Re: Max stepper speed (Sherline)

Peter,
I have a similiar setup on my Sherline 5400 mill. Sherline steppers
wired using half winding, 2A Camtronics driver in half-step mode, a
homebrew power supply consisting of a 24VAC center tapped xformer and
a 10,000MFD cap which runs about 36VDC output. Am using the Sherline
CNC stepper kit, CNCPro software and a 133mhz box. The motors will
sing right along at 60 in/min in all three axis. (Not that you would
want to, I usually keep the max velocity at around 20 in/min).
Contact me off list and we can walk through our systems and see what
we can do. The problem is NOT your steppers or driver. I started
with a 12VDC power supply and got about what you are reporting, the
higher voltage made the difference.
Good luck,
al
PS After reading some of the other posts, I got to wondering if my
memory was failing, actually it is :), so just did a quick check.
The x and y easily went 60 in/min but the +Z stalled out at 50. Had
to put a drop of oil on the Z leadscrew, then it was OK at 60 also. I
have the handwheels, so can use them to confirm that it comes back to
zero, and used a stopwatch to verify timing, ie, 2 inches in 2 sec, 3
inches in 3 sec etc.
al

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "forumtvm" <forumtvm@y...>
wrote:

> "IMService" <imserv@v...> wrote:
> Check out this chart:
>
>http://www.empiremagnetics.com/global_pages/torque_charts/calc_st_tor
> q_U21.htm
> >
> > They have graphed the torque curves for a stepper motor at

various

> > supply voltages. Note on the top chart (2 amp motor), curve #2.
> At 5 rps (revolutions per second)
> > the torque drops from over 50 to around 17.
>
> "Daniel J. Statman" <titanium@c...> in Sherline group wrote: "I am
> using TurboCNC with a 75 MHz Pentium 1 computer running DOS. I have

a

> 26VDC power supply connected to a Xylotex drive running NEMA 23 180
> oz-in stepper motors (200 step per revolution) running in 1/8th

step

> microstepping mode."
>
> I am using the Sherline 9.7 kg-cm (134 oz-in) stepper, camtronics

2A

> driver, 36VDC supply, and steppers stalling badly at 16-18 ipm, and
> greedy for more.
>
> Hope Statman is reading this post. Is the 180 oz-in stepper a

triple

> stack? A 180 oz-in stepper is only a 34% improvement over my 134 oz-
> in, which proportionately will be 24 ipm, so there must be

something

> I can do to improve the performance.
>
> What can I do to get the Statman kind of performance?
>
> Peter