Another Alumunim Drilling Question

[John Weber]

Can aluminum plate (6061) be drilled with a forstner bit? I asked a day or to ago about using a hole saw. If possible I would like to leave about a 1/4" of material, so that means I need to drill a 2" hole 1" deep with a forstner bit - possible or bad idea? Would a router be a better idea, although I don't like the idea of throwing aluminum shavings all over the place.

Thanks - John

[Bob Wingard]

Can aluminum plate (6061) be drilled with a forstner bit? I asked a day or to ago about using a hole saw. If possible I would like to leave about a 1/4" of material, so that means I need to drill a 2" hole 1" deep with a forstner bit - possible or bad idea? Would a router be a better idea, although I don't like the idea of throwing aluminum shavings all over the place.

Thanks - John

My guess is that it will probably work depending, in part on the quality/hardness of the bit. If you try it at all, use regular old kerosene as a cutting fluid .. .. leaves a remarkable finish.

[Don Abele]

John, it would probably do the job without too much dulling of the bit. My concern would be the agreesive teeth catching the aluminum (which catches regular bits very easily). I wouldn't use an expensive forstner, clamp it tight to the table, slow rpm, slow feed rate, and lubricate.

Be well,

Doc

[Mark Singer]

John,
I have used a hole saw and it worked good. It would be best in a drill press and clamping the piece to the table and choosing a slow speed

[Kurt Aebi]

John,

Use th ebimetal hole saw without the pilot drill bit. Set your drill press stop to stop at the depth you require. Get yourself a 3/8" or better yet a 1/2" 2 or 4 flute endmill. Clamp th ealuminum piece in a cross - slide vise. Kick up the RPM's on your drill press and "whittle" out the material inside the hole saw cut to the depth you need. If you do not have a cross-slide vise or if the plate is too big for one, youcan just keep moving the plate around and reclamp it and keep "drilling" flat bottom holes with the endmill until all the hole is at the desired size. Other than using a fly-cutter on a mill, this is the best and safest solution I can come up with.

You may be better off letting a machinist friend do this on a mill with proper tooling. A 2" Hole with a forstner bit is going to probably require more HP than your drill press has or require much more capabilities than a forstnre bit will handle.

[Chris Padilla]

I agree with Kurt. The endmill will cut up the Al like butter and leave a beautiful finish. I would not use ANY woodworking tools on any metal if I could help it.

If you do, heed the others advice, clamp the piece exceedingly well, drill slowly, and use some kind of lubrication or cutting fluid. Al is quite soft.