Converting K40IV CO2 Laser machine to DSP

[baccus61]

Hi Urbantrix

Have you read this post?

viewtopic.php?f=47&t=344

It has a bit of info on how to check the engraving for double image.
It may help you a bit.
Rich.

[TeacDance]

Hi Urbantrix

Have you read this post?

viewtopic.php?f=47&t=344

It has a bit of info on how to check the engraving for double image.
It may help you a bit.
Rich.

Now would be a desire'd build a bigger table for the laser. Any suggestions?


whether baccus61 has pictures of your table, how you build it?

[baccus61]

I don't really have a build log of the table but I do show a lot of pictures of it being built over on the www.cnczone.com web site.
search for "backyard laser" or my nickname of "Mononeuron" and you will get a lot of my posts and what works and what doesn't.
I haven't mode any posts over there for ages as I spend most of my time on this forum now. I do visit it for info on cnc plasma tables though.
Rich.

[Urbantrix]

HI Baccus61,

I have checked the belt and it all seems to be ok, Also it is only when i'm engraving, on the x-swing as i say x-swing unilateralism is fine but so slow.
Also cutting is fine also i do not get double images.

Regards,

Matt

[twehr]

HI Baccus61,

I have checked the belt and it all seems to be ok, Also it is only when i'm engraving, on the x-swing as i say x-swing unilateralism is fine but so slow.
Also cutting is fine also i do not get double images.

Regards,

Matt

I did some major reworking of my laser this weekend and ended up getting the double images just like you (and like Rich earlier). The appearance is as if there is backlash in the x axis, but there is none. Ultimately, I had to resort to using the reverse engraving offset compensation. For me, it was exactly 1 mm that had to be added to get it right. The funny thing is that I previously never had to resort to this.

Along the way, I discovered that there seemed to be a difference in the results depending on the microsteps I had set for my drives. What worked the best for me was 1/4 micro step (with 200 step/turn motors that equals 800 steps/revolution) and a pulse width of (about) 25.4.

I know from experience with other issues that the DSP has issues with certain combinations of microsteps and pulse widths. Some work great while others cause skewing of the image and compression of the y axis for engraving. Several users have discovered this, so it is not just my (or your) setup. You just have to try various combinations till you find the one that works best for you.

[baccus61]

I am using Gecko drives for my table which are set at 10 micro steps and cannot be changed so I have to work with that.

I had the dreaded offset for about as long as I can remember and it wasn't just with the DSP, it was with my original Linkmotion software/hardware as well.
I rewired the table countless times and last year I completely rebuilt the whole table including a new 100 watt laser tube but kept the motors and power supplies. I installed new linear guides, mirrors, lens holder, DSP and numerous other small changes.

Still had the offset !!!!

In the end I swapped out the toroidal transformer, big capacitor and bridge rectifier and I bought a 48 volt regulated power supply for the drives and a 12 volt one for the DSP and that seemed to do the trick. All for the princely sum of $68.

I don't know why it worked, it just did! Go figure.

Rich.

[TeacDance]

Does the new DSP Software for 2012 (v5.2) work here blueversion control? i installed the software but it doesn't find right comport.

[wctx1977]

Hi everybody! I'm new in to this forum and guess what! I also purchased one of those chinese laser engravers with "moshidraw" which forced me to do a major surgery to it by converting to the DSP controller. Well I got the 2012 controller and the stepper drivers this week and I already started working on it. I got the stepper motors working, limit switches installed, laser power supply connected and now is time for some questions and help.


How can I find out if my laser power supply is capable for PWM mode? If it is not PWM capable, is there any module than can be in between to make it work as PWM mode? I just want to avoid to buy another LPS if possible as money is tight right now.

I will appreciate a lot some help, Thank you!

[TeacDance]

Hi everybody! I'm new in to this forum and guess what! I also purchased one of those chinese laser engravers with "moshidraw" which forced me to do a major surgery to it by converting to the DSP controller. Well I got the 2012 controller and the stepper drivers this week and I already started working on it. I got the stepper motors working, limit switches installed, laser power supply connected and now is time for some questions and help.


How can I find out if my laser power supply is capable for PWM mode? If it is not PWM capable, is there any module than can be in between to make it work as PWM mode? I just want to avoid to buy another LPS if possible as money is tight right now.

I will appreciate a lot some help, Thank you!

put a picture of your power supply

[wctx1977]

Hi everybody! I'm new in to this forum and guess what! I also purchased one of those chinese laser engravers with "moshidraw" which forced me to do a major surgery to it by converting to the DSP controller. Well I got the 2012 controller and the stepper drivers this week and I already started working on it. I got the stepper motors working, limit switches installed, laser power supply connected and now is time for some questions and help.


How can I find out if my laser power supply is capable for PWM mode? If it is not PWM capable, is there any module than can be in between to make it work as PWM mode? I just want to avoid to buy another LPS if possible as money is tight right now.

I will appreciate a lot some help, Thank you!

put a picture of your power supply

[Tech_Marco]

This is a PWM power supply that we're selling as well. The K40 manufacturer (Shenghui) used to manufacturer their PW but it's not very good. That's why you found a giant green resistor connected in series with PS to aovid over shoot. Now they go for better power supply and that is a good sign for it. But the Moshi is a piece of "junk" and people need to stay away from it!


