Alternative to BROACHING?

Hi,
I need to cut about two-dozen square 5/8" holes in cold rolled .187"
thick steel bar. I'm thinking that broaching would work, but was
surprised that a 5/8" broach would set me back $300. The holes need
to be square and fairly precise. The .187" CR steel is too thick for
my whitney foot punch to get through, so I'm kind of at loose ends.
Have I overlooked some other alternatives? Is there a source for
cheap square broaches anyone knows about?
Thanks,
--Max
Reply to
Max Krippler
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Grind a broach out of a 5/8 square tool bit, the long 6" style should work for .187" stock.
Good Luck Tom.
Reply to
azotic
You could use a Watts polygonal drill, but it's probably just as expensive as a broach. With the foot punch, have you tried drilling out most of the material and punching out the rest? When I did some work with a Pexto rotary punch (hand powered), I found that with the largest punches, I needed to drill out as much as possible, but then I could punch the rest.
Reply to
woodworker88
If you can live with a 1/16" radius in the corners you could mill the opening with a 1/8" dia. endmill. Set stops at appropriate locations for the X and Y axes, drill a 19/32" dia. hole in the centre of the required opening, switch to endmill, and crank axes to stops. Voila!
Wolfgang
Reply to
wfhabicher
You can buy square hole sleeves and silver solder or weld them in, but at $10-$15 per sleeve, you are competetive with buying a broach. Ugh!
How close to the edge are you? Part size? Holes cannot be round? Milled out with drilled out clearances in the corners? Wire EDM shop ($$$)
Got a fab shop near you. They would likely have a set of dies for an ironworker. No Idea what it would cost. Anywhere from a box of donuts, a case of beer, or all the way up to the cost of a broach, but I doubt that it would cost that.
What's the limit for a Greenlee style punch?
Cheers Trevor Jones
Reply to
Trevor Jones
$300 / 24 = $12.50 ?
This seems reasonable to me.
Plus you get a nice new broach for your collection. Get your customer to pay for it.
Reply to
Dom
EDM or hydrocut should do the trick. Maybe build a EDM machine for your shop?
Reply to
Gerry
Similar to the drill-and-punch idea, has anyone 'spot-faced' 90% of the way through with a mill (diameter equal to the square hole size), then punched?
Dave
Reply to
spamTHISbrp
Thanks to All for those answers, I don't think building an EDM machine is in the cards for me. I guess I'll just have to pony up for the broach.
I don't have an H-frame press (but I suppose this is as good a time as any to get one if I have to). Is it ill advised to try to hammer a broach that size? if hammering it works I'll just do that. Any opinions on who makes the better broach?
Thanks, --Max
wrote:
Reply to
Max Krippler
-Don't hammer the broach - it's brittle and slender. The teeth will chip, and it's not difficult to snap a long broach in half. In production, long broaches are pulled.
-An arbor press is a much better rig than a hydraulic press for broaching in most cases. A Dumont 5/8 square broach is about 16" long; that's a lot of pumping on a manual hydraulic press. The arbor press also gives a better feel, making it less likely the broach will get broken. But it'll take a good size arbor press to handle a 16" long broach.
-Back off the press ram frequently and allow the broach to relax. If the press ram and the broach aren't perfectly parallel, the broach may bend enough to snap if you don't allow it to spring back into line.
-Normal square broaches have a round pilot. The pilot diameter is slightly larger than the distance across the flats, so while the corners of the hole are sharp, the sides bulge a bit.
-McMaster has 5/8 sq broaches for $250.
-Don't hammer the broach.
Reply to
Ned Simmons
There's having it plasma or laser cut - call around to local shops.
Filing could be an option, but depends on the value of fairly precise, and how hard you want to work.
One thing I'm seeing when I look at a 5/8" broach in a catalog (Enco, $249) is that the tooth spacing is 7/16" and the minimum length of cut is 5/8" - so you may need to clamp several of your bars together for a broach to even work properly, unless there are broaches of this size with finer teeth than the Dumont I'm looking at.
Reply to
Ecnerwal
Find a fab shop with an Ironworker. You may have to buy the dies but they may already have the proper die.
John
Reply to
john
Before I bought a broach, I'd talk to your local laserjet company. They might be able to whip those out for you.
They can hold .005" no sweat.
GWE
Max Krippler wrote:
Reply to
Grant Erwin
Good idea on the Greenlee - the bolt has a limit - the two cutting ends have another. Alignment would be the trick.
Martin Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Life; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member.
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Trevor J>
Reply to
Martin H. Eastburn
[ ... ]
Note that broaches require a slightly oversized pilot hole, so you wind up with a side which looks sort of like this:
| ( |
(though this as shown is rather exaggerated). Look up the broaches in the catalogs and see what the pilot drill needs to be.
And if you are not in a hurry, you can sometimes find square broaches on eBay. I've collected several sizes from there.
A quick search only finds a 1" square broach (tolerance 1.0020 - 1.0030", and it requires a pilot drill of 1-3/32" just to give an example. It also appears to be new -- and priced as such.
Note -- put "square broach" in quotes in the search string, or you will get a lot of unrelated items.
Good Luck, DoN.
Reply to
DoN. Nichols
You don't say how precise. If a couple of thou would do, there's this thing called a three-square file. Use a drill for the bulk, files for the corners and a shop made go/no-go gauge to tell you when to stop.
Mark Rand RTFM
Reply to
Mark Rand
Keyway
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Square
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Ouch.
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Slightly less ouch.
Wes
Reply to
Wes
At $300, you might be best off just going to a local shop that has a Scotchman-style single station hydrolic punch and see what they'd charge you. Doesn't take long to set something like that up and run, and you might get it done for $50 or less.
Reply to
Prometheus
That's a possibility, but you're better off if you can get them punched- at least at my shop, laser cutting is $100/hr, but punching is only $60.
Come to think of it, how many parts do you need? Is it a matter of having two dozen holes in one part, or two dozen parts with one square hole each? If it's the former, I could do that for you pretty cheap, provided 1008 CRS would be acceptable. Two dozen parts would cost more, obviously.
Reply to
Prometheus
I have an electric file die grinding double table that works just fine for sell... It works like a jig saw with a file in it... Very heavy duty... It's about the size of an office chair and weights around 250 lbs. 110 volts works great... Upper and lower table... First $150.00 takes it... E-mail at ( kbeitz @ pa.net ) located in Pennsylvania....
Reply to
kbeitz

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