Re: Resonable Stepper Speed under simple Unipol ar drive ?

Mark,

Good to know you've had some success...

Since you've determined that resonance is limiting you, how about
changing it? Many ways to do this. Everything from oil-filled
Lanchester dampers on the motor shafts, to simply
decreasing/increasing the load reflected to the motor(s)...

Try changing something; could be gib adjustment, pulley ratios, power
supply voltage, belt tension,etc... (The idea is to "move" the
resonance if possible to a part of the torque curve where it is
either more easily passed; or where it does not come into play.

One thing some people try out of just not knowing is to increase the
amperage to the motors, figuring that more amps equals more torque,
so that hasta be good, right? But it isn't... So try REDUCING the
amperage to your motors. Sounds likke fo ryou that means adding
resistors... You may be surprised to find the resonance reduced.

While you are fighting a tough battle here, it's one that has been
fought before, and it IS sometimes possible to win<G>

Make some changes and see what happens,

Ballendo


-- In CAD_CAM_EDM_DRO@yahoogroups.com, Mark Thompson <Mark_T3@v...>
wrote:

> Thanks Guys
>
> I just wanted to know that I wasn't completely insane.
>
> This is on an old Jet 9X44 Mill running 3:1 on the original
> lead screws.
>
> It works great as a CNC machine it just slow a snail on a salt

lick.

>
> I have tried to drive the system with the following drivers:
> Mach1
> EMC (Linux)
> Wave Tek (pulse generator)
>
> What I found was that if I pass through the resonate point at just

the right

> acceleration I can get the motors to around 400-500 rpms. But it is

imposable

> to operate near the resonate point with the L/R drives.
>
> Also I found that PC power supplies (IE: CHEAP Switcher) don't work

without a

> significant amount of bulk capacitance to filter them. I ended up

with 50,000uf

> of filter caps on each one to keep the regulators from oscillating.
>
>
> Thanks all
> Mark
>