RE: [CAD_CAM_EDM_DRO] Request for Comparison/Explanation...

Hi, Ian:

|A) Gecko Drives versus Camtronics 3 axis 2A board... do these
|essentially
|serve the same function?... I realise the Geckos cost more and I'd
|need one
|for each axis but are capable of ~7A and are pre-assembled... I'd only be
|driving the sherline motors so 2A is ok... comments?

Yes, the Geckos and Camtronics perform the same task - accepting step and
direction input and converting it into bipolar sequenced currents for the
motor coils. While the Geckos are preassembled, be aware that you will still
have some electrical assembly with either of these solutions. You'll need a
DC power supply capable of driving the two (or three if you get the mill)
motors, power switches, enable switches (handy to remove all power from the
motors for some setup), fuses (from power supply and for each of the three
phase), etc.

|B) Any Pentium computer or better can run CNC right especially linux
|based?... what is more important CPU speed, memory or bus speed?.. any
|comments..

The pentium machines will work, but you can get by with 486's and even
lower. I'm using TurboCNC from DAK Engineering with a Zenith Z-Star EX (486
DX2-50, 8 Mbyte memory). Initially, I had problems with delivering a smooth
pulse train, but this problem was caused by the EMM386.EXE driver hogging
the processor when it was given control during an interrupt. Once I removed
the driver, I was able to pump out at least 4000 pulses per second before my
X motor didn't have enough torque to reliable turn the screw. The Y Axis was
2650 pps and Z was 4000 pps. The software itself could probably work a lot
faster, but the hardware won't.

I'm using Sherline's coupling kit for the mill and will buy their coupling
kit for the lathe when I decide to add CNC to it. Likewise, I'm using
Sherline's stepper motors. They're a bit pricey, but they have shafts on
both ends, which allows me to keep the handwheels on. Some folks will tell
you that, once you've added CNC, that you won't use the handwheels. I found
that having the handwheels, with their calibrated dials, is quite useful for
tuning the machine and determining whether or not backlash compensation is
working or if steps are being lost. Your mileage may vary from either of
these views.

The power supply can range from a simple transformer-bridge-capacitor to a
finely regulated supply. I chose a used regulated supply simply for
expedience; for driving motors, it offers few, if any, advantages from the
simple transformer-bridge-capacitor supply

Hope this helps.

-- Carol & Jerry Jankura
Strongsville, Ohio
So many toys, so little time....