Author Topic: Drill Bits for 3/4" Steel  (Read 1043 times)

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Offline Mike H

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Drill Bits for 3/4" Steel
« on: March 11, 2021, 10:26:16 AM »
I have been working on an ASO (Anvil Shaped Object)
Angle Iron with a 3/4" steel plate welded to it
Know that the face should probably be thicker;
but the 3/4" is what I could get a-hold of.
Tried the other day to drill some holes for the corners
of a Hardy Hole layout. The bits I have (Fractional Twist Drill BigBox Store)
were not even making it. Does this suggest the steel used for face is hardened?
Was able to use same bit/s to drill holes in the bottom of the angle iron
for mounting ASO to a base with relatively no problem.

Offline Bill Houghton

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Re: Drill Bits for 3/4" Steel
« Reply #1 on: March 26, 2021, 09:35:26 PM »
Sounds like it.  Or at least high-carbon steel.  You can get drill bits designed to drill tough materials - even my local hardware store has them.

Offline humber2

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Re: Drill Bits for 3/4" Steel
« Reply #2 on: April 05, 2021, 01:11:30 AM »
Choosing and using the optimum drill speed and feed rate with cutting fluid is the way to go.

Offline Plyerman

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Re: Drill Bits for 3/4" Steel
« Reply #3 on: April 05, 2021, 07:01:55 AM »
Choosing and using the optimum drill speed and feed rate with cutting fluid is the way to go.

I agree. It's also much easier if you drill through first with a smaller bit, and then follow up with the size you want the hole to be. 3/16-inch is a good starter hole diameter. (5mm)
My friends call me Bob. My wife calls me a lot worse.

Offline leg17

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Re: Drill Bits for 3/4" Steel
« Reply #4 on: April 05, 2021, 10:15:44 AM »
In most home shop situations, (and a great many professional shops), a good grade of HSS drill bit 3/4 dia would do well at only 250 RPMs.  You need a stable feed, cutting/coolant, and patience.  As noted above, especially in a non-professional situation, taking three steps up to 3/4 could make life easier, say 5/16, 1/2, then 3/4.

Offline Mike H

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Re: Drill Bits for 3/4" Steel
« Reply #5 on: April 11, 2021, 04:41:44 AM »
Sounds like good advice from all. Thanks
Have been informed on follow-up that the
plate is hardened steel.