After trying to reverse the nut on a ball screw the nut is now jammed and will only move in one direction. Based on a YouTube video apparently some of the balls have entered an area where it shouldn't. How do I get the nut off or release the jam? I can't remove the nut by running it off the screw in the only direction it moves because that end doesn't have threads all the way through.
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Bridgeport Ball Screw Nut Stuck?
- Thread starter beeser
- Start date
- Replies 15
- Views 6,191
Finally figured out how to get the nut removed from the ball screw. Now I'm looking into possibly repacking the nuts myself. There are actually 2 nuts in tandem with a keyway to keep them inline. I don't know why there are separate nuts but suspect it has something to do with keeping tension on the assembly with the screw. Anyone have any guidance before proceeding.
Milland
Diamond
- Joined
- Jul 6, 2006
- Location
- Hillsboro, New Hampshire
Post a few pictures of the ball nut and surrounding area if it's still in the machine. For the nut you freed up, did you get access to any of the individual bearing balls? If so, how did they look? Nice and clean, or worn/flatted/etc.?
The ball screws were just refurbished by RBS so the balls are new. I haven't installed the X-axis screw yet because the nut was installed backwards. Here's a picture of the 2 screws.
Milland
Diamond
- Joined
- Jul 6, 2006
- Location
- Hillsboro, New Hampshire
Oh, so this isn't a case of an older screw having issues. I'd hold on until Tuesday and contact the rebuilder, in fact that should have been your first action today so you could have gotten their feedback. But it's a bad sign if they reassembled one of the nuts backwards.
I wish it were that simple as I'm not sure whether the correct orientation was given to the rebuilder. The ball screw assemblies were in pieces from the previous owner. After viewing a few videos on YouTube I thought reversing the nut would be a straight forward task.
Larry Dickman
Titanium
- Joined
- Jan 30, 2014
- Location
- Temecula, Ca
can you just remove the ball returns and shake all the balls out? Without any balls, there's nothing to hold the nut and screw together,
These nuts have what I think are called internal returns (see picture), which can only be removed from the inside. I was able to get the first nut removed by slightly forcing the nut in the jammed direction. That apparently put pressure on the end nylon retainer which allowed it to be slid out of the nut. The jam was then freed. Unfortunately I can't get the second nut to cooperate in the same way.
Larry Dickman
Titanium
- Joined
- Jan 30, 2014
- Location
- Temecula, Ca
remove the seals from the ends. You'll have to at some point anyway. If balls come out the ends, there's a problem. Also, remove the keys that hold the 2 nuts together. It sounds like you might have a renegade ball stuck in between.
The end seal is what I'm having a problem removing this time. The 2 set screws that hold it in place were removed but the seal doesn't want to come out. There's no way to grab hold of it to pull it out. Maybe a blast of air from the opposite side will do the trick. Also, the second nut is not attached at this point and is already removed from the shaft. I'm only having problem with the nut with the flange on it.
Larry Dickman
Titanium
- Joined
- Jan 30, 2014
- Location
- Temecula, Ca
In the pas, I have seen nuts where the seal was held in place with a pair of set screws, one on the top of each other. Double check there isn't still another set screw down in there. The seal should have a split in it, on the face. You can sometimes use a screwdriver to hold the seal stationary, while you rotate the nut.
Great suggestion! I was able to put a small screwdriver blade in a slot on the nylon seal and rotate it out of the nut. The threads on the ball screw were enough to move it. But the nut is still stuck on the screw. Apparently the jam is taking place further inside the nut. I suppose that one or several of the plastic inserts that direct the balls inside could be drilled out to create an opening but I don't know where replacements can be found. Any other ideas on how to release the jam?
I removed the balls from the one nut that wasn't stuck and off the screw. It makes sense to me now how it works. Each nut has 3 ball return caps allowing 3 circuits. I understand that if any of the balls are placed in a dead end groove or non-circuit a jam could result. What doesn't make sense yet is why the stuck nut will move in one direction but not another. Regardless, I still have to figure out a way to remove it so it can be packed properly. The only thing I can think of is somehow remove one or multiple ball return caps to free up the offending pathway. Any suggestions?
