OT: Knockout sets for Stainless steel

theColonel26

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Feb 2014
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West Michigan
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I have noticed that greenlee knock out sets we use are actually not labeled for use with Stainless Steel and that they actually have a different product for use with stainless steel. Is there a reason for that? do the ones designed for SS last longer or create a cleaner cut?

The regular ones we use only last about 150 (wild guess) holes before they seem worn out and we replace the cutter part because they are putting lips on the holes instead of just cutting though.

Is there a reason to switch to the more expensive ones designed for stainless steel?
 
I think you've answered your own question about the reason, but as for the cost (worth it?) I don't know. Would be interesting to see if it's worthwhile, financially. I do know from experience that drill bits for stainless are treated differently (but abused just the same as regular bits...) and way more expensive. Regular bits don't last at all with stainless.
 
I can say without hesitation that the Greenlee punch and die sets made for stainless are far more durable, although I have no actual metrics to share with you.
 
Ever try to drill stainless steel? It's a lot harder than say the metal of a regular panel. I would bet the expensive set is made with hardened steel or carbide tipped.
 
I hired into a company that had old equipment, but they were in the process of upgrading. They updated a line, that had all new control stations. Stainless Steel. I ran into the same issue. Took a few years... but we finally got some Stainless rated knockouts.

They work great. I try to keep them clean as possible, and use a bunch of cutting oil on both the cutter and the threads.

I would recommend purchasing a set.

The standard set will become dull, and a dull knife, is a dangerous one.
 
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the regular greenlee knockouts will not survive with stainless steel. you might get 2 or 3 holes punched before the stud strips out, breaks, or bends. we went through 2 sets of 1/2" punches and that is what happened to us. ordered the stainless steel ones and no issues.
james
 
The guys I work with all the time have a Milwaukee battery powered punch set - Milwaukee claim it will work with stainless steel - they lie!!!! 2 holes - cracked die.
 
no question Greenlee
they have a set designed for stainless steel been using them for years
if you have a lot to do he Hydraulic will do well
if you are going to use the hand punch's it helps to lube the threads
 
I don't know how big of holes you are making, but for me, anything under a 2" KO, and I'd rather use a carbide hole saw over a KO punch. The layout is simpler, more accurate, and over all the process is a lot faster. The important thing is to let the saw do the work, and use plenty of lube. The best lube I have used for cutting stainless is this one.

Bubba.
 
We are a panel shop so KO sets are everyday tools. I also grew up in a metal stamping plant. 1/2" carbon steel KO have a smaller diamater and a closer tolerance. So they will tend to wear out quicker.

The stainless ones have a larger clearnace. When using them on stainless they work great. If you use them on carbon steel you may have a small burr that will roll up on the edge.
We have hand knockouts, hydraulic and cordless. We use them alot. Its a tool that has a life expectancy and once its hit replace it. If you spend 10 minutes cleaning up a hole that has a burr around the edge you have lost money .
 
Thanks guys

We do mostly 1/2" and 3/4" with some 1-1/4" thrown in.

We also use the Impact wrench to drive the draw stud LOL.

We started using a set of Carbide Hole saws recently I bought while on install trip (I hid it in my trip costs LOL). Boss says our dull greenlee KOs are fine. We only have to spend 5 to 10 minutes on each hole trying to clean the burs off, but hey we are "saving money"
 
I thoughts are for $40 dollars I can have clean holes and not have to spend time cleaning holes. What does it cost when a guy gets cut on a sharp edge because its dull?
 

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