SOLVED Y-Axis question.

Discussion in 'Build Help' started by Crashbombs, Jun 1, 2016.

  1. Crashbombs

    Crashbombs Well-Known Member

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    So I had a couple of question while I was building last night about the Y-Axis.

    1. What does smooth mean? I watched the youtube video about what a smooth y axis looks like, and if I move the carriage forward and back fast like in the video it feels fine. However, if I move the carriage slowly it feels a bit more choppy or "sandy." so I was wondering if I should be working to get it smoother.

    2. One of the steps for the y-axis has you measure from the front of the big box too the the front of the x-axis rod. In the instructions it says both of these measurements should be the same for each side. Well I am using a pair of calipers and the difference is around 1mm. Is that close enough, or do they have to be exact?

    Thanks for the help!
     
  2. Alex9779

    Alex9779 Moderator
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    Hard to tell, I feel that too when moving real slow but this are only the bearing balls which need a little force to get moving, think that is normal.

    They should be exact or close, under 1mm, I just used a normal 1mm ruler, with that you don't try to get too exact. Otherwise the Y axis can brace in the back or front. You won't realize at first but you might get issues when printing like misaligned layers.
     
  3. mike01hu

    mike01hu Well-Known Member

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    1. The Y axis feel is quite difficult to quantify but any roughness is not a good thing. I assume you pre-greased the bushes with lithium grease and that you ran the bushes up and down several times to distribute the grease. Alignment is also critical as any out-of-parallel action will put a twist load on the bush and can affect the running, which brings me to:
    2. If you are 1mm out across the X-axis that will translate into your models not being square, so it is necessary to make that alignment as good as you can. I made this adjustment at the rear as it was easier to measure and I used a pair of identical jigs to set each end of the X-axis the same before locking the pulleys. You can achieve better than 0.1mm if you are careful and use a digital calliper.
     
  4. Dr Jeep

    Dr Jeep Well-Known Member

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    The nature of the linear bearings is that they feel a little bit choppy for small slow movements. The reality is that once you have the mass of the motors on there and the position being held by correctly tensioned belts then it should all smooth out. These linear bearings were designed to operate under higher load conditions than in a 3D printer so under the test conditions moving the axis by hand you can experience a bit of ball skipping. What you are looking for in the axis movement at this stage is no obvious tight spots.

    The supplied bearings also need a good bit of running in and improve with use I found.
     
    Old_Tafr and Alex Stevenson like this.
  5. Crashbombs

    Crashbombs Well-Known Member

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    Thanks a ton guys! I think I did a good job then. I will see what the prints look like and adjust if need be.
     

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