Thread: Stupid! Stupid! Stupid! Ball Screw Mayhem!

Have no suggestions as I know nothing about CNC machines, but with a title like that I just had to stick my nose in. Was a bit daft wasn't it. Have fun.

Alan,

i know it is possible to speak with the suppliers of the ballscrew to find out what size the balls were. Some will tell other will just want you to buy another ballnut. If you do find out what size it is possible to get onto a ball bearing supplier (there are a few that specialize in supplying the balls for ballnuts) and order through them. There are a few threads on the zone which deal with others that have had 'senior moments'.

Daniel
P.S Hope your machine is coming along better than mine. Im still waiting for the machinist. lol. Ive asked for the channel back this week so i can finish the machine first. Then ill sort it out later.

S'pose it depends on the nut design but I have reloaded them before without too much drama.

How will you know if missing any more than the one ball? If only one short, I would not worry about it.

Measure each ball with a micrometer. Some ballnuts have alternately larger - smaller balls so they roll easier. The difference, if there, will only be a couple of thou.

Greg

Thanks for that info Greg. Is there a technique in 'reloading'? I could not work out where the balls went in!

Cheers,

Alan

At some point there must be a channel where the balls go around to the start again.

On the ones I have done it is an external tube which can be removed.

Used a stiff piece of wire with a blunt end. Dipped it in grease so ball would stick to the end and poked them in one at a time.

The first few are the most tricky until there are enough in to support the screw.

Greg

Thanks again ... will try that tomorrow!

Was I correct in my assumption that you need to remove the ball nut to turn down the shaft to fit the ball bearings ... using my vernier calipers it seems that I need about 0.003mm removed to fit the ball bearings?

Cheers,

Alan

lol, kinda like the slides with free ball bearings.

Ask rod as im sure you used his supplier to which he has bought from before.

Originally Posted by Zoot

Thanks again ... will try that tomorrow!

Was I correct in my assumption that you need to remove the ball nut to turn down the shaft to fit the ball bearings ... using my vernier calipers it seems that I need about 0.003mm removed to fit the ball bearings?

Cheers,

Alan

Dam thats small, wouldnt some WD 40 and a little pressure work?


Im pretty sure you have to remove it, then again I have absolutely no experience on the matter.

Don't fret, you aren't the first nor will you be the last.

Have a look inside the nut now that you can and see how many entry/exit hole there are. Some times there are more than one circulation of balls. The loading slots may be bolt on tubes as mention before or they could be nylon plugs that need to be coaxed out. Some pics would hopefully reveal all.

Originally Posted by Zoot

Was I correct in my assumption that you need to remove the ball nut to turn down the shaft to fit the ball bearings

Depending on the size of the lathe (Through headstock Dia.) it it could have been imobilised with cable ties / tape and wrapped in rag.

Hello Zoot

We have all done that, if you have metal working ( not sure if you can cut plastic on a wood lathe ) lathe, make a tool that has an outer dia' the same as the cardboard tube the ballnut came on with a hole bored into the tool the same size as the machined end of the ballscrew, do all the work you have to do on the scew, then fit the nut using the tool, it's almost foolproof, don't forget the ballnut will " slide " very easily so hang on to it when on the tool, I can post a photo but do you need one??

Ed

Hi Zoot,
First a new ballnut from our Chinese supplier is about $30 so it is not an expensive mistake.They come on a steel or carboard tube and you can slip the tube over the end of the machined screw and slide the nut on to the thread.

As they are rolled ballscrews and standard nuts I think you will find that they are 1/8 inch ball bearings. Measure about five with a micrometer (don't use a vernier) and you will soon find out what size they are and if you have alterntive size ball bearings. I think you will find you have same size ball bearing through the nut as it is not made specific for the ballscrew. Any bearing supplier should be able to sell you a few.

Greg has already given you the best method of repacking using grease. What I can add to this is do it over a tray with a towel inside so when you drop a ball bearing it doesn't do the bounce and roll and disappear trick. I had one roll into the slot of my table saw and inside the saw was about 2kg of swarf as I had been cutting a lot of ally plate. Didn't even try to recover that one. Remove the nylon wipers so you can see what is happening inside the nut as you repack. Also when you have finished if you turnn the screw and it locks in one direction this means you have got one or two ball bearing ahead of the return tube so empty it out and start again.

I am glad you fessed up on this as it might save a few others from the grief.

I assume you have other screws to adjust so leave the nut on the screw. Pass the screw through the headstock from the back of the lathe and make sure the nut is outside the headstock. Support the free end of the screw outside the head stock and tape (electrical tape is fine) the nut to the screw. Use a bit of 240 or upwards wet and dry or cloth backed emery paper and carefully remove your 0.003mm. Be patient as it can easily go from tight to sloppy quick so try your bearing often checking for high spots.

If anybody has used my drawing that has 10 X 1mm pitch thread then the nuts are hard to find. I got some steel hex bar and tap to match so yell out if you want nuts made.

Thank you Rod, Greg, Ed and others for your help. Much appreciated. I will sit down quietly this afternoon and see if I can reconstruct my ballnut!

What have I learnt? 1. Think before doing ... 2. Think again before doing! ... 3. Ask the question on the forum before doing.

Not that it matters now, but my theory was that the linear bearings on the rail carriages come off easily with the balls captive. So the ballnuts should also come off easily with the balls captive as well. Stupid theory!!

Thanks again,

Alan

Originally Posted by Zoot

Thanks again ... will try that tomorrow!

Was I correct in my assumption that you need to remove the ball nut to turn down the shaft to fit the ball bearings ... using my vernier calipers it seems that I need about 0.003mm removed to fit the ball bearings?

Cheers,

Alan

Can you just freeze the end of the shaft? That should shrink it by more than 0.003mm.

Zoot - had the ends of my ballscrews turned down with the screws still in place - just used a bit nof the universal 'gaffa' tape - worked well. my measurement of the balls for a 5 thread ballscrew turn out at 3.2mm.
Most newer ballscrews have two small inserted plates of either metal or plastic - you have to remove one of these to access the baal tube.
Cheers
Noel