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sam5500

Printhead doesn't seem to know where it is

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Last week, our Ultimaker 2 started exhibiting a weird problem. The printhead seems to not know where it is in the coordinate system. For example, it does not return the head to the home position in the back left corner like it used to. When you go into the settings and select home head, it simply moves about a half inch towards the front of the machine and a half inch towards the right side. It will continue to do this as many times as you push the option, and when it runs into the front right corner it continues to try and move in that direction and causes all of the belts to skip and make horrible noises. If you go to print something then the printhead starts moving as if it is starting in the back left corner, even when it isn't near the corner and then it runs into the edges of the machine. And no, I cannot manually push the printhead to the back left corner and then print, it is still off-center on the bed and runs into the edges, I've tried this already.

I have checked to make sure the mechanical stop tabs are working, they are. All of the belts are on the correct gears and are turning. I have checked the wires and they all seem to be attached. I have done a factory reset. I reverted to the 14.01 firmware which worked before. I updated to the new 14.03. Still having the issue! The machine was not altered in any way, which makes me feel that it is a software issue, but factory resets and updates didn't work.

What could possibly be the problem?

I contacted Ultimaker, but they have not responded to 2 inquiries. I was hoping to have this back up and running by the end of this week, beginning of May. I figured I would get a response here since they are not responding.

 

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It sounds like maybe one or both of the end stops is triggering permanently, freaking it out.

Manually position the head in the center of the print bed, Download the free Pronterface application, and connect to the printer over USB. That will allow you to manually drive the head around. Try moving in all 6 directions, and see if any work correctly. Also try homing the axes individually, and see if any work correctly.

Where are you located?

 

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Illuminarti,

Thank you for the response! I installed everything properly and got Pronterface up and running. You are correct. No matter where the printhead is located, it says that the endstops are hit if I try to move the head in the +Y or -X. Also, homing the X-axis individually causes the head to move only about a half inch in the +X direction, and homing the Y-axis only moves about a half inch in the -Y direction, as it was doing when selecting home head on the printer itself. Z-axis is working just fine.

Now for a new aspect of the issue, if I home the head in the X-direction and then move the printhead 3 units in the +X direction, then I can move the head 3 units back in the -X direction. Same thing with the Y-axis. So however many spaces I move in the directions that are working, I can manually move the head back those same number of spaces once the head has been homed. However I cannot move past the point in the -X or +Y direction from where it started. This only occurs once I have homed the head, before that, it just gave me the "endstop hit" message. This is an issue though since homing the head does not put the head back in the home position, just moves it in the -Y and +X directions.

I hope this all makes sense. I am trying to include as much info as possible.

How would you propose going about fixing these problems?

My company is located out of Glen Burnie, MD. I would rather fix this in-house if possible because we are trying to get some prototypes made, but I don't want to do anything that might void a warranty or such.

Again, thanks for the help so far. This is actually a very nifty tool to use.

 

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Take the cover off the electronics board (the larger of the two covers underneath the machine). It's held on by two screws that go down through the bottom of the printer.

Identify the endstop cables (they're marked on the board), and see if they are seated ok. Try removing the X connection totally, and then try moving the head around with pronterface. Don't try homing in X, because at best the head will crash into the frame since there is no end stop connected.

Then repeat by reconnecting X, and disconnecting Y. Repeat the manual head moves. The aim is to identify if it is the X or Y endstop that is causing the problem.

 

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Ok, I will relay what I did.

All of the connectors were connected with all of the wires seated properly in the connectors. I disconnected the X-stop while the machine was off and Pronterface could not connect, same thing with the Y-stop. So I left all of the stops connected while the machine was on and then connected with Pronterface, which worked.

I then removed the X-stop while the machine was on and Pronterface was connected. I was able to manually move the head in the +X direction and then back in the -X direction. However, it did not allow me to move farther in the -X direction than I had moved in the +X direction. Then I was able to move in the +Y and -Y directions with a similar problem. It would not allow me to travel farther in the -Y direction than I had moved in the +Y direction (the opposite of how it was acting before). The Y-stop worked correctly with this setup when I moved the head all the way to the +Y edge, but I could not move the head in the -Y direction past where it started, irregardless of where it started in the Y-axis.

I then removed the Y-stop while the machine was on and the X-stop was attached. I was able to manually move the head in the +X direction, but when I went to move in the -X direction it gave me the "endstop hit" error like before no matter where it was in the X-axis. I was able to move the head in both the +Y and -Y directions, even up to the +Y edge where it ran into the edge instead of hitting the endstop since it was disconnected, but like with the X-stop removed, I couldn't move farther in the -Y direction than I had moved in the +Y direction.

