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z axis Motor running in reverse

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IMG 20140121 220538 847


Last night I was close to making my first print when I realized that my ultimaker was making the home position with the table at the very bottom of the of its limits. And when it went all the way to the bottom and hit the limit switch it didn't stop the z axis motor from turning. So I switched the plug-ins on the board for the z-axis stops and when I hit the stop this time it stop at the bottom most position. And I thought at this time something still wasn't right it was at the bottom most position for home. So I decided that the motor had to be rotating backwards. I look at the wire cluster for zaxis pictured above and the green and black wires are reversed compared to all other drives. Question is am I right in my observation. And how should i got about changing it without messing things up. Z axis plug in being in the bottom left corner






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Just one question first, you haven't updated the firmware and installed the UM2 version of the firmware by mistake? The UM2 homes towards the bottom.

If not, it's easy to switch the cables around. If you look into the end of the connector you will see tiny little "barbs" that keep the metal contacts from coming out of the plastic housing. Use a needle to push these barbs in so that you can pull the cable out. After you've done that it's just a matter of plugging the cables back in the correct order. You might need to bend the little barbs out slightly before re-inserting the cable to make sure it latches on. You'll know if you need to do that as the cable will pull out if you tug on it.


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Another possibility to drive a UM1 into the wrong z direction during homing is a customized firmware (self compiled or downloaded from marlinbuilder.robotfuzz.com) with the wrong settings at 'invert z axis'. Forget it if you have the default firmware installed.

EDIT: My last phrase was maybe misleading. The meaning was: If the default firmware is present then there should not be a problem with the firmware. In this case, nothing has to be changed.


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I downloaded the correct firmware i believe from Cura(I probably did it 4 times making sure I did it correctly).

And I was trying to do what you had just told me to do. I was just having a problems with getting the wires out and I didn't want to mess up the plug in or anything. I haven't messed with these smaller plug-ins before.


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Sorry those pictures were from 4 years ago.  You have the Ultimaker Original?  I assume so as that was the only printer from Ultimaker back then.


The ultimaker original is supposed to home up.  At the top.  When you tell it to home, if the bed is in the middle, it should start going upwards.  If it starts out going downwards then yes, your stepper wiring is backwards.  It doesn't really matter how the stepper is wired quite exactly.  There are 24 ways to wire either connector.  About 12 of them result in no movement (but no damage).  About 6 of them result in the correct direction and about 6 of them result in the wrong direction.  It's quite safe to just start swapping wires.  however there are shortcuts to getting it right.


There are two twisted pairs.  So the stepper people already helped you by grouping the wires in pairs.  You want one pair going to two pins on one side of the connector and the other pair going to two pins on the other side of the connector.


Reversing the two pins of one twisted pair (either pair) will reverse the direction of the motor.  If you reverse both pairs the motor will not change direction.


This is very safe.  The tricky part is learning how to push out one of the pins.  Once you have the right tool (a large sewing needle works really well for me -- or a jewelers screwdriver) you push down on a very tiny tab and then the pin slides out towards the "back".  Towards the wires.  Bend the tiny tab back up before re-inserting or the pin might just slide out next time.


OH - THERE IS ANOTHER POSSIBILITY which is that you have the wrong firmware.  All those white circuit boards can work in multiple machines so sometimes they show up with the wrong firmware.  I would re-install the firmware using a USB cable and Cura just to make sure you have the correct and the latest firmware.

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