Homebrew PCBs

For what it's worth I'm using unipolar (6 wire) steppers (the stock Sherline
steppers) on my milling machine, and they're being driven by a Xylotex board,
which uses the Allegro 3977 chip (bipolar driver) using 1/8 steps.

I have them wired up such that I'm only using 2 of the 4 coils. I'm currently
running the X & Y axis at 20 IPM which corresponds to 400 RPM (cause I have
20 tpi leadscrews). This works fine for machining purposes, so it should be
more than adequate for drilling.

If you decide to go with two coils in series, then you need to drop the
current by half (you wind up getting the same amount of torque, but the
increased resistance lowers your high end speed).

By adding some vibration dampeners (see the files section of
http://groups.yahoo.com/group/ComputerControlledMotion/) Jeff was able to get
90 IPM using a similar configuration.

> -----Original Message-----
> From: Homebrew_PCBs@yahoogroups.com 
> [mailto:Homebrew_PCBs@yahoogroups.com] On Behalf Of Alan King
> Sent: Wednesday, June 22, 2005 6:37 AM
> To: Homebrew_PCBs@yahoogroups.com
> Subject: Re: [Homebrew_PCBs] Unipolar stepper motor driver wiring
> 
> 
> 
> > I wouldn't be too sure 'bout that.
> > 
> > By the way, you can use a unipolar stepper in bipolar mode 
> as 2 phase  
> > motor. I've heard it works well.
> > 
> > ST
> > 
> 
> 
>    Have to be careful with this though, four coils on instead 
> of two, so you 
> have to make sure your motors are designed to run that way as 
> well.  More than a 
> few will overheat if you use full power in all four coils.  
> Definite improvement 
> for the ones that can run this way though.
> 
> Alan