Drilling SS - Help

Ok, I've tried slow with cutting oil, with new tungsten bits .
I've tried fast, Dremel...nothing works, well maybe I'm half way through after a combined 20 minutes of drilling.

There just has to be some special bit?? All I need is two very small holes for screws to hold my pump.

Help meeeeeeeeee !

1. Is your drill spinning in the right direction
2. I would use a center drill for a small hole, and a step drill for a larger hole. Get someone to hold the kettle and put a little elbow grease into it.

Stainless will work harden under the incorrect conditions. You want lots of pressure and slow speeds when drilling. Sounds like you have already hardened it. Go buy a few drill bits designed for metal. Not all drill bits are for metal. Add a bit of oil drill slowly with as much pressure as possible.

Good advice here...drill at slow speeds with oil to cool it. Cutting oil is not for lubricant, it is for cooling. Make sure you have a drill bit designed for metal and drill slow with decent pressure, don't "reef" on it, but good steady pressure will make it through. If you already have hardened the steel, you may have to use a smaller bit to get through, then swap to larger bit to finish off. Also, you may need to use a punch to get a smaller bit going, even though you already have begun drilling. Good luck!

aeviaanah said:

Stainless will work harden under the incorrect conditions. You want lots of pressure and slow speeds when drilling. Sounds like you have already hardened it. Go buy a few drill bits designed for metal. Not all drill bits are for metal. Add a bit of oil drill slowly with as much pressure as possible.

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I've had best results using cobalt bits, moving slowly through metal that's kept cool enough (either oil, water, or cutting fluid). As mentioned already, going too fast, without lube will cause it to case harden. You'll then need to remove some material in order to get past that hardened area. Or just move to another spot for the pump mounts. If you can get someone to help you, try running water (slowly) over the piece you're drilling in order to keep it cool. Or, get someone to keep adding oil as you drill. I also make pilot holes first (small bit) then step it up to the size needed. You can sometimes use a step bit, but [IME] that's more for larger holes than you probably need. Also, changing the bits gives the piece some time to cool between steps.

Personally, if at all possible, I like to use a drill press for going through stainless whenever possible. I set it to go as slow as possible, use a cobalt bit, keep the pressure what it needs to be, and use lube.

Something you could try, if you're brave and have the tools needed, is to anneal the stainless if it's been hardened. That can be a tricky process, depending on what you have for equipment.

I suspect that I have hardened it. I did not realize that could happen.

The site is on the brewstand. When I drilled and step drilled 4 holes in my kettles, it was a piece of cake.

Thanks for the good advice.

nealperkins said:

I suspect that I have hardened it. I did not realize that could happen.

The site is on the brewstand. When I drilled and step drilled 4 holes in my kettles, it was a piece of cake.

Thanks for the good advice.

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What's the brewstand, 3/16 thick tubing?

To save you a few bucks buy a few self tapping screws to get a hole started. Not the cheap chrome coated ones, but 5/16 head screws used for applying metal roofs. Once you break through the metal, go slow and steady like previously discussed. You will ruin several bits trying to get through the work hardened steel if it is real bad. And the screws are 15-20 cents a piece.
I have used this trick a lot on work hardened steel

My Machinery's Hand Book suggests 50 feet/minute cutting speed at the drill perimeter, which translates to 1528 RPM if you are drilling a 1/8" pilot hole. A 1/4" hole would be 764 RPM. Keep plenty of oil on the drill to keep it as cool as possible. Stainless work hardens very easily, not only from heating it, but from having the drill rub on it without cutting.

ChuckO said:

My Machinery's Hand Book suggests 50 feet/minute cutting speed at the drill perimeter, which translates to 1528 RPM if you are drilling a 1/8" pilot hole. A 1/4" hole would be 764 RPM. Keep plenty of oil on the drill to keep it as cool as possible. Stainless work hardens very easily, not only from heating it, but from having the drill rub on it without cutting.

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50s probably a little high at this point considering that 1. The material is likely work hardened, probably putting it around the same Rockwell C of Hastelloy or Inconel, and 2. Whether he's using a cheap drill bit or a sheet metal screw he's got something that's probably just slightly harder than the workpiece. Not to mention he doesn't have the rigidity of a chuck/vise or a turret/milling head. I've always found the SFM to be a little in the optimistic in the MH.

I would try to spot face the beginning of the hole with a spade drill/center drill or a punch even. And keep low speeds like has been mentioned, around 300-400 rpm probably.

bottlebomber said:

50s probably a little high at this point considering that 1. The material is likely work hardened, probably putting it around the same Rockwell C of Hastelloy or Inconel, and 2. Whether he's using a cheap drill bit or a sheet metal screw he's got something that's probably just slightly harder than the workpiece. Not to mention he doesn't have the rigidity of a chuck/vise or a turret/milling head. I've always found the SFM to be a little in the optimistic in the MH.

I would try to spot face the beginning of the hole with a spade drill/center drill or a punch even. And keep low speeds like has been mentioned, around 300-400 rpm probably.

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I have used a screw many many times in the past and it has never failed, which is much cheaper than a new bit. Lubrication is key when working with stainless.

After one more big effort, I'm going to move the location up and inch and start over properly.
Thanks for all the expertise!