Re: My cheap Chinese laser experience...


"Neon Forests" <moog@xxxxxxxxxxxx> wrote in message
news:311220072200149991%moog@xxxxxxxxxxxxxxx
In article <13ni96t2is1eke3@xxxxxxxxxxxxxxxxxx>, john jardine
<john.jardine@xxxxxxxxxxx> wrote:

"Neon Forests" <moog@xxxxxxxxxxxx> wrote in message
news:301220072118486731%moog@xxxxxxxxxxxxxxx


http://www.synthfool.com/laser

An interesting read!.

The Roland should respond to something like "VS 1,1" added to the top of
a
HPGL print file, (ie Velocity select #1, for pen #1). Is this not an
option?.



Thanks for reading. :)

It does respond to VS commands as low as 2 and that definitely helps in
slowing it down, but it's not quite slow enough.
I have to do multipasses on some materials to cut them.
Also I'm pushing the limits on the whole current vs torque issue.
As I slow down it down, it has a bit of a problem with torque or
overlapped stepper motor pulses (I haven't investigated yet) and so has
repeatability issues.
But I'm just a hobbyist here and it's a good start.
I may end up ditching the motors and electronics and starting off with
something better, but it was more along the whole "can it be done?"
thing than trying to end up with a piece of reliable production
machinery.

Kevin

Looks suspiciously like the stepper driver motors are being powered down
(too early) to a 'holding torque only' condition about 1/2ms after an X or Y
step pulse has ended (IC134).
A thought only, but maybe linking out R147 and R160 could keep motor power
applied all the time, thus can deal with the slower step rates at full
torque.
Personally, I'd be inclined to drive the motors directly from 2 external
stepper drives fed directly from that printer port. You could then set the
motor current at will. Seems lots of CNC progs available that will translate
HPGL (or G code) to printer steps under your direct control.
Or even, do the translate prog yourself with aBreshenam line and (maybe)
circle draw routine. Most CAD progs out there just seem to generate 'move
to' and 'line to' commands and ignore 99% of the available HPGL or G code
possibilities.
Having said that, I haven't a clue about Macs! and these things simply may
not be possible :(



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