Tuning a Cheap Ball Screw (2 methods of nut overhaul)
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- เผยแพร่เมื่อ 31 พ.ค. 2021
- In this video, we tune-up a cheap Chinese ball screw from the CNC build. We try two methods and conclude the best involves a dismantle, clean, and reassemble...
This one is a rolled screw with a 5mm pitch. It was from the ebay seller "linearmotionbearings2008". The ball bearings benefited from a good clean, stopping excessive wear and jerky linear motion.
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Back then I also bought cheap China ball screw spindles for my CNC. However, within six months these were so worn that they built up backlash. First I ordered a set of recirculating ball nuts, but with the same result. I then found out that the balls that are built into these spindles have a very low quality and hardness.
So I ordered high quality balls, slightly larger than the existing ones. After I installed this, my spindles run flawlessly and no longer build up backlash! Due to the slight increase in diameter of the balls, the stability of the machine has also increased. There is less vibration when machining 7075 aluminum.
Hi Peter, that's really interesting. Can I ask where you got the replacement balls and how much difference in diameter there was?
@@FloweringElbow4SuperNerds Yes, got them from Kugel-Winnie www.kugel-winnie.de. There are 1/100-1/1000 mm larger than the original. But i have all measured with a micrometer and sorted the best out. They are so cheap, i bought a bunch of these to find the best fit.
That other cnc machine you built was huge 👍
WOW! You've got big balls!!!
That ballnut seemed to contain far fewer balls than I've seen in other nuts, though admittedly my experience is limited to little more than repacking the one I accidentally messed up installing on its screw.
Paper towels leave tiny flakes of paper everywhere. Recommend microfiber wipes
This gave me good confidence to clean my X-axis (long) on my other CNC, a 6040, which as you say, sounds like a bag of nails. I will update with results.
Cool. Let us know how it goes. I have heard from peeps having good results with getting new balls and using a micrometer to carefully size them the smallest amount bigger.... Good luck!
@@FloweringElbow4SuperNerds any idea where they bought the new balls? I want to repack my good quality double ballnuts but don't know where to buy them.
@@DodgyBrothersEngineering With a double nut set up the preload should come from the spacer not the ball size.
@@cods1pe3r yes but that doesn't fix things like rust, or out of round balls. I just wanted to freshen it up.
@@DodgyBrothersEngineering fair enough
they have an super lead as they call it. its about 3 rotations to go the entire 400mm
Utter genius
Where did you get that actuator? It would work perfect for my application.
Having worked in the technical area of bearings for a few years (another life 😊) may I say that you are a game man pulling a ball screw apart! So - Bravo! But PLEASE they are BALLS not ball bearings. The latter are things that contain balls and races and cages (usually) etc. Often its the return paths that cause trouble in ball screws perhaps worth taking them out and inspecting for roughness poor fit etc - only in a clean room of course 😏... Martin
PS My, what a big ball screw you have
HAHA. Hi Martin, thanks for this. Correct terminology noted, thanks. I will try and reverse a lifetime of incorrect usage.
I have been away and am still digesting your -email re the casting shenanigans... So much to learn... Thanks again, Bongo.
Hey brother! I have a question. I bought a set of 3 THK 2040 Ballscrews about 2 years ago. Well I just dug them out and I need to clean them, but more importantly, how do I find out information on if I can use them for my cnc? I went to THK website and its all locked down like fort knox haha
Hi friend... I don't know if you read these comments... I actually enjoyed your build.... although, I am a designer, and I want to put this into CAD... specifically SolidWorks V2022. And I have a few changes I want to make. I would enjoy to benefit from some of your experience... such as what size your ball screw is, and where you got your parts. What size Servo Motors, and where did you get your controllers and other electronics. I am a mechanical designer, not an electronics guy. That is why I am asking for such information. I hope you can help me. Have you put together a materials list and where to get the materials? Also some tips about setting up and software you are using for your setup. I do have access to CNC Mill, and a nice lathe and surface grinder and other equipment so I can do this project. So... if you would be inclined to assist me I would really appreciate it.
If your willing to assist me... I am willing to provide you with my designs, and also the plans I make. P.S. setting up the electronics is going to be an issue for me. I can put together components to build computers... so I do have some experience with playing with electronics. But I have never worked with controllers and servos.
I can be reached at... I am Leslieallen inventorshaven@proton.me Please contact me. Friend... if you have Signal Messenger it would be a big help, that way we can easily communicate using video or messaging. I prefer video actually. Anyway, write to us if your willing. Thank you. I will post this on each of your pages... so hopefully you will see it.
Dear my friend
Do you have experience about pmi brand ball screw .
I have problem to remove balls from nut
Hi there. Sorry, no, I have no experience with this make. Good luck.
