Lathe alignment. What is good enough?

[NJHParticipant @njh]

Ah!

Yes Skarven – I see your problem. I guess we are lucky here with good access to reasonably (?) priced bits and it’s difficult to remember that others might not be so lucky.

So I guess my post was useless – still Good Luck though!

 

Regards

 

Norman

[Sub MandrelParticipant @submandrel]

I’m with Terry on this one.

 

How many of you folks have heard of the Schelsinger limits?

 

If you adjust your lathe to be perfect with one material/tool/depth of cut or with a dial gauge, then it will be perfectly adjusted for that situation.

 

Change material, depth/rate of cut, tool or even workshop temperature and it will no longer be perfect. The late Tom Walshaw explained all this better than me, but in short the Schelsinger limits are what you should aim for when setting lathes to factory floor/toolroom/precision measurement situations. They allow for errors acceptable in those situations and aim to get the lathe set up so that the errors imposed by tool loads, bed flexing, the weight or flexibility of the work etc. all act to reduce the errors. I.e. the lathe is set to be acceptably accurate and in a way that in practice you won’t get errors worse than these. It’s very clever and I admit I don’t understand everything about it, but it shows that attempting perfect lathe adjustnments is like catching rainbows.

 

Neil

[Author]

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