It's been over a year since I published a popular Instructable about ultrasonic misting ABS 3D printed parts with acetone vapor. A couple months ago I was inspired to revisit this project by the professional 3D printing "Polysher" machine on Kickstarter.

In this instructable I've redeveloped my original ultrasonic polisher proof of concept into a more polished and professional tool with key functional improvements.

Additionally, after perfecting the machine I performed experiments involving mechanical testing of acetone polished ABS specimens in various orientations; and I observed some very interesting results! (See final step)

In case you didn't see the original project, my goal has always been to build "...a machine that lets me quickly drop parts into a transparent container and be able to press 'go' and have the machine produce a predictable finish on its own. I do not want to have to put together a really involved setup that may be a fire hazard, fume hazard, or something that produces unpredictable surface finishes. Essentially I want something as convenient as a microwave."

The original project involved repurposing the electronics from an ultrasonic water humidifier so that they could be used for acetone instead. The acetone mist/fog was then blown through an open system and filtered through a water bowl before venting into the room.

The result of that project was a functioning polisher that I could operate inside the house, but not without a bit more effort than I had wanted. In practice the water in the filter would readily absorb the acetone, but the water needed to be changed after every use and the process was wasteful with the acetone. Additionally, the form factor of the entire machine was not visually pleasing or fun to lug around.

So after a couple design iterations I've improved the old design into something even more awesome!

The user interface is now simply an ON/OFF switch and a single momentary button for 'go'. The new design now uses a closed pumping system and has been optimized for maximum fog production; So it is completely sealed allowing for indoor use, it takes less time, consumes less acetone to do the job, and no water ever needs changing!

And finally the entire machine is built into one single transparent assembly, so it looks good and is easy to transport to Makerfaires! (See you at PDX-mini this fall!)

Step 1: Polishing Chemicals, Safety First!

The first thing that must be said here is that the solvents used by this machine are flammable and irritating to your eyes, skin, and respiratory system. Always read the MSDS sheets for chemicals before using them, always wear appropriate personal protective equipment when handling chemicals, and always keep solvents away from open flames, sparks, and other possible ignition sources!

Personally, when pouring chemicals I just wear safety glasses and make sure to have adequate ventilation. If you have super sensitive skin then use latex or viton gloves are resisn(not nitrile or PVC).

Despite what is commonly repeated, acetone (and isoproptyl alcohol for that matter) is actually a fairly safe chemical as far as human exposure is concerned. Though it doesn’t smell good, you would have to be exposed to a lot to actually be harmed. It is just an irritant in low concentrations, all the bad stuff happens at high concentration levels. Acetone is not regarded as a carcinogen, a mutagenic chemical, nor a concern for chronic neurotoxicity effects.

The device in this instructable uses materials which enable the safe indoor use of acetone for polishing ABS or isopropyl alcohol for polishing 'PolySmooth' material. Specifically, the tubes are EPDM rubber and latex rubber. All clear containers used are polypropylene. Please do not mix chemicals or use different chemicals than I've recommended without doing appropriate research first!

