Repacking Ball Nut RM-16 C7 Ball Screw
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- เผยแพร่เมื่อ 9 มิ.ย. 2016
- Some times the ball get loose and you need to repack the import ball screws. I do this all the time for the G0704 and PM-25 CNC kits I sell so I wanted to show you guys how I do it.
The ball screw is a C7 16mm 5mm pitch screw but most ball nuts with internal ball returns are the same.
Finding the right size is hard. I do offer repacking for any ball screw if you need it. Most the time you can get .002" or less backlash. A good screw will give .001"
Contact me at davedaxx1@yahoo.com if you need a nut packed.
Thank you!!! Your comment about the space between the recirculators that should be left empty was very helpful.
Watch the video and go from clueless to repacked in a day and back up and running. Saved my day.
great!
I took this thing off all the way on my sfx100 build couldn't figure out what to do. Thank you so much for this video.
Thank you for sharing this! We recently had an issue on the CNC at our shop and some of the bearings fell out of the bottom of the Ball Screw during disassembly. Thanks to your video, I was able to get the bearings placed properly and back onto the lead screw.
That's great!
Excellent video, thank you ! You made my day Mr.
Totally just following your method and it went together like a hot knife through butter!!.. epic explanation
Most helpfull!. Took care of my problem I could not solve. Thank you for your generosity!
You’re my hero here this is a difficult task you make look easy. Small ballscrews where your fingers don’t fit really complicates things. Nice work. I got through one circuit but I had to use the method of preinserting the screw first. Couldn’t do it your way the balls would fall out trying to install.
Thanks, followed your instructions and was able to get in the balls into the ballscrew nut. Excellent 👌👍
Yep, this technique worked a treat, found it a lot better than the drop in method. I used a regular lightweight grease instead of Vaseline and it came out great. Thanks again!
Glad it worked
yes TH-cam the gift that keeps giving.
Glad it helped.
Thanks Mate, appreciate the video, I'll give it a try this way and see how it goes.
Massive thankyou. Helped me resolve my problem. A good thing to know.
Thank you so much for that tutorial, I accidentally let all the balls fall from one, hopefully I got most of them. I'll follow your method. Cheers!
Great Video! At once I didnt know what gap You talk about untill I opened my ball nut :) This was very helpfull! Thanks a lot!
Thanks mate. Really helped when i had to repack after a ball-spill!
Glad it helped
Good fit of ball screw passion!
Very helpful video. Thank you very much!!! You save me!
You did the work!
Thank you for this big smile on my face.. Jam I had 15 times, I started freaking out :)~
th-cam.com/video/xos2MnVxe-c/w-d-xo.html
Once you see that the rest is easy.
Thanks
dave
Well done sir.
I have done many , many of the import screws and there is no correct size that is more common.
The problem is getting things tight but not too tight. The difference in ball size can be .0002" to get a nut from .002" lash to almost zero.
The nut can have some positive preload meaning the balls are actually too big to fit. What happens is with a rolled screw it will have some areas that are tighter and looser. The C7 screws are really a good screw in this respect and generally have really low lead error and diameter error but fitting the right size balls will require trying a few sets to get a good fit.
I do repack other peoples screws for fairly cheep if you email me.
Thanks
Dave
Thanks for this. I purchased a kit from heavy metal cnc and the acme nut on my z axis is installed opposite end of standard🤷♂️. Per the z axis assembly diagram. I looked at dr d Flo’s conversion video and his was also opposite mine. Bruce didn’t do anything wrong, that’s china for you….. bad assembly. I had to remove , repack and reinstall mine.
Thanks great video!
Amazing huge thanks
Well done
How does one determine the correct number of balls for the screw, and what - if any - mental system do you use to keep track as you apply them?
Thanks for this!
I notice this is a single ballnut. I have the RM1605 ballnut/screw combinations from Chai and there are two ballnuts, held together with small metal clips. Do you take those apart and repack the two halves individually?
