Problem with chinese laser

[Dennis Christensen]

I have a laser engraving machine made by WK Laser in China. It has a 600mm x 900mm bed and a 80 watt tube. It has been working good for several years, but it stopped working about a week ago. The x (right-left) movement is erratic. The y movement is fine. If I try to cut a square, it will cut one side then shake and move a small amout across the top then go down the other side. I end up with a rectangle. I have tried switching x and y microstep driver control boxes and motors and there was no difference. I'm not sure what to try next, does anyone know what might be wrong?

[Robert Walters]

Hi Dennis,

Has anything changed (think hard on this)?

Did you...

• Move the machine or the computer (even temporarily)?
• Insert, remove, or replace any cables or wires?
• Install, update, or remove any software or drivers?
• Have you used a new or different material recently (even before the problem started)?

With the power off, if you move the gantry manually by hand, is it smooth in both X and Y axis?


I'm going to speculate you are connected via parallel port to the computer, but if it's via USB it's the same difference.

Using the following diagram (substitute terms as necessary):

[PC]---[CABLE]---[LASER_BREAKOUT_BOARD]
                          |     |
                          |     +--[X_CABLE]---[X_DRIVE]---[X_MOTOR]
                          +--------[Y_CABLE]---[Y_DRIVE]---[Y_MOTOR]

When you say
"I have tried switching x and y microstep driver control boxes and motors"

Did you physically swap the X and Y motors?
Did you just swap the X and Y CABLES?
Did you swap the connections between the motors and the motor drivers?
Something else?

What you need to do is isolate where the problem is, be it mechanical, electrical, electronic, digital (computer), etc.

I'd swap the X and Y cables from the breakout board.
If the issue is still on the X axis, them the problem is between the PC and the breakout board.
If the issue is now on the Y axis, then the problem is between the breakout board and the motor.

You might have something as simple as a loose connection or cable that when the machine is operating is vibrating the connection and you are loosing steps in the stepper motor.

When you get the erratic movement, can you hear the stepper motor?
If so, does it sound like it's "winding up or down"?

I'd also check for loose bolts and screws, the belts for wear/stretch, and roller bearings for smoothness when turned by hand.

A photo of the electrical compartment wouldn't hurt.

Do you have any electrical diagram or schematic?

[Dave Lock]

I have a 9060 Rabbit, similar machines.

Given what you have already tried I'd guess it's a mechanical problem. I would say it is the bearings in the belt tension pulley.

With the power to the machine turned off, grasp the laser head and push it left and right, you may be able to feel the jerkiness in the movement.

[Mark Winlund]

Just call your local rep for Rabbit Lasers..... I am sure they will send someone right out...

Mark

[James Jaragosky]

Just call your local rep for Rabbit Lasers..... I am sure they will send someone right out...

Mark

So a fellow creeker asks for help: and your response is to mock him? How sad.

[David H. Mitchell]

Well Mark, I also have a chinese laser, , when I call my rep he responds right away. Normally within 2 hours. Does your rep respond that fast?

[pete hagan]

Mark, shame on you. This is usually a good natured forum. I wouldn’t plan on asking for help in the future.

Dennis
Look closely for broken wires especially at the point where wires meet the terminals. These Chinese machines don't necessarily use the greatest quality of materials and likewise may not have the most expert assembly. In my case I had an intermittent stepper motor which eventually was chased down to a crimp on a wire end that had broken and was making contact erratically. Take the time to track the problem from the end to beginning starting at the head.

Like others have suggested turn the unit off and see if the head will slide left / right and forward / backward smoothly using light pressure with your hand. If you are able to move smoothly by hand then likely it is motor / control related. If it is sticking then it’s mechanical. If mechanical start looking at bearings or binding on the rails. DON’T start disassembly until you have identified what is sticking if mechanical.

If mechanical is fine then start at the troubled motor and start checking the wires, all the wires, for clean good connections at the terminals. From your comment you swapped the motors / control boxes but still had identical issue then it is either mechanical (sticking), a wiring issue or a controller issue. Try gently tugging the wire at the terminal and see if any separate / are loose at the screw terminal. Chase every wire down individually. You can also disconnect the terminals from the stepper controller (pull the terminal strip up as a whole) and meter the wire from your control board connection, again (pull the terminal strip up as a whole). If you have good continuity on every wire then it may be controller related.

These are really simple machines with no feedback loop so it is a matter of chasing the problem down from the end to the beginning of the chain.

It would help us here if you would identify how your computer is connected to the machine, what boards are in the machine, stepper drivers and control boards as well.

Mine uses USB to load the machine code into the control board and uses an operator panel on the machine to initiate the job. I can test the operation of my machine from the computer and move the head x/y directions.

[John Frazee]

Just call your local rep for Rabbit Lasers..... I am sure they will send someone right out...

Mark

If I have a problem my sales rep jumps on the next flight and he's here. Ask him for yourself, Jim Olsen with Brightstar Lasers. (yes, Chinese)

[Scott Shepherd]

That's odd, I had a problem with our laser engraver (USA) and couldn't get them to come out and look at it. Couldn't get anything done on it. Fought for 6 months or more to get someone to look at it. Never saw a soul until the day they came to buy it back, at which time they looked at the engraving results and said "There's something wrong with this machine".

Yeah, you would have known that had you showed up and looked at it 6 months ago when I started calling. Made in USA, sold in USA, rep lives in USA. So the USA thing doesn't always mean problems solved overnight.

[Robert Walters]

I haven't seen Dennis respond back yet to see if his issues got resolved or not.

[Dennis Christensen]

I got it fixed! It was a broken wire. Thanks for all the good suggestions!

[Mike Null]

Oh no! That can't be right--that's too easy.

[pete hagan]

Glad to hear it's fixed. It took me a day to chase down my broken wire but I did learn quite a bit about my laser.