That's weird. I asked a few weeks ago how they prevent the rods from doing exactly what you described and Daid said that they engineered them so they can't move out. I smell a UM2 upgrade here 
But something is not clear to me. Doesn't this vastly impair print quality? If the rod moves with the print head, wouldn't it start printing an inch or two to the left/right?
Is that exactly 5mm?
The axes are kept in place by the pulleys and black spaces between/behind them. Looks like there might be 1 missing or a lose pulley.
Hi Daid
On the rear rod there is about 2/3mm play left to right but putting some oil on it seems to have stopped the movement..
The front rod as shown in the pic is sticking out about 4.3mm.. there is a black spacer next to the silver cog on that side...
When i push the rod back in and look directly down on the machine the belt does not look straight from back to front of the machine, it looks straight when the rod is poking out. its as if the cog needs to be moved along the rod further. i assume this can not be done as the rod must have a locator for the grub screw....
Here is a picture of the end of the rod when pushed back into position...
I only have the UM original but I'm pretty sure there is no locator. In fact it is recommended not to file any of the rods flat as supposedly that is worse then standard "perfect" rods. So just loosen that grub screw and slide the pulley so that the belt is straighter.
Then of course tighten the heck out of it so it stops moving around.
No, there's no locator hole for the grub screw (unless things changed significantly since the original). So if I'm understanding daid correctly it's just a matter of loosening the pulley, pushing the rod back into place, slide the pulley back into the correct location again and re-tighten the grub screw.
edit: Bah! gr5 beat me. Nothing new there 
Thanks Guys
I am new to 3d printers so did not want to mess with it until i got some advice...
I just assumed there was a locator on the rod for the grub screw to stop this exact thing..
When i get in tomorrow i will loosen off the grub screw and move the pulley along the shaft and hopefully i will be back in action again..
No, there's no locator hole for the grub screw (unless things changed significantly since the original). So if I'm understanding daid correctly it's just a matter of loosening the pulley, pushing the rod back into place, slide the pulley back into the correct location again and re-tighten the grub screw.
Yep, that should do the trick.
The belts should be straight above the axis. So the photo clearly shows that the pulley is not at the proper position (what you call cog is a pulley).
Good to know ;-)
A DHL man just drove up the jard this morning with a shiny new box from the Neatherlands... mmm... I wonder what that could be... ;-) YIPPPPPEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
Ian :-)
I only have the UM original but I'm pretty sure there is no locator. In fact it is recommended not to file any of the rods flat as supposedly that is worse then standard "perfect" rods. So just loosen that grub screw and slide the pulley so that the belt is straighter.
Then of course tighten the heck out of it so it stops moving around.
Be carefull that you don't tighten too much heck out of it! The standard UM pullies tend to deform in an oval shape if you tighten them too much. I had that issue.. so I bought new pullies.
Hi Guys
Yep just loosened off the grub screw slid the pulley along the rod and nipped it up again, about a minutes job. Now back to printing...
P.S. i did not tighten the heck out of it but a nice firm grip
from a 6 hours vet with an ultimaker 2. hahaha
My ultimaker 2 also came with the steel bars slide out. loosen the pulleys. push back the bars... tighten pulley and your back in business.
BUT ! i gotta say... after 3 hours of printing, the bars started to slowly move around... actually they are easy to push with a finger even with pullys tightened... so this.. could be something that needs to be officially addressed and corrected by ultimaker... I mean I dont want a 20 hour print to look WAVY GRAVY BABY !
Ian :-)
Hello,
Indeed, if the only pulleys hold the bar there will be a big problem for print longevity.
Does it occur with agmentation the print speed?
How Ultimaker to himself solved this problem at exhibitions?
It will therefore be important to monitor this. We must see what Palliative were appporté to mechanics.
I read some interesting things about the pulleys. Must be marked with a pencil imdélébile shaft and pulley. I think it will be my first operation upon receipt of the machine. Complete disassembly and inspection of mechanical! This is definitely a bad thing for new users!
Thank you.
Alex.
Hi Ian
That's when my pulley moved and the bar started to come out when i was doing a 20 hour print, when i got up in the morning the bar was poking out of the case :(
I did a 4 hour print last night after tightening it up and it did not move, But still did not want to put another 20 hour print on just in case, so will do another 5 hour print when i get in just to make sure it's not going to come lose again....
im going to try again tonight to get my new ultimaker 2 working.... lets see what the axis bars say ?