Marco

[wctx1977]

Hi Marco, I still a little confused and I hope you understand that. My machine came with this power supply and it has the big green coil in series and I don't know if I need to bypass it now that I'm using the DSP, Should I? also let me make sure I understood you, (you say my power supply is PWM capable or not)? if yes, how do I enable PWM for photo engraving?
Other than that I got my stepper motors running nice and smoothly after a few hours of experimentation with different parameter settings, however it may still need a better tuning but that will come with practice and experience with it.

[twehr]

Hi Marco, I still a little confused and I hope you understand that. My machine came with this power supply and it has the big green coil in series and I don't know if I need to bypass it now that I'm using the DSP, Should I? also let me make sure I understood you, (you say my power supply is PWM capable or not)? if yes, how do I enable PWM for photo engraving?
Other than that I got my stepper motors running nice and smoothly after a few hours of experimentation with different parameter settings, however it may still need a better tuning but that will come with practice and experience with it.

The Power Supply you have IS PWM compatible.

Where is the green coil - on the return from the laser tube or in series someplace between the lps and the controller? If it is on the tube side, I would just leave it alone.

You don't have to "enable" PWM. The LPS takes whatever is presented to it at the "IN" pin. If it is analog (0-5v) then it treats it as analog. If it is PWM (5v - 0-100% frequency) then it treats it as PWM. Just just the standard minimum connections from the documentation and the laser should fire just fine.

You mentioned "enable PWM for photo engraving". The PWM is not related specifically to engraving, or photos, or cutting. It only sets the power at which the operation will be done. For a photo, as example, the entire bitmap will be engraved at the power level set by the software. That level is communicated to the lps via PWM (or analog). If you are thinking that the PWM will make it change levels with various shades of gray, that is incorrect.

[wctx1977]

Hi Marco, I still a little confused and I hope you understand that. My machine came with this power supply and it has the big green coil in series and I don't know if I need to bypass it now that I'm using the DSP, Should I? also let me make sure I understood you, (you say my power supply is PWM capable or not)? if yes, how do I enable PWM for photo engraving?
Other than that I got my stepper motors running nice and smoothly after a few hours of experimentation with different parameter settings, however it may still need a better tuning but that will come with practice and experience with it.

The Power Supply you have IS PWM compatible.

Where is the green coil - on the return from the laser tube or in series someplace between the lps and the controller? If it is on the tube side, I would just leave it alone.

You don't have to "enable" PWM. The LPS takes whatever is presented to it at the "IN" pin. If it is analog (0-5v) then it treats it as analog. If it is PWM (5v - 0-100% frequency) then it treats it as PWM. Just just the standard minimum connections from the documentation and the laser should fire just fine.

You mentioned "enable PWM for photo engraving". The PWM is not related specifically to engraving, or photos, or cutting. It only sets the power at which the operation will be done. For a photo, as example, the entire bitmap will be engraved at the power level set by the software. That level is communicated to the lps via PWM (or analog). If you are thinking that the PWM will make it change levels with various shades of gray, that is incorrect.

Hi twehr,
I appreciate your info and your willingness to help others. Sorry I was confused and thinking that PWM was related specifically to photo engraving. My laser seems to be shooting just fine but then don't know what I need to do to make it engrave photos with various shades of gray. I'll be playing more with it today and see what else I can find.

[twehr]

Hi Marco, I still a little confused and I hope you understand that. My machine came with this power supply and it has the big green coil in series and I don't know if I need to bypass it now that I'm using the DSP, Should I? also let me make sure I understood you, (you say my power supply is PWM capable or not)? if yes, how do I enable PWM for photo engraving?
Other than that I got my stepper motors running nice and smoothly after a few hours of experimentation with different parameter settings, however it may still need a better tuning but that will come with practice and experience with it.

The Power Supply you have IS PWM compatible.

Where is the green coil - on the return from the laser tube or in series someplace between the lps and the controller? If it is on the tube side, I would just leave it alone.

You don't have to "enable" PWM. The LPS takes whatever is presented to it at the "IN" pin. If it is analog (0-5v) then it treats it as analog. If it is PWM (5v - 0-100% frequency) then it treats it as PWM. Just just the standard minimum connections from the documentation and the laser should fire just fine.

You mentioned "enable PWM for photo engraving". The PWM is not related specifically to engraving, or photos, or cutting. It only sets the power at which the operation will be done. For a photo, as example, the entire bitmap will be engraved at the power level set by the software. That level is communicated to the lps via PWM (or analog). If you are thinking that the PWM will make it change levels with various shades of gray, that is incorrect.

Hi twehr,
I appreciate your info and your willingness to help others. Sorry I was confused and thinking that PWM was related specifically to photo engraving. My laser seems to be shooting just fine but then don't know what I need to do to make it engrave photos with various shades of gray. I'll be playing more with it today and see what else I can find.

In PHCad, import a photo. Then dither it (I think it is in the edit menu - look for it). Dithering is what you need to emulate shades of gray.