How to drill a 3/4" hole in metal?

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I need to make (drill?) several 3/4" holes in 1/4" thick aluminum panels.
I have a 3/8" drill, a 1/2" drill bit, a 4" angle grinder, and hand files. It's a tedious job to drill a 1/2" hole and then use a file to enlarge it to 3/4".
Any easy way to do this without getting blisters?
Thanks
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Walter
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3/4" drill with 3/8th shank?
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wrote:

Try a 3/4 inch drill with a 1/2 shank.
http://www.biscotoolsupply.com/home/bis/page_975_62/reduced_shank_drill_bits___shank_fractional_sizes_.html
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Buy a hole saw. They make bits that are large and have a shaft that matches a 3/8 drill motor. Maybe a step bit if you can drill from both sides.

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Aluminum is not difficult to drill through. Use a hole saw or a unibit. Take it slow.
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wrote:

Try a 3/4 inch hole saw.
http://www.ridgid.com/Tools/34-Bi-Metal-Hole-Saw/EN/index.htm
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How many holes?
Aluminum can easily be worked with tools meant for wood
cheap methods follow........
1) Use a 3/4" spade (aka paddle) bit. 2) Use a 3/4" Forstner bit 3) Use step bit but 1/4" is a little thick for a step bit 4) Use a hole saw
don't allow the bits to overheat cheers Bob
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wrote:

'Try a tapered reamer
http://www.icscuttingtools.com/catalog/page_200.pdf
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Walter R. wrote:

hole saw?
nate
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3/4" bi metal hole saw. Should take about a minute or less per hole.
s

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Drill a 3/4" hole.
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All kinds of ways.
For example, many electricians have a "Greenleaf (sp?)" punch.. To use it you drill a 1/4" hole, asemle the male and female parts of the punch with thru bold on the 1/4" hold and tighten the bolt. In about 30 seconds you have your hole.
I have had to make holds for "stuff" in the top of stainless steel sinks. Usually, I just used the biggest drill I had (usually 1/2") and then used and "ball" or "cone" shaped grinding wheel to enlarge the hole.
An Al, you might be able to use a reamer.
Or you can use a saw to roughtly enlarge the hole and then "polish" with a grinder wheel as above.
Except for the punch, the results usualy aren't pretty but you usually cover up the hole so who cares.
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John Gilmer wrote:

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Not for .25 inch thick material.

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Jim Yanik
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I guess we would need to know if the OP is going to cover the holes before we can say "who cares".
I've drilled many holes that do not get covered up, so I usually care what they look like.
One trick I like to use when drilling metal, especially on a drill press, is to clean up the hole with a bit that is a few sizes bigger than my hole. Slight pressure on the press will clean up the rough edges and impart a slight inward bevel. It looks nice, especially with exposed holes.
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http://www.harborfreight.com/cpi/ctaf/displayitem.taf?ItemnumberD460
Works great.....Paul
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Walter R. wrote:

You can get a set of knock out punches from Harborfreight.com for $15.99. It has 1/2, 3/4, 1 and 1 1/4 sizes punches and dies. Up to 10 gauge steel, aluminum, plastic and fiberglass.
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wrote:

Those are nice, but he did say 1/4" aluminum - even a real Greenlee punch might have a hard time with that.
nate
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N8N wrote:

My Greenlee punch set has no problem with 1/4 inch soft aluminum. I'm sure there are some aerospace grades that might break it. Anyway, a 1/2 inch conduit punch cuts a 7/8 inch hole size. (0.885 inches to be precise) Which is why I didn't post it as a suggestion. A mechanical punch for an exact 3/4 inch hole can be obtained but the price may be very high as opposed to that of a standard widely available conduit punch.
TDD
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Go to the drill bit section of your local hardware store. They should have hole saws in that size. Not totally precise sizing, but reasonable. Should cost between eight and fifteen bucks.
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Christopher A. Young
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