Thanks! I just cranked a ballnut off the end of the screw (doh!) and was scratching my head about how to get it back together...
anytime
wow nice job
Thanks for the video.
anytime
I have one from alibaba and one of them has a quite light loop with some backlash, is there something to do about, like slight bigger balls. The good one I feel some resistance when turning around, means there is some little tension on load, that's good to lower the backlash to low levels.
perfect, i was attempting to add a second nut to a 12mm screw and tried to put it on the machined end with the endblock thread and it all went wrong, jammed, removing it and balls came out. ebay ballnut, the balls are 2.38mm / 3/32" . all is not lost, i thought the re-circulation was external but clearly not. not sure if here is a no go groove in the 12mm nut. great vid.
Can you tell me where did you get this fine grade of balls. I am in germany and can't find a reseller that manufactures balls with tolerances of thousandths. Thank you!
You can repack the double nuts but if you have lash you need to add a shim to have positive preload BETWEEN the two nuts.
It is really tricky because the thickness needed is vary small like .0015" thick shim.
Smaller balls in one nut would make it easier.
Yes you can remove the bars. To see how loose they are tighten the two nuts with a little force and check how they move.
You could add a piece of foil or shim between the nuts to see the distance you will need to tighten up the nuts. You only need to remove one nut to add the shim and a 1/2" tube with a little tape on it will stop the balls from falling out.
It took a few tries, but I think I got it without taking the two nuts apart. At least my ballnut is rebuilt and in place in my G0704. It seems to behave normally. I'm not improving or repairing an existing system, I'm doing the CNC conversion from Hoss Machine for the first time. I had some issues with ballnut removal tools and ended up dumping half the balls out of one of the nuts. I was afraid I had lost some but needed three out of the hundred or so in the double nut RM1605 setup.
Thanks again for posting this.
Hi,The 3 red recirculators are all the same?or they have directonal system?Thanks
Does y axis double screw have 46 balls per side this grizzly kit had 92 balls in all is that enough? I couldn't get it in together so I took it apart any help thanks.
All the RM-16 style screws come from China. Good is a bit of a question. The screws are mostly good to really good from most re sellers but the nuts vary greatly. It just takes time to fit a nut with the exact balls to be tight. If you screw is over 4 years old the balls might be slightly larger then .125 all the newer ones are slightly smaller than .125. There was a ebay re seller selling chrome steel balls but I don't think he still is. Balltec in the USA sells them but they cost a lot and it is almost inclosable to get the correct fit on the first try. I have a lot of balls, anymore I get extra from China but with double nuts I generally dont have to change balls just shims.
Thankyou, what an education I have had after knowing full well not to do this, somehow I un-threaded the nut, what was I thinking :)
Yep its easy after a few goes.
What type of lube do you use on these ballscrews?
Thank you so much! I was replacing a controller in a late 90s CNC with beautiful German ballscrews (every indication that the entire machine has barely been used) and accidentally removed the screw. I nearly panicked as I don't have room in my budget for a new ball nut any time soon. You've given me hope and I'm going to try this...tomorrow. Too tired tonight to be worth trying.
One question: Because this is a unit that has long since been installed, I don't have the installation tube/foam that is apparently common. I'm sure I can find or make something appropriate (I have a lathe and tons of materials). How do I determine the ideal fit for the tube? This is a 15mm diameter screw with a 4mm lead and 2.33mm balls. Maybe 13mm?? 12? 12.5? 12.874???
Thank you!
Its easy. You will need to find the right size tube to hold the balls. do one row and then find a tube. Card board with paper and tape on top is OK If you have a lathe then turn something. If you missing a few balls its best to space them between the rows. 5 balls is no big deal. Good luck!
i have head using magnets helps keeping balls in place
Thank you sir i just fix my ball nut
anything I can do.
So what size balls do you usually end up using? I have Chai screws and my Y has ~.0038" of backlash in her, and I'd like to repack. Just wondering what sizes you normally use so I can snag 100 of the range of sizes.
Where do you get the balls from? Actually where is the best place to get decent ball screw assemblies to start with?
