Over a year ago I built my own 600mm x 400mm co2 laser machine, everything was working perfectly, cutting was 100% accurate engraving 100% accurate. anyway I decided to go big to a 4ft x 3ft machine (working area) ordered all the parts I needed to upsize, using all electrical, motors etc from my smaller machine, I finished the build last week, fired it up and everything was working as expected, until I came to test the the cutting and engraving!
I noticed that the Y axis was causing wavy lines, cutting and engraving, I have everything secured in place firmly, adjusted the belt’s tensions, done everything I can think of, but nothing seems to solve the problem.
I have done lots of research and everything says it is a mechanical problem. I just cant seem to pinpoint the problem. my setup is I run my Y axis on 2 belt driven nema 17, 2 amp motors from the same stepper driver. (exactly as i did on my smaller machine, X axis nema 17, 2 amp motor also belt driven.
I pulling my hair out with confusion, does anyone have any suggestions to help me get back up and running
Pictures of the problem might be helpful. Is the issue along the entire Y axis or just at the beginning of a move or just in a specific area of the bed?
Scale this file as large as you can and run it on cardboard at high speed with optomizations turned off and just enough power to get a good mark on the cardboard. Upload a quality photo of the results. This will help show any mechanical deficiencies. BacklashTest.lbrn2 (65.5 KB)
Thanks for the quick reply Tim
Yes it is the whole of the Y axis I have tried it in various places on the bed with the same results.
I bought Hiwin MGN 15 Series linear guide block and linear rails for the new build from Alibaba (china), the blocks were not running freely when they arrived so Ive cleaned out the blocks and they are running free now until I tighten them to the 2040 aluminum profile then the Y axis has resistance, so my thinking is that the aluminum profile is not completely flat. I have bought some engineering brass packers, so my next trouble shoot is to pack up the linear rail where needed so when its secured down, the Y axis runs freely.
I have downloaded the file you sent, I will try it tomorrow and send you the photo showing the results.
New year is approching so unable to do it now, I’m in the Philippines 8.30pm here now.
Generally you can’t take a 600x400mm size machine and double it without some thought as to what kind of power you have available to drive these.
All of the information supplied by you indicates a mechanical issue. Even my 5030 co2 has NEMA23 motors in it, not the smaller, less powerful NEMA17.
Only my low cost led lasers have NEMA17’s in them.
I think the first place to start would be get rid of the NEMA17’s for something a little more substantial. If it’s under powered it will show oscillations, we call ringing, a damping effect, which is what I think you’re seeing. Without photos, it’s hard to tell.
IMHO NEMA17 don’t have what you need when you double the size, even at 600x400mm, I would have picked a larger motor.
Hi Tim, I didnt have any cardboard to hand, so i cut a piece of 6mm plywood the size of my bed. you will need to zoom in on the picture to see better, you will notice every move made by the X axis is perfect, it is the y movement.
I found my frame was slightly twisted, I have rectified that now. the results i am getting have slightly improved but are still a long way off perfect.
see also attached pics of a logo i use here alot. one was engraved at 70 speed and the other at 20 speed (better one of the two) the logo is 2.5" in diameter.
I had another reply from a guy who said my motors are inadequate for the size of my machine, but it is not struggling to get around at high or low speeds. what are your thoughts?
If it is the motors then I will change them in a heart beat, but i personaly think its something else mechanical
Can you please give me a better explanation on why you think the motors are too small, as the way i see it, yes the machine has more than doubled in size but very little change in the load on the motors apart from the extra weight of the longer aluminum profile on the x axis and longer distances to travel, but aside from that very little change.**
I run a small business here in the Philippines. mainly engraved Acrylic products. see attached pics.
180mmps is the fastest that my laser travels, my old 600 x 400 machine worked flawlessly for over a year with no motor issues.
If it is the motors causing wavy lines, then I will change them out no problem!
But before I go to the added expence of changing motors, I would like to know more spesific details of why they are the cause
I just cant see how a bigger working area can be effected by motor size
One of the reasons why I ask for the test pattern to be done on cardboard is there is no visual grain to distract the eye from the actual pattern. I do not pick up any issues with the printout on that material. It may be there, but I’m not seeing it in the picture.
Given the size of your machine, perhaps full scale is too big for a reasonable test result to appear. Maybe try it again at actual size or double size on cardboard or paper and see if the issue appears easier to see. Looking at the photos of some of your work, it appers to be on both axes, unless you are engraving some of the items rotated 90*.
I don’t have any answers as to the cause of your issue, and certainly don’t have input about the motor size mentioned by Jack. He will need to address that.
You have more items that add up the mass you’re trying to move. You have to have a longer Y carriage for a wider machine. This is extra mass the motors have to move. I’m sure you have a longer belt to fit around this wider Y carriage, it also adds mass.
If the motor don’t have enough strength to correctly move the axes.
I have a $2k co2, as cheap as they come, it has NEMA23’s in it. If they could get away with lower priced motors don’t you think they would? If work size area doesn’t matter why would anyone use anything but small motors… You end up creating extra mass, anything on there increases mass.
At what point do you say, that’s a little big for these motors…?
All I’m trying to say is with these symptoms, it could be the motors are too small.
It’s pretty clear it’s a mechanical issue you’re seeing, but I think it’s due to the motors being too small, at least that’s my opinion.
I don’t see anything in the photos to where it has wavy lines… it would help to see them.
Hey Jack (love the quote!)
you have some valid points in your explanation, so Ive decided to change out the 17’s for nema 23’s to see if it solves my problem, as it happens I had two 23’s in my workshop from another project, so ive ordered 1 more and a larger stepper driver 5.6 amp so i can run two of the motors on the Y axis mirrored wired to the same driver so there syncronized.
I will let you know how I get on once they arrive and I have it completed.
Thanks for the information and happy new year to you.
