Big Ball Screw & Ball Nut mistake.

[Jack F]

I have talked to several machine service people and have discovered I made a big mistake taking the ball screw out of the ball nut to get the table off the mill. I now need a ball screw & nut expert to tell me how to put the two back together. I'm learning fast some of the the "don'ts" in machine service and repair. In my post below I refered to the ball nut as the "ball screw" and the ball screw as the "screw" so along with the "don'ts I'm also picking up the proper terms. Anyway, I am praying someone can help me get the ball nut and screw back together. Thanks, Jack.

[HuFlungDung]

Did you catch all the balls that fell out?

Maybe if you could post a picture of what you have, it would help us give pertinent advice.

[ViperTX]

Well Jack F.....which ballscrew and nut do you have....does it have return tubes....can they be removed.....post a pic of the ballnut....

[Jack F]

Here are a few pics of the ball nut & screw. The nut itself is 3" long and has threads (screws) on only 1/2 of it. The rest of nut is smooth on the inside. It also has 4 slots in the 1/2 that has the threads that have matching caps that insert from the inside. The screw is aprox. 1" dia x 52" long. Included also is a pic of the name plate on one of the servos and a pic of a test lift of the mill with head, ram, and table removed. the cherry picker lifted the mill fine so next will be to rent a trailor the get it home. The servo appears to have no encoder so I am wondering how the computer knows where the table is located. Forgive me if these questions sound dumb but as you can tell I am new to the world of cnc and ball nuts & screws. Jack.

[NC Cams]

We did something dumb like that a while back.

We found a local spindle repair guy who reloaded ours "off the books" for $25 cash and he reloaded it with all new balls - naturally, we lost some. Maybe you can get a lucky...

The lesson was cheap at twice the price....

[Jack F]

Thanks to Ed at Mechanical Maintenance and his expert directions the ball screw is back together and working great. One more problem fixed and getting closer to firing the beast up. Thanks again Ed.

[ironDigit]

some ppl in here would love too know

HOW ya fixed that

thx in advance man

[Jack F]

The secret to the whole procedure is the sleeve pictured in the pics below. I machined the outside diameter to be just smaller (.001 or .002) than the inside diameter of the nut with the balls installed. The inside diameter of the sleeve is a two step... first I bored the hole to slip over the screw snout then enlarged one end of the bore to fit over the bearing shoulder. My ball screw is the internal recirculating type. the procedure is to load the nut with all the balls in the proper tracts. Be sure not to have any balls in the void areas. When you load the balls it you will be able to tell where they don't belong. Use petrolium jelly to hold them in place. To get the balls in the nut I used a very small stick with petrolium on the end to hold the ball as I placed it in the nut. When all the balls are loaded carefully slide the sleeve into the nut. It took me several tries to slide it in without knocking any balls out. Alright now.., stop the snickering, this is serious stuff. With the sleeve in the nut slide the sleeve over the snout and the bearing shoulder up to the start of the screw. Start turning the screw into the nut and as the screw enters the nut it will push out the sleeve. Be sure to hold the sleeve tight to the screw as you turn or you may lose some of the balls. I got lucky and got it to work the first time. If you get the screw all the way thru without bringing any balls with it you are home free. When you are thru the screw should turn smooth as silk. If not something went wrong and you will have to start over. I hope this helps somebody. My heart sank when I found out what a mistake I had made but thanks to Ed at Mechanical Maintenance I was able repair my error. The pics below show the sleeve on the screw with the nut already installed. one of the pics shows the sleeve back aways from the bearing shoulder, another shows the sleeve up against the screw. Jack

[Jack F]

I tried to brighten up the pics alittle for this try to show more detail. Jack.

[vacpress]

jack.. you have probably helped alot of people. both with the cautionary tale, and the nice picture-fied description of how to fix the problem.

ive got 2 large ballscrews... i am afraid to even take the bearing blocks off them... having taken a bearing block off a thk rail, i know what is in there...

BALLS!

[RJ.]

Jack,

I was wondering what happened to you and your ballscrew---Glad you got it fixed. Congratulations, that was stressful!

Regards,
Rick

[B.S.R]

happy we can help you out jack

Mechanical Maintenance
Ballscrew Rebuilders
B.S.R