LitePlacer.com forums

The mechanical assembly went well thanks to Juha'a excellent instructions. The electrical took more time than expected and will need to be redone with an enclosure at some point. Unfortunately, I’m stuck on basic setup. After checking the forums, without finding the solutions, here is where I am at:

• The cabling has been checked repeatedly including testing continuity where there were problems
• I am using shielded cable that is properly grounded as well as ferrite cores on the motor end of the cables
• I can move X, Y and Z but not A (see below)
• The LEDs are powered on
• The vacuum pump and solenoid can be turned on and off from the control panel
• X and Y can be homed

The problems:

• A Motor: The motor will NOT rotate using keyboard commands. When the motor power is on, it makes a high-pitched whine. The coil resistance is 4 ohms for the green/black pair and 10 ohms for the black red pair. Unfortunately, there appears to be a short across the coils which probably the problem. The current pot on the TinyG was set to the lowest setting as stated in the instructions. A bad motor?
• Z Motor: When I reset to the defaults, I notice the tick boxes for home, min limit and max limit are all checked even though the setup instructions say they they should be unticked. I'm not certain that is critical but when I check the limit switches per the instructions, I need to untick the boxes then re-tick them to perform the check. The real problem is that I have been unable to home the Z motor. It reaches the limit switch and fails to back off and correctly set the Z home value. It doesn't fault when the limit switch is triggered but when I let it run (only a couple times), it times out. I have tested the cabling for the switch as well as swapping wiring with the Z max switch. Nothing worked.

I have ordered a replacement A motor since I believe Juha is on his way to the U.S. for Maker Faire Bay Area. However, the motor is coming from China so it will take at least 2-5 days with DHL. That still leaves me with the Z motor homing problem. Any suggestions would be appreciated since the project is now at a dead stop until these two problems are resolved. Btw, I am happy to be told these are "pilot errors" if it is something I am doing incorrectly.

Thanks.

With regard to the A motor, it most likely won't turn with the current pot at the very lowest setting.

I found that I needed to up it to about 15% / 20%. The idea is to start at the lowest setting and then turn it up to the lowest level that will reliably turn the motor.

On the Z-Limit switch, do you hear the switch clicking when it should be triggering? If you want to test your wiring and if you have a multi-meter then set it to DC volts and measure the voltage between the relevant terminal on the TinyG and ground.

It should be 3.3v or thereabouts when the switch is open / not triggered and 0v when triggered.

Tommy

Yes, sounds like a bad motor. And unfortunately, I am indeed on the road until 25th.

For z homing, you should enable the tick boxes. The advice not to is valid only for initial connection, as you don't get anywhere if the wiring is faulty and switches enabled. So, enable the switch boxes. Test the switch operation manually; you should get "panic" situation on TinyG when you manually trigger a switch. Reset TinyG and re-establish connection. The topmost switch is the z min, the one touching the pulley is z max.

If homing still doesn't work, what exactly happens when you click home z? For diagnostics, start the software (so that the start up dialogue gets to the log), click home z. Finally, send text $$ to TinyG; that dumps all TinyG internal settings to the log window. Click inside the log window, ctrl+A to select all, copy and paste to a text document and email that to me.

@GilchristT: Thanks for the feedback. I think the A motor is gone because of the coil short. It doesn't work at any current pot setting. Good suggestion to test the limit switch on Zmin. Since it's a NC switch, it should be delivering power until it is tripped and then show an open circuit. It tested out as you noted...3.3V when not triggered and open when triggered. I also checked the continuity on the control wire on the switch back to the TinyG to ensure the proper wire is connect to the Zmin position on the terminal block. It seems to be fine. I also tested the Zmin switch to set if it would panic the TinyG when triggered and it does.

@JuKu: All the boxes are checked and XY homes, tests and parks just fine. I calibrated the machine size and it also is good. When I try to home Z, it reaches the limit and keeps trying to go up but never backs off to set the Zmin value. It will time out if I let it. See the log under separate email cover. It seems to to indicate the homing was done even though it failed and the control panel reports the Z setting as -84. Thanks for your help.

> .., 3.3V when not triggered and open when triggered.

Just to clarify other readers: the switch should deliver 3.3V when not triggered (for better noise immunity) but 0V when activated. Leaving it open would result 3.3V on the switch input because of weak pull-up on TinyG, and TinyG wouldn't see anything. But this is not the case here, as triggering the switch does cause TinyG error.

Z limit switch problem solved thanks to @JuKu and @GilchristT! The obvious thing to check which I never did was whether the switch was actually being triggered as the assembly moved up. Because the switch was pointed down a few degrees more than it should have, the assembly reached the end of its travel before the switch could be triggered. The noise of the assembly banging on the travel limit masked the sound (or lack of) of the switch being triggered. Other noobs like myself need to check whether all limit switches are triggering properly as they move to the end of their travel. I thought I did but might have not been careful enough.