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Lavcat 8th March 2013 12:05 AM

Greenlee punch question
 
I haven't used Greenlee 730 series punches in a long time. My remembrance is that I used a pilot hole the diameter of the draw stud (bolt). I know now that there probably should be some allowance. However in looking at the Greenlee datasheet, the minimum pilot hole diameter specified is much larger than the draw stud diameter.

For example, the 1/2 inch punch has a 1/4 inch draw stud, but a 3/8 inch minimum pilot hole size. The 15/16 inch punch has a 3/8 inch draw stud, but a 1/2 inch minimum pilot hole size.

If one puts a 3/8 inch bolt into a 1/2 inch hole, what keeps the punch centered in the hole?

Greebster 8th March 2013 12:13 AM

Greenlee punch question
 
Also remember that the disc that is cut out is bent reducing the pilot hole size which causes the disc to clamp down on the stud. Makes for easy removal with the larger hole.

kevinkr 8th March 2013 01:20 AM

I drill the pilot holes the same diameter as the draw stud and then use a reamer to ream the hole out no more than 1/10 of an inch over the o.d. of the draw stud. This locates the punch pretty accurately and in 20yrs I've not yet ruined a draw stud.

I think the Greenlee advice is all wet personally.

DaveG 8th March 2013 01:29 AM

For the few I have punched I drew on the piece directly with pencil and a plastic drafting circle template producing a penciled circle the same diameter as the punch.
Then aligned the actual edges of the cutting edge on the penciled circle. I then tightened it up by hand, and then carefully tightened more with a wrench checking alignment as I tightened.

Once the punch dug in to the surface it did not move.

nigelwright7557 8th March 2013 01:30 AM

So long as the hole isn't so tight it damages the threads on the bolt it should be fine.
If the hole is to big then if there is more than one hole to cut then they can be out a bit.

kevinkr 8th March 2013 01:43 AM

:cop: Duplicate thread deleted.

Lavcat 8th March 2013 02:14 AM

I searched before I posted my topic. I could not find any other threads that addressed the question. Oh, I know what may have happened: I refreshed my screen but nothing happened. I then had to reboot my router and then refreshed. I can see where that may have created a duplicate thread. Very sorry.

kevinkr 8th March 2013 02:01 PM

Issue with post order and merge sorted. Greebster your post now appears as post #2 as it should.
The explanation for the duplicate thread makes sense to me, I've done the same thing on more than one occasion. :D

Greebster 8th March 2013 02:03 PM

Mucho Gracias :)

Lavcat 18th March 2013 04:18 AM

I read elsewhere that Greenlee marks the die at 90 degree points for alignment. Sure enough I looked and the marks are there. Never noticed that before. Unfortunately I am not scribing my locations, so I have no marks on my work to align with.

What do people think of just directly drilling the half inch holes, rather than using the Greenlee? This in is 1/8 inch extruded powder coated aluminum. The holes are for mounting pairs of binding posts. One consideration is I have the Greenlee and I don't have a half inch bit. However I don't want the hole locations to be off.


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