Finish out a hardened stainless hole

[jonnojohnson]

I tried cutting a 1" hole in my brewpot lid with a stepped bit but I got stuck at 3/4" diameter after I worked it too hard.
Any suggestions for how to finish it out?
Can it be worked with a hand file? A dremel?

 

[jmcquesten]

I tried cutting a 1" hole in my brewpot lid with a stepped bit but I got stuck at 3/4" diameter after I worked it too hard.
Any suggestions for how to finish it out?
Can it be worked with a hand file? A dremel?

You can use a dremel, but it will be hard to keep it perfectly round. I found a dremel bit at HD that eats through stainless like nothing. Problem is, it tends to take bites out and can get carried away quickly.

 

[Stealthcruiser]

What do you plan to add in that hole?

 

[SanPancho]

Trycoming back at it from the other direction. Sometimes thatll work. And use cutting oil.

 

[Islandboy85]

Half round bastard cut hand file.

 

[LarMoeCur]

From the picture is looks like the hole raised or rounded down. Your pushing to hard on the step bit. Folding the metal down instead of cutting it away. I would use the step bit and cut from the other side. Using light downward pressure let the bit cut lightly. Use oil to keep it cool if it starts really smoking you're drilling to fast. You should should see little smoking flakes of metal and that about it. The bigger the hole the more material you have to remove. Kettle metal is pretty thin step bit should chew right through it.

 

[NeoBrew]

Coming at it from the other side would be helpful. I would also suggest at this point making sure it is really well supported from the backside would help. I disagree that applying less force is the answer. The more force you can put on it the better the bit will cut. If you have access to a drill press you will get better results. You can apply a lot of straight and consistent downward pressure. It is important to use as slow of RPM as you can manage.

Stepped bits also wear out pretty fast in stainless. If you have work hardened the stainless you may have also dulled the bit. You might try taking a very fine metal file and filing along the flat edge of the cutter. If you can get that leading edge sharp it will help in cutting through the hardened SS and then continuing to cut.

 

[IslandLizard]

+1 to @Neobrew ^

If the drilling doesn't yield a perfectly round hole, or after using a hand file or dremel, make sure to leave a little extra material behind (IOW, keep the hole a little bit smaller). Then true it up with a tapered dowel and some medium or fine sandpaper wrapped around it.

BTW, what is the hole for?

 

[Drumminguy81]

Go to harbor freight and pick up a set of knockout punches. They will do the trick. Quick and easy.

 

[Stealthcruiser]

Go to harbor freight and pick up a set of knockout punches. They will do the trick. Quick and easy.

On an oversized pilot hole?......

 

[flugelizor]

The trick is to break past the work hardened bit.
If you make a few small notches with the Dremel - reinforced fiber disk, the step bit will probably bite in. make sure the bit is always removing material.

I have a feeling the material might be too thick for a Greeley punch.

 

[Droot]

Your bit Is toast.

New bit, go S L O W.

David the welder

 

[dyqik]

On an oversized pilot hole?......

Yes, that should be fine. Just tighten the punch by hand to get it positioned so that it cuts all the way round the holes.

 

[pigroaster]

Take a piece of dowel and cut a slit in it . Install a length if emery cloth in slit and install in drill. Back and forth action will get past the work hardened area. Patience. Good luck. If it was easy every brewer would do it!

 

[Stealthcruiser]

Yes, that should be fine. Just tighten the punch by hand to get it positioned so that it cuts all the way round the holes.

( I would foresee an uglier hole........)

But I reckon it could work.

 

[jonnojohnson]

Thanks for all the suggestions. I filed the edges down for a bit then took another go with the stepped bit at a MUCH slower speed and it finished out nicely.

The hole is for a thermowell stopper. I'm trying out using my kettle as a fermenter.