Punch tools for making metal top plates on amps

[jmillerdoc]

Hi,
I have heard and read many times about using "punches" to get the perfect holes in the top plates of DIY amp projects. Exactly what are we talking about here? Is this a big shop tool with a hydraulic press, some giant piece of machinery? Or can one get these punches in a more portable type of tool? I am unfamiliar with the punch type tool people have spoken about. Can somebody refer me to a source for a metal punch tool that I might be able to acquisition at home? Better yet, maybe somebody has a set they are willing to part with.....never hurts to ask, right?

to date I have used a Craftsman drill press and some titanium and steel blade style drill bits used for wood to cut through aluminum. Used with lots of WD-40 this has worked ok but, you can sure wear out a bunch of bits this way real quick. Even though you can buy these bits dirt cheap at Home Depot and similar, it sure seems a waste to trash a bunch of bits when there seems to be a more appropriate tool.


Thanks!
Jeff

[jbateman]

Something like this.
- Harbor Freight Tools - Quality Tools at the Lowest Prices

[SigloOne]

Greenlee punches are the way to go. They can be had on ebay for a fair price at times. The thing is to make sure you know what sizes you will need. I am sure someone here can recommend specific sizes for standard tube sockets. You can also find cheap chinese ones on places like harbor freight, but I have never heard anything to good about them. Better to pay a little more and have a tool that will last.

[TheGimp]

GreenLee makes both Hole Punches and Knock Out Punches (for electrical cabinets). I don't know if there is any difference as far as hole punching chassis. I looked on their site once but couldn't find out any real difference between the two.

Does any one know? Are the Knock Out Punches heavier duty since they expect them to be used on steel electrical cabinets?

I've got a few of the standard hole punches.

[Glowbug]

Originally Posted by TheGimp

GreenLee makes both Hole Punches and Knock Out Punches (for electrical cabinets). I don't know if there is any difference as far as hole punching chassis. I looked on their site once but couldn't find out any real difference between the two.

Does any one know? Are the Knock Out Punches heavier duty since they expect them to be used on steel electrical cabinets?

I've got a few of the standard hole punches.

The difference is between a hole punch made for conduit sizes, and an "actual" diameter punch. So a punch made for 1/2" conduit is actually 7/8" in diameter.

Hope that helps

[Ty_Bower]

Don't buy these from Harbor Fright: Knockout Punch Kit

They're difficult to use, and the sizes are all wrong for vacuum tube sockets. I've used them myself on several projects, and while they can be made to work the results are far from perfect.

[Cliff45]

+1 for the Greenlee punches! These are what I use to make all the holes in any metal chassis I have built. Some brands of tube sockets have dimensions that are very close to the hole sizes produced by these tools, carefully measure the ones you commonly use to make sure the fit inside the hole will be as you expect before buying one of these kind of tools, as they are non inexpensive!

As a previous poster noted, make sure the actual size of hole produced is what you need. The Greenlee punches are often sized for electrical conduit fittings, which have actual dimensions that are often slightly larger than the stated "size" of the punch being used. For example, a 1-inch Greenlee die will produce a hole of 1.362 inches diameter. You can download their PDF catalog for the various hole-making tools from this link: http://www.greenlee.com/cat_docs/Hol...g08_lowrez.pdf


HTH-

[Juergen Knoop]

me has bought a cheap made, but not cheap sold, set of hole punches several years ago. Totally junk! I should have bought a stepped drill instead.
Regards

[Aengus]

Originally Posted by jmillerdoc

...to date I have used a Craftsman drill press and some titanium and steel blade style drill bits used for wood to cut through aluminum. Used with lots of WD-40 this has worked ok but, you can sure wear out a bunch of bits this way real quick. ...

Thanks!
Jeff

Hi Jeff

I'm surprised to learn that your bits are wearing out so quickly from cutting aluminum, which is pretty soft stuff. I wonder if the WD-40 might be counterproductive, in that it may be causing the bit to spin without cutting, then overheat and dull. You can buy cutting fluid designed for aluminum, but for intermittent use I often cut without a lubricant - you need to clamp the aluminum well since the bit can grab. Feed pressure should be reasonably high and steady, so the drill cuts its way through and doesn't sit at one point just skating.

You likely know this, but in case not: when drilling in larger sizes, you need a pilot hole larger in diameter than the flat bit at the leading edge of the drill, so the cutting edges can get to the metal and do their job. If it takes a lot of pressure to make the cut, this could be part of the problem.

I speak without a lot of knowledge in this area - any machinists in the group want to chip in (sorry about that) on why this bit-dulling is happening?

Regards.

Aengus

[jmillerdoc]

Another thing I have seen done so beautifully is the ring of smaller vent holes drilled around the base of a tube socket. I have often mused at how these guys are able to space these holes so precisely, evenly, and spaced perfect from the centerpoint of the tube socket. Does anybody have a good technique for getting such a nice job? I am sure I could come up with something that would work but appearently there is a surefire way of getting this result and I want to know how it is done!
Thanks,
Jeff