First fill one track (full) with steel balls,remove one steel ball (for running clearance),proceed same for another tracks.Life of normal steel balls are less and their accuracy is not up to mark...Visit any reputed bearing dealer shop (like SKF,NTN etc...),They can supply accurate sized and accurate hard steel balls...Bearing balls are costlier than normal but gives a required accuracy and life too.
There is a guy on ebay that sells Chrome Steel balls for ball screws and then there is baltec. www.precisionballs.com/
I have a pair of SFU1204s and followed your video on repacking. I noticed the bearing in mine keeps binding at the orange bearing recycling cap thing. The bearings keep stumbling over each other in that area. Does that happen to you?
If the balls are tight they pop into the tracks when free spinning. It should be vary light. If it binds much at all then the balls are too large. Other things come into play too. All the balls need to be the same size. You may expect them to be but a loose ball nut you cant tell if a ball is too big. When it's tight the big ball will stick each time around. This should only happen about once per 3/4 of a turn. This is also rare, most the time the balls are close enough to the same size.
Do a single row and see how they fit. If one row binds and the others are fine then move the return around and see if the binding follows it. It can be replaced if needed. I have spares but I dont know if the 12mm balls and returns are the same.
If only one row is tight then you could put the smaller balls in it. You will loose 1/3 of the strength, its not needed for routers but mills will need it. You could also just lever the balls out of one row.
SUPER SIR T Q!
Your video is great but I am having a nightmare. Do you try and fill every groove or you mentioned just 3 rows? Also what are the sections to avoid like?
The nut I am trying to sort has tiny 1.48mm balls. Was working fine but wound it out too far.
I have got it back together but it is very tight and loads of backlash.
Just 3 rows. If you look closely you can see a space between the returns that have no where to go. Start from the return and fill one at a time until you get back to the return. Do that 3 times.
@@ArizonaVideo99
Thanks so much for taking the time to reply!
I have a very similar ball nut but my returns are oblong. Does it matter which way they go? My nut jams so I am trying to understand this "zone' you are mentioning. There are three returns and the gap between the returns are different. I am assuming the short gap there should be no balls. And in the larger gap should there be any balls? Wish I could see better in your video. Thanks for the info tho. It's giving me faith.
A jamming nut is almost always a ball in between the returns. You do want to check to make sure you dont have a really large ball.
Spend some time looking at the tracks and the way the return moves the balls from one track to the next. To do this you will have a section of track left unused. It cant have a ball in it because it has no place to go. Its trapped. When you filling the nut its easy to get a ball in the track between the return.
One way to get a good look is to place the ball saver tube in the nut and spin it by hand to remove the extra grease. This sets the balls and you can pick out mis placed balls if you find one. For a 16mm screw the tube is about .535"
Hello! Do the ball returns have to go in the nut in a certain orientation? Or are they universal and always fit in the correct orientation? I know you mentioned you could put any of the three returns in any of the three locations, but I can't tell if you're putting them in a specific way to line up with the thread of the nut.
The returns can go either way but must line up with the track but they will self adjust if they are sitting in all the way. Sometimes I need to put a little grease on the back of them so they don't move around and fall out.
@@ArizonaVideo99 Thank you so much! I tried to look up some diagrams on finding what threads/loops to void and what threads/loops to fill with the balls. Could you describe a little more how you know exactly which ones to fill/not fill? My dad and I have been trying to insert the screw and it kept jamming, so after watching your video I'm certain we are filling a thread/loop we aren't supposed to be. I had a hard time seeing the loops not to fill that you talked about in your video, and was hoping maybe you could add some more details in the reply if you have the chance!
@@haydensarah99 If you look inside the nut you will have 3 plastic returns. The outside returns have the track run past then but if you put balls past the outside return they will just fall out or push out the seal.
The middle return has a small bit of ball track between it and the next return. It is about long enough for 3 balls or so.
If you put balls there they are stuck and will jam the nut. There is two places like that on both sides of the middle return. Once you see it, it becomes easy.
helped! :)
Glad it helped!
I actualy make the same thing but on sfu1204 and he make me crazy. Ball are so small ans space in nut..
