I can´t seem to get my lathe spindle to go faster than 935 rpm (according to the index pulse).
The motor is supposed to do 3600 rpm but no matter what i do, it´s not going faster.
I use a servo motor with encoder connected to the smooth stepper through a servo motor drive.(step & dir)  http://www.cnc2all.com/servo-engine-driver-eng.html
It doesn´t seem to be anything wrong with Mach setup so does anyone know if there is a setting in the smooth stepper that solves this...

Thanks!

Have a look in Spindle Pulleys and check you dont have a max spindle of more than yours is set for.

Hood

Just fitted a smooth stepper which looks OK on general turning.  Tried a thread prog. with the programme spindle speed   100RPM the actual speed is 108RPM a tacho confirms this.
Also the turning diagnostic does not work i.e. cannot see it on the screen. The system worked OK using the printer port? is the spindle feedback not working.

Not sure I am really understanding your problem. You command a spindle of 100 and the feedback reads 108 and you confirmed it is 108 with a tach?
What kind of setup do you have for the spindle?
Have you done a thread and if so what was the problem with it?

Turn Diagnostics was only written for testing purposes during Arts re-writes of the Parallel Port driver so does not concern the SmoothStepper as it doesnt use the driver. Further to that the Turn Diagnostics no longer work with the latest versions of Mach even if you use the parallel port.

Hood

Don't enable the Turn Diagnostics in plug in's. Also have a look at section 7.1 in the Threading on the Lathe write up. I am not sure what you mean by the 100 rpm. If you use  the wizard and input 100 rpm for spindle rpm, when in turn, the true rpm based on the single index will be used. So The feedrate will be changed accordingly. You should see an acurate rpm in the DRO though.
I haven't used my SS in some time so Hood would have a better handle using it.
RICH

The thread Gcode file is generated by Bobcad V3 a line contains S100 I think this means the spindle speed should be 100RPM.

The required spindle speed 100 is in one box the box above actual spindle speed 108RPM , in the setup for the spindle Use spindle feedback in sync mode ticked,
close loop spindle control ticked,spindle averaging ticked. Motor control use spindle motor output ticked PWM ticked. PWM base frequency 20.

What is spindle ratio control which reads 0.1221

The SS is connected to I think a MB-02V6 and a Digispeed DC-03 and a single slot index disk.

I want to cut a thread with 3mm pitch 28 mm dia. I am awaiting some hard wax to cut the thread on so not to waste metal.

I hope the above makes some sense

 

Ok so you command a speed of 100 and in reality you get 108, that is not likely to be a problem as it is probably more to do with your tuning, although I have to say I have never used anything other than servo spindles so have no experience of VFD control.
When threading with the SS the true spindle speed will be used so I dont think you will have any issues at all.
As a test if you MDI M3S100  does it go to 108 true? What about M3S500? what about M3S**** where S is the max for your spindle.

Hood