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Overloaded
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« on: February 24, 2011, 03:51:15 PM »

Hey All,

  To punch or drill .050" dia holes in .035" thick 260 (half hard) brass ...... that is the question.
There will be many, many to do.
A punch seems best but not sure about the punch dia. to material thickness ratio.
The punch will be quite fragile. Any thoughts on this ?

But to drill, initial speed and feed calcs show 18K + rpm with a .0002 or so chip load.
And the set-up would probably require two spindles.

Anybody got any light to shed ?
I'm torn  Undecided
Thanks,
Russ
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« Reply #1 on: February 25, 2011, 03:45:24 AM »

Russ,

I think getting a punch through is no problem but the material has to be held correctly when the punch is withdrawn, any movement here would risk a breakage. The punch could have a short head and reasonable diameter shank for strength so I would not see that as a problem but holding the material down is another story.

Tweakie.
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« Reply #2 on: February 25, 2011, 09:57:39 AM »

Hi Tweakie, I did a test and verified your thoughts.
I used a hard urethane bushing as a stripper and it punched much better than I had expected.
The fixture will have two punches relatively close together so the shank will be .25" max.
Should be no problem punching, greatly simplifies the job !
Thank you for your advise / input.
Regards,
Russ  Smiley


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