a forstner bit or an auger style bit, or would there be no difference?
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post #2 of 10 Old 05-11-2020, 09:48 PM
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A Forstner bit would probably make a cleaner hole.

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post #3 of 10 Old 05-13-2020, 11:30 AM
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Or a plunge router.

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post #4 of 10 Old 05-13-2020, 11:38 PM
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The only thing I used an auger bit for once was to drill holes in a tree stump to fill it with diesel and set afire! A forstner bit will make a much cleaner hole. Just be sure to keep the speed low (no place for the chips and dust to exit) and back up the underside of the wood to prevent splintering or a blowout.
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post #5 of 10 Old 05-14-2020, 07:07 AM Thread Starter
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Quote:
Originally Posted by gmercer_48083 View Post
Or a plunge router.
Yes, if I owned one larger than my 1.5 hp trim router!
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post #6 of 10 Old 05-14-2020, 07:18 AM Thread Starter
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Originally Posted by Splitahair View Post
The only thing I used an auger bit for once was to drill holes in a tree stump to fill it with diesel and set afire! A forstner bit will make a much cleaner hole. Just be sure to keep the speed low (no place for the chips and dust to exit) and back up the underside of the wood to prevent splintering or a blowout.
Ya brings up another controversial point, what is the best sacrificial bench material to use when cutting or drilling?

Iíve watched many YouTube videos and often I see rigid insulation being used. I just wonder about the airborne particles and if wood is actually safer but a little more wearing on the blade.

When cutting with the track saw, I usually place dunnage strips perpendicular to the cit so itís not in constant contact with the blade.
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post #7 of 10 Old 05-14-2020, 07:31 AM
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Auger VS Forstner

Augers have a screw tip point and are self feeding. You don't have any control over the feed rate except to slow down the rotational speed. They have sharp edge cutting tip which gives a clean hole, but upon break through they will leave splinters or tearout.


On the other hand, a Forstner also has a sharp pointed tip and sharp edge cutting blade leaving a clean hole, but will not self feed. The feed rate is determined by the amount of downward pressure applied on the drill. Some Forstners have "sawtooth" edge cutters, others are smooth, no teeth, but either will leave a clean hole.

Other choices are twist drills which don't really work well in wood and may wander and leave lots of tearout on break through. A backer board is best when drtilling wood.

Similarly a spade bit is less likely to wander but will also leave tearout, so a backer board is best here too.

Finally, a brad point bit has a sharp pointed tip and sharp edge cutters leaving a clean hole and is accurate. These drills have spiral flutes like a twist drill which carry the waste up and out of the hole as you drill deeper. A backer board will give the best results, but is not always required.

When drilling holes where no backer can be used, expect some tearout on break through, unfortunately.
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Last edited by woodnthings; 05-14-2020 at 08:01 AM.
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post #8 of 10 Old 05-14-2020, 09:14 AM
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One tip to help if you are going to use a hand drill.
Drill a nice straight 3/4" hole thru a 2x4 and then use that as a guide to keep your dog holes as straight as possible going thru your work bench.
Its very easy to get off at an angle when drilling by hand.
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post #9 of 10 Old 05-14-2020, 10:04 AM Thread Starter
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Originally Posted by GSXRFanIM View Post
One tip to help if you are going to use a hand drill.
Drill a nice straight 3/4" hole thru a 2x4 and then use that as a guide to keep your dog holes as straight as possible going thru your work bench.
Its very easy to get off at an angle when drilling by hand.
I did buy one of those drill guides where you connect your drill to the chuck that slides up and down on the rails and I will be able to set the depth. This should help!
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post #10 of 10 Old 05-15-2020, 01:51 PM
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A lot depends on the hardware you are using to turn the bit.A traditional auger with a lead screw will do a good job in a brace as long as you stop turning it as soon as the lead screw breaks through and then finish the whole by drilling from the other side.A spade bit in a power drill will create a clean hole if the same technique is used.A Forstner bit will leave a clean hole if you use a backing block to restrict the splintering behind the hole.
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