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Messages - bdring

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1
G-Code, CAD, and CAM discussions / Re: G Code Help
« on: October 18, 2009, 11:03:24 PM »
Sure,

Link away.  I'm glad that old page is finally getting some users.

2
G-Code, CAD, and CAM discussions / Re: G Code Help
« on: October 14, 2009, 03:57:01 PM »
Thanks....

It is not perfect.  There are a lot of flavors of G-Code.  I was thinking of adding a "dialect" option so you could get better results for particular implementations like Mach3.  Things like Mach's M10P1 don't really mean anything in regular G-Code, but mean a lot to some Mach users.


3
I saw your video.  It looks like you are doing some great things with your machine.  It is very inspirational.  I hope to have mine engraving this weekend.  I would love to hear more about your machine and it's capabilities.

Here is my understanding of the plugin....Anybody...Please correct me if I am wrong.

The plugin sets a single bit for each step based on the image pixels.  There is no grayscale information.  Since there are usually more steps than pixels, it attempts to dither (http://en.wikipedia.org/wiki/Dither) the grayscale pixel across several steps, but it is still just on/off information per step so the power level does not come into play.  I don't know if mach can store more than one bit per step, but it does not look like it.

I am not sure how fast the power supply can react to power level changes using PWM.  The Mach3 PWM is rather slow for engraving.  If you could change the actual laser power level in 20ms (which I doubt).  It would take 20 seconds to go 1000 steps.  That is probably not practical.

4
I don't think it would be possible.  The laser trigger points only control on/off.  I am not sure PWM power control could react fast enough anyway. 

Could you use some photo editing software to make two images?  One would etch at one power level and the second would etch at the other power level?  It would take more time, but maybe worth a try.

5
Thanks a lot.

6
What do you need to setup in Mach for this to work?  What output/pins need to be setup?  It is driving the X and Y axis correctly, but I need to hook into the power supply.

7
General Mach Discussion / Laser/Impact Engraver Plugin
« on: October 05, 2009, 04:46:36 PM »
What pin is used to control the laser with the Laser Engraver Plugin.  How is it setup?

Thanks

8
Modbus / Re: i need to control spindle inverter by mach 3
« on: August 14, 2009, 03:49:23 PM »
Mach or Smoothstepper can output PWM for the spindle.

9
Modbus / Re: i need to control spindle inverter by mach 3
« on: August 14, 2009, 03:34:40 PM »
It is pretty simple to convert PWM to analog voltage.  If you feed the PWM into a RC low pass filter (1 resistor, 1 capacitor), you will get an analog voltage.  The max voltage will be the PWM on voltage.  That will give you 0 to PWM on voltage.  You may be able to scale that up to the max speed you want in the invertor settings.

If not, you feed the PWM into a transitor first with the collector connected to 10V.  The invertor probably has a 10V source for using a pot for the 0-10V.  You may even find the 0-10V input connection already has a built in low pass filter.  See my ASCII attempt at a schematic below.  R1/C1 is the filter.  Search the web on how to determine the values based on the resolution you want and the PWM freq you choose.

If you get lucky, there already is a low pass filter, you can scale the voltage to speed you want in the invertor settings and you can directly connect the PWM to the invertor.


                    VCC  10V
                     +
                     |
                    .-.
                    | |
                    | |
                    '-'
                     |
                     |
                     |    ___R1
                     |---|___|---+--->   0-10V
                     |           |
          ___      |/            |
PWM >----|___|-----|             |
                   |>           --- C1
                     |          ---
                     |           |
                     |-----------+
                     |
                    ===
                     =  GND

10
Thanks for the generous offer poppabear, but that is more than I need.

The reversal idea seems pretty straight forward....just invert the beam value at the right time  You could probably do it in advance anyway with Photoshop, etc. 

I was just hoping to get an overview of how Mach deals with changing the beam while the axis is moving.  What are the hooks exposed to the plugin author that lets you do this.  A quick overview would be helpful.  I think having the source code and bdock's changes address most of what I immediately desire.

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