Newbie help on Chinese 80 w

[Justin Hensel]

I am a newbie so I apologize up front. I'll try to be precise as I can. I have a JD90120 80w with servo motors and MPC 6252 controller. Changed laser tube yesterday and now i can't even cut through 1/8 Masonite on 15 speed and 100%. I have tried aligning the mirrors and changing them but the laser comes out to the left 2.8 mm from the nozzle. Also when I used masking tape to spot the laser( I place poster board behind it to protect mirror) the laser dot on the third mirror seems wide.its an extremely dark with charring and not much inside the circle. When running test of laser, laser time set at 340ms and a power of 20% 4 short blasts make it through 1/16 plywood but when Running a 25mmx25mm box at 15 speed and 100 power doesn't even make it halfway throug. Any ideas or advice?

[Keith Downing]

Sounds like you still may not have the mirrors aligned correctly. They must be aligned, including the mirror above the lens and the lens, correctly and be clean to get reliable results. Here is a video that outlines the process on a chines machine if you're unsure of what you're doing. https://www.youtube.com/watch?v=wY5D27TQwZI
Also, check to make sure the lens isn't cracked.

If that isn't the problem, then you just need to start eliminating possibilities: tube bad or installed incorrectly, power supply failing, fuses blown, etc. Do you have a mA meter on your machine? If so, what are you seeing at 100% power? That's usually a good place to start.

[Doug Fisher]

Keith made good suggestions so I won't repeat them but here are a few other things to consider:

Have you made sure your laser is aligned correctly from the last mirror down through the lens so that it is coming out of the aperture of the nozzle in the center (e.g. without hitting anywhere on the inside of the nozzle before exiting)?

Is your old power supply appropriate for your new tube?

You said you are driving the tube at 100%. Are you sure that isn't overdriving your water cooled glass tube and thus killing/drastically shortening its life? Do you have a milliampere meter installed and have you obtained the tube manufacturer's max tube milliampere power rating? Many people who actually test find they should not drive their tubes over about 65% to avoid exceeding the maximum rating.

[Bill George]

I am assuming it worked fine or did it before the tube change?
Do a Search here on mirror alignment.

Who told you that you had servo motors, most of the Chinese Imports have steppers.

[Justin Hensel]

Had an upgrade purchased for servo motors. Here is me question I can't find an answer to anywhere and I hop this doesn't sound dumb.357858 When I placed cardboard in front of mirror to check alignment this is what the laser dot looked like. I was under the assumption that even when putting something in front of mirror to check alignment I should just see a small dot burn mark. Is this what it should look like normally?

[Doug Fisher]

Have you made sure the lens at the exit end of the laser tube itself is clean? You need to be very careful cleaning it but I had a similar looking beam that was getting fractured like that and it went away after someone suggested I clean the end of the tube (the mirrors themselves have to be spotless too but I assume you have done that). Use the search function for tips on cleaning.

[Keith Downing]

I can't tell anything from that picture: how large the dot is, or if it's a clean burn.

Who told you to use cardboard in front of the lenses during alignment? I've never heard of that, and it seems like it would be hard to get it to stay on each lens without shifting as you move the x and y axis to test and complete the alignment. Which is the entire point of the process, to confirm that the beam is aligned on each mirror correctly regardless of the position of the head cone.

I don't want to seem rude, but did you watch the youtube video I linked? Seems like the questions about alignment could all be answered clearly if you followed the steps they outline there.

[David Somers]

Justin,

To carry Keith's thought further, if you follow that video link and make sure the optics are aligned all the way through you will also want to be sure that your honeycomb table is parallel to the plane of the XY axis of the gantry. If not you could find that you set the focus in one position of your table, and as the laser moves across the table it is going out of focus. Laser lenses have VERY short depth of field. it is stunning how little it takes to make the beam ineffective. But focus on the optics alignment first. Nothing else matters till you are good from the CO2 tube through the mirrors and out the lens cone.

[Justin Hensel]

So..I have followed the video to a T. When it comes to trying to center the dot to the third mirror I am haveing issues. Then when Laser comes out of the focal tube it shoots to the left so far I don't have enough alignment room to center it. Is there a certain position I can just place all the mirrors at I.e. A zero point and start from scratch?

[Bert Kemp]

Are you sure the beam is not hitting the side of the tube when it comes out. Take the nose cone off and see what happens then to the beam. You say from the second mirror to the third mirror you can't get it to hit center on the third mirror correct. check the second mirror to make sure it didn't move or is loose. or a burned spot on it. Also check the mirror above the lens for all the above. You may have moved that mirror when cleaning the lens or something.

[Ray Scott]

I just wanted to bring this thread to a close and tell other people what the solution was. Justin was able to contact me for help. I visited his workshop and started some extensive cleaning of the optics. The main problem was alignment of the mirror brackets. It appeared that some brackets had come loose during moving... Belt tensioning... Loose sets screws on a reducer pulley... Wrong pulse distance values for X and Y axis... Oh where to start. .... Oh yeah.. Clean the optics first.
... After 8 hours of repairs, alignment, and calibrations... I think that Justin is a happy man again.

thank You

[Justin Hensel]

I just wanted to add my own thoughts also. To those that sent me the messages advising me to contact Ray at Rabbit Laser THANK YOU! And to Ray personally, nothing that I could ever say would to justice to the levees of service you provided. Even when you discovered that I had been taken advantage of and way overpaid for my machine you still have me words of encouragement. You spent many more hours than I would have even thought and got me through my mess of a machine and had it running better than before I bought it. Financially,you could have taken me to the cleaners for the work you provided but did not. You taught more about my machine in one day then I had learned since I owned it and still provides me with business advice on top. When it come to a business owner, Ray, you are in a class by yourself. Ray Scott is the MAN! Thank you so much for everything.

[Bert Kemp]

Justin How bout listing your equipment and location in your signature:)