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  1. #131
    The branding on the bearings is PDF, I tried searching for them but couldn't find them online, I got them off Chai before everyone switched to fred! not to sure about the rails, a bit bowed and terrible looking grinding bounce along the profiled angles but they seem smooth enough when moving by hand with a bit of pressure on them. time will tell I suppose.
    I'm having a right mare trying to machine the faces flat for mounting the rails, it seems I needed a bigger mill because even with the gibstrips adjusted the bed sags with the weight when moving to the extremes of the slideways causing a bowed face so I'm going to clamp it upright and mill with an end mill instead of the flycutter I was using. what this means though is I am more than likely going to have to Epoxy my steel rails cause they are even longer and heavier than the aluminium gantry.

  2. #132
    Just put the bearings on my ballscrew for the gantry and gave it a spin, it's a bit bent, the runout on the ends near the bearings is about 0.001" but in the middle it's over 0.020", my DTI doesnt read any more than that but I estimate it to be about 0.030"/0,75mm. Now I can attempt to straighten it on my mill but before I do, What would be considered as a reasonable amount of runout please?
    Cheers, Charlie

  3. #133
    Quote Originally Posted by CharlieRam View Post
    Just put the bearings on my ballscrew for the gantry and gave it a spin, it's a bit bent, the runout on the ends near the bearings is about 0.001" but in the middle it's over 0.020", my DTI doesnt read any more than that but I estimate it to be about 0.030"/0,75mm. Now I can attempt to straighten it on my mill but before I do, What would be considered as a reasonable amount of runout please?
    Cheers, Charlie
    Obviously the ideal is zero or near but I've seen worse work perfectly fine. I'd just fit it before doing anything because I think you'll find the runout won't be noticable when attched to ballnut mount. If you have vibration then it's an easy thing to remove and straighten.

  4. #134
    Cheers for the info, I will fit it as is for now then.
    Charlie

  5. #135
    Hi, I have a few questions about the BK12 bearing supports, I've tried two of the supplied ones so far and the both exhibit end float, so after searching the forums I have tried placing the bearings back to back, packed with grease and reassembled but I think I need to shim them, the problem is how do I know what to shim, the ID or OD and where can I buy the shims from?
    Also when the ballscrew is pushed fully into the bearings, it doesnt spin freely even with the nut slackened off, I assume I should be able to give the ballscrew a spin and the momentum should keep it spinning for a while, It may be the seal because it occasionally spins with the ballscrew but I have tried pushing it in a bit and pushing it out but it makes no difference? Any advice or help greatly appreciated.
    Thanks, Charlie

    Edit just checking this is Back to Back?Click image for larger version. 

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    Last edited by CharlieRam; 22-02-2016 at 11:42 AM. Reason: added pic

  6. #136
    Hi Charlie, the pic shows them back to back, I've got mine shimmed on the OD (as you want the tightening to pull the inner races together and load the bearings slightly) and cut the shims out of ali cans (good source of 0.1mm thick shim material as well as providing refreshment!) with some sharp scissors for the OD and a stanley knife for the ID. Think I used 2 or 3 shims per BK support but can't remember now.
    Neil...

    Build log...here

  7. #137
    Best get some more beer in then! What about the rubber seal, should it be spinning with the ballscrew?
    Cheers. Charlie

  8. #138
    Quote Originally Posted by CharlieRam View Post
    Best get some more beer in then! What about the rubber seal, should it be spinning with the ballscrew?
    Cheers. Charlie
    No it shouldn't be touching the seal.! . . . Sure you haven't lost the little spacer.?

    Some times they can be different lengths so check this. I've also known them be too short has well thou so it may mean spacer or making another.

  9. #139
    The spacer is the thin tube that fits in the rubber seal upto the bearing ID right? if so then they yes they are there, I will check if both sides are the same length and if not I will swap them over.

  10. #140
    They're different lengths, well mine were!
    Neil...

    Build log...here

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