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Using a Forstner bit to drill aluminum plate

8K views 11 replies 9 participants last post by  oldnovice 
#1 · (Edited by Moderator)
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.
 
#7 · (Edited by Moderator)
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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#9 ·
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.
 
#12 ·
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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