# Using a Forstner bit to drill aluminum plate



## MT_Stringer (Jul 21, 2009)

It may never work again, but using a Forstner bit, I was able to drill a 1/2 inch hole in a Rockler router table insert plate (1/4 inch aluminum).

Previously I had drilled a hole in the insert so I could make adjustments to my Bosch 1617 Router from above the table. Well, it was off a little. Today, I was able to drill another hole just off-center from the first which worked out perfect. First chance I get, I will test the bit. If it doesn't work properly, I will have to replace it. I am just glad to have the access to the router. Previously, I could get my allen wrench into the adjustment socket at an angle but it was a struggle.

I used the slowest speed on my drill press to do the drilling.


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## Loren (May 30, 2008)

I tried to do that last month…. it didn't work well but I'm
sure you used a better quality Forstner bit. Mine are
real cheapies.


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## harvey4804 (Jan 21, 2011)

As a waterjet programmer at a precision welding and machine shop… the sound of this makes me cringe! But at least it worked out for you!


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## tyskkvinna (Mar 23, 2010)

The tool shapes for aluminum are pretty similar to wood. If you took it gentle, it should be just fine.


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## Alexandre (May 26, 2012)

I have twist bits from 1/16 to 3/4…. So I hop I never need to.
Didn't you have a Hole saw?


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## NiteWalker (May 7, 2011)

The key reason he used a forstner, I believe, is that he had to drill another hole off-center to an existing hole. Not many bits besides a forstner will let you do that.


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## MT_Stringer (Jul 21, 2009)

The bit I used was one from the Harbor Freight set. I took it slow and it simply shaved of the aluminum as it wood a piece of wood. A twist bit would have tried to center itself in the original hole. I didn't want that. The forstner bit cuts from the outside of the hole so there was no grabbing, jerking or shuddering.

1/2 inch hole saw? Nope, don't have one.

Here is a pic. You can see part of the original hole which I did a bad job of laying out to center it over the adjustment socket. The new one is drilled in good position and easy to use.


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## Alexandre (May 26, 2012)

Ohhhhh… I see….


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## DIYaholic (Jan 28, 2011)

Many folks over at the cnczone use WW bits in their homemade DIY cnc routers to work aluminium. You need to take very lite cuts and use a lubricant (cutting oil) such as WD40.


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## tyskkvinna (Mar 23, 2010)

WD40 is great with aluminum!


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## bondogaposis (Dec 18, 2011)

I tried drilling brass w/ Forstner bit, it was a very slow process and I don't think I would do it again, perhaps a brad point would be a better choice.


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## oldnovice (Mar 7, 2009)

The problem with twist drills in thin stock (metal) is that the holes are not really round. There must be a relationship between the spacing of the drill bit flutes and the material thickness.

I happen to have an old sheet metal punch that can punch up 1/16" thick aluminum, up to 3/8" diameter …. after that it's the drill press.


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