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Topic: Experimenting with Acetone exposure

This is my first experiment with an acetone smoothing exposure.  I used a "fry baby" with a piece of ceramic floor tile as a base.  The plastic stuck so hard to the tile, I was forced to chip it away from the bottom of the model.  Still, all in all, it worked pretty well on the surface.

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Re: Experimenting with Acetone exposure

How long was your exposure? Did you do it all at once or did you smooth it over several sessions. It looks really good. Some Kapton tape on the ceramic tile might help with the sticking issue...

TiM

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Re: Experimenting with Acetone exposure

mr_tim34 wrote:

How long was your exposure? Did you do it all at once or did you smooth it over several sessions. It looks really good. Some Kapton tape on the ceramic tile might help with the sticking issue...

TiM

This is the result of two "baths".  The first one was allowed to sit in the unit for about 20 minutes afte the initial boiling of acetone, which was only done for about 15 seconds.  The second bath was similar, but with the model hanging upside down.  With my current arrangement, the effect is very dependant on how far above the fluid surface it is.  After two such "baths", I allowed the model to air for about 6 hours before I began trying to separate it from the tile.  I will give the tape idea a try on the next attempt.
Anyone else try Kapton tape for this?

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Re: Experimenting with Acetone exposure

I use kapton on the bottom of the steamer basket in mine, the prints come off fairly easily.  I only keep it in while the acetone is boiling, maybe 40 sec.  If you shut off the heat and leave it in, then the vapor will settle and you will get more smoothing at the bottom.  Better to have exposure while the vapor is evenly distributed in the pot.  I let it dry 20 minutes or so before giving it another short shot or two, then leave it for a few hours to harden up again.  I figure a series of brief exposures will save detail better than a more intense melt.

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Re: Experimenting with Acetone exposure

I use aluminum foil in the bottom of the steamer basket on mine. Its cheap and I can just tear of a piece that just covers the base of whatever I am polishing. That way you are not obstructing the vapor, but still wont have a problem with the part sticking to the basket.

I usually don't leave mine i very long. Put enough acetone in the bottom to cover the bottom completely, put the basket in and put on the lid, turn on the heat just enough to light the lamp. waiting until you hear the evaporation happening and see the object's surface texture to change. Once the noise stops, turn off the heat and wait about 20 seconds. Then open the top, take out the basket and let it sit for an hour or so...

That's my method at least... So far, so good. I only wish the cheap presto fryer was a little taller.

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Re: Experimenting with Acetone exposure

Tried an experiment with the acetone bath technique and had some very unusual results, which perhaps someone can use.

Here's the vapor bath setup I use.  It's a canning pot with the rack for holding mason jars in place, which holds the print up out of the acetone.  I use an old circular saw blade as a base to set the print on, since the rack is too big for most items.

https://sphotos-a-lga.xx.fbcdn.net/hphotos-frc3/q77/s720x720/969859_679525948728420_508139192_n.jpg

And here's a print I was going to smooth.  This was going to be my first "good" print to smooth, as opposed to a failed print I pulled out of the trash solely for testing.  But it was also one I could live without.

https://sphotos-b-lga.xx.fbcdn.net/hphotos-prn1/q71/s720x720/1016624_670161552998193_358520156_n.jpg

In my previous tests, the print melted enough to stick to the saw blade so firmly I almost broke it trying to pry it off, even after letting it sit for hours.  So I decided to do an experiment.  I sprayed a layer of non-stick cooking spray on the saw blade first, then set up the acetone in the pot, set the blade down on it (non-stick side up), and then put the print on top of it.  Four minutes on heat using the trusty one-burner propane cooktop on low, then let it sit for about six hours.  And...

https://sphotos-a-lga.xx.fbcdn.net/hphotos-prn1/q73/s720x720/934692_698353816845633_1323544984_n.jpg

My guess is the oil somehow got into the vapor and created this interesting speckled effect all over the entire print... except, amusingly, on the bottom surface.  Don't know how; the spray didn't get onto the print before vaporizing (it wasn't even in the room when I sprayed it).

It's an interesting look and maybe someone will think of an application where this is a positive.  It's not ideal for this nameplate, though.  I wonder what would happen if I put the same nameplate into another bath (without the non-stick spray).  I suppose there's nothing to lose by trying.

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Re: Experimenting with Acetone exposure

I think the amount of time in your acetone vapor bath is the issue more then the cooking oil spray.  4 minutes of heating, with a 6 hour sit seems like a really long exposure time.  Unless of course you mean 6 hours outside of the bath to allow it to harden.  But I think even the four minutes sounds like too long of a time to let an object sit in a heated vapor bath... But I am by no means expert in this area...

