[superagurk]

Hello,

I've bought some chinese ball screws for my router table some time ago.
Resently I've noticed some noise / scratching from a single axis.
I suspect some dirt inside the ballnut, and want to clean it inside.

Is it possible to unscrew the ballnut from the screw without loosing any balls?
Has anyone tried to dismantle the nut from the screw?


Best regards
Andreas

[Zamet]

Добрый день.
1. Необходимо изготовить втулку у которой -
наружный диаметр равен внутреннему диаметру винта -0,05мм
внутренний диаметр это размер цилиндрической части винта +0,05-0,1мм
длина - длина гайки +30мм.
Удачи.
Но проблема скорей в другом. Нет поверхностной твёрдости винта и гайки.
ps Не забудь отметить положение каждой гайки относительно корпуса.

[fizzissist]

Добрый день.
1. Необходимо изготовить втулку у которой -
наружный диаметр равен внутреннему диаметру винта -0,05мм
внутренний диаметр это размер цилиндрической части винта +0,05-0,1мм
длина - длина гайки +30мм.
Удачи.
Но проблема скорей в другом. Нет поверхностной твёрдости винта и гайки.
ps Не забудь отметить положение каждой гайки относительно корпуса.

That's what I was going to say.

[Walky]

If you take the nut out the balls will fall off, you can put them back but it can be a PITA.

You could try removing the seals and injecting grease through the grease fitting while moving the nut around the screw, some debris might go out at both sides along with the grease. Another way to put grease on is to remove the seals and put grease on the ball grooves on the screw, then move the nut along.

[superagurk]

Ok, thanks!
Not sure if I dare to unscrew it, but removing a seal and pump some grease in could solve the problem.

The scratching sound appear once pr revelation, and seems to be louder when nut is moving one way compared to the other.

Andreas

[Fastest1]

Actually it is quite easy to remove and or repack the ball nut. If you dont want to repack it, buy or get a small length of fuel line with an O.D. very close to the I.D. of the ball races of the screw itself. Simply place the tubing flush against the end of the screw as you unscrew the ballnut off of the screw. You will have to lift the nut at the end just a little to make sure the fuel line passes all of the way thru. Even if you do have to take all of the balls out and clean everything and refill it it is pretty simple. You just start the ball nut on the screw, insert a few balls, screw forward, screw backward, add more balls, screw forward, screw backward. Keep the balls greased as you install them will help them cling to the outer walls while loading. Just a few balls at a time. It would be a shame to work on and or build your own machine and let a few balls intimidate you. A thorough disassembly and cleaning would be the best all the way around. You could also measure the balls and order larger ones to minimze backlash. Here is a video that will give the idea, a bad video at that.
http://youtu.be/4rjWH0UPA9U

[superagurk]

Thanks a lot for your reply! Sounds like a have some dismantling and cleaning to do

Attached a picture of my nearly finished maschine.
Some more work has been done since the picture, and it has been run a few times before making complaining sounds.

[Dylwad]

Nice machine I took a chinese ballscrew apart one night to see how bad reassembly was, took 15 minutes to feed the balls back in, easier than I thought it would be. Put the nut on the end of the screw oriented so you have an opening in the races to slip the balls into, and rotate the nut up and down the screw every so often to get the balls rolling.

I have a C2 ground nsk screw that I wont dare to take apart, looks like they feed the balls in the return slot on the side of the nut, and epoxy the return cage into the slot after all the balls are loaded..

Rolled screws will never sound perfectly smooth, so dont go thinking they will be after you clean them. You could also just soak the nuts in kerosene, blow out with compressed air and re grease them too, all without taking the nut off of the screw. Its only going to take a few minutes of making sawdust to get them dirty again, not much of a seal, more of a shield on them.

[Walky]

Fastest1, I'm really not saying it is a PITA, I'm saying it can be. I think it really depends on the screw/nut, I've had more success reassembling without grease (they fall easier in their races) when reassembling 1204, 1605 and 1610 chinese screws, but it might just be me since the grease method seems to be a favorite around here. It is very important to keep an eye on how many balls belong to each race, otherwise it's easy to have some balls remaining after reassembly (I usually separate the sets of balls for that reason); I think you'll agree with me that when you clearly understand how the balls move inside the nut it becomes easier to get it right and to know when it's time to move to the next race. I agree that the best thing is to clean and reassemble, but I've seen quite a few cases on CNCZone regarding lost balls and some people getting a hard time reassembling them for one reason or another, so I'm sometimes hesitant to recommend that unless it seems absolutely necessary.

[Fastest1]

Wally, I won't let you know how I learned to repack a ball nut :-) by force! The fuel line trick works great. Regardless of what anyone does, do this over a large clean and not desired sheet or towel.

[aarggh]

That's a fantastic build you've done Andreas! Very nice indeed. You'll have to put up some more pics and video.

cheers,
Ian

[superagurk]

Thanks for the compliment

Did the design and building by my self. I'm pleased this far, but realized that some improvements could be done. Learned a lot during this project.

I got carried away at start, so I ended up with a large machine 1.2m x 1.7m, with a working area of approx 900mm x 1350mm.

I was thinking of making a build thread, maybe I will.
Attached picture show the CAD design and machine without table.

Andreas

[aarggh]

You've got quite a generous cutting area, and it looks a very sturdy machine.

A build thread would be of great help to many people I am sure. If you were to do it again, which no doubt you will as that's the nature of CNC, what would you do differently?

cheers,
Ian

[superagurk]

If I should do any changes to the machine or build another one, then I would shortened the Z-axis, and maybe lowered the gantry a bit. I have also been thinking of turning the aluminum profile on the gantry the opposite way to protect the ball screw and the linear bearing from dust and dirt.
I probably would build the machine a bit smaller too.

Andreas