Z-Axis Motor Wiring Wrong

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Z-Axis Motor Wiring Wrong

Postby RetireeJay » 2013-Jan-Thu-14-Jan

I just finished assembling a PB Plus that was shipped in early January. The wiring for the Z-axis motors was wrong.
For X and Y, when I used Pronterface to command movement to "home" the respective parts moved toward the limit switch (the correct behavior). But when I commanded the Z axis to go "home" the carriage moved UP instead of down.

Since both Z motors are connected to the Printrboard at one connector via a cable with two "floating" connectors to the motor wiring, I decided to make the fix at the board connector. It was difficult, but I was able to remove and re-install the left-hand two connector pieces, reversing the order. Here is how the color codes were originally, and how they were after the fix (I'm reading left to right at the board connector):

ORIGINAL
Board to Floating Connector------Floating Connector to Motor
Blue..................................Orange
Yellow................................Black
Green................................Red
Red...................................Yellow


FIXED
Board to Floating Connector------Floating Connector to Motor
Yellow.................................Black
Blue...................................Orange
Green.................................Red
Red...................................Yellow

If you need/want to do the same fix that I did, here is how:
Looking at the white connector that plugs into the board, one side is pretty much solid and the other side has thin plastic "fingers" that lie on top of the metal connector parts underneath. Each metal part is "latched" in by a small metal tang that engages with the end of the finger, preventing it from retracting out of the connector body. But the white plastic is fairly flexible. You must take a very tiny screwdriver (or maybe a large sewing pin) and carefully pry up one plastic finger at a time. Not too far, just enough. When the finger is being held up, away from the metal connector part, then begin to pull the connector part out. It won't just fall out easily, but don't force it or you will break it. It may require some rocking up, down, or side to side, or rotation... but eventually you should be able to remove the metal connector part. Do this ONLY for the two left-hand pins (or the two right-hand pins), not all four. Then re-insert the connector parts in the new order.
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Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick
"My next printer is..." Prusa i3 MK3, upgraded to MK3S
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RetireeJay
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Z-Axis Motor Wiring Wrong

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Re: Z-Axis Motor Wiring Wrong

Postby andersonmatt1125 » 2013-Jul-Thu-21-Jul

I think I am having the same problem with my X-Axis. It is homing the wrong direction, but when printing or controlling through repeteir, it goes the correct direction. Does this sound like the same problem?

If so, I've also seen your post about negative calibration values. I don't think I've gotten that method to work, but I might still try at it. Are these two methods trying to solve the same problem? If so, which would you recommend?
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Re: Z-Axis Motor Wiring Wrong

Postby RetireeJay » 2013-Jul-Fri-09-Jul

Homing in the wrong direction but moving in the right direction?? That sounds more like a problem with your X "home" switch than a problem with your motor direction. When you click "home" does it just move a short distance away from home and then stop? If so, the board thinks your X home switch is activated all the time. Maybe there is something pushing on the lever. Maybe the switch is not plugged into the board. Maybe the switch is bad. Check out these things before you change the direction of motion of the motor.

If you do need to change the motor direction, I now recommend the calibration constant polarity reversal method instead of physical re-wiring. It's much easier to do, and if later you discover that something else was causing the problem it's much easier to un-do.
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Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick
"My next printer is..." Prusa i3 MK3, upgraded to MK3S
User avatar
RetireeJay
My next printer is...
 
Posts: 5002
Joined: 2013-Jan-Wed-13-Jan
Location: Greenville, SC
Reputation: 498

Re: Z-Axis Motor Wiring Wrong

Postby andersonmatt1125 » 2013-Jul-Sun-17-Jul

Yeah, that's right. It will try to home all the way to the right side of the bed. In Repeteir, X home is set to X min. Is there somewhere else that I can change the "home" location?

The part where it moves .5 inch and then stops is a recent problem, but no, the switch is not held down and is plugged in. I'm actually glad because when I hit home previously, it would continue traveling to the right, and grind itself up against the end of the smooth rods. They seem like separate issues.
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andersonmatt1125
Levelling print bed...
 
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Re: Z-Axis Motor Wiring Wrong

Postby RetireeJay » 2013-Jul-Sun-19-Jul

You don't want to change the "home" location; you want to keep the true home at the left edge of your build volume so that the prints come out oriented correctly.
It sounds like you need to reverse the polarity of your X calibration, using the procedure I linked for you in the previous note.
  • 0

Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick
"My next printer is..." Prusa i3 MK3, upgraded to MK3S
User avatar
RetireeJay
My next printer is...
 
Posts: 5002
Joined: 2013-Jan-Wed-13-Jan
Location: Greenville, SC
Reputation: 498

Re: Z-Axis Motor Wiring Wrong

Postby andersonmatt1125 » 2013-Jul-Sun-20-Jul

Unfortunately, when I do that the motor will go the wrong way when printing or controlling through repeteir. For now I'm just moving the X axis home before I turn the printer on.
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andersonmatt1125
Levelling print bed...
 
Posts: 46
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Re: Z-Axis Motor Wiring Wrong

Postby RetireeJay » 2013-Jul-Sun-20-Jul

andersonmatt1125 wrote:In Repeteir, X home is set to X min. Is there somewhere else that I can change the "home" location?


Let me guess... you are on a Mac, right?

The Windows Repetier doesn't have a "Home" button like yours to tell the software that the printhead is at the home position, although I wish it did. In Windows it's all done in hardware.

Our only "home" buttons are little house icons that cause the respective axis actuator to move toward the location of the "end stop" switch, until the switch is activated. Then it stops. Only then does the readout of position on the Repetier screen change from red to black.

(In the EEPROM Settings there is a "homing offset" but that should normally be zero or a very small number. It's useful for fine adjustments to the Z zero in order to get the printhead at the proper clearance above the print bed.)

The fact that it homes in the wrong direction is very confusing.

So you are saying that if you position the printhead at x home (far left) and then turn the printer on, that you can click on a positive "move to the right" button (0.1, 1, 10, or 50mm) and it moves to the right (in the positive X direction), away from home... but if you click on the "home" icon, it moves to the right also? And if you power on with the printhead in the middle, and without homing you click on a negative "move to the left" button, the printhead does not move because it doesn't allow going to negative values of X?
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Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick
"My next printer is..." Prusa i3 MK3, upgraded to MK3S
User avatar
RetireeJay
My next printer is...
 
Posts: 5002
Joined: 2013-Jan-Wed-13-Jan
Location: Greenville, SC
Reputation: 498

Re: Z-Axis Motor Wiring Wrong

Postby andersonmatt1125 » 2013-Jul-Sun-22-Jul

Yeah, that's exactly what happens. At least that's what happened before this new issue with the broken x limit switch.
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andersonmatt1125
Levelling print bed...
 
Posts: 46
Joined: 2013-Jun-Fri-12-Jun
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Re: Z-Axis Motor Wiring Wrong

Postby andersonmatt1125 » 2013-Oct-Tue-12-Oct

Ok, I finally figured out what was wrong with my printer. The motors were wired fine, the problem was definitely with the endstop. I'm not sure exactly what the process is, but obviously the printer uses the opening and closing of the circuit in the switch to know when to stop. Something was very wrong with my endstop, and was tricking my printer into thinking it should go the wrong way (I have no idea what the real problem was). All I had to do was replace the endstop with a new one that printrbot provided, and it started working normally!
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andersonmatt1125
Levelling print bed...
 
Posts: 46
Joined: 2013-Jun-Fri-12-Jun
Reputation: 1


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