Hello Neil,

2 degrees and 25 minutes inclusive. Source Tubal Cain Model Engineer's Handbook 3rd Edition

Brian

Hello Emgee,

I was only quoting what the great man had published, but I agree with you; checking Morse taper standards shows the half angle for say 2MT is not far away from half that value..

Maybe the figure should have been for the half angle, running a taper as fine as MT would grab and lock up in moments.

That would make the bearing taper Neil needs to be 4 degrees and 50 minutes, more in the category of self releasing too. Well spotted!

Regards Brian

Hello Phil,

Tubal Cain's book could have a typo then, that would make the angle 20 degrees 25 minutes—it makes a lot more sense at that. I have in the past taken my spindle out and from memory it is as you say, a much steeper taper.

Sorry Neil, it's all looking like a bugger's muddle now, maybe someone else can weigh in with a correct answer.

Regards Brian

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Now there IS a surprise !!

MichaelG.

I’ve got a spare Super 7 spindle here and just carefully eyeballing it, the taper I get is 12.5 degrees inclusive or 6.25 from the axis. If you’re making your own spindle and bearing, I don’t suppose it’s critical.

Tubal must’ve missed a “1” off the start of his figure.

Based on your first post Neil, you appreciate that any thrust towards the headstock is actually taken by the angular contact ball races? I hope I’m not insulting anyone’s intelligence but the comment about Morse taper angles doesn’t make any difference because the taper plays no part in resisting movement along the bed. It’s purely there so the running clearance can be controlled.

Absolutely. A taper the equivalent of a Morse would need very careful adjustment. Binding may not be quite such a problem with steel against bronze but the point is well made.

When Myford designed the S/7 it was in a time after the war had just finished and the UK was involved in the Korean war and priority was for aircraft and armanents ,lots of industries suffered from this having to modify their products due to non availability of things like alloy steels,chromium plating etc and suitable bearings may not have been available,also there is a lot to be said for plain tapered bearings they do help achieve very good surface finishes ,German instrument lathes used both tapered bronze bearings and hardened steel bearings. If Myford had selected a tapered roller bearing then, I expect that everyone would be now moaning that the type of bearing selected was now obsolete ,at least a bronze bush can be machined up to suit,

My old company circa 1985 purchased a lathe for diamond turning fine finishes and that had plain white metal bearings .