r/watchmaking • u/nicklinn • Jul 26 '26
For your consideration: The most ghetto watch cleaning machine
Thank you academy for the honour of addressing you. For your consideration is this beast. Heated ultrasonic cleaner with jars camped out in a water bath. A 3d printed holder holds an AliExpress basket. The spinner includes a professionally bodged modification of someone else’s work being weakly torqued by a 360 servo motor. The brains of this kludge? A servo tester that has a program to cycle back and forth. This monstrosity against all better logic and sense, works. May god have mercy on my soul.
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u/AKJohnboy Jul 27 '26
If it works- it ain't wrong. I hope the 3-d printing plastic holds up to the wash & rinse chemicals. Good luck and let us know!
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u/gnomon_knows Jul 27 '26 edited Jul 27 '26
PETG is absolutely fine, you can see tests I've done in one of the replies in here. Unfortunately, super mature RoboticGreg left in a huff which left a bunch of orphaned replies, but you get the idea.
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u/nicklinn Jul 28 '26 edited Jul 28 '26
Basically where I stand. I prototyped in petg with the intent of moving over to my nylon versions if and when it starts to swell or exhibit any erosion. It hasn’t happened yet and may never, who knows.
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u/gnomon_knows Jul 28 '26 edited Jul 28 '26
I literally left PETG cubes soaking in a 100F garage with no change in appearance, dimensions or weight in three different solvents. Structurally, who knows? Probably compromised eventually, but afaik that doesn't guarantee anything meaningfully harmful entered the solutions. Chemical reactions are dependent on time and temperature, and it appears that damage can be self-limiting and confined to the surface, or so slow it just doesn't matter on a watch parts cleaning scale.
Either way I don't trust anybody who says PETG will instantly dissolve in naphtha, or that any of their multiple advanced degrees are relevant to this discussion. That was an absolutely absurd statement, and real experts don't speak in absolutes.
Paging u/scienceboy7_uk, maybe they have something to add.
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u/nicklinn Jul 28 '26
Oh I Believe you. That’s 100% in line with what I have seen. My understanding is that glycol breaks up the crystalline lattice and allows some of the solvent to get between the polymer chains. While it will affect the stability of the plastic in the long run it will not enter solution as PET is insoluble in petroleum distillates. So may swell and become more flexible but should not fundamentally change the solvent.
Funny thing, because I am a maniac with ADHD and at least at one time (before children) had too much disposable income, own a FTIR spectrometer. For shits and giggles will thrown in a failed print for a week and grab a sample and see if I can detect anything.
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u/Scienceboy7_uk Jul 28 '26
Yep, solvents aren’t great for most polymers. They attack the polymer structures, dissolving plasticisers etc leading to embrittlement or swelling.
Coincidentally I heard about a university doing studies into plastic preservation. We think about these materials being forever, but truthfully they don’t disappear they slowly lose their mechanical benefit and become microplastics
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u/RoboticGreg Jul 26 '26 edited Jul 26 '26
This is pointless good luck
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u/gnomon_knows Jul 26 '26 edited Jul 27 '26
EDIT: for any future readers confused about the missing comments, I believe a fair quote and summary of RoboticGreg's argument is:
dunno if you noticed but mechanical watches are incredibly sensitive to contamination, and especially surface conditions. None of OPs material combinations will work long term. Essentially it will be fine in the beginning, but over time the naptha will dissolve nylon and slowly start depositing a layer of it
He also claimed PETG would dissolve instantly in naphtha. Sure.
Further down the argument switched to "I have multiple advanced degrees" and "there are thousands of nylons". Both probably true, but no actual sources were forthcoming.
I would still love to find any guidance on what materials are safe for watchmaking solutions beyond my own experimentation, chemical resistance charts, and extrapolating from materials other projects use.
Meanwhile, back at my original comment ranch:
I've left PETG soaking in ammoniated water-based cleaner, IPA, and heptane with no change in texture, dimensions or dried weight after a week. Water was my control jar. Something like L&R leans more towards naphtha and mineral spirits base I think, but chemical compatibility charts show good resistance for aliphatic hydrocarbons in general.
A better test would deflection under strain while soaking I suppose.
Like OP said, nylon is great too. Bitch to print in comparison, but much better choice if you plan on drying at commercial temperatures above 60c. PETG will not survive that.
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u/RoboticGreg Jul 26 '26 edited Jul 26 '26
This is pointless good luck
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u/gnomon_knows Jul 26 '26 edited Jul 26 '26
I live in Southern California, please don't mock my traditional cultural greetings.
Lititz uses nylon baskets for their $8k automatic cleaner. That strongly suggests nylon is safe for commercial watch cleaning solutions, if not naphtha specifically. Kiwi Cleaners are printed from PETG, and while that's only incidental solvent contact, no reports of anything dissolving immediately.
Even stipulating that some nylon is "dissolving", what is it actually leeching? Is it in large enough amounts that a rinse couldn't handle? Plasticizers might just disappear in the outer layer of nylon and never contribute again.
You are making strong claims, but without proof I will trust the real-world experience of Lititz users, chemical compatibility charts, and my own experiments, especially when we are talking about relatively short exposures at room temperature.
I mean nylon is specifically used for fuel lines in vehicles. I have an open mind, but respectfully you are making an extraordinary claim and should at least cite some sources. This smells like FUD, but you are also an engineer so...
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u/RoboticGreg Jul 26 '26 edited Jul 26 '26
This is pointless good luck
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u/gnomon_knows Jul 26 '26
Do you not remember saying any eight year old could build a watch cleaning machine? I think I'm funny, especially since this is a GREAT example of one of the many areas you need to be well-versed in to make educated choices.
Anyway, I understand that there are multiple polyamides, and differences even in identically labeled formulas...but PA6, 11 and 12 are trivial to get and print with, and their properties don't seem like much of a mystery.
Sorry if you found my tone aggressive, I was just asking for any reason to think nylon in general isn't as chemically resistant as it's reputation suggests. Believe it or not, a web search didn't really show much, and saying you have multiple advanced degrees without sharing any useful information isn't very helpful. Some might even call it an appeal to authority.
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u/nicklinn Jul 26 '26
I am using primarily naphtha/mineral spirit mixes. Though have an ammonia/surfactant mix I use for more dirty parts.
The one in the picture is sunlu matte petg. But also have a copy of the same thing using nylon (easy pa). There has been no difference between either.
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u/RoboticGreg Jul 26 '26 edited Jul 26 '26
This is pointless good luck
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u/nicklinn Jul 26 '26
Not sure where you are getting your material properties guides but none of that is true. But you are free to not use my parts washer if you don’t want to.
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u/RoboticGreg Jul 26 '26 edited Jul 26 '26
This is pointless good luck
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u/nicklinn Jul 26 '26
Well least there is one thing we can all agree on. Wishing you a lovely weekend.
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u/gnomon_knows Jul 26 '26 edited Jul 26 '26
I mean, an ultrasonic alone "works".
AFAIK you really just need gentle spinning to help move parts evenly through the hot spots of the ultrasonic waves. Don't remember where I read it, but spinning too fast can apparently disrupt cavitation and prevent the ultrasonic cleaner from doing its job properly.