[Amps] Chassis construction question

[Ian White G/GM3SEK]

Will Matney wrote:


>>Will, how do you not gall the threads on the Greenlee punches when using
>>an
>>impact to force feed them?Jim...

>
>Well, I guess you have to get a feel for using the impact and the 
>punch. I kind of "goose" the impact along and not just run it in at one 
>go. Plus, the through bolt is a grade 8, and fine threads, so it will 
>break before it will stretch any. I've never damaged a punch yet doing 
>that. I have an electric impact now, but when I ran the shop before, I 
>used an air impact and it worked just as good. The trick is watching so 
>to stop it as soon as you hear that pop when the slug breaks free, as 
>if it's bottemed out tight, you have to use something to brake it loose 
>like holding the die in a vise, and back the bolt out with the reverse 
>on the driver, or a wrench. I have done this from time to time, and 
>still never hurt the threads. If you do damage a bolt, you can go buy a 
>grade 8 fine thread bolt as a replacement cheap. If a punch has a 
>square head bolt, I change it out the first thing to a hex head grade 
>8. I never did damage the threded punch, they are harder than the bolt I believ
> e. If ones skiddish about using an impact, you can always use a 
>cheater bar or a long boxed in wrench. It's just more time consuming to 
>do. Another trick is to watch the punch going through from the 
>backkside if you can. Watch for the V in the punch to dissappear and 
>you know your there. Always give the threads and the punch/die a shot 
>of WD-40 about every two holes and that keeps them from seizing. At 
>that if I did ruin one, I can buy punch sets for $20 a set so, 
>replacing one isn't that bad but that I've not done yet. Harbor Freight 
>has these on the cheap. Last, always give the punch a good coating of 
>WD-40 or 3 in 1 oil before you put it up after use. That keeps any rust 
>the next job.

More ways to help a Greenlee or Q-max punch do its work:

1. The hardest work is in the early stages when you're trying to force 
the two blunt points of the punch through the metal. After that it gets 
easier as the edges are progressively shearing around the rest of the 
hole.

A good solution is to drill two pilot holes for the points (typically 
3/8in for a 2in+ punch). These holes are just *inside* the scribed 
circle, so the points of the punch locate into the holes... and after 
that it's easy shearing all the way.

2. Instead of a plain washer, use a ball thrust-race (supplied with some 
larger punches).

3. Use molybdenum disulphide grease on the threads and cutting edges, 
which is designed to lubricate under extreme contact pressure.

4. Clamp the bolt-head in the vice and turn the work for greater 
leverage and control. When using small punches with hard or thick metal, 
grind flats on the head of the cap screw so you can clamp it in the 
vice.



-- 
73 from Ian G/GM3SEK         'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek