FWIW.. Stainless is a b****r to work with as it work hardens when you machine/drill it, just make sure you have spare drills to hand, get your surface speed correct for size / drilling & have plenty of cutting fluid. it looks like your planning on drilling through approx 45mm blocks if you stack plates together, that's some thickness to go at, I would have smaller stacks, & then you would have to really plough your drill through, better if you can use carbide drills, I'm sure other forum members will have better advice on how to drill Stainless, I only use it on little items if need be otherwise I would prefer to use silver steel.

George

I cant see you drilling through a stack of 50, the key to stainless is to keep steady constant pressure all the way through. The slightest let up forms a hard layer in the stainless even on the easily drilled 304, 316, 430 etc. However you  clamp them up there will always be a miniscule gap between each one which will cause a bit of rubbing/hardening and it will become harder the deeper you go quickly dulling the drill. Drilling pilot holes is also a bad idea for the same reason. I've drilled 10mm holes in 316 and 430 sheet using HSS in one with no problem. May take a a lot longer but I'd be doing them one at a time, if you've got some scrap pieces try it and see.

Edited By Mick Berrisford on 06/11/2014 23:51:50

Would you alter the angle on the point of the drill especially if you drill them one at a time ?

Would also recommend sandwiching the plates as a 10mm drill will roll burrs if not razer sharp. It will not be sharp for long either if you run the drill speed too fast. If they burr you will spend even more time removing them….

Packing them 50 deep will work but you will need to keep the drill point cool, downside is the pilot drills will almost certainly wander as it will keep hitting 51 skins of plate, the bottom plate could be a long way out of position as the larger drills will follow the original hole.

If drilling on a mill I would recommend drilling 3/8" (9.5mm) and sizing with a 10mm end mill, if sharp, it will leave a size hole and the edges will be razer sharp and burr free, it will also align any errors caused from drill wander.

Trevor

These are 5mm stainless, the angle is 3mm. Over 150 holes, mostly 6ba clearance with some at 10mm. The larger drill sizes have been sharpened the 4 facet method. They didn't struggle at all. I used a single 6ba clearance drill for the whole job, nothing special but new, from RGD I believe

The trick was using Rocol RTD. All done in one afternoon

Pete

Edited By Doubletop on 07/12/2014 09:37:04