Re: CNC upgrade

Hello Peter,

Seems to me that 7 IPM is pretty slow for the motors you have. It that low
feed rate caused by your motors losing steps or by your computer not being
able to step at a faster rate?

I initially had DeskNC running on a 486 SX25 and it was not capable of
driving the motors beyong about 8 - 9 IPM. I could put in any faster rate I
wanted, but that was as fast as the motors would go. I upgraded to an AMD
K-7 2D 350 and now I can reliably get about 25 IPM and the limitation is the
motors and machine, not the computer as it is happy to try driving the
motors much faster, but they protest.

I am not quite following what you mean by "I would like to upgrade the
programming department "?
Do you mean that you would like to find a different program than the
Compucut HPGL to drive the steppers electronics? If so, you may want to look
at as I know it has the ability to drive unipolar 'phase' systems. I don't
think though that the 386 will cut it.

Have you considered changing to a bipolar stepper electronics? You will get
a lot more power out of your motors and can run a much higher voltage which
will help to bost your feed rates. I would suggest looking at Dan Mauch's 5
amp chopper driver kit. Then you will have a much greater range of programs
you can use as it seems more of the software supports the step and direction
signaling.

Tim
[Denver, CO]

---original message-----

>>>Hello to all you professionals

I have been following all subjects for about four weeks now, I find it very
interesting but I must admit a lot of the electronic & technical stuff goes
over my head.
I am running a far eastern mill 13" X 5" travel with 3 type 34 steppers
2 1/2 volts, 4 1/2 amps (27 amps total running) with 2R0 50 watt resistors,
10tpi leadscrews direct drive, unchecked ( no encoders) max speed 7"p/min
and using a compucut program (HPGL) and interface in unipolar mode, I had
loads of problems with missing steps and interference between axis when I
first set it up, until everything was screened and a good interface cable
was used. It has been very stable, and has ran successfully for about 2
years, At 10 volts I can run all day and the motors just get warm, but I
can push it up to 12 volts for a couple of hours or so if I need the extra
power. It has served very well for the type of work I have been doing.
I would like to upgrade the programming department ( at present
running on an old 386 SX 33 with DOS 6.22 ) , are there any packages that
would run with this interface, or would I have to upgrade to a bi-polar
device, I would prefer 4 axis if I had to change the interface, to include
the dividing head (any idea of costs).
If I had to change the interface, I would use the old one on a
Sherline Mill which I have standing idle at the moment, so it would not be
wasted.
I like the sound of linux and emc for the future, but it does seem a
bit complicated to set up, I priced linux 5.2 locally here in the UK, it
came out at �39.50, but I think I can Get it cheaper as a friend got version
6 for �25.00
I have no other experience in electronics, computing, or
programming, other than creating the above conversion, but learnt a little
in the process.

Yours Faithfully
Peter Smith <<<