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Smart and Brown Lathe Crosslide Screw Renewal

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Divided he ad:
Carry on with this one Darren,

Sooner or later some of us will be doing similar to our machines.... It's always good to have a reference article to browse to help you on your way  :thumbup:



Ralph.

Darren:
Thanks guys, I will continue later...

One thing I forgot to mention was the the "handle" end was machined to size after fitting it to the thread buy holding the threaded section in a lathe collet.

This should make it true to the thread.. :D.

Next job it to make the nuts, thinking of what material to try here....back later... :headbang:

bogstandard:
Darren,

The accepted material for the nuts is bronze (PB1), if you try brass, I think you will find it will wear very quickly. Steel is definitely a no-no, the nut and screw are liable to gall and friction weld together.

John

Darren:
Opps, bit of underlining there...!!

I have some PB1 for one nut but not big enough dia for the other (I could get some of course), but I was thinking of trying Delrin or Teflon both of which I have.

I thought it might be interesting to give them a go?

Darren

bogstandard:
Darren,

You have to remember, the lead screw and nut is not just for positioning, they take the full force of the cutting action. The metal is pushing against the two parts because it doesn't want to be cut, you are forcing the cutting tool into the metal.

That is why you have all your correct cutting angles and clearances, it helps to take the pressure off the cut, so the machine doesn't have to work too hard.

You can try it, and prove me wrong, but I suspect you will start to have trouble almost straight away with the finish, as the tool bounces backwards and forwards because of the flexibility of the nut. You could eliminate the pressure on the nut by tightening the jib lock before starting the cut, but that is not an ideal situation.

John

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