<p>levlandau;</p><p>I have been using 12mm rails. I documented the X axis upgrade here:<br></p><p><a href="https://www.flickr.com/photos/34962649@N00/sets/72157647511189303/" target="_blank" rel="nofollow">https://www.flickr.com/photos/34962649@N00/sets/72157647511189303/</a><br></p>I had a buddy that got away fine with one rail and one car for the X axis. I was worried about the screws slipping with just one car, and my set included two rails and four cars, so I went all out.<br><br>Y axis:<br><br><a href="https://www.flickr.com/photos/34962649@N00/sets/72157651304651086/" target="_blank" rel="nofollow">https://www.flickr.com/photos/34962649@N00/sets/72157651304651086/</a><br><br>Basically, the rails are 12mm width type, and you want to use the low profile cars so that the rail + car height is 13mm.<br><br>I think these systems will all fit: <br><br>CPC MR12MN<br>THK SRSR12M<br>THK RSR12ZM<br>THK RSR12VM<br>IKO LWL12BCS<br>IKO LWL12CS<br>NSK LU12<br>NSK PU12<br>Hiwin MGN12

<p>This is a really cool mod. I really like it. Can you tell me what linear bearings you are using for the x-axis? I really want to upgrade from the standard &nbsp;bushing which have a good amount of play.</p>