$32 CO2 Laser Controller

[Retroplayer]

You would have to tell the controller to increase the speed of the pulses to keep the same speed (of the motor) when you increase microstepping.

Agreed. And I will concede that point because it does make some sense and I can't seem to find my sources of that information to verify.

I still say the advantages far outweigh any possible disadvantage for this application. Appreciate the exercise in brain cells this morning!

[Rolf_K]

Has anyone tried this eBay item:

Usbcnc 3 Axis Stepper Motor USB Driver Board Controller Laser Board for CNC E | eBay

From what I have learned from everybody so generously responding to my original post/question, the below items should work in conjunction with great instructions and links that Retroplayer posted.

(No stepper drivers included.)

Arduino Mega 2560 from Canada, $11.08 including shipping:
Microcontroller Board ATMEGA2560 16AU USB Cable for Arduino Module R3 MEGA2560 | eBay

Reprap RAMS 1.4 w/ display, from China, $16.32 free shipping:
RepRap RAMPS1 4 12864 LCD Display Controlle with Adapter Mendel Prusa 3D Printer | eBay

Total $27.40

Did I miss anything?

[Retroplayer]

From what I have learned from everybody so generously responding to my original post/question, the below items should work in conjunction with great instructions and links that Retroplayer posted.

(No stepper drivers included.)

Arduino Mega 2560 from Canada, $11.08 including shipping:
Microcontroller Board ATMEGA2560 16AU USB Cable for Arduino Module R3 MEGA2560 | eBay

Reprap RAMS 1.4 w/ display, from China, $16.32 free shipping:
RepRap RAMPS1 4 12864 LCD Display Controlle with Adapter Mendel Prusa 3D Printer | eBay

Total $27.40

Did I miss anything?

Looks good. You didn't answer me whether you are sure you have compatible stepper drivers, but I am assuming you must?

The only possible addition: If you plan to run this off the 24V from the laser power supply, keep in mind it will require some minor modifications to the RAMPS board with a solder iron. Nothing major, but want to be sure you are prepared to do that if you chose that route. I will note that this is the best way also, unless you change out the steppers as well. So, if you are comfortable with a soldering iron, I recommend it.

If you chose to go to 12V, you will need to buy a 12V 10A supply as well.

[ELaser]

Agreed. And I will concede that point because it does make some sense and I can't seem to find my sources of that information to verify.

I still say the advantages far outweigh any possible disadvantage for this application. Appreciate the exercise in brain cells this morning!

Torque in steppers falls off a cliff at a given RPM, different for each motor, this is where servos won.

microstepping 90 x 16 = 1,440 to get one full revolution vs 90 x 4 = 360 to get one full revolution (assuming 90 steps per 360 deg) doesn't make a blind bit of difference to anything except the controller software and hardware it is running on, and practically for 99.9% of people the bottleneck is the interface between the control software / PC and the stepper drivers.

If you're using legacy parallel port stuff you are severely limited before you start dropping steps in how many steps you can push through per second, going to USB2 for example dramatically boosts this.

This issue with 99.9% of stepper installations is there is no closed feedback loop, if 14,400 steps are sent to a 90x16 stepper controller the software is going to ASSUME that is exactly what the stepper did, apart from periodic recalibration by hitting the home limit switches, it's all open loop.

In a closed loop system the axis will always tell the control software (via reading an optical encoder or some such) exactly where it is, which direction it is travelling, and what speed it is doing.

I know absolutely bugger all about arduino's etc, but I suspect that the lack of CPU heavy lifting capacity compared to say a core i5 laptop will also be a factor in how many steps it can output per second.

Don't forget peak X+Y step rates will be significantly higher than X only or Y only, eg trying to do a circle at 100 mm/sec requires a lot more pulses than a line in either X or Y at 100 mm/sec, so you need to drop your step rate low enough to account for this and don't tune just on X or just on Y axis performance.