Ian
Half way through a 4 hour print and i can notice a clonking again, guess what you got it now my y axis bars a poking out the back of the machine, so when the print head moves front to back you get the clonking noise as the rods are moving and banging up against the spacer....
Time to move all the pulleys again and tighten them up, another wasted print.
EDIT---- Right i have now tightened every pulley i can get access too and started the print again..
Seems like the pulleys must be shifting on the rods then, or the spacers are missing... if everything stays locked in place at both ends of the rod, then it isn't possible for the rod to slide through the bearing.
Having the rods move around isn't ideal, of course - but the negative effect comes from the fact that it may twist the other axis' pulley and belt out of alignment, and/or eventually pull the rod out of the bearings totally. At first glance you might intuit that the rod is moving instead of the head, but it's the other way round: the moving belt drags the head into the right place. If the head happens to drag the rod that it is sliding on with it, as it moves, that's not actually going to affect the final position of the head.
At first glance you might intuit that the rod is moving instead of the head, but it's the other way round: the moving belt drags the head into the right place. If the head happens to drag the rod that it is sliding on with it, as it moves, that's not actually going to affect the final position of the head.
That is good to know. you are correct that the head drags the bar back and forth and when the spacer hits the case/bearing you get the banging/clonking noise..
Pulleys are moving on the rods as the spacers are there.
Time to move all the pulleys again and tighten them up, another wasted print.
That sounds crazy. You cancelled a print because it *might* fail?
I removed one of the endcaps of my old UM Original and the rod sticks out but if I just ignore it, it never gets worse. It's in a happy place now. Some day I will look into it and see if I can adjust the pulleys (slide them along the rod and re-tighten) but for now it can print for months and months like this.
Having the rods move around isn't ideal, of course - but the negative effect comes from the fact that it may twist the other axis' pulley and belt out of alignment, and/or eventually pull the rod out of the bearings totally.
Hi gr5
Like illuminarti said if the pulleys are lose and moving along the rod, there is nothing holding the rod in place, if the pulley continues to move along the rod, which it will do i assuem if it already has moved then the print head will fall onto the print/hotbed.. wonder what that would look like when i get up in the morning....
So...
Now that I've seen Ian's photos and looked my UM2 over carefully - there is a system of locked pulleys, black spacers and pulleys against the walls of the inside of the UM2. 8 of them. NONE of the rods should be sliding around. If they are then either you are missing a black spacer, or more likely one of your set screws in one of your pulleys is loose.
The one with the problem will actually always be the one closest to where the rod is poking *out*. So push the rod back in and slide the pulley against the spacer (if there is one) and then against the outer wall, and then tighten the pulley set screw.
So ?
Not sure where your coming from gr5, you can see in my pics i have spacers, you can also see i have now had to tighten pulleys twice..
Are you suggestion just suck it up and tighten the pulleys every few prints, and deal with it if they move during a 20 hour print ? not to sure where your coming from with your suggestions to help prevent my issue as i have done what you suggest already....
No, I think George (gr5) is just diagnosing the issue... if the problem happens, then that's what causing it, and where to look for the fix.
Clearly you shouldn't need to tighten the pulleys repeatedly - although we long standing UM1 users know that getting them sufficiently tight can be surprisingly difficult.
If the problem persists, and you are unable to tighten the pulleys enough to fix the problem, then obviously something is wrong with your pulleys or most likely the set screws. You should definitely open a support ticket with Ultimaker, and have them help you fix the problem.
Also, please bear in mind that George and I just end users, like you. We don't work for Ultimaker, and can't speak on their behalf.
illuminarti
I full understand you guys are trying to help and its much appreciated.. your right some of the screws are hard to get at and tighten but i have been round all the ones i can reach and put as much tension on as possible, i have done 2 prints since and nothing has moved...
Hopefully all will be fine now (fingers crossed) if not i will open up a ticket to see if ultimaker can come up with a solution...
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cor3ys 28
It seems the rod just pushed back in, then on the next print it came back out again and the rear rod was knocking left and right during the print...
What i did was push it back in and added a little cooking oil to the front and rear rods this seems to have stopped the rear rod moving left and right (knocking stopped)
But it has not stopped the front rod from protruding out of the case still...
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