Punch size opinion

About a year or so ago I was at an electrical supply and noticed the greenlee punch set, made a spontaneous purchase...
Now I find, the punches are conduit sized.. Doh!

SO, the 3/4" punch I have makes a 0.89 hole... Not the 0.750...
That leaves 0.07 clearance around the 9pin base I have for my current project...
When placed exactly over center, you cannot see any airspace, but only the tabs of the base will be
actually supporting the base itself....

The 9pin base mounting holes will have plenty of meat to grab on to...
Do I bite the bullet, and get the 0.75 or just use what I have ?

I think it will be fine BUT want opinions before I make any holes in my chassis...
 
I have had my punches for better than 50 years. The real issue to keeping lots of punches is, do you know how to sharpen them? I use a granite plate and 400 grit silicon carbide paper to give them two sets of figure 8 swirls before each use. Actually now sharper than when new. One oil for the threads before each use and a different cutting oil on the cutting edges EVERY time I use them. Larger punches do have ball bearing plates.

Of course most of my punching these days is with a Nisshinbo Map 500 turret punch. https://www.gindumac.com/product/nisshinbo-map-500_NL-PUN-NIS-2001-00001

So bite the bullet and splurge for a punch that should last several lifetimes.
 
  • Like
Reactions: AudioFanMan
Greenlee chassis punches in route!

Chassis just delivered and wow, they look sweet....

New concern....
I guess I didn't pay enough attention to the sellers spec :headbash:

.125" thick extruded aluminum plate!!!
Beefy for certain...

Anyone ever work with 0.125 plate aluminum ?
Will the greenlee's knock out the holes (3/4 & 1 1/8) with zero issue or will I be wrecking the chassis ?
 
If you are working aluminium a step drill in a drill press is usually better. The Greenlee punch will survive, but you may not. I once used one to punch a 1 inch hole in a 1970's Chevy Suburban bumper. It was .125 steel. I needed the biggest wrench I could find. It worked but took a while and getting the slug out was a PITA. That was a ball bearing punch.
 
Update...
Greenlee responded to my email, said the punches should be fine... i looked up on an online calculator which said .125 aluminum needed less tonnage than the rated guage of mild steel.. (.076 thou if i remember correctly) so i have a scrap sq ft of .125 on its way. Id like to see the finish as compared to a carbide tipped hole saw...
 
Anyone ever work with 0.125 plate aluminum ?
I do it all the time. A-9 aluminum cutting fluid (not to be confused with A-1 steak sauce; A-9 tastes very different) is your friend in need.

I'd get a stepped drill bit. Get one that's either in fractional inch increments or mm increments. I have one by Irwin that I picked up at one of the home improvement warehouses. Another option is to get a hole saw for each hole diameter you need. I bought a 24 mm diameter one for use with Neutrik XLR connectors. It was around $10 at Bezos' Bookstore. Carbide tipped, made in China of course. But it works great - especially with the A-9.

Tom