Shop made punch

[darryl]

So many times a punch would have made short work out of making custom holes in sheet metal. Today I drilled a series of holes, ripped out the webs between them with needle nose pliers, then used a jigsaw to rough cut the opening. Some file work later, the hole is done. Time consuming, noisy, prone to jamming the jig saw blade, basically just too crude. This particular hole is for a decora style ac socket- I need to add some holes for regular switches.

What it all comes down to is I need to make some kind of punch. Foot operated would be fine- my finger bender works that way and I like it. I have whatever control of pressure and speed I want, all hinging on whether I'm heavy enough to push the pedal down. If I could punch a reasonable sized hole in 16 ga with foot pressure, I'd be happy. What's a reasonable sized hole? 3/8 square is what I'm thinking.

Some years ago I made a punching machine that uses a 1/4 inch square hss cutting tool as the punch, and I prepped a 1/4 inch drive socket to be the die. That worked fine, and I'd consider doing the same with the 3/8 size. This existing machine is too light to punch 16 ga steel, so now I want to build a 'real' one. Anybody have an example of something you've made that works well?

[754]

Maybe try adapting your tooling to an arbor press..

[Ian B]

It sounds as if you're in the market for a fly press. Ian

[reggie_obe]

For punching a given size hole and gauge, determine the force necessary first.
A fly press or OBI press might be a little overkill when a kick press would do for a few holes.

[J Tiers]

One key consideration is how far from the edge of the piece of metal you want to punch. Another is how many holes you want to punch during a project.

For a few holes now and then, something similar to the Greenlee punches is OK. Driven by a screw, you drill a hole for the screw at the location first. They can punch a hole in almost any size sheet of material, in thickness up to 10 gauge, depending on the punch.

You can buy them or reasonably easily make them. For instance, I made a punch that cuts two holes for a standard double AC outlet, driven by two fine-thread half inch cap screws. Works fine, just takes longer, although it is far faster than drilling and filing. Angling the punch edge reduces the required force by changing to more of a shearing action.

If you want to punch many holes, in anything larger than a few inches wide, now you need a frame that is at least larger than half the workpiece (for a "C" type frame), plus a lever or other system to drive the punch, and it gets a good deal more complicated if you want to make the thing yourself.

To begin with, even if you have a press frame of some sort, you need rather good alignment of the punch and die to get a good hole, and it needs to be stable. A bending brake may not be "tight" enough to hold the alignment. The amount of allowable error is less than half the "clearance" of the punch and die, which may be only a few thou to begin with.

[754]

I think you are looking for a Unitool punch , and just dont know it ..yet..

[reggie_obe]

I think you are looking for a Unitool punch , and just dont know it ..yet..

Or a Pexto 118 or 218.

[J Tiers]

The 118 has a relatively short throat, around 6 or 7 inches. The 218 is bigger, something like a foot deep

Either is OK for some things, it all depends on the panel size.

[Corbettprime]

Sounds like you need a nibbler, Mouser and others still show then. Were used to modify electronic chassis back in the tube days.

[reggie_obe]

Sounds like you need a nibbler, Mouser and others still show then. Were used to modify electronic chassis back in the tube days.

Maybe a Die Filer? Any shape hole with just a starting hole.

[BCRider]

Sounds like you need a nibbler, Mouser and others still show then. Were used to modify electronic chassis back in the tube days.

If I were after something that would just make the odd holes in the middle of a panel this is what I'd opt for as well. It's the easiest and least bulky option. It can also work for making odd shaped holes such as the cutout that started this thread idea.

It's also a nice option for making holes in boxes where most of the other options need to start out with flat sheet stock.

I looked up the Unitool mentioned above. That's slick and all but the ones I saw are fixtured for a much bigger press. Not exactly small shop. Or do they make a smaller setup that is hand or foot operated?

On your HSS tool and modified socket. That's all fine for a few holes. But for a more frequently used tool you'd want some ground in relief on the punch and a better tool steel in the die. And such punch and die sets are easily bought if you want an overarm style punch. If you wanted to make a frame for such a punch that's fine. But I'd sure base it around a commercial punch and die set. If you go to this much trouble to cut solid plate or weld up a frame from heavy wall 4x6 tubing or something of the sort you want to get the most range of use from it. And to me that screams for the option of using the commercially available sets.

[darryl]

When I woke up this morning I had an image in my head of what might be called a die filer. I make one hole and just file the rest out- with a machine instead of by hand. Today I'm going to have to file these out 'cause I don't think I have an option right now.

I looked at some of those punches you guys have suggested. Some have some pretty hefty springs, I assume to retract the punch out of the material. That's a weak point on my 1/4 inch punch- no return spring. Whatever I do this time, there will be a stripper mechanism of some kind.

Nibbler- I have the Radio Shack version. I don't think it's up to 16 ga material. I have broken it before, I don't want to break it again. Finding the part would be impossible now.

I'll have to stew on these ideas for a while. I think I'll go to my local sheet metal place and see if they have something suitable that they don't use anymore, and would be good for me. I'll start there. Thanks gentlemen.

[BCRider]

Radio Shack? So a little hand power nibbler? Yeah, those were not all that great. Fine little things for 18Ga or thinner aluminium but that was about it. Or tinplate such as found in heating duct work.

If you were keen on doing a nibbler I wonder about the idea of a larger version but done with the top support much like the power tools have. And make it foot operated. Such a thing could be a nice compact post design. And I think I'd make it optional to switch from foot control for doing more careful work over to motor powered for broader stroke?

The ones that Corbettprime and I were suggesting are the better powered ones. You won't like the price but here is a KMS TOOLS LINK to the Makita nibbler that is rated at 16Ga mild steel.

[754]

I think the unitool can easily be mounted in a small press like maybe even a 12 ton, will beed a plate thsr covers s lot of the open hole in the press.
Whitney also made screw in punches, a bigger version of their small hand punch dies, round, squares, oval, triangle .

[darryl]

Well, I went and had a look around. KMS has a nibbler, but 18 ga maximum. They had nothing else. The sheet metal shop had their punch, but no square dies. It looks like my project will be using my press, and I'll just make my own die. I bought a 3/8 sq. cutting tool blank today, and I'll make a mount so I can fit it on the press. The bottom die- well I could use a 3/8 drive socket as I suggested, or I can cobble up a square hole using pieces of hss hacksaw blade- the ones that are .1 inch thick.

There's another way of making the die- take 2 of these hss tool bits and cut them in half. Then arrange the 4 pieces with the ends facing each other. That defines a 3/8 square hole, and the ends of each piece have the rake angle already on them, so the hole would be tapered and the punched out bits can just fall through. The tedious part of this process is cutting the hss parts. I'll have a look through my sockets first and see if I can find a suitable one which has square corners in it- many of them have rounded corners, which would have to be removed if I wanted a neat hole for the punch to go through.

At any rate, with the work of punching a hole done by the press, the work of pulling the punch out of the hole has to be worked out. I'm thinkin that a square sleeve surrounding the punch can be used to do the stripping. It would either be spring loaded, or have a lever which pushes it downwards to pull the punch out of the hole. I like the sleeve idea because it would be compact, and not interfere with vision when you're lining up the piece to be punched.

For now however, I'll make these holes the old way so I can get this job done.