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Greenlee/Instrument Knock out punches

A

AllanC

Active Member
I hate borrowing other people's tools, although I will loan mine to people I know and trust to return them as soon as they're finished! But, I need to cut 4 holes in a sub panel - 3-1/8" and 2-1/4" diameter, and checked out suppliers of greenlee punches. Boy, was I sticker shocked. For 2 of the punches, over $500 ????

I don't like hole saws, unless someone can recommend a source for a really good unit, but I may have to borrow a couple of the greenlee punches again.....any other solutions out there??

Allan
 
For holes on nice flat stock, nothing much cheaper than a fly cutter. If the sub is already mounted, a hole saw is pretty much it. On the hole saws, I use the el cheapos because I only need them once or twice and they cut aluminum like butter.
 
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Wag-Aero sells one for $123. They work pretty well. The last panel I made it seemed like a fly-cutter made slightly nicer circles. The punch sometimes distorted the metal a bit.
 
I have an instrument hole punch from Aircraft Tool Supply that produces nice clean holes, both 2 1/4" & 3 1/8".
It is not as nice as a Greenlee but works very well. There current catalog list it for $129.95.
 
If panel is mounted

Believe it or not you can actually use a flycutter in a battery dril if you go slow.

I have done it twice on a painted panel even.

Frank
 
Check out e-bay

Just a few weeks ago I bought a Greenlee 2.25 hole punch on e-bay - $50. Did a great job on my firewall (cabin heat vent). I don't think I will have much more use for it very soon and may post it on the clasifieds soon.
 
Thanks guys,

I knew that you would come through with some great solutions. However, flycutters scare me to death, especially on small pieces of panel material, so I'll try an el cheapo punch.....I'll also need the templet for the instrument corner holes as well.

Allan
 
AllanC said:
For 2 of the punches, over $500 ????

I don't like hole saws, unless someone can recommend a source for a really good unit, but I may have to borrow a couple of the greenlee punches again.....any other solutions out there??

Allan
Click to expand...


You may be able to rent them from a tool store. If there is a machine shop close by they may have something called a rotopunch that is like a paper hole punch for metal, it rotates (roto) and has 40 or so different hole sizes it can punch. They don't have a lot of throat but if the reach is enough for your four holes will take about 30 seconds to punch them all. Electrical contractors often have Greenlee punches and you might be able to talk one of them into punching the holes for you, but be careful (even if you are buying new). There are conduit sizes and then hole sizes. Make sure you are completely clear on what size finished hole the punch produces. You might check McMaster-Carr for prices. They usually are about as inexpensive as you can find, but Greenlee punches are still expensive. Get the bearing that goes with the punch if you do purchase one. It's important when you get up to larger sized punches.

Like someone else said, if you are careful and take your time a fly-cutter is about as cheap as you can get...

Good luck,
Dave
 
<<instrument hole punch from Aircraft Tool Supply that produces nice clean holes, both 2 1/4" & 3 1/8".....$129.95>>

Used the 2-1/4 side of the above a few weeks ago without removing the panel from the airplane. Worked fine, no distortion.
 
Thanks again guys, I just ordered a 2 sided greenlee type hole punch from Chief Aircraft for $139, as when I punched up the Aircraft Tools page I was redirected immediately to another advertising page. (is that kidnapping or hijacking?)

I didn't know these could be bought to do 2 sizes with one reversible die, so I'm fine now. And I bought the instrument screw hole thingymajig...

Allan
 
After years of using fly cutters and assorted implements of destruction, I finally bought the two-sided punch from Avery last week and enjoyed cutting the holes in Louise's new panel in about 20 minutes of quiet, angst-free work. Heck, I spend more than that on Avgas in a typical weekend!

Paul
 
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