Drilling 316 L stainless

[ShowMeHHO]

I need some input on drilling some 5/16 holes in some plates. There is not to many places here in this small town to have anything done so I am probably going to end up driling them myself . What bit cuts can cut through it good .....

[EdCaffreyMS]

Either cobalt or carbide drill bits are my choices for drilling this type of material. I also have a drill doctor sharpener in my shop, so I can re-sharpen when things get dull.

Cobalt, and especially solid carbide drill bits are fairly pricey. You can get through stainless steel with High speed steel bits, if the stainless is annealed (softened), if you know whether you have hot or cold rolled stock, that will help you decide. Hot rolled stock is generally sold in annealed form, whereas cold rolled is generally whats known as "half hard", which means there is some hardness in the stock and it will much more difficult to work/drill.

[Q-Hack!]

I just use the el-cheapo bit set I bought at Sam's club. Just make sure you use a slow speed setting on the drill and use a lubricant like WD-40. Slow and steady gets the job done.

[overtaker]

I just drilled a bunch of 5/16 holes yesterday. What worked good for me was to drill a pilot hole first then the larger bit. I also clamped a piece of plexi-glass over the stainless which helped tremendously. I was using a drill press at a lower speed.

[FuzzyTomCat]

I've drilled over 200 plates with a "5/16 hole, 2 places on each plate using the "same" drill bit with out sharpining .......... always using CRC thread cutting oil in a spray can. It's a little smokie but cuts stainless steel like butter and you can drill up to 5-8 plates at a time.

Good Luck all,
Fuzzy

[ShowMeHHO]

I've drilled over 200 plates with a "5/16 hole, 2 places on each plate using the "same" drill bit with out sharpining .......... always using CRC thread cutting oil in a spray can. It's a little smokie but cuts stainless steel like butter and you can drill up to 5-8 plates at a time.

Good Luck all,
Fuzzy

What kind of drill bit did you use ?


Thanks

[computerclinic]

I use a carbide bit...also use a drill press, too...Using the press will prolong the life and sharpness of the bit, and it will make the drilling alot easier as well....

[hydrotinkerer]

I use a cobalt bit, just because that is what I have at work. Cobalt or carbide, both need cutting oil.

[sp1r0]

I would rec slow speed and increase sizes 1 at a time if you have a hand held electric drill. Like someone else said, even with slow speed, add some lubricant like WD-40. A slow speed press drill would be ideal, whilst increasing bit size 1 at a time. Working with SS316 is a pain! Worth it in the end.

[insane4evr]

Placing the plate on a flat hard surface (steel preferred) and with a pin punch, I lightly punch the ss plate so that the starting drill bit will not wander. Hard surface will prevent deforming the plate.

Starting bit I used is 1/16 inch, I don't have a machine shop where they have special pilot hole drill which will not require pin punching. Using drill press or hand drill, specially hand drill, press firmly for the tip to cut but not too hard as you might break the drill. Use slow speed, too fast will burn up the drill tip. Use lubricant (cutting oil, or even cooking oil) and don't let the drill bit run dry.

Do not drill thru in one pass, pull out the drill bit from the work to remove debris from inside the hole even though it is still shallow. This also gives you the opportunity to lubricate the drill tip cutting edge. Once the hole is drilled thru, use the next size higher and do the same procedure. This time, you may drill thru in one pass as the debris will fall thru the pilot hole. But I still pull out since it allows me to apply lubricant at the cutting edge where it is needed.

Slow but sure.