Thread: Hercus 9A Leadscrew Removal

Hi everyone,

I got good advice last time, so here I go again!

I just took the gearbox and leadscrew off my 9A for a cleanup. The problem now is that I can't get the second nut off the end of the leadscrew, inside the gearbox.

The locknut came off okay, but the second nut won't come undone - it's very tight and the leadscrew just turns. I've tried holding it with vicegrips padded with leather (and clamped very tight) but that's not doing it.

I did think about chocking up the gearbox somehow, but I'd hate to break a tooth.

Any suggestions on stopping it turning? It's a bit hard to do much with the gearbox with the leadscrew hanging off it!

Thanks,
Ant

The way you tried it already but without the leather,if you grip it on the bare shaft you may get a few jaw marks but nothing that you wont be able to remove,apart from the appearance.

You could try your vice grips with emery instead of leather.

If the vice grips still wont hold you may have to try stillsons,or if you have an offset bench vice you may need to try that.

1- try heating the nut with a powerful hot air gun or a torch. Shield the painted parts with metal sheet from the heat/flame. Then try with the leather as you did. I assume you already applied some WD40 (or hydraulic oil with kerosene) and let it soak for a few days?

2- you could drill a hole radially through the LS at the gearbox end, then use a rod to lock the LS. If you keep the hole say 4mm it will not significantly weaken your leadscrew.

Do not be tempted to use a pipe wrench on the naked leadscrew. Its disrespectful doing that to a precision machine tool part, no matter how old it is. Pipe wrenches are made for plumbers to use on pipes, not lathe leasdcrews. There are other less destructive methods to try first should 1 and 2 above not work. Chris

Yeah Peter, even I'd draw the line before using Stillson's on a leadscrew. How could you be so brutish to the old girl?

Just a thought: If you had access to a worn set of half nuts (probably too risky on a good pair), these mounted in a vice could be used to grip the leadscrew?

Jordan

Thanks for the tips everyone, all good suggestions.

I kind of took the advice of holding the leadscrew without the leather, but I contemplated making a pair of brass jaws - one with a concave shape in it to match the leadscrew, the other with the same concave shape and a protrusion to match the leadscrew spline. I then made my brass jaws very crudely with hacksaw and file and without the protrusion, used those in the vicegrips VERY tight and managed to get the nut undone without damaging anything.

Now on to the gearbox itself.

Glad it came off,sometimes it only requires a little extra pressure on the leadscrew to release the nut.