[How-To] Conversion to VFD

[matthewsx]

Thanks for this John. Why won’t braking work for a screw on chuck? Too much chance of it undoing under the pressure of suddenly stopping?


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Yes, there are only two use cases for braking I can think of, faster production work and emergency stop.

When I got my new to me lathe I reversed it and spun the chuck right off, kinda scary and made a big thud as it hit the wall. Fortunately nothing broken and nobody hurt. Now I have it set to only go forward, might change that eventually but haven’t needed reverse yet. Also haven’t gotten into an e-stop situation but it can certainly happen.

John

 

[Ben17484]

Yes, there are only two use cases for braking I can think of, faster production work and emergency stop.

When I got my new to me lathe I reversed it and spun the chuck right off, kinda scary and made a big thud as it hit the wall. Fortunately nothing broken and nobody hurt. Now I have it set to only go forward, might change that eventually but haven’t needed reverse yet. Also haven’t gotten into an e-stop situation but it can certainly happen.

John

Wow, that’s scary.

By faster production work, do you mean quickly reversing the spindle to reverse the carriage for threading etc? Like this guy does here:

(at the 11 minute mark)?

I wonder if there’s a way to modify a lathe with screw on chuck to have something to lock it fully in so it can’t spin off?


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[rabler]

Thanks Rabler. Is the same speed necessary or would a faster speed be ok too? I know my lathewasn’t designed to take faster speeds, so I wouldn’t run it that fast, but if a faster motor at a good price comes up for sale, there’s no reason not to buy it and run it slower, right?


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That’s not ideal, but will work. Say you start with 2 motors of the same HP, but one runs at 1800 and the other at 3600 rpm. If you take the 3600 RPM motor and run it at 1800 rpm with a VFD, you get roughly 1/2 the HP as the 1800 rpm motor running at 1800 rpm.