Hello! I had a quick question. I'm currently designing up a different type cnc, and it appears rotating nut ballscrew might solve some of my problems. I remember reading somewhere when researching this for a router that there are some issues with using a regular ball nut in this way, and I can't seem to find that again. Do you happen to know what these concerns are? I am going to get a ground THK ballscrew not rolled, and I can accurately mount the double angular contact bearings concentric with the screw. I remember there being something else. Like maybe how the internal ball path is? but to me it seems like the balls take the same path either way. but they would be spinning and therefore centrifugal acceleration would cause loading on the ball return channel or something?
Hey Cody, thanks for getting in touch. As long as the nut is very concentric as it spins, I'm not aware of any other issues... I people usually go for a shorter nut with the rotating ballnut method, so any inaccuracies are less amplified...
If I were to do over, I would go for a narrower screw (mines 32mm) as the nuts can't spin as fast on wider ones and you need much more expensive AC bearings to fit over the screw...
Good luck, let us know how it goes, and/or if you find other issues I haven't thought of. If you're getting THK screws, THK do a rotating nut option, where the bearings are built into the flange of the nut, and presumably other parts are tweaked for optimal performance in that particular use. They are not super common, or the kind of thing you find on ebay, so I didn't pursue it because of cost, but it could be worth looking into.
Have you considered a roller screw?
Alright mate! Could I ask who supplied your ballscrews? I am looking at purchasing similar sizes and see you have not had any major issues with yours.
Hi David, see the vid description...
Thanks!
Gave you a thumbs up and a subscribe one minute in the video. Forgive me for not finding you earlier
Welcome aboard Irfan!
Did you consider using a rack and pinion? Getting close to ordering something myself, but still researching.
Hi sorry for the late reply. Yes, I did consider it, but wanted to have a crack at this method and thought it might be more accurate for the same cost...
Thank you for the reply, I found the rack to be far cheaper than ball screws here in Australia especially with frieght. A big factor for me is that got a CNC machine for free that already has one 2400 mm axis with a rack, it is quite a sold machine made for doing rotary work only. It is able to work with 2400mm long by 300 diameter with 2 spindles and 2 rotary axes. But the frame is onlr 750mm wide. What I am about to do is cut it up and rebuild it to the same size as your machine. My plan is be able build wind generators with blades up 2400mm long so a rotating diameter of around 5 metres. Previously I was thinking of making the blades with rotary axis but have decided it will be better to use 2 indexed positions instead. Getting software for the rotary axis work is expensive and there are backlash issues. I don't want to spend the money on Fusion 360 for what I am doing.
I have also been looking a lot at your alloy casting videos with the intention of making blade hubs etc and using the CNC router to machine them. I plan to be using a motor generator from a Prius as the actual generator.@@FloweringElbow4SuperNerds
@@XXXXIndices Did you end up using rack and pinion (RP)? I am thinking of similar CNC project for milling steel. I'd like to use RP for X and Y axis and ballscrew for Z axis. Any suggestions @FloweringElbow4SuperNerds ? Would this make the CNC not accurate and rigid enough to mill steel?
@@iReza Hi, I have had to put this project on hold for the moment but I will be using ballscrews. The research I found said with rack you are going to get around 0.10MM play which is totally unacceptable for what I want which includes machining steel. My machine will end up with a cutting area of 2400 X 1200 X 400 and I will be using 3210 fixed ballscrews on X & Y with rotating nuts like FlowingEldow ended up doing.
@@XXXXIndices Hi there and thank you for responding!
What would you use for your Z-axis?
Also what motors (type and size) for each axis? (I'm thinking of Servo 34)
So you did all this work to use them with WD40?
WD40 was just for cleaning. They need oil or grease for regular lubrication.
how is that running? i heard from an weapon freak, that WD 40 is the root cause of many western mechanical
problems....
and i suppose, that this might have killed my bicycle ballbearings. i am not shure though.....
At about 26 seconds where you say it is catching the shaft looks bent.
Where did you buy the better ground ballscrew?
It's in the description ;)
@@FloweringElbow4SuperNerds I saw you said where the rolled one was from. Where was the ground one fron? I assume that one is good quality?
@@Audio_Simon Ah ha, sorry the ground one is on the y-axis. It is of better quality indeed. It was from dy-global, a seller on e-bay, that sometimes does 'new old stock' type items. I had to cut it down, and turn the bearing surface, but it was a real bargain.
Hope that helps.
What grease are you using and what is its viscosity?
Good morning Bender. For sticking them back in, I was using JCB Special high pressure grease - it seemed nice and sticky. For running, I'm not sure what I'll end up using... Any recommendations?
@@FloweringElbow4SuperNerds I converted my lathe to ball screws and fitted a hand pump to oil the ways and tied the ball screws into the oil plumbing. I use proper way oil, which is very sticky. Both the ways and ball screws are as smooth as silk. Here is a link to the lathe mods if you are interested
th-cam.com/play/PLyn2snGjYlHwvzi0ztHJVwwFANxyTc2Kj.html
seems too much, unless I could somehow reduce the steps to a point where literally it was barely turning, but I dont know if that would work.
