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mja

UM2 Bent Rods

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Hello,

i have my um2 for quite a bit of time and it used to give me a headache from time to time with the well debated issue (top layer lines not touching, etc.). It's definitely not underextrusion in my case.

The issue seemed to come and go, we learned to live with it and we ditch the failed prints when the issue came back. However, during the recent maintenance of the printer as i moved the printhead by hand i noticed the rods (the thick ones, X/Y) are not straight. I can even see it with naked eye, the rod is bent and as i slide the printhead, it moves and it has some effect on the printhead (it is raising/lowering the head by just tiny bit)

I think this issue has been there since we bought the printer and has caused this issue. I'm now clueless what to do - where should i get new x/y rods?

Thank you,

Martin

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If they are bendt since assembly you could try and contact your reseller and see if they can send you new ones.

If you need to buy new ones, also most resellers can get you new ones, the prices I got from my reseller was slighty higher than the prices I got from IGUS, so I ordered new ones from IGUS, also from IGUS you need to tell them the length.

That suited me very good, as I'm running direct drive on my Ultimaker and I ordered 16mm longer ones, so they stick out and motors connect.

The IGUS ones are found here :

http://www.igus.eu/product/?artnr=SWMH-08

their site is a bit difficult to navigate, but the rods are called

SWMH-08 drylin® accessories, steel shafts 1.1213 hard-chromed

Be sure to go for normal steel shafts, as stainless steel ones are many times more expensive :)

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Thank you, i got my UM2 directly from Ultimaker, but i guess i'm out of luck since the machine is out of warranty already.

I'll take a look at the igus site, thank you again

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There is also a risk of bending the rods by atomic pulls, if you do them too brutally, or by lifting the printer by pulling on the rods. I am not saying that has happened to your printer, it's just as precaution.

If you want to use a more gentle atomic pull, try this method:

https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/

Instead of pulling brutally, this method uses gentle wiggling and twisting instead, plus much deeper cooling to room temp, before reheating. But no brute force at all. Cleaning results are similar to the standard atomic pull.

I should update that manual a bit, but meanwhile you can still use it.

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Yeah i'm aware of that and i'm very carful about the atomic pulls.

However, i'm still convinced it's there since the beginning, because when i move the head by hand in one direction (eg. towards the front of the printer) it does not move in

"smooth" fashion, but it does so in a series of "jumps" or "waves" - not sure how to describe it.

The same happens if i try to pull the head diagonally (equally X and Y) - the head does not follow the hand smoothly along the X=Y, but it tries naturally to follow X-Y zigzag pattern. I think these are the symptoms of the rods being dead.

I always thought it's normal, until i recently saw another ultimaker which didn't had this problem, that lead me to discovery of the bent rods.

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I have faced same problem.I am building an ultimaker clone and I received bent axis. I have seen lot of video for straightening a shaft but they all requires some special setup like dial gauge, some propane torch or some sophisticated machine. Now when you have only 04-06 rods to look after, you should not go for purchasing those exotic showcase piece of measuring instruments.

 

So I resolved that I would straighten the rods with my own hands (literally!!) and without any dial gauge to the highest possible resolution of human eyes (Fortunately, I am engineer by the grace of God could detect misalignment with quite good with naked eyes).

 

You see, there is no end to precision you can achieve however bottom line is - it should just work for you. And this is exactly the purpose of my innovation (??).

 

You will probably laugh at ridiculously simple method when you see the video which is having unfortunately very high level of background noise but believe me I have straightened all four rods with exact same problem as yours with a sketch pen (for detecting runout), 02 bearing with bearing holders (so that you can rotate the steel rods) , one piece of wood (for pressing the rod downwards after you detected run out), 02 great eye ball with safety spectacle on it :) and 02 strong hands. Just see the video ( I will try to do version without background noise also) and just let me know if any help is required. That is what community is for - we are band of brothers (psst Sisters also - no gender bias).

 

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You don't show the part where you actually apply the force, do you?  I didn't see that part.  I would love to see roughly how hard you are pushing.

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Ok.. :) I could not show that part because no one was around to film it. My bad. However, if you look at the  video I posted, you will see a small wooden piece (around 6 inch) lying near by the set up. That is the thing I used. How hard I pressed? Well, that is subjective however I used to press till I could see that rod has flexed quite good (make a shallow arch may be 2-3mm deep)  and than hold there till count of 15 (why 15?..lol... that's after trial and error.  Because when i have halted till count of 20, I end up bending the rod on otherside). You need passions for my method to work, but believe me it works without spending a penny. Rather than bending what I wanted to show is how to detect the run out with sufficient accuracy without use of sophisticated instruments,bending etc.. is trivial task. 

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3 hours ago, virenchocha said:

Rather than bending what I wanted to show is how to detect the run out with sufficient accuracy without use of sophisticated instruments,bending etc.. is trivial task. 

I don't know the term "run out" but after watching the video I think you mean "error".

 

Yes your method of measuring the rod bend is great and it shows where to push as well!

 

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