I manage a small prototyping machine shop for my employer. I have alot of experience with milling and turning, but less with sheetmetal. We have a good shear, notcher and finger brake. We also have a little hand puncher, but it is only good for holes close to an edge. We have no capability for punching holes inside a part or for punching larger holes. That falls onto the milling machine, and there are not many people qualified on the mill.
I'm trying to decide if it makes sense to budget for more equipment next year. I know there are dedicated punching machines, but I don't think we'll have the floorspace or money to buy a wide selection of tooling. Most of our work is with 1/8" or less aluminum and 16 gauge or less steel. Most cutouts are small connector cutouts or rectangular notches. Typically less than 1 sq in. Maybe up to 2 sq in.
I looked at Grizzly, and they don't have any punching machines that I could find. Mostly just bending and shearing.
We have a 3 ton arbor press, and I'm wondering if that can do any meaningful punching? My general impression is that it will not be useful for punching. And that we would have to create any tooling ourselves.
Would a larger capacity hydraulic frame press be useful? Again, what about tooling?
I've also thought about buying a selection of Greenlee punches, but they are only available on larger sizes.
Start with required tonnage, then figure required throat distance, then start pricing machines and don't forget to thoroughly research tooling pricing and availability. I had a nice No. 91 Whitney Jensen 10 ton bench punch which had about a 10" throat which did nice round holes up to 9/16", for example, but that might have been a little small for you. That is about a $400-500 machine.
Your decision must be made on requirements for punching holes in sheet metal and throat distance. If you have one hole to punch a month, then get a set of car body-working punches. These are individual punches that require you to drill a pilot hole first, then mount a punch and die on opposite sides of the metal and using your faithful air drive wrench, pull punch/die together and make the cut. This system would work if you have ten or more holes per week. And you don't have to worry about shop space because it can be done anywhere and no worry about throat dimensions either.
On Fri, 14 Jul 2006 09:32:18 -0500, No Spam wrote: SNIP
You would be running close to capacity for cheap ones, but have you considered "nibblers"? Good for one-offs or limited work. They come with either of a round punch or a square punch. The round one is easier to steer, but has a diameter of something around 1/8" or greater, so leaves a radius in a corner.
The square cut ones are harder to "steer", other than straight ahead, but do a clean square corner. Available as air or electric powered, from el-cheapo at Harbor Freight to big bucks at such as Makita-grade dealers.and there are industrial/commercial grades available and different design styles too.
Depending on how many you do in a given time, try this.
For the thickness you are using, consider a Uni-bit to start with with. Then, use a Greenlee punch for the appropriate connector profile. They make punches for most standard connectors such as DB25, DA15, etc. It is, however, not a good idea to 'nibble' edge notches with these as the loading is uneven, usually damaging the punch or die.
Outside of stock profiles, we ended us using a kick-press with a very large assortment of punches. Custom punches are available, but are pricey.
Greenlee, Deltron, etc., have a lot of screw-drawn punches that specialize in these sorts of connectors. Especially if quantities are small or they're all one-offs, this is the level of tooling you want/need.
I don't think you're looking at the right catalogs. I recall them having punches down to 1/2" diameter for many common connectors etc. (including the all-important D and Double-D's), D-sub connectors, etc., and they go up from there.
There used to be lots of hand punches available like this, but nobody in industry uses em much any more, so there are very few available used. I have a nice 24" throat W.A. Whitney ( a different company from Roper Whitney) which is a 5 ton hand punch- but they dont make em any more. It will punch up to about 1 1/4" in diameter in 20 ga, smaller holes in
16 ga.
Roper Whitney still makes some hand punches- Including this 12" throat 4 ton-
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cheap, though.
I would consider finding an older Strippit, Di-Acro, or similar punch. these have deeper throats, more tonnage- ( a plus for your 1/8" aluminum, which will eat up more tonnage than you might think) and are available either as single station punches, or more conveniently, as turret punches. They cost more money, but can do a whole heck of a lot more work, much more quickly.
