best way to get 1/2" holes through 1/2" Stainless Steel Plate?

Hello,
I had this issue last year and with the help of someone from this newsgroup, I got 14 1/2" holes drilled through a 1/2" plate of 316L
Stainless Steel. (the plate is around 28" x 10")
Now I have a new sculpture and need it done again.
The problem? We ended up going through 5 of my drill bits and 2 of his just to get all the holes I needed!!!
Can anyone make any suggestions as to the best way to do this?
Does anyone know of a Local (Seattle / Tacoma / Bremerton area) shop that can simply punch the 1/2" holes? Does anyone have the abiltiy in their shop to do this?
I'm an artist on a tight budget, but, no matter, I need to get it done.
Thank you, James, Port Orchard
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I don't know why these couldn't be done with an ironworker. It looks to me like you'd need about 30 tons of pressure (0.5*0.5*80*1.5 tons) which is a mild requirement for most modern ironworkers. I have a 35 ton ironworker but I don't know if I can punch to the center of a 10" plate. What is the largest dimension from the hole center to nearest plate edge?
I live in Kirkland, up across the lake from Seattle.
To contact me privately, see http://www.tinyisland.com/email.html
Grant Erwin
RainLover wrote:

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Hi Grant,
While my plate is 10" x 28" or so, all of the holes will be about 1.5" from the edge. I'm not sure about the formulas for punching, but I know with breaking and shearing machines, the operator has to subtract 20% from the mild steel values to work with Stainless... obviously, if you're calculations are right, your ironworker would still punch it like butter. What's the "80" in your calculation?
I may be contacting you in the very near future. :-)
Thanks, James.
www.jameskelseystudios.com
On Thu, 27 Nov 2003 12:15:14 -0800, Grant Erwin

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Oh, the 80 is a rule of thumb I got from the Cleveland Steel Tool web site. The 1.50 is a fudge factor for going from mild steel to stainless.
GWE
RainLover wrote:

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The 80 is 80 tons per inch of diameter which is 25 tons per linear inch (25 x pi = 80) 25 tons per inch per inch of thickness is a shear strength of 50,000 psi. And the 1.5 is to compensate for the expected shear strength of the stainless.
BTW: if you do a lot of stainless punching, you need to add a bit of clearance to the punch or else your punch loads will go up dramatically.
Grant Erwin wrote:

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www.roperwhitney.com has some good technical info on punching requirements for various materials and hole sizes.
-- Regards, Carl Ijames snipped-for-privacy@verizon.net
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Punching is a good idea, but generally SS isn't _that_ hard to work with, given the right tools.
Do you have a drill press? An 8" unit probably will have trouble, but something like a 13"+ shouldn't have too much trouble. Buy some high cobalt HSS drills (normally referred to as "cobalt drills").
You'll want to predrill, roughly 15-30% (.075-.150") and then go to your 1/2" drill. Use cutting fluid. Easy on the RPM. Roughly 300 RPM for the 1/2" drill. Slower if you can (to prolong tool life). Press hard. I'm not sure if 316 work hardens, but if your drill stops cutting (you let off on the pressure) and the material is capable, it will work harden - then there's a problem.
And if you do it yourself, you'll be able to.... Do it yourself! the next time.
Regards,
Robin

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He said press hard. As in both hands on the drill press handle. Don't even think of trying it with a portable drill, you can't keep the heavy CONTINUOUS pressure on it to.
A floor mount drill press from Harbor Freight should be less than $200. Buy a handful of 1/2" cobalt drills from MSC, a can of cutting fluid and you should be good to go.
Robin S. wrote:

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wrote:

And don't forget to clamp the work *GOOD AND PROPER*!!!
-- you can contact me via http://aardvark.co.nz/contact /
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