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 06:03 PM.
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.
Good Luck! It may be, and I sincerely hope so, that the smoothness will show up after a couple of hours use.
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?
Last edited by CharlieRam; 30-04-2016 at 10:39 AM.
Last edited by Lee Roberts; 03-05-2016 at 04:17 PM..Me
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.
Last edited by Lee Roberts; 03-05-2016 at 09:38 PM..Me
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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