Tool question

dantheman · May 29, 2016

At work , we frequently have the occasion to mount and run flex into stainless steel junction boxes . Drilling the hole to allow the knockout to be inserted is the problem . We have tried all manner of drill bits , Uni-Bits , etc. and that stainless just gives it hell . Any suggestions ?

buttanic · May 29, 2016

Drilling and machining stainless is tough on tool bits. Cutting oil helps to prolong bit sharpness. Cobalt bits with cutting oil, slow speed and high pressure, a small pilot hole first makes it somewhat easier. Drilling with a hand drill will always be tough because you really can't generate enough pressure. A drill press works best.

dantheman · May 29, 2016

Yeah , all of this is done out in the field . Drill Press isn't an option .

Request Dust Off · May 29, 2016

dantheman said:
At work , we frequently have the occasion to mount and run flex into stainless steel junction boxes . Drilling the hole to allow the knockout to be inserted is the problem . We have tried all manner of drill bits , Uni-Bits , etc. and that stainless just gives it hell . Any suggestions ?

Not following you 100%

Are you calling this a "knockout"
http://www.bing.com/images/search?q...+punch&qpvt=junction+box+hole+punch&FORM=IGRE

What about a hole punch to do the pilot hole? Whitney Roper #5 would be right about $80.
It just depend on access to the side of the JB and SS thickness. If you let me know how thick the SS is I can maybe tell you. As hole size goes up the pressure goes up exponentially. That is why you see shearing on the punches.

A center punch to start the hole and the right lube helps on drilling. Short straight flute drills may help as well. A wax type cutting paste that melts can be beneficial also.

dantheman · May 29, 2016

https://greenlee.ebizcdn.com/cfa258af990f9cb188d36ddb5c6eb650

Something along these lines except ours uses a gear driven mandrel . Knocking out the hole isn't the problem . Drilling through the stainless is the issue .

sgt z · May 29, 2016

Maybe ask the guys who sell or manufacture the box what the best method suggested for drilling boxes. Sometimes they know or sell products to make using their product easier so they can sell more boxes.

buttanic · May 29, 2016

Do you have to drill the hole with the box mounted in place or before mounting it. If you are drilling before mounting a small potable drill press like this might be the answer to drill the pilot hole for the punch.

http://www.sears.com/grizzly-5-spee...M1127853514?prdNo=13&blockNo=13&blockType=G13

dk.easterly · May 29, 2016

Always have to start small and work your way up with stainless.

bsoileau24 · May 29, 2016

I use cobalt drill bits when drilling stainless. They work better than hss bits to me. I have used carbide bits in the past also and found them to be britle and break alot easier than others. Almost every control panel or new panel that we add at work is stainless and now use just cobalt bits to drill the holes for the knock out draw stud.

Sent from my SAMSUNG-SM-G900A using Tapatalk

dantheman · May 29, 2016

bsoileau24 said:
I use cobalt drill bits when drilling stainless. They work better than hss bits to me. I have used carbide bits in the past also and found them to be britle and break alot easier than others. Almost every control panel or new panel that we add at work is stainless and now use just cobalt bits to drill the holes for the knock out draw stud.

Sent from my SAMSUNG-SM-G900A using Tapatalk

That's what I'm looking for . Thanks .

JBP55 · May 29, 2016

Solid Carbide Drill Bits, lubricate, start small and go slow. Also good to sharpen your knives.

Metryshooter · May 29, 2016

Yes use Cobalt preferably, but the Titanium oxide stuff works OK. The trick is to not try to drill a 3/8" hole in one shot. More time consuming on the surface but pop a 1/8, then say 1/4 and then the 3/8. Give the but a path to follow and use oil.

SVTFreak · May 29, 2016

If its sheet metal, you need a knockout punch set. The only efficient way to do it.

dantheman · May 29, 2016

SVTFreak said:
If its sheet metal, you need a knockout punch set. The only efficient way to do it.

I'm using a knockout set specifically for stainless .

JHenley17 · May 29, 2016

I've never had a problem, but I keep the speed pretty low and start with a 1/16" pr 1/8" bit if I can. Don't heat them up too much and you can drill a hell of a lot more holes with a bit. I'll watch guys burn up a bit before they finish their first hole while I can use the same bit for a week.

SVTFreak · May 29, 2016

dantheman said:
I'm using a knockout set specifically for stainless .

I'm sorry I misunderstood your question. Youre having trouble drilling that pilot hole.

The right speed (see a speed chart for stainless and drill size to get the right speed) and cutting fluid should make the job fairly easy. I don't drill stainless often but when I do I follow the chart and use oil and it's not bad.

Metryshooter · May 29, 2016

The most annoying part I've found in the past isn't the drilling, it's having the knocked out slug stick in the cup. Regular steel usually busts in two but the stainless just bends and deforms into the cup. Make sure to have some vise grips and a screwdriver handy.

dantheman · May 30, 2016

Metryshooter said:
The most annoying part I've found in the past isn't the drilling, it's having the knocked out slug stick in the cup. Regular steel usually busts in two but the stainless just bends and deforms into the cup. Make sure to have some vise grips and a screwdriver handy.

Oh yeah . Been there many times .

Suburbazine · May 30, 2016

Doing lots of stainless? That will burn up a lot of bits pretty quickly, especially since the holes are being discarded anyways.

Get yourself a plasma cutter and just plasma punch all your pilot holes. Fast, efficient, maybe initially expensive but way easier than drilling through dozens of bits.

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