1 Tonne Arbor Press suitability for broaching EN1A

The easier alternative, if milling facilities are not available, or where work must be done insitue like here, is to file a simple flat on the shaft and hold the key against this, it's not strictly necessary to use a key seat but the grip is not as good so thats something you have to consider/weigh up.

< post deleted ... thought better of it >

Edited By Michael Gilligan on 27/03/2016 19:14:49

The problem with Michaels Option 2 is that I don’t have a way of drilling longitudinally down the shaft – other than with a hand drill, but I don’t think that would go well.

I still like pgk pgk’s idea ‘Could you get away with a semicircular top on your key and just mill down the handle?’. The only thing that’s putting me off is that it doesn’t seem to be gaining any momentum on this thread!

David

Michael the reason a press with daylight is needed is that the broach is some 300mm long for a 6mm width, this does not change whether broaching a hole or a shaft not that you could broach a shaft.

So its the hub that causes the problem.

Take this shorter 3/16" broach. You need head room to get in the guide bush which in this case will be longer than the hub (marked in blue) and the length of the broach less its lead in. Even this shorter one won't fit in a 1T press with 100mm in the throat.

Shaft can just be milled and a straight keyway saves also having to buy a woodruff cutter.

Edited By JasonB on 27/03/2016 19:38:01

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How can you get started with a 300mm long broach on a press that only has half of that in workable hight. ?

Also broaches are precision ground HSS and by virtue of the way they are made with very deep open teeth on the front and two sides the last thing you want to be doing it hitting one with a hammer.

Rest assured these will not bend but shatter.

This thread has another alternative

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I think the 'rectangular bottom & semicircular top' would indeed be a good solution.

+1 from me.

MichaelG.

May not be enough room on the hub but a wedged cotter would work, thousands of bike cranks can't be wrong

You may get away without such a sophisticated approach. I have built an etching press similar to yours, but slightly smaller. A threaded hole through the side of the handle bush for a screw, bearing on a flat filed on the roller shaft worked for me. I have used and serviced commercially-built presses for my local printmaking studio, and although they seem to be engineered to survive a nuclear assault, I'm not sure that a keyed shaft is really necessary. It is, however, a more elegant solution than mine, so I can understand why you would want to go that way. Good luck with it anyway.

Pete

David -

Where are you ion the planet? If anywhere near west Gloucestershire, (UK) I've got a small(ish) slotter in my shed for exactly this job.

Alternatively I've likely got a keyway broach to suit, and certainly a hydraulic press. It'll take longer to boil the kettle and make a cup of tea than do the job.

If you want to take this further, I think all you do is press the "message member" button, we can exchange locations and see how to proceed.

Best rgds Simon

Edited By Michael Walters on 27/03/2016 21:02:27

Here's another idea, just my beginner's input.

**LINK**

Ed.

I just finished 4 off pulleys on my 3 tonne press that were 38mm thick with a 6mm key for a 19mm motor shaft. Apart from doing the odd bit of monkey hanging due to getting the broach cocked they go through well with some good cutting fluid (Ambersil Tuff Cut).

Three passes, no shim, 1 shim and then 2 shims to finish. Using C type broach (300mm long?)

look at ebay number 161976203311 for the type of press I have

Mark

So in the end I went for the 'rectangular bottom & semicircular top' option. Photo below.

I was going to make the ‘semicircular’ top next – but thinking about it, is there anything wrong with some sort of grub screw to hold the key in place ?

Anyway, thank you again for all the help, and thank you Simon. That was a very kind offer but it looks like I’ve got a work around.

David

Looking good so-far, David.

MichaelG.

To answer the OP, probably not. I've broached 3/32" and 1/8" keyways through 1.5" of EN1A and 1" of cast iron respectively, using the quill on the Bridgeport mill. But there's no way it would have driven a 6mm broach through steel. I now have a proper arbor press, for scale it's about 20" high:

Andrew