What size of Greenlee punch should I use for octal sockets?

[dehughes]

Hello all,

I am in need of punching a hole in a steel chassis (well, enlarging one...from a nine-pin to an octal...) and am considering just buying a hole punch (preferably used...). However, in researching the different sizes of octal sockets I'm noticing that they vary in size, from 1" on up... What size of Greenlee punch should I purchase to use for octal sockets? 1 1/4"? Bigger? I'd like to use higher quality octal sockets, and I find that those are often on the larger end of things, though it seems the Belton sockets are the largest. I've honestly never paid attention to socket size and hole size (I just buy the sockets and they fit in the chassis holes...) so I could use some advice before I sink money into a nice punch.

Thanks!

[Allynmey]

1-1/8"

[dehughes]

1-1/8"

Nice. So that's a good "catch-all" size, then? I ask because I see lots of different octal socket dimensions on http://www.mojomusicalsupply.com/products.asp?id=569613 and I'm not so sure I'll be using the same sockets from build to build. Still though, I could always just file out the hole a bit should I need another 1/8".

Thanks!

[kec]

I'd get a unibit (step drill). That way you can cover a wide range of holes.

[Phil_S]

For casual work, IMO the cost of a punch isn't justified. If you get a used one that is dull, you won't be happy with it. Get a step bit (also called uni-bit). You can buy them new at your local hardware superstore or for half that price or less on eBay. A decent one in your size range is probably about $40- $50 new. You need one that will cut a 1-1/8" hole. Some sockets need 1-1/4", so get one that goes to at least that size.

The step bit is easy to use and perfect for the home hobby builder. I have a couple of them and I've punched several chassis with them. It goes right in your hand held drill and it's hard to mess up with them unless you cut the hole to a larger size than you intend!

[mooreamps]

For punching holes in "steel" chassis, you may end up having to use a greenlee punch. Look into Lowes or Home Depot for single punch sets.
-g

[muchxs]

There are two sizes for octal chassis holes, they are 1" and 1 1/8". You'll find high quality sockets in either size although 1 1/8" seems to be more common. I prefer to punch exactly the size I need and no larger, it looks like a hack job to have all that air around the socket if you punch oversize.

Greenlees aren't all that expensive and they're worth every penny. If you do chassis work you'll wonder how you did without them.

Mouser offers their own line of Greenlee style punches but I think they're only available in metric sizes. Remember to round UP when you do the conversion and you'll be o.k..

[tunghaichuan]

+1 on the Greenlee punches.

A few years ago I lucked into a bunch of Cinch 1" octal sockets, dirt cheap.

I have 1", 1.062" and 1.125" Greenlee chassis punches. Expensive, but worth every penny.

[drhulsey]

[quote="dehughes] ... and am considering just buying a hole punch (preferably used...[/quote]
Since hole punches are just a series of beveled chisels, you should be able to sharpen them. It would have to be by hand because of the shape of the die. Anybody ever done this

[UR12]

The only thing you need to be careful about when purchasing punch sets like the cheap ones at Harbor frieght is that they are designed for punching holes for pipes/conduit and when it says 1" it is really something like 1 1/8" because a 1"pipe has a 1" ID and not OD. That's probably more confusing but just make sure you read the box carefully if your not buying Greenlee. I've already broke a set from Harbor frieght on a Hammond 1/8" cast box I was using for a snake. If your doing steel pay the extra money for the Greenlee

[muchxs]

... and am considering just buying a hole punch (preferably used...

Since hole punches are just a series of beveled chisels, you should be able to sharpen them. It would have to be by hand because of the shape of the die. Anybody ever done this

Greenlees are hardened tool steel so it's probably a chore. I equate it to sharpening a drill bit by hand.

My 1 1/8" looks like the kids played street hockey with it. Most of the manganese phosphate is worn off and it has the battle scars of an old warrior. I've had it for 20 years or so and I've never sharpened it, if it didn't punch a clean hole I'd consider sharpening it. That's why I don't think Greenlees are expensive.

[dehughes]

Thanks guys. I'm looking at some new Greenlees in 1 1/8" and 3/4", as that would cover all the common holes for amp work (save for cap cans...). I'll be punching a couple of pretty solid steel chassis, so I'll go for a quality Greenlee, even if they are more expensive. I've tried drilling/filing/etc. when it comes to chassis, so I'll try a good punch this time.

I understand that when one punches steel it is important to use some sort of oil, yes? Both on the chassis and in the threaded shaft of the punch? Any particular oil (gear, cutting, etc.)?

[muchxs]

I understand that when one punches steel it is important to use some sort of oil, yes? Both on the chassis and in the threaded shaft of the punch? Any particular oil (gear, cutting, etc.)?

I lube the stud on the punch and keep the workpiece dry. It would probably be good industrial practice to oil the workpiece although for the volume of work we're doing it's not necessary. Oil creates other problems such as if you try to solder to an oily chassis later.

Any light oil will do on the workpiece. Use motor oil on the Greenlee stud. Industry is moving away from petroleum based oil for cutting and stamping, they're substituting vegetable oil for stamping. OSHA considers petroleum oil mist to be more of a hazard than vegetable oil.

[krash]

+1 on the unibit recommendation. since it's just a one time job, maybe try and borrow one. i think keeping a punch centered and working right in a hole you are trying to make only 1/8" larger in radius is going to be exceedingly difficult.

fwiw my unibit is my favorite tool. I can do an entire aluminum chassis with a paper template, auto punch, 1/8" drill bit for every hole, then everything but the tube sockets gets done with a unibit in my cordless drill and it's quick & easy. socket holes are 7/8" forstner bit in the drill press. the holes always come out perfect, and i can't say the same for regular twist bits or punches.

[WholeToneMusic]

If your planning on doing a lot of fabrication I would definately recommend the greenlee punches. They cut clean and are easy to use, with proper care and oiling they should last a while. The unibit is good for the home DIYer however it leaves a fine metal curls attached to the other side that must be filed (alot more work.) If you do not get the undercarriage flat then your grounds will be less that satisfactory. The octal hole that you need depends on the octal socket you use. There are top mount and bottom mount sockets which may require a different socket hole. What type of socket are you using?

Tonefuly yours,
Brian
www.whole-tonemusic.com