On Thursday 07 August 2014 04:57:50 David Armstrong did opine
And Gene did reply:
> Gene
> go for the highest voltage the drivers will take, i also tend to buy
> the drive that can take 60v+ , i run mine mostly at 48v or 60v , it
> makes so much of a difference it's worth it
> 
> Dave

When I last "rebuilt" the mills control box, I had not fully understood 
that, and there was an ultra cheap medical grade 28 volt nearly 12 amp 
supply at all-electronics I could get for a $30 bill.  But for reliable 
duty, I find I can't ask it to move, with the ball screws in the XY, more 
than about 18 ipm.  When I built the same box for the lathe, I raided the 
midden heap and was able to get a choke input put together that made 
around 37 volts.  That extra 9 volts on the z motor, which is geared down 
2/1 to the ball screw, allows it to march right along at 60ipm dead 
reliably.  The change in performance seems all out of proportion to the 
change in voltage and its amazing to see the damper on the Z motor looking 
like its turning well over 1000 rpms.

Find suitable psu components to cobble up the higher voltage supplies is 
always a frustrating task.  So for an input choke on the lathe, I have the 
primary well isolated, and am using the 5 volt winding of a filament 
transformer as the choke.  At around 6 amps load, its likely near magnetic 
saturation but is aided by running the 8 wire X motor is series mode since 
its speed is quite sufficient to do a G76 threading operation at 6 or 7 
hundred rpms even in that mode.

But the mill, with its 4 motor load, needing 2x the amperage, will 
probably wind up with another analog psu external to the box.  The 28 v 
unit in it, also has a 5 v logic supply output that runs the BOB, so if I 
remove it, I'll need to find a substitute for that.  Those are commodity 
items though, and not a problem to source at reasonable $.  All I need is 
time & luck at finding the power iron.

Choke input filtering is much easier on the transformers as they can 
deliver more current for the same amount of heating, and the unregulated 
output is much better regulated.

With several thousand mf on the output side, these drivers & motors seem 
to love it.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>
US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS

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