Drilling Stainless

[Sterling]

I am making ladder racks out of stainless box tubing and plate for a friend's new truck. Any tips on drilling mounting holes in the 1/8" thick stainless plate to bolt to his existing tool boxes? I also have to drill holes in the uprights so it can be removed. This is my first project with stainless,I think I will be able to weld it together.

[joebass]

I would not build it out of stainless. If this is your first project with SS chances are it will twist like a snake because of heat. What process are you using?

To answer your question, get some good cobalt drill bits. I like Precision Twist Drill. If you can drill them in a press it will be easier. If it has to be by hand I like to use the shorter screw machine length. Use alot of pressure, some coolant, and a slow feed. if you stop making chips you are work hardening it.

[dyn88]

medium speed high pressure and use lube. Push as hard as you can while still maintaining control of the tool. use a drill bit thats just long enough to drill through what you need.

[Sundown]

1/8" hole first then gradually make it bigger until you get the size you need. Drill press is the was to go for sure if you can, SS is pricey for use as a ladder rack but it sue would look nice I guess .. I prefer MS and just paint it satin black, I did mine about 4 years ago now and havn't had to repaint it yet.

[Sterling]

Thnaks for the replies. I have cobalt bits and a drill press, I will try them. I have a Lincoln Presision Tig 185 that I was going to use to tig weld it. The pockets that weld to the 1/8" plate are 1" box 1/8" , the rest of the frame is 3/4" box, 1/16" . I normally would not make it out of stainless, but this is what was given to me to build it out of. There is a scrap dealer about 20 mi. from my house that sells metal by the pound, that is where it came from. I got a piece of 1/8" x 8" mild steel plate 4' long for $6.00 last weekend. I got enough stainless to build probably 3 racks. Thanks again.

[Fishy Jim]

That's cheap steel!

I just got another chunk of 1/4" plate that was 11x32" and it cost me 12 bucks as drop.

[aametalmaster]

Stainless isn't as hard to work with as people make it. I drilled thousands of holes when i worked in the tin shop, both by hand and with a drill press. Alot of it was 1/2" thick in all grades of SS. Just use a sharp bit and some coolant and you will be fine, don't push so hard you melt the bit just let it cut...Bob

[Sterling]

That sounds good, but my problem is sharp bits. It seems everyone who drills holes in my shop grabs my good cobalt drills first.If they don't break them,they burn them. My dad and brother are the worst.I guess I will start sharpening.

[Engloid]

Notice that people mentioned COOLANT, not oil. That's not to say that oil (cutting fluid) is bad, but the most important factor is keeping it cool, not lubrication. I have even drilled things submerged in water before. Of course you don't want your drill in the water, but if the part is submersed in water, you will find the best drilling conditions you have ever seen. The bit and the part will stay cool.

Tell your brother and dad that turning speed does NOT equal cutting speed. By drilling stainless with a fast turning speed, you will only heat it up, which makes it harder to drill and dulls the bit. ...or make them buy you some new drill bits once in a while.

[martymar333]

great advice from Engloig, keep the bit cool, ......i am currently messing with a design on a submerged drilling fixture for one of our mills at work, i'll let ya'll know how it turns out.


marty

[martymar333]

Engloid even....lol

[precisionworks]

The answer depends on the alloy.

The more common alloys are the 200-300 series. 304, 306, 314, etc. Sharpen to a point angle of 135-140*, and run the drill at 20 - 40 SFM.

The less common alloys (that you'll find at most metal dealers) are the 400 series, as well as the PH series. 440 & 17-4PH are in this class. Sharpen to 118* point angle & run at 30 - 60 SFM.

If you ease up on the pressure, even for just a second, the material will become harder than ****. Slower speed, sharp drills, steady pressure, a squirt bottle of water and you'll be done quickly.

[MACH4]

Notice that people mentioned COOLANT, not oil. That's not to say that oil (cutting fluid) is bad, but the most important factor is keeping it cool, not lubrication. I have even drilled things submerged in water before. Of course you don't want your drill in the water, but if the part is submersed in water, you will find the best drilling conditions you have ever seen. The bit and the part will stay cool.

Tell your brother and dad that turning speed does NOT equal cutting speed. By drilling stainless with a fast turning speed, you will only heat it up, which makes it harder to drill and dulls the bit. ...or make them buy you some new drill bits once in a while.

As far as cooling the bit goes,I had a "seasoned hand" at ADM tell me he always used Dawn dish soap and vinegar when drilling/sawing SS. He never gave me a factual reasoning why this worked,but I stll use his "formula" even today. Hope this helps.
Good luck!
Mike
MACH4

[millermania]

Soap provides lubricity, but it is a base and can react with metals. By throwing in a bit of vinegar (an acid), you neutralize the soap so that it isn't going to react with the metal (and the drill bit), but still provides lubrication. You need to get the mixture right though. Too much vinegar makes the solution acidic, and too little leaves the solution basic. Both are reactive.

[stseely]

I have the best luck with the drill bits if I turn them slow. In my shop the only drills I try to make available to people is my 1/2" MAC air drill it only turns at 600 RPM and works great for drilling and reaming.