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Movement seems stiff, is this right?

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Posted · Movement seems stiff, is this right?

I'm at the stage where I'm calibrating the x-y axes and the limit switches, but while I'm moving the extruder around it seems like hard work, it's really stiff to move. Shouldn't it be a nice smooth motion? Quite easy? Or will the motors move it along fine?

Thanks,

Gino

 

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Posted · Movement seems stiff, is this right?

This is often because the end caps are too tight. You should be able to move the head using the smallest finger on each hand placed on the two blocks on either side of the head.

 

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Posted · Movement seems stiff, is this right?

Thanks, I just losened the ends caps until they wobble and it's slightly easier but still stiffer than you describe. Anything else that could be causing the problem?

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Posted · Movement seems stiff, is this right?

When I added the linear bearings I noticed a few things. Firstly a tiny BB fell out of one of the bearings, and secondly, one of the axes didn't move smoothly through either bearing, but the other axes mostly moved smoothly through them. Is this probably the main cause? What can I do about it?

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Posted · Movement seems stiff, is this right?

not saying this is your fault, but if you're not careful inserting the rod the linear bearing can be damaged. could be the case that there was a ball bearing left over from the factory.

if things have not improved by now and if you suspect a bad bearing, i would loosen everything, all the belts including short ones, and see how the movement is. if that still shows a lot of friction, remove the entire hot including small rods and try to inspect. once you've looked inside to see if there is any damage, carefully slide a rod through the suspect linear bearing to see how it slides.

 

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Posted · Movement seems stiff, is this right?

Hi @fluxline, thanks for your help. Perhaps I should have been a bit clearer!

The BB fell out when I picked up the linear bearing, before I put the rod in so I'm sure I didn't damage it myself. I imagine it was just left over from the factory perhaps.

The issue I have is that one of the rods moved perfectly fine through both linear bearings (lovely and smooth) but the other rod was not moving smoothly, so I suspect the problem is the rod and not the bearing (though one of the bearings was worse than the other!)

I'm going to try applying a drop of oil to the rods to see if there's any improvement to the jerky motion. Can anyone recommend a good brand or type of oil?

 

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Posted · Movement seems stiff, is this right?

just make sure it is oil and not grease, also not WD40! Light mineral oil, sewing machine or razor oil works well.

edit: It might be that the rod is bent, sounds odd that one rod slides well and the other not.

 

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Posted · Movement seems stiff, is this right?

Thanks, I'll get some of the right stuff.

Yes that's what I thought, should I contact Ultimaker to ask for a straight rod? Is there a good way to test for straightness other than rolling it along a flat surface?

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Posted · Movement seems stiff, is this right?

I don't know why UM seems not to be able anymore to deliver straight rods. I had the same issue on my UMO. However, I replaced it with rods from Misumi.

It is interesting that I have a 'guest' UMO atm. It is an older model with electronics version 1.5.6. But it has straight rods and concentric pulleys!!!

 

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Posted · Movement seems stiff, is this right?

For anyone still interested, I've taken the printer apart and tested the X/Y rods, sure enough one is bent and the other one seems to be slightly too wide in diameter. I've emailed Ultimaker support to let them know, I think it's fair to ask for replacement rods as the ones they sent me aren't suitable, right?

 

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Posted · Movement seems stiff, is this right?

I had the same problem with the end caps being far too snug a fit for the rods when screwed on tightly. Loosened them and then spent the next 2 weeks periodically picking up nuts and bolts as they fell off the machine - if you leave them loose, they work themselves apart from the vibration of the machine! As a result also, one of the rods started pushing out sideways. Not good. In the end I printed these

 

http://www.thingiverse.com/thing:23835

[gr5 edit: fixed link]

and after installing them everything is running smoothly and nothing is falling off anymore...phew!

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Posted · Movement seems stiff, is this right?

I get a 404 error from that link.

BTW, there is also a really cool nut holder for the inside side of the rod ends. Just search youmagine or thingiverse for "ultimaker nut holder" or something like that. It is U shaped, so you can put it on without removing the rods. Makes installing and removing rod end covers a million times easier.

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Posted · Movement seems stiff, is this right?

When you move the hotend (extruder head), make sure to grab only the slider blocks, never the head itself!

This way you put significantly less stress on the gantry, and it's also easier to move.

 

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Posted · Movement seems stiff, is this right?

I'm building an ultimaker original and I have encountered the same problem - stiff movement on xy gantry. I got the endcaps out of the way(they are way too tight) and the moovement is still very stiff and jaggedy(feels like it's rapidly accelerating and slowing down along the movement). Any thoughts on what might cause this?

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