[buddydog]

Torque in steppers falls off a cliff at a given RPM, different for each motor, this is where servos won.

microstepping 90 x 16 = 1,440 to get one full revolution vs 90 x 4 = 360 to get one full revolution (assuming 90 steps per 360 deg) doesn't make a blind bit of difference to anything except the controller software and hardware it is running on, and practically for 99.9% of people the bottleneck is the interface between the control software / PC and the stepper drivers.

If you're using legacy parallel port stuff you are severely limited before you start dropping steps in how many steps you can push through per second, going to USB2 for example dramatically boosts this.

This issue with 99.9% of stepper installations is there is no closed feedback loop, if 14,400 steps are sent to a 90x16 stepper controller the software is going to ASSUME that is exactly what the stepper did, apart from periodic recalibration by hitting the home limit switches, it's all open loop.

In a closed loop system the axis will always tell the control software (via reading an optical encoder or some such) exactly where it is, which direction it is travelling, and what speed it is doing.

I know absolutely bugger all about arduino's etc, but I suspect that the lack of CPU heavy lifting capacity compared to say a core i5 laptop will also be a factor in how many steps it can output per second.

Don't forget peak X+Y step rates will be significantly higher than X only or Y only, eg trying to do a circle at 100 mm/sec requires a lot more pulses than a line in either X or Y at 100 mm/sec, so you need to drop your step rate low enough to account for this and don't tune just on X or just on Y axis performance.

Maybe there is something different about a laser than a 3D printer, but in the real world my arduino runs the 3D printer at speeds I would never run the hobby laser at. Maybe the resolution suffers or something but again the 3D printer has terrific resolution for gearhead mechanical project parts so that's maybe the difference. I have seen advertisements for servo units verses steppers and maybe for commercial artwork would improve both resolution and speed but these being hobby units I can't see the need. If I was in the business it would be probably Epilogue (do they use servos?) all the way. Thank goodness I'm not!

[ELaser]

Maybe there is something different about a laser than a 3D printer, but in the real world my arduino runs the 3D printer at speeds I would never run the hobby laser at. Maybe the resolution suffers or something but again the 3D printer has terrific resolution for gearhead mechanical project parts so that's maybe the difference. I have seen advertisements for servo units verses steppers and maybe for commercial artwork would improve both resolution and speed but these being hobby units I can't see the need. If I was in the business it would be probably Epilogue (do they use servos?) all the way. Thank goodness I'm not!

3D printers aren't high res or large envelope though....

10 micron on a 1000 x 1000 bed (mine is actually bigger than this) = 10,000,000,000 possible positions (not including the Z axis yet) all of which have to be sent as signals, so it would take ten billion signals sent to the stepper controllers, at 3,600 seconds and hour if you wanted to do the whole lot in one hour that would be 10,000.000.000 / 3,600 = over 2.7 million instructions per second.

My CNC vertical mill is theoretical 5 micron accuracy, it's ludicrous, thermal expansion of the work during heavily milling will impact on it, I'm lucky if I ever do a thou on it (25 micron)

[Rolf_K]

Looks good. You didn't answer me whether you are sure you have compatible stepper drivers, but I am assuming you must?

The only possible addition: If you plan to run this off the 24V from the laser power supply, keep in mind it will require some minor modifications to the RAMPS board with a solder iron. Nothing major, but want to be sure you are prepared to do that if you chose that route. I will note that this is the best way also, unless you change out the steppers as well. So, if you are comfortable with a soldering iron, I recommend it.

If you chose to go to 12V, you will need to buy a 12V 10A supply as well.

Here is a picture of one of the stepper motor controllers that is installed:

Don't you think the 12 V supply only needs a few hundred milliamps when there are no step motors to drive, except for the singnal voltage?

[Retroplayer]

3D printers aren't high res or large envelope though....

