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

Question

Hello,I had this issue last year and with the help of someone from thisnewsgroup, I got 14 1/2"  holes drilled through a 1/2" plate of 316LStainless 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 ofhis 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) shopthat can simply punch the 1/2" holes?  Does anyone have the abiltiy intheir shop to do this?I'm an artist on a tight budget, but, no matter, I need to get itdone.Thank you,James, Port Orchard

Grant Erwin · Accepted Answer

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 c> Hello,

RainLover · Answer

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 Iknow with breaking and shearing machines, the operator has to subtract20% from the mild steel values to work with Stainless...  obviously,if you're calculations are right, your ironworker would still punch itlike butter.  What's the "80" in your calculation?I may be contacting you in the very near future.  :-)Thanks,James.

Bruce Simpson · Answer

And don't forget to clamp the work *GOOD AND PROPER*!!!--you can contact me via

Grant Erwin · Answer

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.GWERa

Carl Ijames · Answer

has some good technical info on punchingrequirements for various materials and hole sizes.--Regards,Carl Ijames

Robin S. · Answer

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

Leigh Knudson · Answer

Drilling them is pretty simple. Keep the spindle speed below about

200 rpm and use a little cutting oil. Should take about an hour to do this task. I Don't think you can get a 1/2" punch through 1/2" 316 without breaking it, the punch. You'd be welcome to try but I'd drill it and be done while you are out trying to find someone willing to risk a couple of punches. We have a a job in house that requires 9/16" holes in 1/4" 316L and we probably won't sharpen the drill but once every 100 holes and this is done manually on a mill due to the big size of the plates. Leigh@MarMachine

Roy J · Answer

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 sta> Oh, the 80 is a rule of thumb I got from the Cleveland Steel Tool web site.

Roy J · Answer

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 cutt> Punching is a good idea, but generally SS isn't _that_ hard to work with,

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

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