Re: camtronics vs gecko

Andrew,

I started putting my system together about two years ago. Sherline
mill, Sherline steppers wired half coil, Camtronics 2A board half
stepping, CNCPro, PC is a P-133.

Started with an old (tired) PC 12VDC PS, which pulled down to 8
1/2 or 9 volts under load. Rapids were very dependent on loading,
maybe 15 or 16 IPM in X & Y, but only 8 or 10 in the plus Z. Tried
various other software demo's, some I never did get to do more than
stutter and jump. CNCPro was recommended by this list and it did the
best of the ones that I tried.

Then built up a 36VDC PS. Rapids jumped up to 60 IPM, and all axis,
(I have 4) top out at almost exactly the same place, (that is about
8000 steps/sec). The Z runs just as fast going up as down. It would
seem that the limit is now determined by something in the system
other than the size of the steppers. Needless to say, that is more
than enough for a Sherline IMO. At 60 IPM (1200 RPM) the imbalance
of the Z-handwheel will cause the entire machine to shake! I usually
keep the MAX speeds set at around 20 IPM or less.

I hope this gives you a feel for what your system SHOULD be capable
of. One last thought, the software has to be 'tuned' just right to
achieve these speeds. Some is trickier than others I think.

Keep trying,
Al Lenz

P.S. The PS is a 24 VAC, 10 Amp X'former that I got from Marlin P
Jones for about $17 as I recall, a 10,000mf cap and a pretty husky,
(but inexpensive), full bridge rectifier. This unit weighs a ton but
it stays in the 34 - 36 VDC range under max load. This was the only
thing that I changed to get the big jump in performance.
al

--- In CAD_CAM_EDM_DRO@y..., "andrewyslee" <andrewlee@s...> wrote:
> "Tim Goldstein" <timg@k...> wrote:
>
> > To get good microstepping you need to have the voltage in the
10 -
> 25 X
> > the rated motor voltage. Half stepping is very tolerant of low
> voltage.
> > What is the voltage rating of your motors?
>
> 3.2V 2A
>
> So 10X - 25x will make it 32 - 80. I have a 24VAC transformer
which
> makes the PS 36VDC which will take it to the lower of the range
you
> mention for the Gecko.
>
> > You say that you are "faulting out". Tell us more.
>
> I mean the motor making chattering noise without any movement.
>
> I have previously noticed that sometime when you set your max.
> stepping rate to a low enough value, one can enter 1000 ipm and
the
> motor will whirr happily without any problem, but at that max.
> stepping rate, not the commanded ipm. In this case, when I command
a
> move at, say 11 ipm, the motor just shudder, but does not move.
>
>
> What software are you
> > using and is the fault something the software is throwing or do
> you mean
> > the drive is actually having a hardware fault?
>
> I am using DeskWinNC driven from a P3
>
>
> I will guess that you may
> > be using EMC and are seeing a follow error under freqmod.o. If
so
> you
> > need to tune the PID loop to eliminate the follow errors as they
> are
> > totally software derived and related to your increased step rate
> and
> > have nothing to do with the ability of the drivers.
>
> Wish I can muster up enough courage to migrate to Linux, but that
> will be a future project. Unfortunately still stuck to Bill Gates.
>
>
> Getting flooded with emails, but vaguesly remembered some posts
> where someone was using almost the same config - sherline-
camtronics-
> sherline motors but getting much higher speed > 30 ipm. What do
they
> have that I don't?
>
> Thanks
>
> andrew