<p>ok, here I go....</p><p>1) somebody already mentioned before, but was too late for me, the small black fogger is indeed acetone soluble....</p><p>2) however today I got this model, <a href="https://fr.aliexpress.com/item/DC-24V-19W-Ultrasonic-Mist-Maker-Air-Humidifier-Waterscape-Atomization-Atomizer/32725166052.html?spm=2114.13010608.0.0.0P8w02" rel="nofollow">https://fr.aliexpress.com/item/DC-24V-19W-Ultrason...</a></p><p>I immerged it for a couple of hours in acetone and is still working. I'm leaving it overnight, but I'm optimistic.</p><p>3) there is also this model with the piezo and the driver... <a href="https://fr.aliexpress.com/item/38V-Humidifiers-accessories-General-Control-panel-circuit-board-sprayer-plate-pulverizer/32610450535.html?spm=2114.13010608.0.0.0P8w02" rel="nofollow">https://fr.aliexpress.com/item/38V-Humidifiers-acc...</a></p><p>Which I beleive is almost the same as mr. Frog gutts....</p><p>4) I'm planning to use a first reservoir that will pour the acetone in a second one (using some capilarity effect) containing the fogger in order to always keep the level to its &quot;optimum&quot;... </p><p>5) about the pump.... What about a simple aquarium diaphragm pump? The diaphragm is made out of rubber so it might work, right?</p><p>Type 1 <a href="https://www.amazon.com/Generic-Diaphragm-Pump-water-Aquarium/dp/B00MP4BKL2" rel="nofollow">https://www.amazon.com/Generic-Diaphragm-Pump-wate...</a></p><p>Type 2 (the old noisy pump) <a href="https://www.amazon.com/VicTsing-Aquarium-Oxygen-stones-Silicone/dp/B00L17IPEO/ref=lp_2975471011_1_1?s=pet-supplies&ie=UTF8&qid=1487019788&sr=1-1" rel="nofollow">https://www.amazon.com/VicTsing-Aquarium-Oxygen-st...</a></p><p>Type 3 (just found it... Apparently a piston pump... Safety concerns on my mind) <a href="https://www.amazon.com/gp/product/B00BVLBNB2/ref=s9_acsd_zwish_hd_bw_b3FMlvv_c_x_w?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=merchandised-search-9&pf_rd_r=AJ8FHSV8TF725TSG8BW7&pf_rd_t=101&pf_rd_p=37f6288c-7bd2-5d3e-a2d9-4bb6ddf022ab&pf_rd_i=2975471011" rel="nofollow">https://www.amazon.com/gp/product/B00BVLBNB2/ref=s...</a></p>
<p>btw, I'm not that cheap and I beleive your pump is worth every penny but I'm in france and shipping + eventual custom fees will easily double the price...</p>
<p>I'm in Canada so shipping, taxes and brokerage fees are killer.</p>
<p>My take on this project is that its not really worth it and a big old money pit.</p><p>The biggest problem with this project is gluing polypropylene. It is what's called a 'low surface energy' plastic (very little can stick to it). Silicone will just about stick to it but it doesn't create a secure bond, this means Acetone is highly likely to leak out of the bottom of the container you put it in.</p><p>After discovering this I tried mounting the transducer inside a new pot with no hole in the bottom and it melted clean through the new pot in seconds.</p><p>I then tried another new pot and suspended the transducer half way up in the pot, but this still malted a spot directly below the transducer. The acetone didn't boil, so I am guessing the ultrasonic vibrations simply passed through the acetone into the plastic and melted it.</p><p>My only suggestion if you really want to commit to this project is to buy a 500ml or so empty paint pot from ebay and use this as the container, you can use silicone to your hearts content on tin and it will create a solid seal.</p>
<p>do you think i could use metal fittings instead of nylon? I'm having a tough time finding them for a reasonable price (I'm not in the US).</p>
<p>Absolutely you could. </p>
<p>Righto, found the source of my acetone leak, and now I am at a loss as to how the original project has no leaks.</p><p>Silicone sticks to most things with a vengeance, it does not however stick to polypropylene. This isn't just me, search google for example and you will quickly find a link like this:<a href="http://www.stealth316.com/2-dp8005.htm" rel="nofollow">http://www.stealth316.com/2-dp8005.htm</a></p><p>Which says this:&quot;Despite their widespread usefulness, &quot;low energy&quot; plastics have a quality that can make them hard to work with - they are difficult to seal or bond using commonly available sealant adhesives. Cyanoacrylate, epoxy, polyurethane, silicone (RTV for example), and most acrylic adhesives do not stick to polypropylene and polyethylene.&quot;</p><p>I think the original project must have got very lucky not to have had leaks with Silicone.</p><p>The above link however handily leads you to a 3M adhesive: DP-8005, which is resistant to acetone and and sticks to PP.</p>
<p>After deciding I didn't want to spend &pound;23 on glue I bought a new container for the acetone. This time I am going to feed the transducer in through the top side of the acetone container so there are no holes in the bottom and then cover the transducer wire completely in silicone to protect it. Although from reading it seems the heat shrink covering the wires is probably polyolefin which is fine in acetone anyway. In addition Acetone is barely conductive so I think it should be ok even if it does get to the wires. </p>
