#2 in Knockout punches
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Reddit mentions of Greenlee 730BB-3/4 Knockout Punch Unit
Sentiment score: 1
Reddit mentions: 3
We found 3 Reddit mentions of Greenlee 730BB-3/4 Knockout Punch Unit. Here are the top ones.
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Round standard metal punch units are complete units consist of punch, die and draw studUse with battery-powered, hydraulic, ratchet or manual driversProperly assembled through pilot holes, they will make clean, fast and accurate holesSlug falls free in dieCan be used on mild steel up to 14 gauge.The size referenced on the product is referring to the size of the conduit, not the size of the product itself
Specs:
| Height | 12 Inches |
| Length | 10 Inches |
| Number of items | 1 |
| Size | 3/4 in |
| Weight | 0.3 Pounds |
| Width | 10 Inches |
Clearance below the NMO is about 3/8 inch (~10mm). You really only need a bit more than the clearance of the coax in the bushing assembly as shown here.
I just drilled a couple of NMO's on my (aluminium body) F-150 last weekend and I use a wrench tightened metal hole punch like this one: https://www.amazon.com/Greenlee-730BB-3-Standard-Knockout-4-Inch/dp/B001UL13M2
It produces a clean burr-free cut.
http://www.amazon.ca/Greenlee-730BB-3-Standard-Knockout-4-Inch/dp/B001UL13M2
This is what you want. Ask on your local homebrew club's forum if someone has one, because these are expensive and only used a few times. You can also go to a metal shop in an industrial park and ask them to do it for you. They won't charge a lot and they will clean it up nice for you.
What you are looking for is a radio punch instead of a conduit punch. This will work:
http://www.amazon.com/Greenlee-730BB-3-Standard-Knockout-4-Inch/dp/B001UL13M2