I have a problem where the gloss effect after drying has an inconsistent wrinkled look to the texture.  Hrmmm.... maybe I should submit a pic... I think I'll go do that. 

Anyways, I'd suggest decreasing your heating time to a significantly lower amount, pulling it out of the vapor bath after45 secondish of exposure, and then letting it sit to dry...

8 (edited by Krythis 2013-08-06 23:03:48)

Re: Experimenting with Acetone exposure

I'm trying to use an small crockpot for my acetone bath and having poor results. I put a good amount of acetone in the bottom of the pot and turned it on high until I saw moisture on the lid. Inserted three printed parts sitting on tin foil. After 20m the parts are not smoothed, only appear to be beginning to have a shiny surface, and began forming bubbles. Really should have started experimenting with this using scrap pieces hmm

Bubbles appear on the bottom of this piece, but were found on the bottom, top, and middle of others.

http://i.imgur.com/QpQl8UI.jpg

E3D-v4 Hotend, MK5 carriage with round plastic wire conduit , 3/16" tempered glass,  Well nut, SureStepr SD8825 1/32 Extruder Driver, PowerEdge 2650 500W PS, QU-BD heated bed, circuit board fan, hinged plexiglass enclosure with plastic tray top. Other than that mostly stock SD3

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Re: Experimenting with Acetone exposure

I never leave the print in the pot for more than a minute, and take it out to dry.  The point is to have the vapor condense into an even layer of acetone on the part, and penetrate just part enough into the plastic to make the top .1mm or less of the surface flow together.  Keeping it in the vapor prevents the acetone from drying off before it has a chance to do anything, but it doesn't need to stay for long.   If it isn't smooth enough you can give it a few short applications rather than melt a lot all at once.   Also turn the pot on only enough for it to start heating.  Acetone boils at 134F so it should be the very lowest heat rather than high.

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Re: Experimenting with Acetone exposure

Ya I think I left the heat on too long. Also, I watched a video where they kept the part in there for something like 45m. Try, try, and try again smile  Thanks for the input Ian

E3D-v4 Hotend, MK5 carriage with round plastic wire conduit , 3/16" tempered glass,  Well nut, SureStepr SD8825 1/32 Extruder Driver, PowerEdge 2650 500W PS, QU-BD heated bed, circuit board fan, hinged plexiglass enclosure with plastic tray top. Other than that mostly stock SD3

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Re: Experimenting with Acetone exposure

thats a nice print to begin with did you modify you Z axis at all?

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Re: Experimenting with Acetone exposure

My previous attempts didn't even get that much softening with four minutes on heat and six hours in the can.  Odd that with nothing else changed, I need to do a tenth as much exposure to get more softening.  I wonder if I'm ever going to figure this stuff out.

This is the previous test under the same heat and exposure levels:
https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-ash3/580208_681128195234862_1316511748_n.jpg

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Re: Experimenting with Acetone exposure

Figured it couldn't hurt to put the speckled print in for a second round.  So I did.  Same setup except no non-stick oil.  So, acetone heated about four minutes, then left to sit about six hours.  Here's how it came out:

https://sphotos-a-lga.xx.fbcdn.net/hphotos-prn1/61257_699489696732045_735095551_n.jpg

So it definitely smoothed out most of the pitting and other artifacts of the with-oil pass, though the result is still mottled and bumpy, but they're smooth, glossy bumps.  Makes me think that it would have worked without the oil, despite the comments upthread.

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Re: Experimenting with Acetone exposure

To get the best results from the vapor bath, it's still better to start with .1mm layers.  It's hard to get them completely smoothed at .3mm without several exposures and maybe melting more detail than you would like.  If I have a simple part I will print at .3 layers, then give it a once over with 80 grit sandpaper.  80 grit removes plenty of plastic, and gets the layers most of the way down, then the vapor finishes it off.

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Re: Experimenting with Acetone exposure

.2mm layer is greatly enough... you are too extreme ian...

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Re: Experimenting with Acetone exposure

Has anyone ever tried powder blasting a part? In my motorcycle life I used baking soda and a cheap Harbor Freight sandblast gun to smooth delicate metal parts. Looks like, if you didn't go nuts with it, it might smooth some of the roughness on an ABS part. Be sure to give it a water bath later to get all the soda out of the crevices.

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