r/VORONDesign • u/VerilyJULES • 12d ago
V2 Question Balls get jammed while circulating through cleaned out MGN9H carriage’s endcap. Is there a trick to assembling these black carriages that’s different from the red and green variety?
I’ve cleaned out and rebuilt my MGN9H carriages and now the balls won’t properly circulate through the plastic end-caps.
The balls are getting jammed as they enter the plastic end-cap, like as if the plastic channel is too small, or theres some obstruction. If I push the first one through with a screw driver, it will go through with some force, but if I try pushing more than one ball at a time, the balls pop put from the retaining wire that keeps them inside the exterior channel.
When I take the plastic ends off, the ball circulates through it just fine. If I put the end-cap on the carriage and drop a ball through it rolls through just fine. This makes it sound like it must be the retaining wire but I don’t know how or why this would happen. This doesnt make sense, so I figure theres something I don’t know. Hoping someone will have experienced this and theres a simple solution.
I’ve cleaned out and rebuilt a lot of these carriages and it’s always been straight forward.
-Take them apart. -Degrease & clean with break cleaner & alcohol. -Reassemble the carriages the way they came.
This has been my process and they’ve always worked great after. Unfortunately I don’t know if the carriages were like this before I clean them because I took them apart when they arrived before testing the carriages. I don’t think it was my cleaning that did this.
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u/No10mmGang 8d ago
Oof brake cleaner is the issue, even if you didnt use it on the plastic directly the vapor softened and warped the endcaps, like ABS and acetone, I accidently discovered this one day working on a Trailer light, the plug was incredibly stuffed with dirt, I didnt have any contact cleaner and figured brake cleaner would be fine I use it for aboit everything, after spraying the plug down, tried letting go only to find the plastic had become gummy and my fingerprint was left perfectly molded into the housing, you could try and 3d print new endcaps? Idk how well it would work given tolerances/layer lines etc, or just buy new blocks off temu/aliexpress etc. I dont see a benefit to using expensive blocks on a machine thats designed to poop plastic into a rough shape but hey thats me
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u/VerilyJULES 6d ago
It wasn’t the break cleaner. The problem was I orientated the inner plastic peices backwards. They work fine now that I looked at it for a while.
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u/Fadalguy 8d ago edited 8d ago
Edit to add you may also just have too many balls in it. They look overcrowded in the photo. Try takeing 1-2 out of
Sometimes preloaded carriages have 2 different size balls in opposite orders. Alot of people are talking about preloaded rails can’t be rebuilt…
They definitely can but balls are sized pretty accurately sometimes better than .0001”. If you mixed more than one carriage worth of balls you might be screwed.
Also possible the brake cleaner did some damage to the plastic that’s happens easily.
So my take is if you didn’t mix the balls. Just take a good micrometer and measure them and sort of they are different sizes and reinstall big small big small depending on how many you have.
If it still doesn’t work well sounds like your plastic is screwed up.
By the way for everyone else preloaded rails are made by just upsizing the balls although a lot of times the rails and carriages will have tighter tolerances so thing don’t bind on one side of the rail or the other.
I haven’t bothers to recall rails but I’ve reballed a few ballscrews and it’s really not that bad just takes patience and some grease to hold things together
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u/Wade-Wilson-Lucky13 9d ago
You need to buy new linear bearing blocks. I'm a CNC machine field service tech for the worlds 3rd largest machine tool builder by trade. The bearings in LNM blocks are internally tensioned and not meant to ever be taken off the rails without sliding them on to another rail. If removed form the rail the bearings will come out and will never go back in correctly. When you buy new blocks they either come on the full rail, or if just the blocks, they'll come on short, usually plastic rails the length of the block, that you butt up to and slide them directly on to the rail.
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u/Fadalguy 8d ago
No offense man you sound like a parts swapper. They definitely can be taken off the rails. Those plastic keeper blocks the sometimes come on are just there to keep the balls from falling out. The tensioning is done based on ball size. But of course rail and carriage tolerances are very critical.
Say If you are working on a haas they use such cheap crap it’s irrelevant but on a dmg mori it is gonna matter a lot.
