Hi,
My steps per are set to 400, I guess I should halve that ?
For a given set of parameters (pulses/rev, ballscrew pitch, gear/belt reduction) there is one and only one right answer. You
cannot set it at will UNLESS you also change the parameters that determine it.
Are you going to change ballscrews? No, I didn't think so. The parameter of ballscrew pitch is fixed.
Are you going to put gear or belt reduction instead of direct drive? No, I didn't think so. The parameter of gear/belt reduction
is fixed.
Are you going to change your stepper drive microstep regime. You certainly can, it easy and costs nothing.
On the one hand you want to set the pulses per rev (PPR) as high as you can to get the smoothness of motion that
microstepping offers. On the other hand high PPR means high pulse rates and so Machs parallel port may limit the ultimate
speed of your steppers.
The calculation with the existing PPR setting of 2000:
25,000 /2000 x 60 = 750 rpm. With a 5mm pitch means a max velocity of 3750 mm/min
If you want to go faster then you have a couple of choices:
1) increase the parallel port kernel........OR
2) get an external controller like a SmoothStepper which can output up to 4Mhz....plenty.....OR
3) reduce your microstepping regime to 1000 PPR say.
If you choose the later then the same max speed calculation becomes:
25,000 / 1000 x 60 = 1500 rpm or (5mm pitch assumed) 7500mm/min.
I rather doubt you'll be able to get your steppers to go anything like that speed, especially with such a low voltage supply,
however Mach's parallel port will give you that head room.
The potential resolution assuming 1000 PPR, 5mm pitch and direct drive is:
5 / 1000= 0.05mm......which is probably quite adequate for a router.
If you assume 1000 PPR the last parameter is now determined. The 'Steps per Unit' in the motor tuning page is:
1000 / 5 =200 steps per unit. Once again this is fixed by other choices you have made, the ONLY way you can change it is by
revisiting the choices you made for those parameters.
To get your steppers to go as fast as you can you should use the highest voltage that your drivers can handle. They are rated to 50V.
You should be using a 48V supply. I have seen different recommendations for the voltage, including one formula that looked
interesting but the bottom line is use the highest you can, in your case 50V.
I have Vexta 5 phase steppers with genuine Vexta drives. Each drive has its own power supply built in, you just hook it up to
230VAC and the drive does the rest. The DC voltage the drives use to move the motors is about 150VDC!!! It really makes
those steppers sing. They can do 3000 rpm with pretty good authority, ie not losing steps, but I run them at 2400 rpm max
just to be on the safe side. I doubt you'll find any drives for two phase steppers to match those but it does show the principle.....
high voltage equals high speed.
Craig