Z-Axis only goes down

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Posts: 2
Joined: Thu Jun 16, 2016 7:12 pm
Location: Portland, TN

Z-Axis only goes down

Post by timmins » Sat Sep 29, 2018 8:48 pm

Thunderlaser Mini-60, 60W

I've had this machine almost 3 years without one problem until today.

My z-axis stopped moving in the up/positive direction. It goes down/negative just fine. My initial thought was a limit switch was stuck in a closed position...it behaves just like it...the motor will only move in one direction.

- I toggled the switch (S4) no change,
- I replaced the switch no change. (The diagnostics screen shows the Z+ limit switch is on.)
- I can toggle all the other limit switches and they are fine.
- I traced the wire back to the controller: all the connections are tight.
- The common/neg wire at the switch side is grounded.
- There is only 0.75 volts across the positive/red wire to the switch AND at the controller.
- Neither wire is shorted to ground at either end of the wire and there is 4Mohm between them.
- Stepper wires are all connected (power, gnd, step, direction etc.) and solid at the driver and stepper (no loose wires, or shorts.)

These are the obvious (to me) steps to check...I've power cycled the machine multiple times, same outcome...the Z- limit switch stays active.

Any troubleshooting next steps? I couldn't search for similar issues...my keywords are too generic.

thanks in advance for your help

Posts: 123
Joined: Tue May 24, 2016 9:06 am

Re: Z-Axis only goes down

Post by Ben » Sun Sep 30, 2018 2:04 am

Hi Timmins,

I'm wondering if your machine have installed this kinds of sensor on laser head for auto focus,see below.
1.png (600.1 KiB) Viewed 673 times
If yes,please check if the sensor is always on red light,which means it's stuck or conducting the object so the working table cannot move up any more.
Please check as following:
1.Check if the autofocus sensor is dirty,use some alcohol to clean it.
proximity sensor.jpg
proximity sensor.jpg (201.74 KiB) Viewed 673 times
2.The sensitivity of auto focus is too active,please adjust to give it back to work.
3.png (1.44 MiB) Viewed 673 times
If still nothing,please unplug the interface and see what will happen.
4.png (1.34 MiB) Viewed 673 times

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Posts: 2
Joined: Thu Jun 16, 2016 7:12 pm
Location: Portland, TN

Re: Z-Axis only goes down

Post by timmins » Sun Sep 30, 2018 2:46 am

Excellent...that took care of the problem! The sensor was clean but when I bumped the sensitivity adjustment, it began working. I never use the autofocus function as it was not repeatable with materials I use. I believe I'll leave it disconnected. Thank-you for your quick response and resolution!

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