Re: [CAD_CAM_EDM_DRO] Re: added laser cutter to my mill (pics)

Hello Rick,

Here is how I hope to do it. Maybe you will get totry it first.

Use the clock for the Z axis to pulse the laser for a fixed period on each clock pulse. That way the pulses occur at fixed spatial intervals. For example, you might want a pulse for every 0.001 inch of X,Y travel...regardless of travel direction. You would make a circle of equally spaced pulses by programming a helix. A straight line of equally spaced pulses is done by choosing the proper delta Z value for the line.

If you really need the Z axis for motion then create a 4th axis for the laser. Not sure how to sync a 4th axis but EMC may already do that.

Tom Hubin
thubin@...

*******************

-----Original Message-----
From: skykotech <rick@...>
Sent: Aug 5, 2004 9:16 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: added laser cutter to my mill (pics)

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Graham Stabler" <eexgs@n...>
wrote:

> This is a little off the cuff but here goes:
>
> To turn the laser on and off, why not define another axis, an
> imaginery axis really. Before a cutting move such as G01 just send
> what equates to a single pulse to this axis, to turn it off send

two

> pulses and have your little uP interpret these. This would need
> some sort of post processing of your gcode but it would be super
> simple for someone to write a little program to do it. I think

this

> would also mean that the turning on and off was done in the same
> time frame as machining i.e by the real time bits. Perhaps it is
> even possible to intergrate the switching into the single move, so
> if you were going to move in X,Y to make the cut you effectively
> define a 3D move but rather than in X,Y,Z it would be in X,Y,L

where

> L is the laser axis. So the laser would be turned on the moment

the

> moves started and if you were real clever about it you might be

able

> to use the pulse rate of the imaginery L axis to control laser

power

> so that at the start of the move the power would be less and the
> same at the end.
>

Graham, you da man! :-)

What a great and yet simple idea. In EMC I can just use pins 8 and 9
(the 4th axis) to control the laser on/off and power! Things are
spinning around in my head now...ok, so maybe use the 4th AND 5th
axis in EMC. The 4th axis direction bit turns the laser on and off,
the 5th axis step bit pulses increase or decrease the laser power
based on the 5th axis direction bit. Easy as pie to feed the pulse
line into the atmel microcontroller and count pulses and convert that
into the correct PWM output to control the Synrad laser (5khz PWM).

Oh yeah, I am rolling with this. Thanks!

I will try and find some 1/64" ply (they make ply that thin???) and
see how little it takes to cut it. What project do you have in mind?
microflight airplanes?

I cut the same wooden gear out of 1/8" acrylic in 2 passes at 60IPM
per pass and I swear you could not tell it from a molded gear. I
think it would even be useable in a gear train on a small robot or
something. Every time I look around the house now, I am eyeing
things to cut with the laser :-)

Rick




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