Used Strippits are often available, with drawers full of punches and dies, for as little as 2 to 5 grand, since they are not CNC. The CNC models are more like 10 grand and up. Check out this thing- and see if it will do what you want-
We have a WA Whitney punch that may be just what you're looking for. Ours has a 10" throat and easily punches 3/16" mild steel. The punches have a shearing action on the larger sizes. The last time I tried to get obround punces, I was directed to
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, since WA Whitney no longer makes punches for their machine.
We have all shapes up to 2" diameter and does a fine job for a manual punch.
McMaster Carr sells this punch on page 2164, item # 3443A112. Do a search for Bench Punch on their site.
Not Grizzley or any other import, then? I tend to like DiAcro, though you would have to buy used these days, I fear. (But then, that is how I got *all* of my sheet metal tools. :-)
A turret punch would be nice -- up to certain size limits. DiAcro made one with something like 12 or 18 stations in the turret. You just spin the turret to select a different punch, with the two geared together so they won't get out of step.
The manual (which I downloaded some time ago) does not show either the maximum punch size, or the distance from the edge of the workpiece -- though looking at the photos, I would suggest that the maximum distance from the edge would be on the order of 18 to 24 inches on the 18-station machine. The overall diameter of the punch cartridges seems to be on the order of 3", which would suggest perhaps 2-1/2" or 2" as a maximum punch size.
There are available punches for all kinds of connector, switch, and the like cutouts. I particularly like to have the "key" punch for toggle switches, and two sizes of "D" punches for things like fuse holders. Of course, I don't have the turret punch, and don't have floorspace for *myself* in the shop, so I have to use the Greenlee chassis punches for the purpose. :-(
Hmm ... 2 square inches -- not two inches square. That would limit a round punch to about 1.6" diameter, which should be within the range of the turret punch -- but rectangular with a large aspect ratio would probably be too big.
And not particularly good ones, if what I have read is true.
Robin can give you the tonnage needed according to the total border length of the hole needed, based on material and thickness. But I strongly doubt that a 3-ton arbor press would suffice for much of anything.
A hydraulic frame press might work well enough, with fixtures to hold the punch and die in proper alignment. Note that you need to be careful in setting up the punch and die -- mis-alignment can destroy the punch and die -- or even possibly the press frame.
The larger the sheet metal, the larger the frame of the punch, and thus the larger the needed cross-sectional area of the frame members to have sufficient strength.
Define "larger sizes". In my experience, they range from 1/2" up to several inches.
Be careful not to get "knockout punches" from Greenlee -- or at least to determine what size hole they *really* punch, because those are named for the size of conduit fittings which they will accept, not the actual diameter. "Chassis punches" punch to near the nominal size.
You can also get chassis punches in weird shapes, such as for the various D-series connector mountings, and things like the socket rectangle for the Potter & Brumfield 4PDT relay sockets.
You can also get single punches for these shapes in a bench-mount press. The problem is the time taken to change out a punch for another when you need the next shape -- again a critical alignment job to keep from destroying the punch and die.
You can also get hydraulic drivers for the Greenlee chassis punches -- a *lot* easier to use when making a large hole, compared to trying to wrench one through -- even with the ball-bearing drive screws. For short production runs, the hand-pumped ones will do. For more serious production -- consider electrically pumped hydraulics.
Of course -- a lot of the complex connector shapes can be done with a CNC milling machine, and the right outline information.
I have the 45 hand punch myself - beats the heck out of plasma torch burning a small hole in thin copper or Al.
Martin Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member
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T>>>I manage a small prototyping machine shop for my employer. I have alot
I have a couple of used punches available here in SoCal. I don't know where you are. I would be glad to walk you through a purchase if you are really interested. I sell Jet as well and think they have a couple of punches also but would have to veify that tomorrow. Leigh at MarMachine
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