Originally Posted by
RCaffin
there are lots of users that have been using Mach3 Lathe for threading for years without any problems
True I am sure. I had no problems with low diameter aluminium and plastic, as the motor and solid chuck had enough guts to handle them.
It's when the diameter goes up or you switch to steel that the torque required starts to worry the motor.
If the spindle slows down so does the Z axes to match the set pitch, you can even move the chuck by hand and the Z axis will follow
Ah ... if the Z axis is actually geared to the spindle, yes to the second part. But with most CNC lathes this does not happen. After all, why should it?
The first part can happen if you are running an ESS with the latest driver and an encoder on the spindle/motor. But this is a function NOT of Mach3 but of the ESS itself. That is, the sync is done entirely by the ESS as Mach3 does not know anything about it.
In more detail: Mach3 does sense the Index pulse and get the RPM from that, but it can only update the spindle drive once per revolution. If it is doing speed averaging it may not be even that fast. So the spindle can slow right down for a long way before Mach3 even knows about it. This can also be seen by the loss of thread-profile: the machined gap between threads gets wider. There are a couple of Forum threads on this on the Warp9 web site, some of them between Andy of Warp9 and me.
Cheers
Roger