<p>Ok, so I have just finished building and it seems to work ok with the new internals of the humidifier. However I have a few notes for anyone else going in to this.</p><p>The UK version of this humidifier comes with a plug transformer, so the transformer coil inside the unit is not there (this is a good thing as you are never dealing with mains voltage)</p><p>However buying an expensive humidifier isn't really necessary. </p><p>You can buy the actual component for a couple of quid: <a href="https://www.aliexpress.com/item/20mm-transducer-film-atomization-ultrasonic-nebulizer-chip-oscillator-piezoelectric-ceramic-humidifier-with-I6B2/32693221060.html" rel="nofollow">https://www.aliexpress.com/item/20mm-transducer-fi...</a></p><p>So you would just need to figure out how to drive it. The silicone surround is important to stop the Acetone leaking, you could probably just buy this: <a href="https://www.aliexpress.com/item/High-Quality-Ultrasonic-Mist-Maker-24v-Nebulizer-Atomizer-Head-without-Lights-for-Humidifier/32636337409.html" rel="nofollow">https://www.aliexpress.com/item/High-Quality-Ultra...</a></p><p>take it apart and hope it had the silicone membrane. </p><p>Then all you would need is a small piece of metal and drill your own holes in it to mount it to the acetone container.</p><p>You would save yourself a good wad of cash and this project becomes more tempting to do.</p><p>In addition to the above the bottom project box is basically not needed, and only really serves the purpose of making the pump sound very noisy. It would be much neater to create a mount for the motor, buttons and circuitry on your 3d printer. Having it out in the open would also mean much less chance of Acetone ever gathering near the electronics with the potential for a spark and explosion.</p><p>Also I cannot understand the placement of extraction placement for the pump. Acetone vapour created by the mister is clearly heavier than air and I would have thought a better circulation would have been created by placing the extraction neat the bottom of the container. </p><p>Finally I think if the return from the pump to the acetone container had a pipe that went in from the top and ended under the level of the acetone this would help it return to its liquid state much quicker as it would bubble through the acetone. </p><p>There is a lot of potential to this project, but I feel it is very much deserved of a 'mk3' with some revisions that would improve the whole thing and make it look slightly less 'hacky'. </p>
<p>In addition to the above I have just realised the Acetone is escaping from the bottom of the container when idle. I had thoroughly covered the bottom of the ultrasonic transducer with the silicone gasket maker as well as putting it on the inside of the silicone surround the transducer is in, but obviously didn't get a proper seal. </p><p>If you are doing this with the new design you will need to really smother the bottom of the transducer in gasket maker, make sure there is no way for the acetone to escape. </p>
<p>&quot;Also I cannot understand the placement of extraction placement for the pump.&quot;</p><p>Should read</p><p>&quot;Also I cannot understand the placement of the extraction pipe for the pump.&quot;</p><p>And near not neat... and edit button would be nice on these comments!</p>
<p>Also... reed switch... why are you holding it in the up position with a cable tie?</p><p>It's a switch with two wires, which means its normally open or normally closed, so the connection needs either cutting or shorting. (It's shorting in this case, I'm just wondering why you chose the odd method of manually rigging the switch)</p>
<p>I guess I was high from all the fumes. I might have had intentions of re-adding in the float switch at some point because running dry on acetone has the potential to hurt the machine (by shaking without a load and also by overheating).</p>
<p>Also... why do you have a fan on your purchase list when the Humidifier comes with one?</p>
<p>It makes sence to do this in retrospect. This project is a rebuild, a version 2 that followed a version 1 where I threw out that fan and forgot about it!</p>
<p>Images of the 'new' atomiser</p>
<p>I think I like the looks of this one more than mine. Mine has electronics right underneath the acetone container, so if the seal is bad then acetone drips onto the board. On this new one if you were to cut the metal right down the middle you could put the electronics farther away and still use the 4 hole pattern to press against the vibrator seal</p>
<p>In addition to the above the transformer has gone and it now has a 24v power pack. this may be an advantage one I figure it out as less power in the box is a good thing. </p>
<p>The internals were changed at some point. It appears to have happened to all of the models regardless of the animal model. Here are the two models side by side. </p>
