Re: Stepper Motor Resonance ?

[Ray Henry <rehenry-at-up.net>]

I didn't really have the time to do all the tuning but I've noticed that 
freqmod.o seems to loose steps on the two most recent installs that I've 
done.  These were with both TNG and 2.18.  Sorry that I didn't have the 
time to really sit down and figure out what was going on with them.  
Steppermod was enough for both.

Now to the resonance problems.  Dean is right on in suggesting that you 
look at the drivers.  Resonance is really encouraged by full step drivers 
and is somewhat of a problem with half step drivers.  It is discouraged 
by micro stepping stuff like that used in the Gecko drives where multiple 
steps per input pulse are done by stepping through all of the microsteps 
to get to final position.  

Ray


On Sunday 24 November 2002 05:26 pm, you wrote:
> On Saturday 23 November 2002 04:45 am, Tim & Heather Smith wrote:
> > Has anyone out there had any problems with resonance when driving
> > stepper motors?
>
> Definetly try freqmod.o,  makes a big improvement.  Be prepared
> to spend some time tweaking emc.ini if you do.
>
> Also,  what type of driver are you using for those steppers?
> Switching to a good constant current type made a difference in my case.
> The fact that this type of controller overcomes the inductive reactance
> of the motors seems to supress the resonance issue.
>
> Well heck, might as well do a review on my controller right now for the
> benefit of the rest of the list.   Here is the one that I am using:
>
> http://www.brewingtontech.com/
>
> This is a pretty good deal for the EMC stepper user. 3-axis -at- $115
>
> The specs are here : http://www.brewingtontech.com/ds3ax7026.pdf
>
> Pros:  Low cost,  constant current, Good heatsink,  fan connection
> provided. Up to 3 amps per phase.   Nice connectors,  easy hookup. 
> Extra inputs are bused for emc inputs (limit switches probe input
> etc...)
>
> Cons :  Step/Dir are not on the standard emc pins.  So I cut
> traced/jumped the pcb.  The is a nice area on the board to do this.  
> Board does not have "idle mode" so constant current flows even when the
> motors are not moving. I accomodate this by having a switch to turn off
> the driver when idled (but I may add my own watchdog circuit to do
> this, should be easy)
> You have to purchase a seperate high amperage 32VAC transformer to
> power this controller (Brewington does not sell it).  I purchased mine
> from a surplus mail order house.
>
> Overall I am pretty happy with it.