Hi,
What is the term for that? Its like a stall
Just 'stall' or 'losing steps'.
Looking further, with a 5mm pitch it appears I am asking the steppers to run at 400rpm and that seems to be the limit with the torque dropping right off yes?
All stepper motors, irrespective of design drop torque as the speed increases. The principle determinant in how quickly the torque
degrades is the inductance of the motor. The most common specification of a stepper is its holding torque, in your case
425 oz.in. Inexperienced buyers tend to focus of holding torque. Savvy buyers on the other hand look for the inductance
of a motor, the lower the inductance the better because the motor will run faster with less torque degradation.
It may well be that if you bought steppers of the same size (23) and holding torque (425oz.in) but low (less than 2mH)
inductance would handily outperform the steppers you have. It may be also that if you bought lower torque motors,
say 300 oz.in but had really low inductance, 0.8 mH say, they would do better than your more 'powerful' steppers.
Often steppers that have very high holding torque also suffer from high inductance. If you were going to replace them
look for motors of less than 2mH or better still 1mH. If you can't find a specification for inductance or a speed-torque
diagram then walk away, they are being pitched to newcomers, and you are not. If the manufacturer or supplier cannot
supply a spec then they are rubbish.
One way to counteract the negative effect of inductance is to increase the voltage of the driver. Gecko, Leadshine and
other leading manufacturers offer drivers capable of 80V. Were you to use one of those drivers
and 70-80V power supply your existing steppers would go a lot faster before losing steps.
https://www.geckodrive.com/g203v-digital-step-drive.htmlhttp://www.leadshine.com/productdetail.aspx?type=products&category=stepper-products&producttype=stepper-drives&series=AM&model=AM882What you have discovered is that your particular steppers with the load of your gantry have borderline sufficient
torque to maintain steps at 400 rpm with your current driver. With either lower inductance steppers and/or higher
voltage drives and power supply you might find you could double or triple that limit.
Its not impossible that the kernel speed of Mach3 is limiting the rate that steps can be taken, but this occurs when you
have made an unrealistic choice of microstepping. Further your description of the symptoms and noise suggest losing
steps not any limitation on the behalf of Mach but rather just the plain loss of torque at speed.
Craig