<p>Just took the humidifier I bought apart and the design of the atomiser mount is completely different. real bummer as it doesn't lend itself nearly as well to mounting and I will have to make sure it is watertight so there are no leaks.</p><p>Worth warning that these humidifiers are not all the same. I bought the duck but I imagine its an actual change in design rather than a difference between animals. </p>
I just purchased the Crane humidifier (frog one) from the link. Apparently they made a new version that has different internals than yours. The ultrasonic bit is completely different.
<p>Woah thanks for posting this, would you mind sharing a picture of the internals too?</p>
<p>Do you just pop your parts on the bottom of the container, do you find they stick to the bottom at all?</p>
<p>The sticking I've seen is superficial, you can always get the part out with a little knock. easier than popping a printed part off a build plate. </p>
<p>Did you check what the output of the transformer in the Frog was? Looks like a dual output - 28v &amp; 13.5v (cant tell if rectified to DC), so if it were using the 13.5V and were rectified you could probably run the whole system off the one transformer i.e. timer, pump as well.</p>
<p>I remember that the 28v &amp; ~13v were both AC. I realize now that I wasn't thinking and I just connected it to a single diode and noted that the result was unusable for operating the timer. I should have ran it through a full wave rectifier and that would likely have been able to run the whole system. </p>
<p>Congrats, nice project. I am trying to do the same, however, I tried first with a very cheap mist maker from ebay, as others have suggested here. However, it will not work because the external case is made of abs and will dissolve inside the acetone. I think you should mention this, to warn people that your designe is the only way to go.</p><p>Another thing, I also made a return circuit, so the vapor can better circulate from one box to another.</p>
<p>Hi great instructable , i will definettly make it, but i have a few quenstion. What is used for the pump? Is it for economy acetone? after for example 360 seconds, this pump starts andtake the atomized acetone and return it back to the tank of acetone?</p><p>If it so, if you don't use pump ,what is around the amount of the acetone is spended for 360 second? 10ml or less? I read your artivle but i didn't realize when it get place</p>
<p>Very, very complicated solution for a simple problem. You could have done it way easier.</p><p>Acetone BOILS at 56 degrees Celsius (133 F) and produces VAPOR. You take dirt cheap ceramic resistor, for example, 6.8Kohm rated at 20W. When plugged in into wall socket with 220V they dissipate 10W of energy. Connect cheap KSD7000 thermal relay rated at 60 degrees Celsius in series for safety and you are done. </p><p>Electric current will heat the resistor and acetone will boil. Its vapor will fill the box. Relay will cut the current once the temperature rises to 60C. As it cools down to 45C, it will reset and process will repeat.</p><p>Only one important note - you'll have to use silicone-coated wires, others will be dissolved with the risk of short circuit. You can buy them anywhere, just search for &quot;multimeter probe wires&quot;.</p><p>Even simpler solution - put some acetone in a glass jar, throw something at the bottom and then place your ABS model on top so it won't touch acetone. Close the lid and put the jar into boiling water. Water will ensure that acetone isn't heated above 100C and won't explode. It will just boil nicely.</p>
<p>Please give details on what parts are used to make the pump.</p>
<p>Great instructable!</p><p>Do you think it would be possible to modify this to use THF (Tetrahydrofuran), which is a solvent for PLA?</p>
<p>You can try pure ethyl acetate or &quot;MEK substitute&quot; (which is mostly ethyl acetate too). It's not as effective as THF though and it also bleaches the material if left in for too long. Still, it's worth a try.</p>
<p>Thanks! Unfortunately, THF would destroy the latex and EPDM hoses &amp; pump components and may even fog over the PP container. I don't have any suggestions for chemicals to use on PLA. </p>
In my experience, vapor polishing also reduces fatigue load resistance significantly. Parts subjected to repeated loading in the X-Y plane will fail after a significantly smaller number of loading cycles if vapor polished.
<p>Nice job man! Have you considered modifying your project to be suitable for various solvents?</p>
<p>Thanks! I try to work with commonly available materials and I was happy that this setup is able to handle the two chemicals that will have the most use for polishing. As I understand it, filaments aside from ABS and Polysmooth require substantially more dangerous chemicals to have this effect, if you can even find something that will work!</p>