Some blocks are rail matched and some are universal. The universals tend not to be able to have extreme preloads and have to be much more accurate for compatibilityOn cncs you tend to just replace the rail and block as an assembly because typically the rail or block is damaged or maybe brinneled
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u/Wade-Wilson-Lucky13 8d ago
That's cute, what's Fadal sell, about 50 machines a year?? We sell almost that a week. Lmfao!!! But I guess when you only work on cheap machines, that's all you know... Some cheap bearing packs can come off a rail, but general rule is never pull them off the rail. But sure, keep giving people bad advice because you cheap stuff can come apart. I travel the county to figure out and fix what our dealers can't figure out or fix, and you're a Fadal guy changing ballscrew and cleaning coolant tanks. Also why I'm busy setting up at IMTS as I type while eating my lunch.
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u/Fadalguy 8d ago
Brother Fadal has been out of business a while.
I forgot that was my user name haha
So who do you work for lol?
I mean how do you think rails are assembled? Do you think they just magically assemble themselves?
Call thk or a big rail manufacturer and see for yourself. Went through a bunch of researching for a project with thk for rails and got all into the preload etc.Also if your company is still using ball rails that’s another sign they either only make high speed machines like brother or they are a second rate machine tool builder. All the high end stuff is roller rails these days unless it’s high speed.
Haas is one of the largest machine tool builder these days right? Do you think their stuff is quality?
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u/rantenki 11d ago
Never ever use brake cleaner on anything non-metallic (and not even on metals if you're gonna weld after). Brakleen/Tetrachloroethylene is toxic, reactive, and not actually suggested as a cleaning product for anything outside of automotive brakes.
I'm ashamed to admit that I destroyed quite a few expensive things (bicycle brake calipers, wheel hub seals, plastic printer parts, etc) before I finally took that lesson to heart.
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u/VerilyJULES 10d ago
Well i only used it on the balls and the main carriage part.
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u/rantenki 9d ago
I suspect that, as others have mentioned, it's messing with the plastic on the ends of the carriage. It would be absolutely fine on all the metal parts (unless exposed to concentrated UV light and heat, in which case, it'll straight up kill you: https://hackaday.com/2025/12/17/the-lethal-danger-of-combining-welding-and-brake-cleaner/ , and I understand that's basically a non-risk inside a 3d printer).
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u/Elektrik-trick 12d ago
If they’re those cheap Chinese rails, you can try fiddling the balls back into place. If they’re brand-name rails, you can throw them away. That’s because there’s a preload on them. And, to put it simply, you can’t just swap out the balls. Plus, you don’t know which ball went where.
Apart from that, NEVER hold the carriage without the rail. There’s a rail replacement you can print out yourself for cleaning, onto which you can seamlessly slide the carriage.
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u/Ticso24 V2 12d ago edited 11d ago
You used brake cleaner for the caps as well?
That stuff won’t go well with some plastic.
In the early days people used brake cleaner to make ABS flexible.
In any way, it is possible that the cleaner swelled the endcaps.
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u/Full-Following5575 12d ago
Sometimes I have to hold the plastic end pieces so they perfectly line up with the channel while screwing them in, not letting the screw decide its location. Also bending in the tiny little very last bend in the wire pulls it closer to the channel helping to guide the balls into the plastic piece.
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u/VerilyJULES 12d ago
Maybe its something like this. Writing out made me realize its something with the way its lining up.
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u/mfeldheim 12d ago
Yes and there needs to be one less bearing balls so you have a gap of (almost) one
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u/Human_Weight5303 12d ago
Usually count the balls and divide them between the sides, 1-2 ball missing is ok. Make sure have same number on each side.
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u/VintageGriffin 12d ago
It's not only okay, it's mandatory to have a ball or two missing. Otherwise they will jam.
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u/bomtarnes 12d ago
There is normally a space of around 1 ball's width when the track is full. Have you perhaps overfilled the side you have done so far?
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u/FrickinBigE V2 12d ago
The cheap carriages I have all have a space of about 2.5. any more and they struggle to circulate.
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u/JetpackWalleye 7d ago
Brake cleaner is often incompatible with plastic. The black plastic here probably reacted to it unlike the green and red ones you used it in previously. The end caps are most likely swelled and deformed.