Using my punches???

[Satamax]

Hi everybody!

I've just bought a new set of punches, is there anything i should know before using them? I don't have small ones, smalest is 3/5. For pots and fuse holders etc, is the stepped drill good enough?

[Rob Mercure]

Max,

I assume that you mean chassis punches? If so the best USA made ones are the Greenlee brand but I'm sure that there are great ones made in other lands - but you do "get what you pay for" - the cheap Japanese ones such as those sold by Triode are just "OK" - good for occasional light use - in aluminum - but very tiring to use compared to Greenlee, etc,.

Generally a step drills works great but the resulting "hole" in the metal will be "tapered" and sightly sharp and will tend to quickly become slightly over size if you have to file it for any reason (such as to get rid of the sharp edge). It's also hard to drill in very thin metals unless you can "pin" them to a wooden backing or solder them to a heavier piece of metal. But using punches on really thin metal is also trying and the same trick of laminating the to-be-punched metal to a piece of heavier, softer metal works as does "backing" the thin metal to a self stick vinyl floor tile.

Chassis punches, like all metal cutting tools, like lubrication and you'll cut quicker and cleaner holes with less effort if you use a good lubricant such as a machinist's "cutting oil" or some of the ultra low friction lubricants available through jewelers supply. Be aware that the "blank" that you punch out in the middle becomes distorted and the center hole become an elipse which tends to bind against the punch's threads - an "oversized" hole helps, how much "oversized" depends on the size punch used but I like at least 0.02" over (read: "twenty - thousandths" - was trained as a machinist once but no metric in 1975).

One advantage of step drills is the ability to work on an existing chassis without removing as many parts to gain clearance - as you would need to do with a chassis punch. The disadvantage, which the punch doesn't have, is having to be sure that metal chips and shavings don't get into existing circuitry (but if you insist on doing this aluminum shavings provide much brighter and more exciting fireworks than steel ones do! <grin>).

Have fun with your punches - if you've got a good set you'll probably start popping holes in "most everything" for the fun of it (yeah, your car does needs another drain hole in the trunk - I agree! <grin>)

Rob

[bob p]

I've got a handful of Greenlees that were given to me by a friend who had retired. They're 50+ years old and they still work well. The only downside to the Greenlees is that they're really expensive. The circular ones aren't bad -- they start at about US$30 around here, but the square ones and the "D" and double-D shaped ones cost over US$200 each. Yikes!

Does anyone know a good source for those at a better price? I hate to think that because I have to draw the line at the $200 punch, I'm going to spend the rest of my life using a nibbler when I try to cut the holes for the AC power cords...

[Satamax]

Have you tried to look at RS components???? http://rswww.com

I've tried mine today, they leave marks on the aluminium i have but who cares!