Surface Finish Improvement

Apparently those acetone vapor baths are quite simple to make, and work really, really well.

Take a stainless steel bowl, add about 1/2 oz of acetone, bring to boil on a flameless heat source. I'm guessing a double boiler would work well. I used a lab hot plate. Set a metal lid (with dangling part) on top for 30s. Remove the lid/part and let it dry for a while.

The results speak for themselves.

[i211.photobucket.com]
[i211.photobucket.com]
[i211.photobucket.com]
[i211.photobucket.com]

It works alright at .4mm layer thickness, but it works really well for .25mm which is what I usually print at. It won't make your parts look much better if they aren't well aligned though. It just makes errors reflect light very well and be very obvious...

I hear MEK would be a possible solvent, too.


NOTE: Please be careful. You are making an explosive vapor. Do so with the utmost caution and precautions or bad things may happen to you.






Probably a good idea to do this in a fireproof area with excellent ventilation (outside)

Perhaps a dumb question but do you throw your print into the bowl after the acetone has boiled? How do you stop it from deforming from the heat of the bowl?

Indeed a dumb question - I didn't read "with dangling part" properly.

Cheers,
Gary

Edited 1 time(s). Last edit at 06/14/2011 03:42AM by garyhodgson.

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Is the heat needed, or could a ultrasonic mist maker be used to produce the vapor?.

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Random Precision

Great results, thanks for sharing

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johnrpm Wrote:
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> Is the heat needed, or could a ultrasonic mist
> maker be used to produce the vapor?.

I'm not really sure.

My gut feeling is yes, since the difference in part-vapor temperature makes the vapors condense on the part.

Somebody will just have to try it with an ultrasonic mist maker.

Andrew Diehl Wrote:
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> I hear MEK would be a possible solvent, too.

Possibly, but I'd stick with acetone - MEK is some nasty stuff. I hear EMT's commonly refer to it as 'methyl ethyl killya'.

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[haveblue.org]

Haha, I just had another friend tell me that as well. Somehow I was under the impression MEK was no more harmful, and less volatile, than acetone. Apparently not...

I tried it on some not so great parts last night, and there was a significant improvement in the finish, although there was slight discoloration (Red ABS). It does take a while for the part to harden again though. Rough parts like the ones I used need longer exposure, so the acetone tends to penetrate deeper. Using a heat gun to try and dry one of the parts resulted in rapid outgassing, which immediately ruins the surface by producing bubbles.

This also holds promise for restoring parts with layer separation.

Instead of heating the chemicals your using try freezing your part in a zip lock bag then quickly remove the part from the zip lock and expose to the "smoothing chemical"

What this does is evenly coat the part.

Stratasys has used many different chemicals in their smoothing station but the best so far is dupont vertrel........works great but VERY NASTY stuff.

I attached a picture of the warning label on the bottle. read the label and picture it was delivered in that glass bottle by fedex express. LOL, but WTF

> Instead of heating the chemicals your using try
> freezing your part in a zip lock bag then quickly
> remove the part from the zip lock and expose to
> the "smoothing chemical"

I'm not sure that will work particularly well under most normal conditions.

The cold part will condense not just solvent, but also water vapor. I'm fairly confident the reason you get a 'foggy' appearance on parts dipped in liquid solvent is because as the solvent evaporates, it cools down the part, and water condenses on the surface. This is the same reason spray painting when it is humid and cool doesn't work well.

Heating the liquid solves the problem because everything seems to stay well above ambient temperature.

Maybe if you live somewhere dry?

Or perhaps use a vacuum chamber to make the solvent boil below room temperature. That will remove any moisture, and as the pressure returns to normal the solvent might condense on the part?

Works perfectly if you move the part from the bag to a sealed container with smoothing chemical. Never seen foggy parts.

I've been working on a smoothing fluid for a little while that's ketone/xylene/toluene mix and it works as good if not better than the stratasys 40K smoothing station. Simply spray on with a preval sprayer let it evaporate, repeat until your happy.

Heating solvents is not a good idea unless you know you can control the temp below the flash point, double boiler or not. Solvents can have very low flash points. I work with one solvent for water transfer printing and it has a 18oC flash point

Problems with spray bombs are the propellants

Cool beans.

What exactly is your ketone/xylene/toluene mix ratio?

What effect does mixing solvents have? Do you get something that dissolves better than any of them on their own?

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[www.hydraraptor.blogspot.com]

I used a metal coffee can with a hole in the center of the plastic lid. I put a bunch of metal bolts in the can and heated them up with a hot air gun. Once it was nice and hot, I dumped in a small amount of acetone, hanging the part from the hole i the lid using a small wire.

The ketone based solvent is doing the work of smoothing the plastic. You can use this on its own but it will take longer to evaporate and the surface of the plastic will stay a bit soft for a day or two.

The Xylene and toluene is to make the ketone based solvent evaporate quickly.

By volume a decent mix for smoothing ABS plastics.

45% Toluene (paint stores, over the counter)
45% Xylene (Under the counter at the paint store. You won't find this on the shelf because its commonly used to make crystal meth you need to ask)
10% Ketone

My mix has a few other goodies added for adhesion of water transfer films to materials other than ABS, but the mix above should work nicely. You can also use it to apply water transfer films to your ABS parts(camo, carbon fibre.. wood grain....ect) ........

Hey,

I know this is an old post, but I feel like somebody needs to speak up about this mixing of solvents. Anyone stumbling upon this page from Google might be tempted to give this a try without realizing what they're dealing with. As a result, somebody could seriously be harmed. Please don't post advice of this nature without at least warning people who are less knowledgeable about the possible risks. For instance, you're messing a a whole lot of teratogenic compounds there. Whatever they tell you 'teratogen' means, you need to understand that it basically means 'monster maker'. If you've seen the pictures of babies born without skulls or brains or an arm growing out of their head at birth, and then there's my personal favorite harlequin ichthyosis, then you might begin to get the idea of what you're dealing with... especially toluene. Sheesh. Also, xylene has a flash point of 27 to 32 degrees C or 81 to 90 degrees F. That data is coming straight from OSHA. I wouldn't be surprised to learn that some poor soul has attempted to follow your footsteps and suffered badly for it. In the future, please think before you post.

For Pete's sake, people.... stay the blazes away from this stuff unless you really know what you're doing.

What he said ^^^^

When i first read this thread, i winced at MEK. When i got to toluene, i closed the tab.
In retrospect, i probably should've written something along the lines of the previous post.

Edited 1 time(s). Last edit at 12/06/2012 08:29PM by orcinus.