Using a Forstner bit to drill aluminum plate

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Forum topic by MT_Stringer posted 07-30-2012 03:36 AM 5752 views 0 times favorited 11 replies Add to Favorites Watch
View MT_Stringer's profile


3183 posts in 3468 days

07-30-2012 03:36 AM

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.

-- Handcrafted by Mike Henderson - Channelview, Texas

11 replies so far

View Loren's profile


10477 posts in 3885 days

#1 posted 07-30-2012 06:14 AM

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.

View harvey4804's profile


120 posts in 2919 days

#2 posted 07-30-2012 06:59 AM

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!

-- Ryan, FRMR HMM165 - HMX1 01-10

View tyskkvinna's profile


1310 posts in 3223 days

#3 posted 07-30-2012 01:16 PM

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

-- Lis - Michigan - -

View Alexandre's profile


1417 posts in 2428 days

#4 posted 07-30-2012 01:24 PM

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

-- My terrible signature...

View NiteWalker's profile


2738 posts in 2814 days

#5 posted 07-30-2012 06:03 PM

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.

-- He who dies with the most tools... dies with the emptiest wallet.

View MT_Stringer's profile


3183 posts in 3468 days

#6 posted 07-30-2012 06:16 PM

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.

-- Handcrafted by Mike Henderson - Channelview, Texas

View Alexandre's profile


1417 posts in 2428 days

#7 posted 07-30-2012 07:18 PM

Ohhhhh… I see….

-- My terrible signature...

View DIYaholic's profile


19741 posts in 2912 days

#8 posted 07-30-2012 08:35 PM

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.

-- Randy-- I may not be good...but I am slow! If good things come to those who wait.... Why is procrastination a bad thing?

View tyskkvinna's profile


1310 posts in 3223 days

#9 posted 07-30-2012 09:22 PM

WD40 is great with aluminum!

-- Lis - Michigan - -

View bondogaposis's profile


5151 posts in 2588 days

#10 posted 07-30-2012 10:05 PM

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.

-- Bondo Gaposis

View oldnovice's profile


7380 posts in 3605 days

#11 posted 07-30-2012 11:32 PM

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.

-- "I never met a board I didn't like!"

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