I'll be up front here, I've never built a CNC machine, nor am I likely to.
Having said that I'd like to make a suggestion for those that have, or are likely to have, such a project on the go. It is this:
Instead of a ball screw to control the accurate motion of the axes, consider a rack-and-pinion drive of standard commercial quality. To eliminate backlash between rack and pinion, the pinion can be spring loaded onto the rack as is done with rack-and-pinion steering in modern cars. Bear in mind there are other ways to eliminate backlash, too.
For position feed-back consider magnetic linear encoders. The magnetic strip is quite inexpensive and can be had in practically any length. Thus the position feed-back is independent of the rack or screw.
The stepper or servo feed motor would simply drive the axis until the linear encoder command position is satisfied.
Would anyone care to comment on the pro and con of such a system? Has anyone experience with such a system? Thanks.
Separate encoders are fine when you are driving with tradition servo motors, which are not limited to a step resolution. With steppers you are limited to the resolution of the steps or micro-steps that you chose. Modern steppers can come with built in position feedback so you can trust the positioning to your chosen resolution, if you overload them to the extent of missing steps then the controllers will throw an error. So there is no incentive to fit additional encoders.
Rack and pinion is a solution usually reserved for very long travels where flex in ball screws becomes a problem.
I have to say that I'm surprised to see that you're working on improving the ballscrew when you're driving the ballnut with a toothed belt. The biggest difference you could make here is to implement a direct drive and eliminate all of the backlash associated with that belt.
How can you direct drive a rotating ball nut? I planned to do the same as here so would love to know a better way.
@@dev-debug Backlash on my direct drive mill is 0.02mm
What is the backlash on your belt driven setup?
👍👍👍👍👍🙏🙏♻️
you're a mad scientist. SpaceX needs your type!
lol. Appreciate that Krugtech :)
WD 40 is not (!) an lubricant. It removes the grease from the bearing balls. Better you use an hydraulic oil. A good grease is dumping the klicks from flipping the bearing balls into an other direction.
Correct. Here we only use it to 'clean' not to lubricate...
Very good point! When I worked in shipping a pallet jack/fork lift serviceman told me that WD-40 was probably responsible for 20% of there service calls. If I hadn't mentioned that the new guy I had hired had been spraying pallet jacks with WD until I threatened to can him, I doubt he would have brought it up even though it was the obvious cause. It will stop the squeaks in the bearings and clean out the old grease, sure. They will roll alot easier than before, for about 3 days. Then the bearings are trashed.
Very good point! When I worked in shipping a pallet jack/fork lift serviceman told me that WD-40 was probably responsible for 20% of there service calls. If I hadn't mentioned that the new guy I had hired had been spraying pallet jacks with WD until I threatened to can him, I doubt he would have brought it up even though it was the obvious cause. It will stop the squeaks in the bearings and clean out the old grease, sure. They will roll alot easier than before, for about 3 days. Then the bearings are trashed.
Very good point! When I worked in shipping a pallet jack/fork lift serviceman told me that WD-40 was probably responsible for 20% of there service calls. If I hadn't mentioned that the new guy I had hired had been spraying pallet jacks with WD until I threatened to can him, I doubt he would have brought it up even though it was the obvious cause. It will stop the squeaks in the bearings and clean out the old grease, sure. They will roll alot easier than before, for about 3 days. Then the bearings are trashed.
Very good point! When I worked in shipping a pallet jack/fork lift serviceman told me that WD-40 was probably responsible for 20% of there service calls. If I hadn't mentioned that the new guy I had hired had been spraying pallet jacks with WD until I threatened to can him, I doubt he would have brought it up even though it was the obvious cause. It will stop the squeaks in the bearings and clean out the old grease, sure. They will roll alot easier than before, for about 3 days. Then the bearings are trashed.
You'd never take apart a precision machined and ground ball screw. They are silky smooth and taling it apart will only serve to damage or makes things worse. The cheaper the rolled ball screw, the worse the balls fit the grooves. I've seen then where they contact less than 20% of the groove and the contact area is in different places on each side of the groove.
The balls spin in directions they shouldn't and they sound awful. Your better off living with the higher backlash then trying to correct it. Run then in for a few hours and they get better. Trying to clean with wd-40 and blowing out with shop air can make things a lot worse. Unless you got high end water, particle and oil filters installed your blowing in air contaminated with water, oil and particulate. The standard ones that come with compressors or home depot do nothing to stop this. They let as much water and oul through as they stop. Simplev air tool motors don't care as long as they see a bit of lube, most bearings are sealed in these. If your blowing out any bearing with air or using a parts cleaner to clean the bearing you've effectively reduced the bearings life by atleast 50%.