Z axis broke?

[Scott Buehler]

So I was running a 3d carving last night. About an hour and a half into it, I hear a weird noise. I walked over to the machine and see that my 1/8" bn bit had broken and my z axis down as far as it could go, collet burning into my piece of mdf. I stopped the program immediately and try to assess the problem. My work piece was ruined, so i cancelled the remaining time. From there, I try to home the machine and the z axis made a weird noise as it went up. It then stopped moving and I could only get small movements out of it, while still sounding like it was binding or something, the weird part was that no matter if I pushed + or - on z, it would only go one direction( I think down) . I took the metal cover off to see if anything looked broke or out of norm. All I could see is that the z motor seemed to be binding or,maybe broke?? Anyone have any suggestions before I call tech support?

[Steve Burke]

Sounds like either the Z axis drive belt or loose ball screws. Have you done any maintenance on the machine such as lube the ballscrews?

[Bill George]

What brand of machine? I have never wet lubed any of my ball screws, maybe I am wrong but I do not want sawdust collecting on it. I use a dry spray moly lube.

[Scott Buehler]

It's a Laguna IQ, I clean the rails and ball screws with mineral spirits and then wipe down with a bit of oil, but that's about it. I checked the belt, it seems fine?

[Steve Burke]

To check the ballscrew you'll have to disconnect the drive motor and see if it can be moved by hand. If there is any binding or roughness in the travel that's the problem. If thats not the problem, then it is the motor.

[Scott Buehler]

I turns easy by hand, it's definitely the motor that is binding, but why...do they just go out sometimes?

[Steve Burke]

It happens. It doesn't matter if its a $500 dollar Chinese machine or a million dollar machine. If it breaks it breaks.

[Scott Buehler]

Ok thanks for the help. I'll contact Laguna and get one ordered

[Mark Canada]

I've had this happen on a machine with stepper motors. If your machine has a stepper motor for Z it could be one a damaged cable. The motor can't commutate if just one of the 4 (or 6/8 depending on motor setup) doesn't have a connector, or the cable is frayed internally. When its connection is bad, it sounds the same as when it loses steps - a grinding clunking noise.

You can check it with any multimeter.

If you have continuity checker mode (beeps when the the probes touch) check each wire by touching the probes to the pins of the connector. If it all looks good, try the ohm test.
If you have ohms test (shows resistance), the resistance should be well below 10ohms (allowing for cheap meter error). Anything more and the cable is fubared.
If you have dont have that (what sort of multimeter do you have???), but have a diode test mode (symbol looks like -|>-) you can check with this too, touch the probes together, you'll get some sort of voltage displayed on the screen, probably around -3v or so, you should see pretty much the same voltage when you probe each wire in the cable. Anything else, and the wire is fubared.

If you're not sure which wire in the cable goes to which pin, just keep one probe on one wire and try all the wires at the other end of the cable - at least one should respond ;)



Motors dont really die unless you've been running them stupidly hot and the insulation has broken down - OR - a bearing has disintegrated (never seen this happen!)

[Brad Shipton]

How many hours on the motor approx?

[Scott Buehler]

That sounds like it could be the culprit. I'll check the wire when I get home. I bought it used a month ago, previous user said he barely used it.. I have put about 15 hours on it so fairly new machine. I did recently install dust collector and at one time( the day before this happened) the hose from dc was kind of rubbing against the z cable??? Maybe that loosened something, and then it gave way the next day? I'll check with a meter later tonight :)

[Jerome Stanek]

Can you replace it with one of the other motors and see if that one does the same thing. That is what we do.

[Scott Buehler]

Another good idea Jerome, thank you

[Brad Shipton]

If the motor is indeed cooked after 15hrs + light usage by previous owner, something seems off. I would try to find the root cause or see if that brand of motor has a reputation of problems. The motors are not particularly expensive, but waiting for parts can be tiresome.

[Mark Canada]

Copper work hardens as it flexes, they all break (fracture) eventually in drag chains. There is drag chain specific cable of course, but its also *really* expensive relative to cheap 4 core or 4 core shielded cable so not a lot of people use it in their machines - even this is only rated for so many actuations.

[Scott Buehler]

So I found the connection where the z touch puck goes into the machine was very loose. I tightened that and now my z axis goes up and down much better( still sounds a bit weird) but it does not home it self, it goes to home in the x and y axis but the z continues to go up, then down, then up...like its lost or something? Do I need to "reboot" it or something? I put in a call to technical support on Thursday, didn't hear back from them, got an email saying they were busy and that they would get in touch with me I Friday..nothing. Hopefully they get with me on Monday.

[Mark Canada]

Something's still wrong with your connection or cable. Check the contacts in the cable, if the connector was loose it might have arced the contacts a bunch and damaged them. Going randomly up/down/chicken dancing is how my router's Z axis behaved when the cable was damaged.

[Scott Buehler]

Been on the phone the last two days with tech support. Ruled out any bad drivers, all wires seem to be tight and good connections. They are sending me a new motor to try. He said he wasn't sure that would fix it but he was stumped especially with the z axis intermittently going up and down erratically, but I guess this will rule out wether or not it's a bad motor or not..

[Steve Burke]

Scott, did you get the problem solved. Just curious.

[Scott Buehler]

Yes, just figured it out this weekend! Mark Canada nailed it on the head, my cable to the control box must have been damaged. I bypassed it with new wire straight to the box and it worked perfect. I need to go get a new cable and reroute it now and all should be good, a project I'll get to in the next few days. I'll pull the old cable out and see if there is any visible damage. I still think it's odd that the cable would go bad, but I guess "stuff" happens. Thanks everyone for all your help!