laser galvo scan head

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05 Feb 2019 15:03 - 05 Feb 2019 15:09 #125740 by vre
laser galvo scan head was created by vre
Can i control a laser galvo scan head with linuxcnc & mesa fpga ?
Something like this

I want 2 operations raster/vector engraving & vector cutting.
Scan head has 2 little servo motors but can not controlled at servo thread
because the small servos must move very precise & quickly.

What is the stage of datapainter mesa firmware ?
Last edit: 05 Feb 2019 15:09 by vre.

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05 Feb 2019 16:12 #125749 by tommylight
Replied by tommylight on topic laser galvo scan head
How fast do the motors/mirrors have to turn ?
There is a config named ETCH Servo that comes with Linuxcnc that could be used for that, it controls 2 small servo motors with encoders directly from parallel port.
I did test it and it can do up to 1800 RPM on a very low latency computer ( a Fujitsu Siemens workstation ) with 100 CPR encoders. It uses a single L298 IC to drive both motors up to 2A each.
Just to be on the safe side, i would not try to get over 1000 RPM on such a system, but that should be enough for what you need.

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05 Feb 2019 16:35 - 05 Feb 2019 16:39 #125750 by vre
Replied by vre on topic laser galvo scan head
100cpr encoders are too low.
What exists for 5000cpr encoders?
The only option i see is mesa fpga with buffer for laser pwm.
Also what kinematics a system like this must use?
Last edit: 05 Feb 2019 16:39 by vre.

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05 Feb 2019 19:08 #125755 by Todd Zuercher
Replied by Todd Zuercher on topic laser galvo scan head
I'm not sure how well suited Linuxcnc is for such an application.

The restrictions of servothread speed may prove too limiting..

I think I'd start with getting the fastest computer I could lay my hands on and see just how fast you can make a servo thread run without getting too many real time errors. Base thread speed isn't going to matter much because you need the motion planning to be super fast, and that is only in the servo thread.

Then try to see if you can get intouch with whoever it was, that was working on the datapainter for Mesa hardware, and offer your assistance in developing it.

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07 Feb 2019 02:37 - 08 Feb 2019 04:25 #125902 by vre
Replied by vre on topic laser galvo scan head
For moving mirrors i can use small servo motors or galvanometers like these
www.ebay.com/itm/20KPPS-30KPPS-laser-sca...-laser-/261517002270
www.instructables.com/id/Arduino-Laser-Show-With-Real-Galvos/
If mesa fpga has some buffer slow servo thread will not be a problem
Also what about kinematics of this system?

I have a synrad FH series marking head that originally driven by fiber optic.
But iam missing the fiber optic card is there any change to drive it from linuxcnc?
Galvos have 3 power wires & 4 feedback wires each one also head has integrated
the galvo drivers so i need only to drive these drivers.
Last edit: 08 Feb 2019 04:25 by vre.

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