Any idea what to do if the nut gets seized on the screw? I can get mine to turn a little, but it gets pretty damn stuck if I go too far. Thanks
If you get a ball between two tracks it will lock the nut from rotating. Most the time it is more in one direction than in the other so you can still un screw the ball nut if you only go one direction.
Sometimes it locks in both directions. You can use a good vice and soft jaws to hold the screws and just force it. What happens is it will crush the ball return so it will need replacement. I have a lot of extra if you want one.
Good luck.
Dave
could you please post the O.D. of your plastic ball bearing retaining tube? My nuts came pre-installed on the ball screw and I need to fab a tube to re-install the ball nut.
.540" for the 16mm ball screws.
Just fill each track. No need to count. I think the total is 62 balls but it can be different depending on how big the balls.
The fit is determined by the ball size. load handling is the number of balls. They are rated at 500 pounds
I received a new rolled ball screw & nut like this but either the threaded hardware that goes into the hole in the flange was missing or it fell out somehow. It's only threaded in the first 1/4" or so- I would expect it should be something like a set screw and maybe a spring or ball channel or some type. I have no reference- only an empty hole. Can you tell me what is supposed to go in there?
I dont understand the question
@@ArizonaVideo99 There is a threaded hole in the flange, perpendicular to the axis of the ball screw. There is nothing in that hole, and balls can fall out of it. I'm assuming that is not normal and something should occupy that hole. i.imgur.com/ftb5iUM.jpg
@@salukikev It's for lubrication, usually they include a zerk fitting.
I've found petroleum jelly (Vaseline) loses viscosity too fast. Bearing gets warm from handling it, and then starts to thin out (loses its tack). Grease is better.
correct.
You can put the ball nut in the cooler. I just did not want grease on my hands everyday.
I like your video very much. Can you tell me, where I can buy new seals for my ball nut? do you sell them. Thank you
I might have a few. I keep forgetting to order extra.
If you want, you can bought from us, good quality, email:sales@aresmotion.com
i just repacked the same nut dry, i put the journal in just about 3-4mm's, not exceeding the polymer bushing, poured bunch of bearing balls, with a little shaking to balls to settle in the tracks, i slowly inserted the journal all the way in. then by shaking, i removed the balls in the excess tracks. it looks to be working perfectly. is there anything wrong with my method?
There is two places between the ball tracks that can not have ball in place or the nut will jam. you can fill it like you said but you must remove the balls from the dead areas which is hard if the balls are loose.
firstly, congratulations on understanding my comment, lol. yeah i thought about the same possibility but those balls in the dead area weirdly doesnt seem to cause any jam, nut rotates all the way through the 500mm ball screw, without any minor blocking that can be felt. should i really remove those balls?
Yes, they will drag often times they will let the nut go on one direction but not in the other. I have found that if the balls fit tight you can never have a ball in the dead zone as it will alway jam in one direction. If the fit is loose that allows for the ball to skid. If it cant roll it has to skit and that is not a good thing.
Hi. What diameter is the red tube? Thanks for the video!!
.540" Tape on a 1/2 tube works. Thanks
Dave
@@ArizonaVideo99 thank you!! I ended up using a AA Battery....worked great!!
Dear my friend
Do you have experience of pmi brand ball screw .
I have problem to remove balls from nut .
Can you help me
I have not done PMI. If the nut is jammed it might have a broken ball. I could fix it but i mostly have balls around .125" and other screws use different sizes..
Just shot you an email from JW Memorabilia.
where can l get china 12 mm balls new to reload ?
The ball size can be different. The standard ball size is .125"
The balls are metric and most new ball nuts are slightly smaller than .125". I have no way to know what is in yours.
Look for Chrome steal balls.
This ball you mentioned that is extra at 7:22 is falling.
The last track was full so I left it out.
What's a sign that your ball screw needs to be repacked?
Just the amount of backlash they have. Most of the China screws come with loose balls. For single nuts anything over .003" should be re packed. If the screw has over 1000 hours it might be more tricky with the high use area being looser.
I watched 10 video to see how to install plastic seal no one did that
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