Drilling Stainless Steel Bits

[scratchedup]

McMstr-Carr has Cobalt coated bits with a tip angle of 130 or 135 degrees.

Would these be the best for SS drilling....vs 118 degree?

VS- Norseman Drill 3/8" Heavy Duty 6" Length Super Premium 39410?

THX

 

[jimbbski]

It may be that one is better then the other but what I have always done when drilling SS is to make a small pilot hole first. An 1/8 bit is all that is needed and even something a bit smaller will work.

First their cheaper to replace when they get dull and when you go to use the bigger bit it doesn't have to work as hard and will last longer.

That and using lubricant when drilling.

 

[Ign]

Any quality HSS bit will do it. Peck drill, reduce speed, and lots of lube. Spend your money on a quality cutting oil (Butterfield makes a really viscous one) before uber high-end bits.

No machinist orders mystery cutting tools from McMaster. Enco or MSC.

 

[EdT]

Most stainless steel is hard to drill because the material tends to work harden where the bit is trying to cut, Once that happens you will just melt the end off the bit regardless of how good a bit you bought. IMHO, the main trick to avoid this is to start aggressively and once you are making a chip, keep going. If you back off and stop cutting, it will work harden and you're stuck. Of course, all the suggestions above are good. Sharp bit, good lube etc. is still important, but not stopping is key based on my experience. Pilot hole is a good idea because the center of a larger bit has a hard time moving material because it is not moving very fast.

 

[trentonmakes]

It may be that one is better then the other but what I have always done when drilling SS is to make a small pilot hole first. An 1/8 bit is all that is needed and even something a bit smaller will work.

First their cheaper to replace when they get dull and when you go to use the bigger bit it doesn't have to work as hard and will last longer.

That and using lubricant when drilling.

X2!


Sent from my LG-D801 using Tapatalk

 

[Ign]

Stainless creates a great deal of friction and it builds QUICKLY. If you just keep going you only increase heat exponentially, easily to the point where it boils cutting oils and coolants. You want to peck drill so heat doesn't build too much.

This is one reason peck cycles are standard on all CNC

 

[scratchedup]

I had to drill (6) 3/8 holes in 1/4" 304 SS. This was a learning experience. In the process I broke 2 $$$ Norseman bits...but I did gain a lot of knowledge.

The first hole I drilled I used a pilot hole then came in with a 3/8 bit and it was done but on the other 5 it was a disaster.

Since I had a hardened coated P bit that is slightly smaller then 3/8 I pre-drilled with this. The problem was that it was so close in size to 3/8, that for what ever reason, it was impossible to then drill with a 3/8ths bit...it would not budge....maybe the small amount of material got so hot so quickly that it hardened. ??? Still lack understanding here.

I ended up using using 6 bits incrementally up to 3/8...4 lettered then 2 fractional and even this was tortuous and I broke 2 expensive bits.

Later I had to drill (4) 1/4" holes. I bought a Cobalt, split tip bit. Using a hand power drill and pressing as hard as I could I was successful... stopping every 10- 15 seconds to lube.

Any input on 118 vs 135?

+ where does a machinist buy bits?

It sounds like using expensive coated bits on SS is a waste of money???

 

[383 240z]

It's all about your feed rate and your drill speed. Then a good lube. My machine at work will drill 2500 holes a day in 304. Oil bath lube, HSS drills, properly sharpened and feed at the correct speed, work turning at the correct speed. I swap to a new drill after lunch if the surface finish is off. I generally go about 2500 parts on a single drill. Keith

 

[Ign]

I had to drill (6) 3/8 holes in 1/4" 304 SS. This was a learning experience. In the process I broke 2 $$$ Norseman bits...but I did gain a lot of knowledge.

The first hole I drilled I used a pilot hole then came in with a 3/8 bit and it was done but on the other 5 it was a disaster.

Since I had a hardened coated P bit that is slightly smaller then 3/8 I pre-drilled with this. The problem was that it was so close in size to 3/8, that for what ever reason, it was impossible to then drill with a 3/8ths bit...it would not budge....maybe the small amount of material got so hot so quickly that it hardened. ??? Still lack understanding here.

I ended up using using 6 bits incrementally up to 3/8...4 lettered then 2 fractional and even this was tortuous and I broke 2 expensive bits.

Later I had to drill (4) 1/4" holes. I bought a Cobalt, split tip bit. Using a hand power drill and pressing as hard as I could I was successful... stopping every 10- 15 seconds to lube.

Any input on 118 vs 135?

+ where does a machinist buy bits?

It sounds like using expensive coated bits on SS is a waste of money???

People greatly misunderstand pilot holes. Your pilot hole should be tiny, no larger than the web of your bit at the pointy tip. For a 3/8" hole in 303/304, I most certainly would not do a pilot hole; waste of time and you risk breaking such small bits.

The larger the pilot, the harder it is on the cutting edges of the larger bit.

I buy drill bits from a machinist supply like Enco, MSC or Traver's. Avoid Shars and CDCO for cutting tools (some of their inexpensive insert tooling can be ok for a budget user, not really applicable to sizes like 3/8" though).

No, I have no input on 118 vs 135 as either will do what you want, but if cost is equal get 135 for SS.

If I were doing what you are, I'd center drill or spot drill, then throw in a quality HSS bit (I like PTD, Precision Twist Drill, but Hertel is ok on a budget) at 3/8" and go to town around 350 to 450 rpm. Heavy feed down maybe an 1/8", back out, fresh lube w an acid brush, and repeat.

 

[Edward_Anderson]

I'll weigh in on this, almost all I do at work is cut, drill and weld stainless in varying thicknesses from 14g tubing up to 3"+ plate. Mainly I just use good quality HSS bits, correct feeds and speeds (slow with an aggressive feed). Spot drill, then go at it for holes smaller than 9/16" we use AGS stick wax for almost all our drilling that isn'.t done on a milling machine.

If you're just drilling stainless on a drill press or heaven forbid a hand drill, peck drilling on normal size holes gains you nothing.

 

[scratchedup]

If you're just drilling stainless on a drill press or heaven forbid a hand drill, peck drilling on normal size holes gains you nothing.

Can you elaborate???

 

[pete379]

several results on home shop machinist search page. common theme-- drill slow, keep steady pressure,lots of coolant. some guys say 135 degree is better, mcmaster may not always be the same brand,but it will be good quality. my 2 pennies, ymmv