10 micron on a 1000 x 1000 bed (mine is actually bigger than this) = 10,000,000,000 possible positions (not including the Z axis yet) all of which have to be sent as signals, so it would take ten billion signals sent to the stepper controllers, at 3,600 seconds and hour if you wanted to do the whole lot in one hour that would be 10,000.000.000 / 3,600 = over 2.7 million instructions per second.

My CNC vertical mill is theoretical 5 micron accuracy, it's ludicrous, thermal expansion of the work during heavily milling will impact on it, I'm lucky if I ever do a thou on it (25 micron)

Yep. Which gets back to my point that the resolution of the 1/32 microstepping is not really one of the advantages here. It already exceeds the width of the beam, I believe. The real advantage in this particular application is:

1. It's MUCH quieter
2. Movements are much smoother which decreases vibration, which translates into the final quality of an engraving, and possibly even a reduction in re-alignments since the machine is not going through an earthquake (exaggeratng). This is also the real advantage above resolution in 3D printing. Since there is much less 'jerk' and vibration with a higher microstep factor, less artifacts show up in your print.

As for torque? Not really an issue here. The only real friction in the system is the contacts between the rollers, bearings, belt-tooth interface, etc.. There is no real load on the actual optics head like in a CNC mill, router, plotter, or 3D printer. Speed is not a huge thing either because you are limited how fast your laser can move to actually cut or mark the material anyway. You already have to slow down with the existing controller. That is 1/16 microstepping, if they are using the max the driver is capable of. It is capable of full, half, quarter, and 16 microsteps. This is selected on by grounding pins on the chip. And on the RAMPS, you can select this with jumpers on the board.

[Retroplayer]

Here is a picture of one of the stepper motor controllers that is installed:

Don't you think the 12 V supply only needs a few hundred milliamps when there are no step motors to drive, except for the singnal voltage?

Cue music... dun dun duh! And then, the other hand reveals itself!


You have step, pulse, and enable. So, it should work. A little bit of hackery will be needed in the form of soldering to those pins on the RAMPS controller directly.

With those drivers, you don't need 24V or 12V for the RAMPS board at all. Instead, you can run the Arduino directly off the 5V.

We can do, but yours will be a custom case different than Buddy's or mine. I'm sure I can help you through it, though.

[Retroplayer]

BTW, if speed is really something you want, buy some 12V steppers and run them at 36V (but make sure you have drivers that can handle that much current) Voltage is the real contributor to speed.

[Rolf_K]

From what I have learned from everybody so generously responding to my original post/question, the below items should work in conjunction with great instructions and links that Retroplayer posted.

(No stepper drivers included.)

Arduino Mega 2560 from Canada, $11.08 including shipping:
Microcontroller Board ATMEGA2560 16AU USB Cable for Arduino Module R3 MEGA2560 | eBay

Reprap RAMS 1.4 w/ display, from China, $16.32 free shipping:
RepRap RAMPS1 4 12864 LCD Display Controlle with Adapter Mendel Prusa 3D Printer | eBay

Total $27.40

Did I miss anything?

Finally found a useful link to someone that has done this successfully:
WeisTek Engineeing

[Retroplayer]

We blew through so many pages so fast, you must have missed that link in post#4 http://www.cnczone.com/forums/genera...ml#post1629770

Great blog to follow as he is continuing his upgrades and seems to have some big plans. Note again, though, that he outlines using the 24V and modifying the RAMPS board which is what most people are doing. But with your stepper drivers, you won't need to do this.

BTW, did you bite the bullet yet?

[naveenraj]

Hi,
Great post sir! You really posted a great article and it will help all the person. Who are wanting help from someone. Your information is very helpful. Also solved my printer problem at my all google searches i got solution from from here.

[Retroplayer]

Hi,
Great post sir! You really posted a great article and it will help all the person. Who are wanting help from someone. Your information is very helpful. Also solved my printer problem at my all google searches i got solution from from here.

