Those two links look like the same information? One cheap, one expensive!

Does the machine have a vertical head?

Edited By not done it yet on 19/01/2020 17:51:10

I know it's not a lot of help, but I've got both – albeit on a slightly later Automill which is a 2B with knobs on. To be strictly accurate the left hand threaded one is ex Deckel, so maybe they're special, but I would normally expect the nut to be right handed.

I've just had a quick check in the manual for the 2A and it just says undo it, but doesn't give any indication of whether the arbor would be right or left hand thread. It's a pound to a pinch of snuff that the arbor isn't original, so I think you're on your own.

Apologies if you already know this, but be sure to have the outboard bearing in place to support the end of the arbor before swinging on it. After than try lefty-loosey first, if that doesn't work go for the left hand option. I think it's less torture to the machine to give the spanner a good clout with a soft rawhide mallet with the drive in bottom gear than trying to wrestle with it. A bit of gentle warmth probably won't hurt – eg from a paint stripper gun.

Someone will be wincing at the idea to hit against the gears – yes OK but they are gert steel lumps and you'll have to try hard to damage them.

Good luck and do let us know how you get on.

HTH Simon

Edit – my post is now irrelevant, but good luck with it anyway

Edited By Simon Williams 3 on 19/01/2020 18:35:47