Greenlee and other KO hole punches?

[Kyle]

So I think the guy that wrote the guide to building an electric home brewery (very good read) said that one should use a chassis / radio hole punch instead of a conduit one, does anyone recall why this is?

I've checked out various sources for punches, from the low end of:
http://www.harborfreight.com/knockout-punch-kit-91201.html
to more high-grade stuff from Greenlee. The holes I'll be making are 7/8" and 1.25"

On HBT there are people saying the conduit punches work fine on keggles and are rated to mild steel in general up to 10ga. Is there any reason that you can think of not to go with a conduit punch? Mild steel is not the same as stainless, tho IIRC.

[Kyle]

Actually, I think I found his answer:
"Make sure to purchase a chassis (sometimes called radio) punch to make this hole. Conduit punches are also available but the punch size does not actually match the size of the hole it makes as the punch size is actually the NPT (national pipe thread) pipe size - just to make things confusing! When in doubt double check what size hole the punch will actually make before using it! The punch you want is the GreenLee 1-1/4" chassis/radio punch that makes a hole that is 1-1/4" (1.25") in diameter" - p 43 of the e-book.

The conduit ones still seem much more readily available, I wonder if they will work, if i can match the actual hole size.

[JohnQ]

He likes them because they create very clean holes, but they are VERY expensive.
I've used my step bit for all 4 holes so far without using a punch and they've worked like a charm.
Just used LOTS of oil with them to keep them cool.

JQ

[Kyle]

yeah, I've used a step bit on other materials and it was both cheap(er) and effective, so I'm thinking step bit at this point as well.

[JohnQ]

yeah, I've used a step bit on other materials and it was both cheap(er) and effective, so I'm thinking step bit at this point as well.

If you don't have a way of filing the edges clean afterwards, I can bring my dremel like kit to the next meeting and you could do it there.  That's how I got it nice and smooth after the step bit, you might not even need it.

Kal is an engineer, and (as amazing as his system is) they do tend to "engineer".


JQ

[Kyle]

Thanks John, I won't be at the next meeting, but once I have the holes done, I'll see if they need dremel-ing