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  1. #151
    So I stripped the carriage, 119 ball bearings, measured quite a few of them and they were 3,975-3,988 ish so my measurement last night was good, still notchy :-(

    Would the lack of one ball really cause this issue? degreased and checked all ball tracks, checked the end plastic things by pushing the balls back and forth and they seem ok? Could the plastic cage thing be chafing?

    Just out of interest I got some digital kitchen scales on the end of each rail and pushed on it until the rails started to move, the good one started to move at about 400g of pressure, the notchy one was just over 1000g, for info the rails are 375mm long.

    BTW, the brand is PDF and model is DFH20A
    Last edited by CharlieRam; 21-04-2016 at 07:03 PM.

  2. #152
    I also have a set of 600mm PDF 20mm profile rails, which dont run smooth at all. I will change them out with hiwin down the road when I get some leftover money to do so. For now Im gonna keep it as it is until it proves to be a huge problem.

  3. #153
    Lee Roberts's Avatar
    Lives in Wigan, United Kingdom. Current Activity: Viewing Moderator Control Panel Has been a member for 9-10 years. Has a total post count of 2,438. Received thanks 130 times, giving thanks to others 612 times. Made a monetary donation to the upkeep of the community. Referred 9 members to the community.
    Quote Originally Posted by CharlieRam View Post
    So I stripped the carriage, 119 ball bearings, measured quite a few of them and they were 3,975-3,988 ish so my measurement last night was good, still notchy :-(
    I would think they are to the closest standard size of 5/32in then, your in luck as well because I've got some that size, PM me if you want me to send you some, call it the postage cost...

    Lee
    .Me

  4. #154
    Quote Originally Posted by sinnsvak View Post
    I also have a set of 600mm PDF 20mm profile rails, which dont run smooth at all. I will change them out with hiwin down the road when I get some leftover money to do so. For now Im gonna keep it as it is until it proves to be a huge problem.
    Lee Roberts is sending me some ball bearings, I'll see if it makes a difference and if not I will fettle the carriage a little......Now wheres that bastard file ;-)

  5. #155
    Good Luck! It may be, and I sincerely hope so, that the smoothness will show up after a couple of hours use.

  6. #156
    Well that's been a few days of discovery I won't forget in a hurry!

    I stripped the carriage again, gave it a good clean and scotchbrite on all ports and ball ways, reassembled the carriage temporarily, put it back on the rail and started to slide it up and down to check the tightness and then....the end came off and 120 balls all over the floor! F$%k, I found 118 of them and still had 2 spare from Lee luckily.

    Oh yeah, I also decided to check the other carriages now I'm confident the balls wont go flying if I remove them a couple of the others seem to have one ball missing too!

    Cleaned it all again and secured it properly this time but it still felt tight, that is when I noticed the carriages looked slightly different on the exterior, so I checked the serial numbers again, both are DFH20A but the nice fitting ones have S01411040 and the tight one has S01207841. Does anyone know if any of these numbers signify the preload, I'm thinking I may have a higher preload carriage or is it just a batch number and one was made at a different time with not such a good QC?

    More Importantly, will it affect the build having a mis matched carriage?

    Cheers, Charlie
    Last edited by CharlieRam; 30-04-2016 at 11:39 AM.

  7. #157
    Lee Roberts's Avatar
    Lives in Wigan, United Kingdom. Current Activity: Viewing Moderator Control Panel Has been a member for 9-10 years. Has a total post count of 2,438. Received thanks 130 times, giving thanks to others 612 times. Made a monetary donation to the upkeep of the community. Referred 9 members to the community.
    Hi Lee,

    Quote Originally Posted by CharlieRam View Post
    so I checked the serial numbers again, both are DFH20A but the nice fitting ones have S01411040 and the tight one has S01207841. Does anyone know if any of these numbers signify the preload, I'm thinking I may have a higher preload carriage or is it just a batch number and one was made at a different time with not such a good QC?
    Cant help there sorry, what you could do is mic the ball's and see if they are diffrent, this may give you the anwser.

    Quote Originally Posted by CharlieRam View Post
    More Importantly, will it affect the build having a mis matched carriage?
    I can’t see it being a problem, so would just go with it, others may know better but I can’t think what problems it may introduce, ultimately if it is a preload difference then its unbalanced but would suggest it’s going to be such a small amount, just leaving you with the least amount of preload as your best number, so again not a problem.

    .Me
    Last edited by Lee Roberts; 03-05-2016 at 05:17 PM.
    .Me

  8. #158
    Quote Originally Posted by Lee Roberts View Post
    Hi Lee,

    Cant help there sorry, what you could do is mic the ball's and see if they are diffrent, this may give you the anwser.

    .Me
    Is that how the preload is set then? with slightly larger ball's?

  9. #159
    Lee Roberts's Avatar
    Lives in Wigan, United Kingdom. Current Activity: Viewing Moderator Control Panel Has been a member for 9-10 years. Has a total post count of 2,438. Received thanks 130 times, giving thanks to others 612 times. Made a monetary donation to the upkeep of the community. Referred 9 members to the community.
    Quote Originally Posted by CharlieRam View Post
    Is that how the preload is set then? with slightly larger ball's?
    Hiya,

    Pretty much yes, if you use slightly bigger ball bearings than the distance between the carriages and rail.

    The ball bearing size (relative) determines the amount of preload achieved. From what I've read, the most common amounts of preload used for linear guides are 8, 5 and 2 percent of their load rating (dynamic).

    For ballscrews and nuts you can do the same thing with the ball sizing, use an adjustable nut or use two nuts.

    .Me
    Last edited by Lee Roberts; 03-05-2016 at 10:38 PM.
    .Me

  10. #160
    Well.....I've been a bit quiet on here and for good reason, I found out my good wife was having an affair!! So dealing with a lot of shit at the minute, mainly custody of the kids and making sure I still have a family home and some cash left at the end of it. Just had my Decree nisi date for the 1st September so all being well and if we can come to a fair agreement on asset splitting (Fair to me would be she got F all but that ain't gonna happen) Hopefully I will be divorced middle of November, What a waste of 22 years! but onward and upward and hopefully I will be in the mood to start/finish my machine soon. Think I need a hobby to get me out the house and meet some new people.
    Take care and if you feel like lifes getting you down....Just think about me and how it could be worse and have a good chuckle :) I know it's not quite life or death but sometimes it feels like it!

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