laser raster engraving
I want to retrofit it to linuxcnc so i plan to buy a Mesa 7i93.
The machine works ok except of engraving that is poor quality.
I have seen an other machine that has the same glass tube and PSU with mine
but has a proprietary controller optimized for raster engraving and this machine gives perfect photo engraving results.
So the controller is the key to achieve good engraving this is the reason why i want to retrofit my machine.
The question is possible to do with linuxcnc raster engraving ?
I have seen this wiki.linuxcnc.org/cgi-bin/wiki.pl?Rastering_With_A_Laser but is old and some links not working.
I don't know rubby & python (i know java) to check the code but this old code (is from 2009) will work with linuxcnc 2.7 ?
Have anyone do with success a conversion like this and has good raster engraving ?
skunkworks wrote: Not yet - there isn't currently a way to get the laser trigger information streamed to the mesa card... I think it has been thought about - but no one has implemented it.
Is that sending pulses per mm of movement or something like that?
skunkworks wrote: This is a good thread (printer port rasterizing..)
I read this. Interesting. On Page 14, he starts to use Mesa hardware.... He said it was easier becasue the PWM signals are generated on the Mesa board... Good luck!
For raster engraving image he not finished because he says that this function must embedded to fpga
and modified linuxcnc code.
parport is useless because the speeds are low and engraving needs high speeds.
In raster engraving the speed of x axis must be constant and the laser fire synchronized with motion.
I would save the current position and compare the distance moved since the last pass through the component (or simply check the current velocity). Either way, you can calculate the distance moved in real time so you can synchronise the laser pulses with motion and turn a pin on and off to pulse the laser.
So now if you could take control of one of the Mesa stepgens (which is probably a simple as commanding an unused axis to run at a given velocity) you could pulse the laser at speeds of up to 10 Mhz until you tell it to alter the velocity. So as you run through the servo thread, check if the velocity has changed then alter the stepgen frequency from your custom component.
Another crazier idea might be to use one of the $69 Mesa THCAD-10 cards which converts a 0-10 volt signal to a frequency. The frequency alters from card to card but mine peaks at 925 kHz. I think though that maintaining a PWM 10 volt signal might not be as responsive as a stepgen.
With the printer port rastering running a base thread - you can up that to 20 -40khz.
The only way around this is to somehow offload the raster information to the mesa card. Again - I know it has been discussed but no one has coded it. PCW would have more info.