Drilling through stainless steel

[Rough Magic]

I use bacon grease for cutting oil. Work great and starts smoking at 400 F to tell you to stop. Also safe to eat.

[sailortype]

after you drill with it..?

[Cheechako]

Go slow rpm, you need to "feel" the bite. When drilling anything it's important that the bit digs in and pulls up the metal, too fast and it burns and smears. Drilling a tiny pilot hole first helps a lot if you are drilling over maybe 3/16. I like to use a "center drill" (tip only) for a pilot hole.

[Rough Magic]

HA! It just smells good.

[Kita]

Also nobody has said anything about alot of stainless ladders & boat parts are anodized and that coating is extremely hard! I have even went so far as to touch it with a grinder or Dremel just to knock the anodized coating off and then proceeded to drill after getting a good center punch or center drill to start the whole otherwise everything everyone has said it is absolutely accurate very slow with coolant and pressure

[Terra Nova]

Originally Posted by Kita

Also nobody has said anything about alot of stainless ladders & boat parts are anodized...

Stainless does not get anodized; aluminum does.

[Kita]

Originally Posted by Terra Nova

Stainless does not get anodized; aluminum does.

Ask around about that,you may be surprised. .they do it for protection & it's not on everything...as a welder I have dealt with it occasionally and was quite surprised myself

[Terra Nova]

Stainless gets passivated and/or electropolished, or just manually polished, not anodized.

[Cheechako]

Originally Posted by Kita

Ask around about that,you may be surprised. .they do it for protection & it's not on everything...as a welder I have dealt with it occasionally and was quite surprised myself

No ss does not get anodized. It may be electropolished though...

[Cadence]

The PO was only asking about SS tubing. A slow pilot hole and then what ever he needs slowly and cutting oil. A center punch would probably be good, try stating a bit without one is damn near impossible..

[Nicholson58]

Originally Posted by Kita

Ask around about that,you may be surprised. .they do it for protection & it's not on everything...as a welder I have dealt with it occasionally and was quite surprised myself

I’m retired chief engineer and machine designer for a custom builder.

SS is NOT anodized. Aluminum is. What we see is called clear anodized. It provides some level of corrosion protection and surface hardness. It is very thin and easily penetrated with ordinary drills. Hard anodizing, also on aluminum, you will not likely see. It is dark grey and not available at most anodizers.

SS is hard to cut, drill mostly because it will bond to tooling at high speeds due to the temperature. It is called built up edge and causes the tool to stop cutting and smear metal around. For the same reasons, thread cutting is made difficult.

There is no fighting this with hand tools. Slow the rpm, add coolant or cutting fluid. Apply firm pressure. Use a pilot hole first.

[Reefmagnet]

Most stainless steel tube has a disadvantage when it comes to drilling that it is already partially work hardened. This is because it is manufactured from slit sheet and cold formed into tube using a series of dies with the seam being fused closed with a high speed welding process that doesn't add enough heat to perform any sort of annealing.

[Rorzech]

You can drill SS all day long with a cobalt bit as long as you keep the RPM low.
It took me a couple of broken and dulled bits to learn. You can tell when your bit is getting hot just by putting your finger on it. Don't be in a rush and give the bit a chance to cool off every few seconds of hard drilling. Your goal is getting nice holes without ruining bits, not how fast you can make a hole. But once you got it, you can drill all you want with no fear ! I never used cutting oil of any kind, and always work my way up in size for holes above 1/8" in size.

[Marksman]

Also, if the drill location has work hardened to a point where you can no longer get a drill to cut, I have had good luck using a propane torch to anneal the area. Let it cool down slow and you can resume drilling. Any discoloration comes off with a wire brush or polishing. This only works if the wall thickness is thin enough.

[HopCar]

How about avoid drilling holes and use clamps like this?