Slowing down a plotter

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Slowing down a plotter
rbarrioss
10-09-2007

rbarrioss posted on
October 9, 2007, 5:08 am

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Hi all,

I've got a Roland DXY series plotter that I use to directly draw PCB
tracks on copper. I'm currently getting acceptable results but it
would work much better if I could further reduce the plotting speed
(yes, I'm already using the slowest speed).

I don't have experience with stepper motors but I assume (wrong?) that
if I run the microcontroller on the plotter mainboard at 1/2 the
current clock speed, the plotting speed with also becamo just 1/2 of
the original. I expect that (at least) as a side effect the serial
port communications will also require 1/2 the bps speed.

I'm thinking in changing the crystal (I haven't even checked it's
frequency yet) and give it a try.

Could it work at all? Am I completely wrong?

Thanks a lot,
Roberto

Don McKenzie posted on
October 10, 2007, 4:32 am
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Re: Slowing down a plotter

I think I still have one of these hanging around here somewhere. I did
the same thing many years ago, that is, draw directly to copper.

From what I recall, it wasn't a great job either. Glad some decent CAD
packages came along that allowed us to submit artwork directly to
manufacturers.

But the nature of rs-232 comms means halving your crystal frequency,
should allow you to run your comms at half speed without error.

Don't know about any other time critical functions of the Roland. I
would suck it and see. What have you got to loose?

Don...

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rbarrioss posted on
October 15, 2007, 4:35 am
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Re: Slowing down a plotter

cards.http://www.dontronics-shop.com/product.php?productid 659- Hide quoted
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Yes, I'll give it a try.

Thank you
Roberto

aiiadict posted on
October 11, 2007, 3:08 pm
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Re: Slowing down a plotter

seems like it would work....

maybe instead:  cut the traces that power the transistors that go to
the stepper...  put a circuit between the ?CPU? and the transistors
that will "divide by two".    should be able to do that easily with a
PIC...

how many coils does the stepper have?

on PIC:

INPUT1 (coil 1, from plotter CPU)
INPUT2
INPUT3
INPUT4

OUTPUT1 through 4 (going to driver transistors)

state1 through 4 (variables holding previous state of INPUTS)

when input1~4 <> state1~4, the CPU has stepped the motor.

you would need a table of some sort to OUTPUT to the driver
transistors.