Stainless steel

[Gregor 4,846]

I have some small stainless steel straps I need to drill. I need a 9/64" hole, but I fear I am going to burn up every drill bit I have trying to drill these things. Is there a secret to drilling stainless that I need to know about? 

Thanks  Greg

[ebinmaine 67,592]

Trina and I were just talking about this to our fabricator friend the other day. Let me find out what I can and I'll get back to you...

[Pullstart 62,905]

QUALITY drill bits, hefty amount of drill oil.  Medium speed, medium pressure.  I like to think that will come naturally, but stainless has a strength to it as to where you think everything is great, then WHAM! you have no bit left.

[Achto 27,601]

Never really had an issue drilling stainless. Sharp bit, low RPMs with a lot of pressure, the bit should walk right through.

[ebinmaine 67,592]

Her method:

 

Low speed. 300 to 600 RPM max.

Cutting oil is a MUST.

Low to medium pressure. Take your time.

DO NOT let the bit get overheated.

VERY good quality drill bits specifically designed for hardened metals must be used.

Do not let the drill bit stop in the process because that creates a ridge that can be very difficult to restart.

Also be sure to watch that you are throwing chips and don't stop cutting when the drill gets dull. That will heat both metals pretty quickly.

 

[squonk 41,150]

Colbalt bits. There are different levels of stainless. I had to drill out stainless screws in commercial kitchen equipment all the time. Slow and steady.

 

[peter lena 8,634]

agree with  @Achto  and @ebinmaine  , on the detailing with drilling stainless , done a lot of work with it , drill press is your best bet for  ,  a very sold base , and total control over your work .   316  s/s , pete

[Pullstart 62,905]

19 minutes ago, squonk said:

Colbalt bits. There are different levels of stainless. I had to drill out stainless screws in commercial kitchen equipment all the time. Slow and steady.

 

 

that’s the style of drill that ate my hand a while back.  7/16” eats meaty flesh pretty quickly!

[ri702bill 8,328]

As @squonk said, cobalt bits will work, I have had good success using carbide tipped masonry bits - but - the hole will come out oversized. Unlike drilling mid steel where you usually drill using progressively larger diameter bits, if you do go with the masonry bit route, do it in one pass. cutting with just the edge of a carbide tipped bit in an existing hole will chip it.

Bill

[ri702bill 8,328]

3 minutes ago, Pullstart said:

that’s the style of drill that ate my hand a while back.  7/16” eats meaty flesh pretty quickly!

From their limited run "Man Eater" series, I suppose .....

[Ed Kennell 38,209]

Drilling stainless steel - 5 easy steps - Cobalt drill bits (ttp-hard-drills.com)

[lynnmor 7,307]

Stainless steel comes in many types just like other steels, so the machinability varies. In your case, you said straps so that my be you biggest problem.  Breaking thru thin metal may cause the drill to corkscrew in and causing damage to the strap. 

[Chaz54 57]

44 minutes ago, ri702bill said:

I have had good success using carbide tipped masonry bits

I would avoid using carbide-tipped masonry bits. As others have noted, the cobalt drill bits are recommended over HSS (high speed steel) drill bits.

 

A drill press would also be best but otherwise, clamp the parts to something secure or in a vise. Stainless is not that hard of a material to drill, but using a high drill speed causes the stainless to get hot which in turn causes the stainless to harden. That is why you need oil to help keep both the stainless part and the drill bit from getting hot.

[JoeM 7,874]

Magic tap cutting oil.

 

And the art of stainless drilling is not for everyone only the.......

 

 

You too can be one!

[squonk 41,150]

15 minutes ago, JoeM said:

 

 

 

You too can be one!

Do they teach you how not to drill thru body parts? 

[ri702bill 8,328]

And.. once you have mastered that, try to drill & tap copper busbars. The hole closes up from the localized heat and grabs the drill or tap. Fun times...

[Pullstart 62,905]

14 minutes ago, ri702bill said:

And.. once you have mastered that, try to drill & tap copper busbars. The hole closes up from the localized heat and grabs the drill or tap. Fun times...

Seems like drilling copper and brass, we would grind a negative (dull) angle on the big bits at the die shop?  

[ri702bill 8,328]

I had not tried that, but anything to reduce heat while cutting would be helpful. I recall using a thin viscosity quick evaporating cutting liquid that would actually "chill" the copper - had to reapply it several times while tapping... I do not miss that at all.

Bill

[bds1984 1,435]

5 hours ago, Pullstart said:

 

that’s the style of drill that ate my hand a while back.  7/16” eats meaty flesh pretty quickly!

It could have been worse than a 7/16 bit....

[rjg854 11,378]

8 hours ago, Pullstart said:

that’s the style of drill that ate my hand a while back.  7/16” eats meaty flesh pretty quickly!

So would you give it 5 stars for the quality of the bore 

[squonk 41,150]

15 hours ago, rjg854 said:

So would you give it 5 stars for the quality of the bore 

It probably ran cool until the yelling started! 

[clueless 3,002]

21 hours ago, bds1984 said:

It could have been worse than a 7/16 bit....

"My that's a big one".

Edited April 27, 2022 by clueless