With both of these new setups, it's as if it believes the printhead is starting in the front left corner when it is not. I can move in the +Y and +X directions without problem. Whereas before, it was as if it believed the printhead was starting in the back left corner. So it seems with either stop removed, the same problem persists but the issue with the movement in the Y-direction has flipped.

 

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The printer has no knowledge of it's position, except keeping track of the distance it has tried to move. When you turn it on, it assumes it is at the home position, and won't let you go past that on either axis. Which is why you can't move back past the starting point. That is normal.

The act of homing the head is what brings the printers world view back into line with reality, and the origin is defined as the (actually, front left) corner. Until it has been homed, the printer just has to guess.

It sounds like the x-stop is what is causing problems. Repeat the test, and this time try plugging the x end stop into the y socket. And vice versa. Now I think x should move both ways, but not past starting point, where as y will only move one way (or possibly neither, since the y-switch is actually at the max y value, not the minimum).

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Ok, I flipped the two stops and I'm getting the same response as I was initially getting when the problem first occurred. The head moves in the +X direction and -Y direction. If I try and move it in the opposite direction for either axis it gives me the "endstop hit" error for each respective direction. Homing the X and Y directions does the same as initially (moves the head a half inch in the +X direction and half inch in the -Y direction). Same exact movements as in post #3.

 

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With the Y-stop in the X-stops connector, and nothing in the Y-stops connector, I am no longer getting an endstop error in either direction. I can move the head in the +X direction towards the right and the -Y direction towards the front, and then back in both directions to the starting point.

I went ahead and did the exact opposite (the X-stop in the Y-stop connector, and nothing in the X-stop connector) and I am getting the same exact response as the Y-stop in the X-stop connector and nothing in the Y-stop connector. No more endstop errors.

 

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Ok, I'm pretty sure that the problem is the X-endstop switch itself. Although I'm not sure why plugging it into the Y connector works ok. Maybe it's because Y homes to its max value, not the minimum. Or perhaps it's an intermittent fault on the switch, that works sometimes.

But it seems like the X switch is the problem - it's reading as closed to often. Do you see anything physically wrong with the switch or the wires going to it? It's in the back left corner of the printer, secured under the top plate.

Do you have a multimeter? If so, you could check whether it reads as permanently open or closed circuit, and see whether it varies as you move the wires or prod the switch. See if it changes as you activate the switch. (Either use a continuity test mode, or measure the resistance, looking for it to be virtually nothing, or infinite). Compare the X switch to the Y switch.

 

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I don't see anything wrong with the switch. It isn't depressed in its normal state, just like the Y switch. If you push on the lever it clicks the switch, just like the Y switch does too. I don't see anything wrong with the cables either. I don't have access to a multimeter at this moment.

We purchased the unit not too long ago and I believe we have had it since February of this year, so it should still be under warranty. Is there a place close by that I could send this to get it fixed or order the part and get it in so we can fix it here?

 

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Just to be sure we're all on the same page :-) when you're talking about the 'X' endstop - that's the one with the blue cable, that's attached to the top plate of the printer frame, right?

It's pretty well hidden up in that corner, and fiddly to work with. How confident do you feel swapping it out yourself, if you had a new switch?

 

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Yes the X switch with the blue cables was the one I was looking at. And comparing it directly with the Y switch with the red cables, I could not find any noticeable differences that would cause a bad connection or such, so it must be an internal problem in the switch or maybe something bad on the motherboard (hopefully not).

I feel fairly confident that I could do it myself, but this is a company machine and the final decision is not up to me. Since this is practically a new machine that has barely been used and is still under warranty, the company would like to send it in for repairs. How would I go about sending it in to have it maintenanced? And what kind of timeline for getting the machine back would we be looking at?

Thank you for your help in this so far!

 

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I got the same error while upgrading Ultimaker2 to 2+. Homing like this, isn't it?

In my case, when I replaced feeder motor, I crunched X sensor blue wires between motor and wall. I stared the other side of wall and hadn't noticed that. As most weirest point, I couldn't notice that first because I checked X switch is working properly with tester. Pins on PCB is shorten only when switch is clicked.

But I found homing process is changed when X sensor is connected/disconnected to PCB (Take care to turn off main power switch before hitting left wall!). Then I found cable is damaged. I cut crushed part of wires, soldered and covered with heat shrinkable tubes. Then everything worked well!

I cannot confirm you have a same situation but if you find any damage on X sensor cable, I recommend you to replace it even though it looks fine.

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