If it was able to turn metal - builder would upload it for sure. Just makes me think is it not rigid enough???? not able to turn metal???
Will you Jonathan treat us with some action video??
This lathe has sat on the side doing nothing since I posted here, just not had time for it. A few days ago a 12Nm stepper motor arrived, which just so happens to fit the lathe mount, so how could I resist using it to power the spindle?
A few moments later:
I had to take the covers off since now I don't have the right length belt which means the motor is in a funny place. I chose a 36:22 (motor:spindle) ratio since if we take the speed/torque curve from Zapp's site and convert it to more meaningful units, the peak power is around 600rpm so around 1000rpm spindle speed with that ratio.
I've only got the motor on 70V (DM860 drive), so that graph isn't ideal, but it seems to work well and runs the spindle up to 2000rpm. The motor was fine with drilling a 6mm hole in aluminium and general turning. I think I'll make a bigger pulley for the motor and try it anyway. The finish leaves a bit to be desired, but I think that's mainly the lathe itself being weak and having to have the material quite far from the chuck as currently the rear shaft on the motor interferes with the saddle. I don't think that will be a problem with the longer belt and if it is I can easily mill a little bit off the steel block I attached to the saddle to get clearance.
I configured LinuxCNC to run the stepper motor as the spindle by editing the .hal file - pretty simple. Next step is to get G33/G63 to work so I can do threading. I could just run it as an A-axis and program a ramp (e.g G1 Z-10 A10), but I'd prefer to do it properly...
Anyway, it seems this thread is useless without a video, so here goes:
Edit: Almost forgot to mention I solved the backlash problem on Z. Turns out it was just the belt being a bit loose, tightened it up and now the backlash is essentially zero - the 0.0001" indicator returns, as far as I can see, precisely to the same mark if approached from either direction.
I just need to make one piece for the X-axis so I can put the second nut in to get the same result. I wonder where the Belleville washers went. I think I've broken the magneto bearings whilst working out what was wrong, so I'll buy some better ones. He's got 708A and 708C so presumably that's the different contact angles - it would be good to know which is which so I can get the ones that tolerate higher axial forces!
Last edited by Jonathan; 22-09-2012 at 05:49 PM.
Looks fantastic Great video mate
Fiction is far more plausible when wrapped around a thread of truth
Nothing great was ever achieved without enthusiasm.
Ralph Waldo Emerson
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