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J Tiers
08-23-2005, 12:48 PM
I got, in with a bunch of other tooling, a broach for 1/4" square holes.

It is fairly short, 7" or so, and might be either a push or pull broach, I don't know. IIRC, (I am not near it now) it has no obvious groove in what would be the "pull" end.

Now, I know the thing would be pretty easy to foul up, but it would be useful to me if I can use it without fouling it up... so....

How would I tell if it is intended for push or pull usage?

I assume an arbor press would have to be pretty tight with no play in order to use it with a push broach, but even a tight arbor press isn't great...is it best to use a "real" broaching press to avoid breakage?

Would it be used in the socket hole of a press, or un-attached same as a keyway broach would be used? (I would assume in the socket)

It has marked on it the size starter hole to drill first.

Mcgyver
08-23-2005, 01:41 PM
If its some special pull arrangement for use on a broaching machine, I have no clue

…but I can tell you broaching is readily done with a sloppy old arbor press. I’ve done keyway, hex and square broaching in my press and it’s anything but tight. I sense from your comment you are concerned that if not, it puts lateral stress on the broach. It’s a valid concern . do the broaching action in small steps each time releasing pressure on the arm. If the broach had started to get pushed sideways, this lets everything get back into shape before the next downwards movement.

Here’s a shot my arbor press and a couple of homemade broaches. The square one is 3/16 and I managed to broach steel without busting anything.

also, design your parts with minimal broaching lengh to reduce the todal force required (how many teeth cut at once) Do proceed with caution , they are fragile!

http://i20.photobucket.com/albums/b201/michael0100/broaching/arborpress.jpg

http://i20.photobucket.com/albums/b201/michael0100/broaching/homemadebroaches.jpg


[This message has been edited by Mcgyver (edited 08-23-2005).]

JCHannum
08-23-2005, 02:54 PM
Generally speaking, you can push a pull broach, but you can't pull a push broach. The only requirement to push is enough shank at the end to allow the broach to be pushed clear of the finished hole.

Most square broaches have a minimum hole size, and may only produce a round hole with square corners. You might want to experiment with a few different sizes, and get a feel of the cutting action.

I would rather use a beat up old arbor press, and have the feel of the cutting action and pressure than a hydraulic press.

The rest is as Mcgyver says plus the warning, broaches are like reamers, do not back them up.

tattoomike68
08-23-2005, 02:56 PM
I have a 1/4 square broach and have put it through 1" round 1018 cr with nothing more than a dead shot and a small brass hammer.(its nice to make a boring bar or line booring tool.)

I am guessing, but I think pull type are for production and it would be obvious on the small end if it were the pull type.

If it just has a pilot its a pusher.

If pressing the tool just let up and let the brooch spring back strait, like the minute man keyway broaches,use lots of oil, no problems.

what are you building? a tool?

[This message has been edited by tattoomike68 (edited 08-23-2005).]

wierdscience
08-23-2005, 08:41 PM
I got a set of the small keyway broaches(1/4-1/2" bore)I hate using them in the arbor press,so what I do is use them in the lathe tailstock or the b-port quill with an adapter machined up from colled rolled.

The little square broaches can be made eaiser by hogging out the corners with a hss tool bit in the b-port quill,then switching to the broach.

J Tiers
08-23-2005, 09:29 PM
Thanks for the pointers.

As far as what I am making.... well I didn't expect the broach, I bought the lot for some Acme taps, but it looks handy for making boring bars, etc.

Weird: Whaddaya mean "hogging out on B-port"? I think something went past me on that.....

wierdscience
08-23-2005, 10:25 PM
<font face="Verdana, Arial" size="2">Originally posted by J Tiers:
Thanks for the pointers.

As far as what I am making.... well I didn't expect the broach, I bought the lot for some Acme taps, but it looks handy for making boring bars, etc.

Weird: Whaddaya mean "hogging out on B-port"? I think something went past me on that..... </font>

Well you drill the pilot hole and then use a 1/8 or 3/16" square toolbit in a collet to act as a push broach using the quill for power/positioning to shave out the corners to a point slightly smaller than the finished square,then pass the broach through,should take less pressure to push the broach that way.You could do the whole thing with the toolbit,but heck you have the broach.If it's in good shape It would also fetch a good price on Ebay,maybe more than you paid for everything you got.

J Tiers
08-24-2005, 12:30 PM
Ah, using the B-port just as a hand slotter...... OK. I have done that with different equipment.... although its hard work and probably not good for the quills.

As far as the broach, its still in its protective waxy plastic dip..... Maybe it SHOULD go to ebay in favor of money to get more generally useful items...... decisions....

BillH
08-24-2005, 02:55 PM
Look right here, great pictures
http://livesteam.proboards23.com/index.cgi?board=general&action=display&thread=1124729380

Mcgyver
08-24-2005, 08:37 PM
that jig is cool - where he controls the radial position of the key. just index the axle 90 degrees when you cut the corresponding key and your'e perfectly quartered!