Ball Screw Experts - I Need Help!

FoothillFurnitur · Apr 1, 2019

I am building a machine and have it 90% up and running. I had to take one of my Y ball screws out and stupidly spilled the balls out everywhere. I'm confident that I have all of them and I have tried repacking it several times, but it jams almost immediately every time I try to screw the nut back on.

I know that the balls are in the track properly and there are none in the area where there shouldn't be any, but I just can't get it to work. I am using a the tube placeholder when I try to screw it on. The weird thing is that even when I unscrew it after it jams, the balls are all still in the correct threads. I can't figure out why it jamming?

Anyone have any ideas?

Thanks!

Larry Dickman · Apr 1, 2019

need a better description, or perhaps some pictures

charlie gary · Apr 1, 2019

Have you measured the diameter of the balls? Sometimes you have two different sizes, and you have to alternate sizes as you put them back in.

Mud · Apr 1, 2019

charlie gary said:
Have you measured the diameter of the balls? Sometimes you have two different sizes, and you have to alternate sizes as you put them back in.

^^^^ This.
Measure the balls and separate them. Alternate large and small balls as you load them. It only takes a few large balls side by side to lock up the nut. The smaller balls are spacers and don't carry load, they just keep the larger ones separated and rotate in the opposite direction. They should be at least .001 smaller.

huleo · Apr 1, 2019

I would look closely at the installation sleeve. It should NOT fit tight in the nut. This sounds like the balls are not circulating in the nut when starting. They have to or it will bind up. You know you need this surgical clean, right?

atomarc · Apr 1, 2019

Unless these are super precision-very high end ball screws, the balls will usually be the same size and that isn't your problem. If your ball nuts have end returns make sure you're not loading the balls further out than the returns..it's easy to do and not obvious.

Often, the sleeve that comes with the nuts is a hair too small. In the past I have reloaded nuts using a Delrin mandrel I have made myself that's a bit larger than the one supplied by the factory.

Stuart

DavidScott · Apr 1, 2019

Put the nut on the screw then put the balls in. My guess from here is you have them outside of the intended circuit, which will make it jam up like you describe.

atomarc · Apr 1, 2019

DavidScott said:
Put the nut on the screw then put the balls in.

IMHO..that will only work with an external recirculating style nut, otherwise you must load the nut with the balls first then thread the screw on. My guess is the OP is dealing with a non-external recirculating type nut.

Stuart

Larry Dickman · Apr 1, 2019

atomarc said:
My guess is the OP is dealing with a non-external recirculating type nut.

Stuart

since the OP doesn't want to share any details, I suppose that's all we can do is guess

atomarc · Apr 1, 2019

Larry Dickman said:
since the OP doesn't want to share any details, I suppose that's all we can do is guess

Larry,

A brand new member..a furniture maker by trade with a single post..my guess is a small CNC retrofit with Chinese ballscrews, which don't usually have external recirculating guides...but as I said, it's only a guess.

Stuart

adama · Apr 1, 2019

Honestly im in the reload the balls from the end with the screw in camp, its the only way i have had any luck doing it, basically put the nut on, fill the first track then wind it on in and fill the next, its slow, its fiddly and its a pain in the ass.

Before that everything needs to be lick-ably clean! No anything and the ball ways rinsed out with carb cleaner or similar, its amazing how much shit there can be in a ball nut, the unused ways - locations really trap it.

michiganbuck · Apr 1, 2019

Might be good to seek help.

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Larry Dickman · Apr 1, 2019

michiganbuck said:
Might be good to seek help.

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I think Atomark is probably right. Some cheezy ass Chinese screw that's not worth fixing

jz79 · Apr 1, 2019

I'm no expert in this, but just went through this with one of my machines, took apart 2 ball screws with internal returns in a Swiss made machine to measure what balls to buy, 3 ball circuits in a nut, half of the total count were larger and pretty chewed up, other half smaller, suggesting the smaller ones were spacers, size difference was 0,15mm (0,006"), smaller ones 3,00mm, larger ones 3,15mm (hard to tell the original size, since they were more cube shaped...)

after cleaning and degreasing everything I filled the channels in the nuts with some molybdenum disulfide grease (any sticky grease will work) and carefully populated the channels with balls alternating their size, used tweezers for this, started at the return insert and just followed the groove till it was full, the grease holds balls in place nicely when I screwed the nuts on the screws, the screw is lubricated with way oil dripping on it, I figured I'll leave the grease in for now, it will eventually be diluted down with the oil (no wipers in these nuts), but one could easily wash the grease out with something like acetone or brake cleaner

FoothillFurnitur · Apr 1, 2019

Thanks everyone for the replies! Haven't had a chance to take a look until now. Yes, it is a self built 4'x4' Machine with Chinese ball screws that are not worth sending off to have reloaded. I talked to a guy today with a company in GA that does this and he said he would be glad to do it, but it would cost as much as new ones.
I'm torn about it because new ones will take almost a month to arrive and I use my machine daily in my business, I can still do what I need to do, it will just take me longer.
These are internal returns, but I'm not sure how many ball circuits. There are 4 plastic inserts.
I have tried loading these every which way, with grease putting the balls in before and trying to load them in with the nut on the screw...that didn't work at all.
I never knew there might be different size balls, I will definitely check for this first thing tomorrow. I have ordered a new nut, but like I said, between 25 and 30 days to arrive. Can't find one ANYWHERE in the states that sells nuts by themselves?
I guess I will keep trying but, honestly every time I do I got so pissed off, so I might just leave it alone until the new nut arrives :-) Better for my mental health!
thanks again for the tips everyone!

Vancbiker · Apr 1, 2019

If you take your inquiry to a forum more oriented toward hobby and DIY CNCs you might find someone that could help you source a replacement screw with less leadtime.

EmGo · Apr 2, 2019

Larry Dickman said:
Some cheezy ass Chinese screw that's not worth fixing

A large percentage of the ballscrews in all of your machines are ... umm ... Chinese. Linear ways, too.

Ahem

adama · Apr 2, 2019

EmanuelGoldstein said:
A large percentage of the ballscrews in all of your machines are ... umm ... Chinese. Linear ways, too.

Ahem

Really depends on how well you agree or disagree as to if Taiwan is in china, if you consider that so the odds get even higher! :cheers:

4 inserts should mean 4 ball paths, measure the balls and try just loading the furthest apart 2, on cheaper Chinese screws the inserts simply jump the balls from one path to the next. You should have then no balls to the next insert, then 1 turn of balls, then none, then 1 turn of balls etc. With just 2 paths loaded it should work, don't cram em full of balls either, there should be at least 1 less ball that there's space for.

Tight either means crap in there, damaged ball return or a ball not in the correct part of the nut!

Ebay is the best source of these i know in the typical cheap Chinese style, sure there must be USA stockists, i know there is here, what size - pitch are you actually after though?

Watch this, YouTube

FoothillFurnitur · Apr 2, 2019

I need a 1610 nut. I have found several 1605's available, but that does me no good. These chinese ballscrews and nuts work great on wood router CNC machines, very accurate and fast. Not sure how they would be on something that would put more of a load on them.

Milland · Apr 2, 2019

I'm still confused why you need a new nut when all you did was spin the old one off. A number of folks here have asked you to post some pics of the nut so they could offer reballing advice, but so far nothing from you.

You can add pictures using the "Advanced" posting tab, why not do so?

Ball Screw Experts - I Need Help!

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