Looks like punched hole?

I have a chassis that I can't get my punch into and would like to get best
looking hole I can by drilling.
To the best of my knowledge I would resort to using a unibit (or step drill)
but is there anything out there I may be missing?
Any new bit that will give an almost punched look to aluminum? need 3/16"
holes.
The step drill isn't bad but not good enough.
I'm dreaming out loud no doubt.
Reply to
Michael
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Well, I mill all my larger holes on a CNC milling machine, using a 4-flute end mill. The ID of the holes look like glass. Of course, if you don't have a CNC mill, that't a pretty expensive way to drill one hole.
Actually, if you have a decent drill press, you could try a 3/16" 4-flute end mill of the center-cutting variety. If the machine is stiff and the work well clamped, the hole will be very smooth and round. Don't even think about trying this with a hand-held electric drill, though!
Jon
Reply to
Jon Elson
Brad-point drills will drill aluminum and their point geometry lends to sheet metal. They're usually pretty cheap.
Regards,
Robin
Reply to
Robin S.
I'll be darn, it payed to ask.
I have plenty of brad points so I'll try those but Jon, I was wondering if you could do me a favor.
At their site....
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If you type in "4 flute", it gives a full page of mill bits and as I'm not familiar with these and have never used them, which one's would you recommend I try? I'll go ahead and order some today.
I didn't see anything that referenced to "center cutting".
Sounds like fun to try these out....I do have a nice shopsmith drill with vari-speed. (the lower rpm the better to start?)
THANKS guys.
Reply to
Michael
Drill and ream to final ID
Reply to
daniel peterman
A regular spiral router bit will do just fine in aluminum. If you have a plung router even better but you can use them in a drill
Reply to
daniel peterman
They probably all are center-cutting. As long as they don't have a hole for a lathe center in the middle of the end, then they are center cutting.
You can also get two flute, which will work just as well. Anyway, the first group "square end" are what you want. Don't get any fancy coatings, solid carbide or any of that for this use. You just want the most basic version. But, that usually comes with a 3/8" shank, so you can't run those in a router. Which is good, because you can't hold a router steady enough with these. A good, solid drill press, and solidly clamped workpieces will do.
Jon
Reply to
Jon Elson
Thanks Jon...I'll order a variety from Mcarr. (love that place...have everything and in Indiana you see it in one day).
I tried the brad point this morning and that was pretty impressive also...I deburred the outgoing side with my step drill but the incoming side was a perfect circle.
Here I thought I was stupid to ask in the first place.
Live and learn.
Reply to
Michael

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