Quote Originally Posted by MikeyC38 View Post
Hi bluesking
When I built mine (see here) It moved by it self once I had pushed gently.The ballscrew was NOT connected for this test so that you can detect any binding in the bearings. However I am using SBR bearings on a supported round rail. These are more tolerant of misalignment than the bearings you are using. With the bearings you are using for the gantry, accurate alignment is a must, I'm afraid, but they are the best you can buy!
Thanks Mikey,
Thing is, even just running a single hiwin hgr 20 carriage along a single rail (hence no opportunity for misalignment), you give it a little push and it moves, but as soon as you stop applying force it stops - no momentum retained. I think this is due to the relatively high pre-load on the the HGR carriages - they just behave that way. Anyway, with no ballscrew connected I think things behave well overall (see my video above). Connecting the ballscrew introduced the problems - though these have been much reduced now - I just don't know what I am aiming for!