CNC4A - Quiet Linear Bearings (in 4K UHD)
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- Опубликовано: 14 июл 2024
- / thewizard
This is Video Number 254. How Many Have You Watched?
CNC4A once again takes you to the next level by showing you how to reduce the noise and remove the slop in linear bearings. 
Хобби
Thank you for going into such detail on demonstrating the acoustic qualities of the polymer bushings, VERY much appreciated
My pleasure and thanks for watching. Here's another 3D Print tip you will find useful.
ruclips.net/video/35Yj7Iy3o50/видео.html
Why there is play in lm8uu based linear rail , I measure the diameter of different roads all diameter is less than 8mm it's around 7.6 to 7.8 mm is it common tolorance or perfect 8mm rods are also available??
Good Question. It has got to do with manufacturing tolerances and the intended end use. To make something to a tight tolerance is more expensive to make. If a hole is just to take a bolt you can just drill, but if it is for a shaft you may need to ream the bore or even bore it. So the engineers came up with a series of fits. Interference, Push, Sliding, etc and tolerances for the hole Hxx and the shaft Letterxx. A reamer will have the code on it so you know what size the finished reamed hole will be. So a 10mm reamer will not ream a 10mm hole. It will be oversize, the amount will be determined by the fit class. Google British Standard Selected Fits, etc and you will see the charts then you can determine what class yours are. Now for a quick fix. You can replace the ball with larger ones. Or for a simpler quicker one tilt the housing so it is on an angle to each other and the shaft will hit the bottom ball on the left and the top ball on the right (if mounted vertical) etc. Watch my cnc videos and I mention in one of them about twisting the ball nut to take the backlash out, etc. I hope this explanation helps you out and points you in the right direction. And as always thanks for watching.
I believe the Igus RJMP bushings are slightly oversized because they're intended to be press fit into their housing and compress, otherwise they tend to have a bit of slop. At least that's what they claim. I've never had great experiences with them myself.
Correct Nibato. It also depending on how the God's are looking down on you. The injected bush may have flashing, burrs, seems, scratches, etc left on and its tolerance on the OD and ID. The quality and the tolerance of the linear bush block as some are machined and cheaper ones left as die cast. The rod diameter (OD) also varies and cheap ones are usually under size. So you need to mix and match your set to get the best fit on all. If the tolerances are one way it may end up too tight and the other too loose. You are after the Goldilocks moment, "ah Just Right". And as always thanks for watching Nibato.
Note that typical db measurements are taken at 1m, so this isnt easily comparable to other measurements
Correct. If you are comparing stated official isolated readings then they must be at 1 metre. If, however you are just doing a comparison in the same setup then the readings are relative to each other. If you measure at say 0.5m for both and one is twice the reading of the other it will still be twice the reading at 1M. It will always be twice as loud as the other no matter where you stand.
I just bought these to upgrade my 3d printer:www.amazon.com/gp/product/B07DN1VBL1/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1. I'm not sure where I can buy the plastic bushings to replace the metal bearings. Maybe once I got the new rails installed, I'll try to print the bushings in nylon. Thanks for sharing very useful information.
Thanks for watching Nghi. The split bearings make it a lot more difficult to find the plastic ones. You could always cut a slot in a round one for clearance and it may work. The only problem I see is that the round ones have ribs in them that squeeze in and distribute the force equally around the diameter. With a notch in them it may be sloppy in one directions, etc. You could always buy one and test it to see how well it works. If you print your own make sure you use a slippery plastic, like nylon (the soapy to the feel type) to make them last longer.
@@TheWizard You're right about finding open plastic ones. I think I only worry about the force from the heated bed down against the rails, so a cut at the bottom of the bushing is probably ok. I'll get a set and see how it goes. But noisy or not, the dual rails I'm trying to fit on my printer should beat the stock V-slot rollers by a mile in bed leveling.
@@TheWizard I've discovered an amazing idea on plastic bushing here:ruclips.net/video/HjRh_Fa9G2I/видео.html. I definitely will toss the steel bearings and print these myself.
All Teflon bushes are the way to go Nghi but they are expensive. The hybrid in the video seems good in the theory but in the real world, not so great. You have to remember that the full circumference of the bore takes all the wear so if you have a 10mm bore the circumference, in round figures, is 30mm that slides on the rod. Now if you put those four 2-3mm Teflon rods in you are only having a contact area of less than 1mm (diameter touching diameter) so the load (weight, etc) is 30 times more (psi) than the original bush. So it will be silent and smooth for a while before the thin edge has worn down and you are touching the original bore again. If the Telfon doesn't work loose and wears a long time and is not expensive then it would be good. I have heard of people just pushing in a stack of Teflon washers to make a pancake of them. You would have to be lucky to find some off-the -shelf ones that fit though. In my video 3Dprint4A - Anet A8 Mods 13 - Table Levelling To A Thou
ruclips.net/video/-tUzgewv80o/видео.html I show how to get your bed very level. But the problem is most of the aluminium hotbeds and carriages are bent like a banana. Most of the frames are stamped out and have a few mm bend in them from one adjusting screw to another. You could always flatten them with a sheet of emery cloth and sheet glass but I have found with the thin fingers of the bed carriage they distort with the heat, that's why I normally use a raft, a pain I know but easier in other ways. Hope you do manage to take your 3D printer to the next level Nghi.
You're giving me much food for thought, and you did change my mind on the ptfe tubing idea. I'm in the process of modeling up a plastic bushing like the one on your desk, I just need to cut a split in it for my SBR rails. Actually, the problem with my printer is not bed leveling, but that its four corners keep changing. I only need to do the mesh bed leveling once, and subsequently, if I take time to level the corners before printing, I'd always get good prints. So my thought is that while the V-slot rollers keep the bed pretty solid along the single center track in the Y-axis, they have problems maintaining a constant distance to the nozzle along the Z-axis. Therefore this experiment. Thank you for taking the time to share your ideas.