View Full Version : Re-filling a ball nut

Robin Hewitt
10-08-2011, 10:18 AM
I have been having fun with ball nuts :whistling:

Cut one screw too short, assumed they were both the same. Spilt all the balls from one nut, need to de-grit 3 more :whistling:

Rather than try and fight the balls in I decided to make a tool and it works amazingly well.

All you need is to hold a ball retaining rod central to the nut, cut a groove in the top to carry the balls down in to the thread while holding the others in place. Be able to move the rod up and down to fill each circuit in turn. Use the oil seal screws to hold the nut on the tool. The pictures explain all.

The tool took the best part of an hour to make but has probably saved me over an hour of angst and frustration already. I have no worry about dropping the balls from the other three nuts so I can give them a wash in the ultrasonic tank then blast them dry with compressed air to remove any magnetic debris.

I lost 6 balls in the cascade, but Gary says he will send some with the new screw. Useful chap Gary.

The balls were 2.34 mm which I took for undersize 3/32". I tried 3/32" balls but it was tight.

Web Goblin
10-08-2011, 10:30 AM
Ballnuts are loads of fun. I've done it the interesting way with tweezers and grease.
The wooden ruler brings back some long forgotten scary memories of school.


10-08-2011, 11:32 AM
I've lost the balls once in my RM1610 screw ... I made a rod the right diameter (pitch diameter minus diameter of balls, though it's not critical) and just stuck a big magnet on the side of it. That makes all the balls just stick in place easily without grease or anything.

The magnet I had was a spare from my wind turbine (2"x1"x0.5" neodymium) so extremely strong ... but you could probably do it with less.