Drilling Stainless Steel

[Tom_F]

Mods, if this belongs elsewhere please move it for me.

I have had a few projects that have languished for a long time as they involved drilling stainless steel. Until yesterday every effort I have made to drill stainless has failed - bits dulled before they even scratched the surface, broken bits, etc. I found these and have finally managed to drill a hole (until I dropped the bit overboard, but that was on me). NFI, but if any of you are struggling then consider these. They are expensive, but worth it in my opinion.

https://www.mcmaster.com/product/8882A641

[MicHughV]

I got one word for you...."cobalt"

Not the plated one's, but all cobalt....they are pricey for sure, but will do the job.

[Mal Reynolds]

135 degree cobalt bits. Have plenty on hand. Go super slow, push hard, cutting oil. You want a curly thread coming off the bit. As soon as the bit spins without cutting, the SS hardens even more and you will likely need a new bit.

Tradesmen keep separate bit sets for metal vs. general purpose cheap sets.

[Cheechako]

Originally Posted by Tom_F

Mods, if this belongs elsewhere please move it for me.

I have had a few projects that have languished for a long time as they involved drilling stainless steel. Until yesterday every effort I have made to drill stainless has failed - bits dulled before they even scratched the surface, broken bits, etc. I found these and have finally managed to drill a hole (until I dropped the bit overboard, but that was on me). NFI, but if any of you are struggling then consider these. They are expensive, but worth it in my opinion.

https://www.mcmaster.com/product/8882A641

Use a small drill press, do not try to hand drill unless absolutely necessary and small size drilling. If drilling much you can get a little drill press for ~ under $50
It's all about pressure, feed and rpm. Cobalt is great for sure, but not a 'must have' with a DP in normal SS.

[s/v Jedi]

Search for M42 drill bits.

Like others said: slow rpm but high pressure and cutting oil.

[skipperpete]

“Trefolex” drilling and tapping compound …. slow drill speed.

[coopec43]

Originally Posted by Tom_F

Mods, if this belongs elsewhere please move it for me.

I have had a few projects that have languished for a long time as they involved drilling stainless steel. Until yesterday every effort I have made to drill stainless has failed - bits dulled before they even scratched the surface, broken bits, etc. I found these and have finally managed to drill a hole (until I dropped the bit overboard, but that was on me). NFI, but if any of you are struggling then consider these. They are expensive, but worth it in my opinion.

https://www.mcmaster.com/product/8882A641

Maybe you should have a look at this recent thread?

https://www.cruisersforum.com/forums...ml#post3897561


HSS drill bits are designed for drilling Stainless Steel.

High-Speed steel drill bits – This type of bits are specifically designed for drilling stainless steel. The best HSS drill bits to use for this application are those with a Titanium Nitride tip to help reduce friction and heat.


How to Drill Stainless Steel

https://www.thyssenkrupp-materials.co.uk/technical-knowledge-hub/how-to-drill-stainless-steel

[ejs]

I use a cole drill like the one pictured. You can crank in lots of pressure and since it turns by hand, the bit turns slowly. Works very well. I've done a 19mm, hole with it.

[s/v Jedi]

They once designed cork life vests that would save your life. Today we have better options.

It is the same with drill bits. If you can afford to buy better (M42) ones, they will make it easier and if you use them often, they will easily earn the extra investment back because of a much longer lifespan.

But beware you get genuine M42 bits. These from Bosch are good: https://www.boschtools.com/us/en/cob...-43598-ocs-ac/

[coopec43]

How to drill stainless steel

First of all you should read our 6 step guide to drilling through metal which will explain the basics of drilling metals.
A split point cobalt drill bit is the best choice when using a hand drill.
The split point prevents the drill bit from ‘walking’ or sliding.


Beware of too much heat

Probably the biggest problem which can occur when drilling stainless is for it to ‘work harden’. This happens when excessive friction causes too much heat build up. The result is that the metal actually becomes harder than it was in the first place. It is crucial that you avoid this happening.


You can avoid work hardening by

• 1. Drilling at a slow to moderate speed so as to avoid excessive friction.
• 2. Using plenty of drilling lubricant.
• 3. Applying moderate pressure – above all do not apply too much pressure.
• 4. Rest periods – allow the drill bit to cool down between drilling sessions.
• 5. If drilling a large hole then first of all start with a smaller diameter hole first and then work up gradually to desired size

https://www.ttp-hard-drills.net/dril...ainless-steel/

[hpeer]

I has a bunch of 1/4" holes to drill in place, and awkward position.

I called McMaster-Carr (or Grainger?) for advice and the service lady put me straight through to a "drill bit expert." Best thing I ever did.

I forget the exact bit, but that is not the point. Good free professional advice was available.

[rslifkin]

As others have said, start with good bits. From there, the key is to keep lots of pressure on the bit, keep the RPM down, and keep it cool and lubricated. Basically the goal is to make sure the bit keeps cutting rather than work hardening the metal under it.

[mcon12000]

I’m not sure what your overall project is or if it’s portable but I have a great deal of experience drilling stainless. I would either take the pieces to a fabrication shop that has a drill press or rent/buy a drill press. Doing it with a hand held drill is painful for me to even think about.

Now don’t go to Harbor Freight and buy the cheapest press they have it won’t solve your problem. You need decent press with very low rpm capabilities and high quantity bits.

If you’re doing chain plates you’ll need anular bits which will go through plate like butter but require a different chuck.

I have a 1hp Grizzly Tools press that has worked well for stainless. The press and quality bits is around $800-$1k and it’s too big to keep onboard permanently which is why I recommend you just take everything to someone with the proper equipment, knowledge and skills.

[singlespeed]

This is not a place to economize. Buy a cobalt set and use it only to drill into stainless steel, unless you want flecks of rust appearing around the hole/s you drilled.

[Nicholson58]

Originally Posted by skipperpete

“Trefolex” drilling and tapping compound …. slow drill speed.

Slow speed, high pressure, good cutting fluid, cobalt or titanium bits