Reviving my K40 + DSP project

[kristoforo]

Hi everybody,

Background story:
I purchased a k40 Chinese laser a few years ago and got a DSP from Marco right after that. I didn't even turn the laser on in its original "glory". I got it to work, did a few small projects but was never 100% satisfied with the quality of the cut or engraving. Then I got busy with life, my son was born and didn't have the time to tinker around with anymore. I recently decided to pick up the project again and make it work properly.

My goal is to make the machine work reasonably well without breaking the bank and that's what I need help with as my experience is pretty limited. I did and will search the forum for info but I have a few things that I can't find an answer for.
For reference the parts that have been installed:
- DSP
- 2M542 drivers
- air assist
- z table (not installed yet)

The very first thing I need help with is the power supply. The laser does work with it and it appears to be a PWM power supply however it looks different from all the ones that's been posted here. Could somebody confirm that it is good enough for the DSP?
I kept the big green resistor (I don't know why) but it will be flying out of there very soon.

The second problem I have is that the cut edge on the acrylic is not smooth. It has irregular grooves in it. I'll post a picture of it later. I know that the laser leaves a pattern on the cut edge but what I see is not normal and appears to come from a problem with the motor that moves the head on the Y axis. It also shows up when I engrave something. It looks like after engraving a line the head is supposed to move down a step but it doesn't. Engraves on top of the previous line and then it jumps down 2 steps. This only happens on certain spots but always on the same places. Also that motor is very loud when moves and gets very hot. The controller is set to the lowest current (as far as I know).

The third thing is that I can't find the software for it on my computer or on lightobject.com. I have an earlier version but I don't know which one.

Thank you very much for all the help in advance!

Krisz

[kristoforo]

I attached a picture of a piece of acrylic I engraved. You can see the lines where it was skipping.

[Tech_Marco]

To engrave acrylic, you may want to out-focus a little bit (intentionally to set focus point over a little). It may reduce the "lines" effect a bit.
How fast did you run? K40 should be run over 400mm/s as over than that the machine may suffer from vibration and escaping.


Marco

[kristoforo]

Hi Marco,

My problem is not the small lines but the bigger ones that you can see in the pictures. It's not visible here but if you look at it with bare eyes you see that they are higher than the rest of the engraved surface. It makes me think that the motor skipped a step.

Also could you look at my power supply? Is that good for the DSP? I didn't see anybody posting one like that.

Thanks!

Krisz

Edit:
The lines are horizontal BTW. I just turned it this way so they are more visible for the camera.

[Tech_Marco]

Why don't you do the job on a piece of better acrylic?? I have hard time to see the image and not sure what exactly you mean.
The power supply looks good to me. You just need to limit the current not over 18mA to your K40 machine

By the way, make sure you have good grounding connection on your machine. Otherwise, interference from static may cause escaping

Marco

[kristoforo]

Marco,

Please, read my first post. I haven't used my laser for 2 years now. This piece was made back then. Right now I can't even use it because I can't find the software for it. I'm trying to finish it and make it usable.

I'll take better pictures when I get home so you can see what I mean.

Another question for you:
I'm thinking about upgrading at least the Y axis motor using a lema 17 you offer. Somebody mentioned that it is not a direct swap. Could you tell me what I need to modify to be able to install it?
Thanks for your help!
Krisz

[kristoforo]

I managed to take some pictures. I hope they will help. When I looked at it closer I also noticed that the grooves the laser left behind are not spaced out evenly. There are sections where they are closer to each other and where they are further apart.

[Tech_Marco]

Just PM you the last PHCad I have. The card is no longer support and no hardware patch.
One thing I saw wasn't right is that you're using 2M542 motor driver which output current is much higher than the motor can support
The K40 need 0.4A on X and 0.9A on Y. Micro-stepping should be set to 1/8 or 1/16.

You may change the "Falling Edge" or "Rising Edge" on the setup as it may fix the issue. There is not much I can support as I no longer carry the board.


Marco

[kristoforo]

Thanks for the link!!

I remember when I worked on the laser the last time I was checking the motors and the X motor (which moves the head left and right, if I'm not mistaken) was not even warm to the touch even though it should only be able to handle 0.4A. It also worked flawlessly and it's virtually silent when moves. The other one however gets quite hot and it's loud as well. I could still touch it but it was almost burning my hand.

I just though about something. I remember that the machine I bought was advertised as a laser engraver instead of a laser cutter. And it also didn't come with moshidraw. It was some other software but I can't remember what. Is it possible that because it was meant to be an engraver it has a stronger X motor? They did give it a PWM power supply... I'll check what the model# is on that motor.

I will try to fire it up this weekend and play with the settings.
I understand that the help you can give me is limited but if you can give me some guidance (which you did already) I will be able to figure it out.

Thanks!

Krisz

[kristoforo]

I checked on the stepper motors and here's what I found:

X axis motor: 42BYG113A
Step angle: 0.9 deg
Voltage: 12V
Current: 0.6A

Y axis motor: 42BYG112LS
Step angle: 0.9 deg
Voltage: 1.8V !!!!!!!!!
Current: 0.6A

Now this explains why that motor was getting so hot. I also checked the setting on the controller. Both controllers are set to 1A with 0.5A standby current and 800 steps per revolution. If I look at the specs 0.9 degrees step angle means 400 steps per revolution but how comes the 1/8 and 1/16 microstepping into play? Does it mean I need to set it to 3200 or 6400?

The X motor is pretty happy with these settings and it does not get hot but the Y is on flames. Do I need to replace it with a 12V version?

Thanks!

Krisz

PS: oh! and the software the laser came with was newlydraw.

[Tech_Marco]

It really doesn't matter whether is the motor 1.6v,2.6v, or 5v. It is all about the current setting on the motor driver. If it is a 0.6A, you better drive it 0.6A or a little below. As I mentioned, you're not using proper motor driver "2M542" the minimum is 1A if I'm not forgotten. Even 0.8A can drive your motor hot enough to burn your finger if the motor idle for a while.

Second, it is not important but I don't think that it is 0.9 degree motor available for K40. Most case it is 1.8 degree. Just set your motor driver o 3000~4000 micro-steps would be fine. We're using motor driver to subdivide the the stepping to make it finer to be precise enough. For 1.8 degree motor, usually it is set to 1/8 or 1/16 and the "um" is running about 12.6 or 6.4. May not be accurate enough but it is good enough to start your machine in smooth movement


Marco

[kristoforo]

Thanks Marco!

I found the specs for these motors online and all of them said 0.9 degrees.

You are correct. The lowest current setting of 2M542 is 1A but it can cut it in half for stand by and that's how I'm using it. I'm ordering a 2M415 driver right now and will test it with the Y motor. The X appears to be fine with the 2M542 but I will keep an eye on it.

Thanks again!

Krisz

[kristoforo]

I finally had some time to work on the K40. I pulled out the 2M542 that was driving the Y motor and wired up a 2M415. Now it behaves a lot better and got more quiet as well. I set the micro stepping to the highest setting (highest detail) and it's smooth as butter. I might set it lower a bit because it's an overkill and got very slow as well but I think setting the Um will fix that.
Also checked the X motor and it does get hot so I ordered another 2M415. It should be here in a day or two. Then install air assist, new focus lens, table and realign the laser. 1 more year and it will be done.

[Tech_Marco]

1 more year and it will be done.

Marco