deskthority

Some people tout ultrasonic cleaning as a magic bullet. News flash: it isn't. It does, however, produce spectacular results when used knowledgeably and intentionally.

1. Purchasing an Ultrasonic Cleaner
TL;DR: Buy the highest power rating in the tank size range that you can.

Ultrasonic cleaners have three major performance altering characteristics: tank shape, tank volume, and transducer power. Some offer special transducer synchronization circuits and other efficiency improvements, but things on a keyboard scale usually don't require advanced features. Brute ultrasonic force and power line level synchronization is acceptable.

• Tank Shape
  Tanks should be cuboid and not overly shallow. It is rare to find tanks that are poorly proportioned.
• Tank Volume
  Tank volume and transducer power modify one another significantly. Larger tanks require more total power, but they require less power relative to their volume than smaller tanks. Small tanks dissipate significant amounts of ultrasonic energy, as the waves cannot travel far before meeting metal.
• Transducer Power
  The watt per gallon (or liter) rating is a general indicator of ultrasonic cleaner performance. It is by no means the end all in ultrasonic cleaner performance, particularly in larger installations, but for our purposes (less than 5 liter tanks) a higher watt per gallon rating is better. Smaller tanks tend to negate and dissipate ultrasonic waves due to their high surface area relative to water volume.
  
  This PDF contains a chart, located on page three, that lists a rough ideal watt per gallon rating based on tank size:
  http://www.ctgclean.com/sites/www.ctgcl ... Volume.pdf

2. Using an Ultrasonic Cleaner
TL;DR: Only clean a few parts, including keycaps (1/4 of a set or less and you MUST stir them), in a single ultrasonic batch (a six minute run time should clean things that aren't very crusty). Use gentle cleaners like denture tablets and warm, not hot, water (which will be heated by the transducers, so be careful).

Ultrasonic cleaning effectiveness is limited by two factors: energy dissipation of materials and shape complexity / volume. Cleaning compounds are used to change the physical characteristics of water, which acts as the primary solution for grime removal. Gentle cleaners like denture tablets and dish soap perform well in most keyboard applications. The cleaner's transducers will gradually heat the water, so keep an eye on it.

• Energy Dissipation of Materials
  Rubber and soft plastics can absorb and diminish ultrasonic waves to an extent.
• Item Complexity / Volume
  Parts that take up significant space in the bath can reduce overall effectiveness by creating dead zones. Complex objects can create dead zones while simultaneously reflecting, blocking, or otherwise diminishing the ultrasonic waves. Stirring is necessary for workloads like keycaps, even when watt per gallon ratings are high.

You should also note that grime type affects cleaning time. Crusted on grit is more difficult for cleaners to handle. Lubricants, finger grease, and other thin coatings are blasted from the material quickly.

3. Mark Recommends a Cleaner

I recommend a Chinese 3.2 liter ultrasonic cleaner that has a greater than 100 watt per gallon rating, even when transducer inefficiency is factored in. Two 60 watt transducers reduce potential dead zones.

http://www.ebay.com/itm/New-Stainless-S ... 2844739182

Most low end units, regardless of their advertising, have a single 60 watt transducer and a less than ideal watt per gallon rating. If their rating ends up high enough, their tank size is often small and minimally useful.

Thanks a bunch for this write up. I ended up buying the one you recommended.

Should you stir while the machine is running or stop it first?

Stirring while running is fine. You'll clean your stirring implement.

Use your finger. It tingles

Be careful. Powerful ultrasonic cleaners actually hurt if you stick a finger in them. I remember yelping when I stick my finger over an ultrasonic humidifier transducer while it was on.

ohaimark wrote: Be careful. Powerful ultrasonic cleaners actually hurt if you stick a finger in them. I remember yelping when I stick my finger over an ultrasonic humidifier transducer while it was on.

Wouldn't recommend it, they can damage your joints and even lead to rheumatic diseases

What exactly is the stirring supposed to do?

It changes the location of dead zones and reflective spots in cleaning loads like keycaps, which tend to have a lot of angles and blind holes.

ohaimark wrote: Be careful. Powerful ultrasonic cleaners actually hurt if you stick a finger in them. I remember yelping when I stick my finger over an ultrasonic humidifier transducer while it was on.

It huts when you touch a 400v mains filter capacitor too but i did that

andrewjoy wrote: It huts when you touch a 400v mains filter capacitor too but i did that

Gee, and I thought I was Death Incarnate because I once touched the contacts of a 9V battery with my tongue!

Nah , thats just fun.

The cap hurts, but you can usually smell your own flesh burning before you feel the burn.

I touched the contacts of a 9 inch mono CRT once , now that is painful. It gives you a large respect for working with that stuff, when i was working with a 32inch sony cube CRT i was very careful the 9 inch was bad enough.

I should touch the 9V contacts more often, maybe that reminds me to be more careful with 230V. Got shocked briefly yesterday, because I assumed my coworkers would think like I had.

One time I plugged something into a US outlet without its external cover on. My fingers slipped past the plug and onto the bare leads. That was a breathtaking experience.

Would something like https://is.gd/H4gi1p be ok for very occasional use? It's low power, but small volume - it would mainly be used for cleaning jewellery. tia

Just did some ultrasonic cleaning on some semi-dirty Alps switch housings, and after drying I noticed they still had a thin but hard layer of dust or other grime caked on. After reassembly some still feel crap and scratchy.