Glad I could help, Naveenraj

[Rolf_K]

We blew through so many pages so fast, you must have missed that link in post#4 http://www.cnczone.com/forums/genera...ml#post1629770

Great blog to follow as he is continuing his upgrades and seems to have some big plans. Note again, though, that he outlines using the 24V and modifying the RAMPS board which is what most people are doing. But with your stepper drivers, you won't need to do this.

BTW, did you bite the bullet yet?

Yes, it is on order and on its way :-)

[Rolf_K]

Cue music... dun dun duh! And then, the other hand reveals itself!


You have step, pulse, and enable. So, it should work. A little bit of hackery will be needed in the form of soldering to those pins on the RAMPS controller directly.

With those drivers, you don't need 24V or 12V for the RAMPS board at all. Instead, you can run the Arduino directly off the 5V.

We can do, but yours will be a custom case different than Buddy's or mine. I'm sure I can help you through it, though.

Like I stated in a the previous post, I had this laser working before from from another controller using the same stepper motor drivers. So I was visualizing doing the same with this new Arduino set up.
Anyhow, Retroplayer I appreciate you confirming my line of thinking and the offer to help. Now I just have to twiddle my toms until the parts gets here, luckily the Arduino is shipped from Canada and should get here pretty soon so that I can get started on the firmware/software. I don't see why it should be any different software wise from Buddy's or yours :-)

[Retroplayer]

Like I stated in a the previous post, I had this laser working before from from another controller using the same stepper motor drivers. So I was visualizing doing the same with this new Arduino set up.
Anyhow, Retroplayer I appreciate you confirming my line of thinking and the offer to help. Now I just have to twiddle my toms until the parts gets here, luckily the Arduino is shipped from Canada and should get here pretty soon so that I can get started on the firmware/software. I don't see why it should be any different software wise from Buddy's or yours :-)

Software should remain the same. Its only the connections of the hardware that will be a little different.

[Rolf_K]

Finally found a useful link to someone that has done this successfully:
WeisTek Engineeing

Now that I have found this schematic for the RAMPS 1.4, and had a little bit of time looking it over everything makes more sense. I think everybody interested in this project should take a look at it, here is the link:
http://reprap.org/mediawiki/images/f...4schematic.png

[mcphill]

Before I dig too far in to the details on this, can someone state what the "max" cutting ability for this type of system would be? How thick a piece of ABS, wood, paper, etc. could this cut through (not engrave/burn, but cut)?

I have an old Chines laser engraver that was damaged in transit to me that I have never run. I think it is a 20 W CO2 from what I recall, but again, before I invest time in trying to resurrect it I want to know what reasonable expectations for performance are... Thanks in advance!

[buddydog]

Before I dig too far in to the details on this, can someone state what the "max" cutting ability for this type of system would be? How thick a piece of ABS, wood, paper, etc. could this cut through (not engrave/burn, but cut)?

I have an old Chines laser engraver that was damaged in transit to me that I have never run. I think it is a 20 W CO2 from what I recall, but again, before I invest time in trying to resurrect it I want to know what reasonable expectations for performance are... Thanks in advance!

Well it depends on what "20 watts" means and in the case of the Chinese the meaning of watts is a moving target. Our K40 machines are rated at 40 watts but most every one agrees they are actually less than 30. In radio work the difference in talk power between 30 and 60watts is almost nothing. 3 db is just discernible. On the other hand improvements in the transmission line, antenna and height are always the best investment. Lasers are of course not the same thing since the beam is focused but I have found that with tweaking the alignment, air assist, cooling the tube, and clean mirrors and so on makes the little machine cut up to 1/4 inch plywood and acrylic at low speed. While not practical for commercial use, fine for hobby. Any more than that and the speed and quality of the cut would suffer greatly. Elaser has a video of what I think is a high power laser cutting 1" acrylic and it clearly shows that any CO2 "focused" laser can't make straight cuts as thickness increases because the beam is tapered to and past the focal point of the lens. It's v shaped going in and inverted v shaped going out of the back side. Good luck!