<p>I promise this question is for you. <br>I have read your article quite a few times. I have decided to build one but i have a question for you.<br>Why a whole humidifier? If your goal is to atomize the acetone, wouldn't just buying an atomizer be cheaper and work just as well?<br>Take this for instance.<br><a href="http://www.ebay.com/itm/Mist-Maker-Humidifier-AC-100-240V-To-DC-24V-1A-Adapter-US-Plug-Hot-Pond-Nice-t/172224804515?_trksid=p2141725.c100338.m3726&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20150313114020%26meid%3D34c3447fbf5b4e5484a7615be36761a8%26pid%3D100338%26rk%3D2%26rkt%3D7%26sd%3D380831298424" rel="nofollow">http://www.ebay.com/itm/Mist-Maker-Humidifier-AC-1...</a></p><p>I can get the whole thing for 6 bucks and rig it up exactly the same way you do without the extra effort. Is there a reason you choose the humidifier or was it just what you had on hand. because i can get behind recycling. </p>
<p>I hate excessive waste too, but there a functional reason I used the whole humidifier aside from 'I already had one'. That the system is physically large and has readily adaptable mounting holes for this purpose. Looking at step 4, the speaker-like shaking disc is ~1.5&quot; in diameter and is mounted to a metal plate with 4 holes in it. </p><p> On the other hand the tiny ones are cheap enough that you could probably hook up 3 in the same chamber to get more output. Id love to hear about it if you gave one of those a try. </p>
<p>soon as i get mine built i will let you know.</p>
<p>Amazing results for a homemade product! Of course you could just send it off to an SLA printing service and call it a day but not everyone has one available around them and I'd imagine the print jobs aren't too cheap either so this is a nice workaround to get that SLA like finish!</p>
<p>This is amazing! Thanks for your contribution man,</p><p>I'd be happy to purchase the pump you've got listed for sale on ebay, but it doesn't ship to canada. I don't have any way to get this part.<br> Any suggestions? I know you said it was difficult to source this. Would a 12v fuel pump from ebay work at least for a while?<br>Can you give any tips on what flow rate / pressure to look for?</p>
<p>Thanks!! And my mistake on not setting up the international shipping option, its updated now. As for alternatives, I honestly haven't been able to find anything else suitable. Fuel pumps are meant to be submerged and would overheat in this application...Not good! I wasn't picky on the pressure and flow rate, it just needs to circulate the air without melting down/leaking/or heating up. </p>
<p>What type of pump is it, presumably peristaltic. It looks 3D printed, are the STLs available?</p>
<p>It is a positive displacement pump made with chemical resistant plastics &amp; rubber. There are 3d printed components but it wouldn't do you any good without the rest of the assembly. The setup had to be custom because it is so hard to find pumps capable of moving solvents. </p>
<p>A great instructable, love the idea. Having watched loads of videos of people trying to polish their prints by placing them in pots with tissue soaked in acetone to just pouring in acetone this seems a more efficient way of doing it. <br>Have you considered a kickstarter project ?</p>
<p>I disagree. Why make a contraption like this when you can do the bucket/tissue way? </p><p>The bucket/paper towel idea is much simpler. </p><p>I use a paint can and paper towel held with magnets.</p><p>You would be still &quot;pouring&quot; the acetone on the tissues. My parts are smooth in 40-60 mins. This is a project that is meant for those who want to tinker...its not a necessity for smoothing ABS. </p>
<p>No doubt about it, smoothing can be accomplished with a significantly less complicated setup. The primary benefits of doing it this way are the reduced human exposure to chemical fumes, the ability to see the process in action (no paper towels hindering my view), and that it will stop the smoothing after a predetermined (timed) extent. You don't have to worry about forgetting what you were doing and returning to find your print is a pile of mush. </p>
<p>I admire your tinkering skills, though...and the extra step of posting this online. It takes a lot of time to organize a project for people to see. Thank you. Got anything else? </p><p>However, I wouldn't attach a motor/live wires near acetone or alcohol, especially in vapor form. But...it could be a good way to speed up natural selection. ;) </p>
Why not make the &quot;contraption&quot;? Because you can! Or as you seem to have answered your own question..... because there are people who like to tinker.<br>Its a nice project, its tidy and more controlled. No It's not a necessity and my comment or the creator haven't suggested as such. But like i say its a nice project/idea accompanied with a good instructable.
<p>Sorry. My bad. I thought you recommending a kickstarter for this implied a necessity for something...not just a tinkering project. </p>

About This Instructable




Bio: Hi I'm Michael! I'm a dog owner, husband, writer, and mechanical engineer and I love getting my hands dirty building stuff. If you ... More »
More by MechEngineerMike:A Practical Guide to FDM 3D Printing Gears Easy Removable Milk Crate for a Bike Automated Ultrasonic Misting 3D Print Polisher PRO 
Add instructable to: