Broaching

Hi

am anyone tell me if a 3 mm broach 128mm long will fit in a no1 arbor press with a 25mm flywheel please?

Ian

Please provide the specification of your “No 1 Press”. I expect it will.

If the flywheel is 25mm diameter, most certainly yes. If flywheel diameter is over about 350mm it might be getting tight? Depends a lot on the shaft diameter, I expect, when approaching the maximum (but maybe the flywheel might fit over the press, if there were few spokes?).

I’m guessing/assuming the throat depth of your No1 arbor press to be around 180mm?

Depends on who's No1 it is some No1s are 1ton, others 3ton so capacity will vary

You will loose about 12mm of that 128mm length as the lead will enter the bush so if hub width is 25mm then you need about 140mm under the ram

Hi

I have not bought a press yet, which is why I am asking the question. Arc’s broach is 128 long, and the flywheel is 180 dia x 20mm thick.

I used to slot with the lathe, but find a 3mm slot in a10mm hole is a bit fragile, so want to try broaching.

Ian

Thanks Jason, that is what I suspected, didn’t know how deep the broach went into the hole before cutting started.

Ian

That depends entirely on the shim thickness in use, surely? The supplied shim(s) will likely start the next cut while using the full length of the broach. A thinner shim added will mean the broach will ‘fall in’ part-way before the teeth engage? think what would occur if a shim wasn't added!

Hi ndny

Shims are added after the first cut according to Arc.

Ian

No. look at any keyway broach and you will see that the teeth do not start at the very end so you can start the broach in the bush's slot. You may also find the first few teeth will also inter depending on exact size of the hole and the depth of slot in the bush

Yes first cut is done without the shim, subsequent cuts with shims depending on specific broach size and type (A, B, C)

Edited By JasonB on 21/06/2023 18:26:35

It is better to have the broach partially start in the part, if the cut is long or too hard it may be all the cut the broach wants to take on the first pass.

This is a 1/8" broach, as you can see the "lead" has entered and can be seen sticking out below the gear, I was just able to push the first tooth into the hole by hand

Blue mark was at the top of the bush so you can see how much length could be deducted from the total of part plus O/A broach length. The 12mm or so is what would go in before first tooth.

Edited By JasonB on 21/06/2023 18:36:46

Thanks for that, looks like the no1 will just do for what I want, collecting the pieces for a Farmboy to keep me occupied over the winter.much appreciated.

Ian

A quick update, I purchased a no1 press, the clearance is 140mm from the top of the ram to the base with the punch plate removed, so it has enough clearance.

It was a cheap press on offer vat free, so I didn’t expect much and have spent a couple of afternoons squaring up the ram etc. Should be set for winter, got all the bar stock and flywheels before prices rise.

Thanks for the replies, appreciated.

Ian

I make my guides/inserts. If the slot is too deep, I add a suitable packing piece/shim - even before the first cut.

Most of my recent keyways have been cut on the shaper, but in the past I have only bought the broach I needed.

Making a guide is not rocket science machining. Shims likewise.

Edited By not done it yet on 28/06/2023 19:14:42