Z axis error - Need help!

[kendall22]

Hi all,
I just started with CNC a few months ago. I have put about 10 hours or less on my Shark with no real errors that were not user related. Last night I encountered a major problem and need help resolving it.

In the middle of a toolpath the machine plunged into the board. I stopped it, put on a new board, loaded a different toolpath, and proceeded to carve again. This toolpath went fine. I loaded another and about two minutes through the toolpath the router plunged into the board again. I reset everything and tried the same tool path again. This time after less than a minute it plunged into the board again.

The second and third time I checked the Z-axis from the control panel. Both times it indicated that the Z-axis was where it should be. However, when I returned the machine to 0,0,0 the Z-axis was a half inch lower than when I started. When the machine plunched about a half inch into the board, the control panel indicated the Z-axis was at -0.024. It is as if the Z-axis resets its zero in the middle of the toolpath.

Any suggestions? Thanks!
Daniel

[Eagle55]

Hi Daniel,
I don't know about you but the way you described the problem sent chills down my spine. You seemed to have gotten a lot of information from you attempts. I sounds like the zero is changing downward, and its not a problem with your tool paths. I have seen and can relate to it changing in the upward direction, but downward is hard to explain. I am inclined to think that it may be something wrong in the control box. It may be related to the seating of the SD card in its slot but I am almost clueless on that symptom. I think I would call Nextwave tech support if it was as frequent as that. It really doesn't sound like you are doing anything to cause it, and it doesn't sound like a dirt or lubrication problem, but it wouldn't hurt to clean it up and lube it and make sure.

Roger

[saramos]

A couple of possiblilities to check. Check the coupling for the Z motor. If it slips when raising the router, the router will be lower than the control panel indicates, and when it decends, it will go below what you had set as zero. The same thing can happen if the Z motor stalls when raising the router. Two causes of stalls could be, the lead screw or linear bearings are chatching and need to be cleaned and lubed. The other is if you are working on a particularly thick piece, or have a long bit, you might be topping out the z axis. I doubt it is the last item as you stated that the code ran fine on a different run.

Also, there have been issues with the wires to the motors. I don't recall the particulars but if you do a search, you should be able to find further info.

Scott

[pjmayer]

Daniel,

When this happens, does the jog up button cause the z-axis to move down?

It sounds to me like your machine is doing the same thing that I had trouble with. There is one wire to the z-axis motor that tells the motor which way to turn. If the wire is disconnected, every step sent to the motor is seen as a down step. You may have a pin on the z-axis connector that is not securely seated. You might try pushing the connector pins tighter together using a small screwdriver or pointed object.

PJ

[Eagle55]

Wow, I didn't know that! Thats good to know. Hope that helps the situation... still could be several places along that wire though.

[kendall22]

Thanks for all the information and help.

I contacted Next Wave and they responded very quickly with the recommendation that I use a different SD card and change the USB cable as well as checking that everything was tight.

Everything was tight as it should be. It jogged correctly a different speeds. I changed the USB cable and tried using a different jump drive. So far no more problems.

I honestly do not know what caused the problem, but it seems to have been resolved. Thanks again for all the help!