Is that normal or is my ultrasonic cleaner just rubbish? I used tap water with a negligible drop of detergent.

That would work fine for jewelry if you leave it in for a very long time. I would recommend something less chintzy, as it barely outputs 50 watts according to its specs.

Madness: If it's a "60 watt ultrasonic power" cleaner it's probably rubbish.

ohaimark wrote: That would work fine for jewelry if you leave it in for a very long time. I would recommend something less chintzy, as it barely outputs 50 watts according to its specs.

Madness: If it's a "60 watt ultrasonic power" cleaner it's probably rubbish.

What about 50W?

Anyway it passes the foil test so I know it's working properly. I put a scummy electric toothbrush head in the cleaner and it cleaned up the outside nice but not the inside.

The dust on my Alps switch housings is caked on hard enough that I need to scrape it to get it off. Should I realistically expect ultrasonic cleaning with just tap water to be able to remove this?

50 watt single transducer systems typically aren't powerful enough to clean blind holes.

If you leave the housings in for a really long time with simple green or another strong cleaner you might get results.

The above information are quite rich and detailed - I have always been interested in using ultrasonic cleaner.

But one most important information is missing for me, as a broke student:
Price

One can always opts for the industrial best standard or even military grade stuff, even in a hobby, as long as one can afford; however, just like the thread about de-soldering tool, I would get the one can cost me only $5, as long as it works reasonably well to desolder 20 to 30+ boards, instead of the desolder gun that cost > $100.

Or to be more exactly, what is the minimal price I can spent to achieve reasonable result. If all I want to clean is some small parts less than the size of a can of coke, e.g. a bunch of leaf springs from vintage Alps switches.

An additional question is, if a cheap (say within $30) ultrasonic cleaner would totally not work, are there services out there to help people to ultrasonic clean articles using the higher grade ultrasonic cleaners?

You can get by with a cheap ultrasonic cleaner if you put in very small batches, but even then it may struggle.

Ultrasonic cleaners with two transducers (and all powerful cleaners in general) are inflated in price due to their use in labs and medical facilities.

I'm not familiar with any ultrasonic cleaning services. The shipping would nullify any temporary savings very quickly. If you have access to university facilities, however, you might know someone with access to a good cleaner.

ohaimark wrote: You can get by with a cheap ultrasonic cleaner if you put in very small batches, but even then it may struggle.

Ultrasonic cleaners with two transducers (and all powerful cleaners in general) are inflated in price due to their use in labs and medical facilities.

I'm not familiar with any ultrasonic cleaning services. The shipping would nullify any temporary savings very quickly. If you have access to university facilities, however, you might know someone with access to a good cleaner.

Can you provide an estimation of how much in total the "temporary savings" should reach for a good ultrasonic cleaner with decent performance? And I believe I may use it for only max 3-4 times / patches. So I have to consider the resale value of the ultrasonic cleaner, because there is no storage space for me to store a piece of huge equipment that I am going to use, perhaps > 5 days per year. (This is the scenario when the abuse of 90-days return policy in the US may happen - get a super high-end ultrasonic cleaner, "test" it a few times, and then return it "as new" because you "don't like it".)
Please estimate with a number for a certain currency, in euro's even better.

I have access to some university / research facilities, but those areas, while still in the sciences, involve supercomputers and behavioral tracing systems and neuro-imaging, totally no need for an ultrasonic cleaner.

It depends on what you're cleaning / where you're shipping the parts to.

In USD, a keycap set shipment could run you around $2. $4 would be your round trip. Let's say that the cleaning service costs $10. That's $14 per cleaning load.

Thus, after about 6 loads, you would have spent enough to purchase a cleaner.

A 3.2l cleaner isn't that big and has a number of uses. Heck, you could even use it to clean silverware and jewelry.

As for the return policy abuse... To each their own.

That's a good calculation.
And you are correct that the more professional models seem to start at 3L volume.
For example this one:
http://www.ebay.de/itm/301735791114

It's not good to abuse the return policy, so perhaps I should stick to my dirty hardware and look for 1 more part-time job, while continue the job hunting and completing my dissertation.

Could someone who bought that recommended machine post the interior dimensions of the tank and basket?

I will later tonight or tomorrow night.

Make sure your wife knows it works great on jewelries too. She will get on board.

it got my old swimming goggles clean too . cleaned years of chlorine and salt off them.

Would not recomend eyeglasses in it due to coatings . But any small glass or clear plastic parts should be good and clean.

andrewjoy wrote:it got my old swimming goggles clean too . cleaned years of chlorine and salt off them.

Would not recomend eyeglasses in it due to coatings . But any small glass or clear plastic parts should be good and clean.

Is it safe to use once the water was changed? Asking because I might get one to get my glasses clear and clean some switches/caps at random occasions..

Thanks for writing this up! I was wondering if anyone had recommendations for temperatures settings. I'm mainly worried about what temperature to clean keycaps and switch housings at.

Use temperature safely below the glass transition temperature of the specific plastic used. E.g. for ABS the glass transition is around 80 °C. So use temperature of about 60 °C (or less).

I do not know what temperature I used for my ABS keycaps. It was fairly hot. I could not keep my hand in it but it was safe to briefly touch.