Topic: DIY Smoothing Station II

After a lot of debating, reading around, and helpful guidance, I feel like I have a smoothing station I am finally pleased with...

First, thanks to Ian for many helpful suggestions and inspirations in creating the station...

Second, acetone is dangerous... We all know it is dangerous... Please be careful, cautious, and smart... I did everything I could to make this setup catch on fire, blow up, damage my brain, etc... just to test how dangerous this would really be.  I've used acetone in labs for cleaning, on girls nails to clean off nail polish, to make glue, and so on... It is useful, just don't be stupid and we should make a separate thread for a debate if people want to argue the safety implications.  By the way, do everything with the acetone smoothing outside away from your grill, candles, and kids.

I began by attempting to make a hot pot, separate acetone pot, condenser coils with pumps and throttling, and a tub of ice water... The setup felt like it took up my entire porch, it had a lot of random parts, and was just clunky.  Therefore, I decided if I could get over the fear of cooking acetone, I could do it much more simply.  After countless hours wandering around bed bath and beyond, pier 1, some fancy cooking place I can't remember, and more... I went to Wal-Mart and found exactly what I was looking for...  A Presto Multicooker

http://www.walmart.com/ip/14321003?adid … mp;veh=sem

A little steep at $25 after spending a $100 on my first setup, but I'll survive.  This had everything I was looking for.  A pot that was self heating, a tempered glass lid, and a 6 inch flat bottomed basket.  This is why it is perfect...


Notice I laid down a layer of kapton tape at the bottom of the steamer basket so that the holes didn't poke through onto my pieces.

The first step was to bring my cooker outside and plug it in without turning it on.  I put in the basket of pieces I want to smooth and quickly, I pour just enough acetone into the cooker to cover the bottom of the pot.


Here, I put a couple of bolts through the holes in the bottom to make sure the pot stood a few cm's off the bottom.

I Acetone has a boiling point at around 130 F.  What I wanted was  a 2 phase mixture with the quality not climbing much above 25%.  At this point, you will have basically completely filled your cooker with a acetone vapor both.  Just turning the heating dial far enough to get the light on right before the warm setting brings the pot up to about 130 F. To get the acetone to condense and sink back down towards the pieces, I freeze my tempered glass lid.  The cool region at the top will help to condense the acetone.  As I understand it, tempered glass should be ok going from frozen to hot in a hurry, but not the other way around.


If it looks like this, it is frozen enough.

The lid will heat up pretty quickly and within a minute, you will see the drops of acetone start to condense on the lid.  As soon as the acetone is condensing on the lid, the 2 phase mixture is hitting and maybe even exceeding the 25% quality region.  Notice here that I stuffed a little paper towel in the opening where the removed handle is.  This absorbs some of the acetone vapor and keeps the pressure from building up without letting too much of the vapor to escape into the air and sink down around the plug connection. I immediately unplug the cooker at this point.  After another 20 seconds the condensed acetone begins to run down the sides of the lid.  As it finishes condensing on the lid and stops running down the sides of the lid, I take out the basket and quickly replace lid.


This is the acetone beginning to condense on the lid


The condensed acetone finishing its run off.

I now let the basket just sit for about 20 minutes while still outside to allow the remaining vapor escaping the pieces to evaporate.  I then carefully remove the pieces from the basket and place them in between 2 fans to encourage a little faster drying of the pieces.  I haven't determined the exact amount of time the acetone takes to finish doing its job, but it seems like waiting an hour or two will have them ready for blasting.  The longer you wait, the better, but I get impatient and don't like to wait.

Next phase is the blasting portion of the smoothing...  I really am not a fan of the glossy look in most cases and definitely prefer a matte look with a dryer texture.  I will continue to experiment with different mediums, grits, and pressures, but this set up seems to have the best combination of being fast, controllable, and producing an attractive finish. 

I am using crushed walnut shells because they are less aggressive and supposedly less dusty; they are also always dry in the bag and ready to use...

http://www.petsmart.com/product/index.j … Id=2752164

I got my blast cabinet from Harbor Freight and I am so glad I didn't try to build one after using this since it is perfect for the job and relatively inexpensive...

http://www.harborfreight.com/garage-sho … 42202.html

It says to make sure you use at least a 1 HP compressor running at 100 psi.  I chose this one since it has an 8 gallon tank and recovers quick enough I don't have to stop while blasting a piece.  It seems like most compressors should work though since I found 40 psi to be the best pressure.

http://www.harborfreight.com/air-tools/ … 68740.html


Entire Setup


Compressor Settings

To use the blaster, mostly follow the instructions that came with it.  The quick and dirty is to bring the hose in through the back...


Connect the hose to the gun and fill the hopper with the media, in this case, the crushed walnut...


The process of actually blasting the media is more of a subjective thing than most of this stuff...  My rule of thumb is to never stay still, and try to make about two passes around the entire piece.  I like to spray from about 3-4" away, continually waving the gun and moving on from every area after a few seconds.  The best way to explain is to just watch the video... I don't claim to be an expert on this, but it seems to be working so far... Turn down your volume since I didn't detach it and it is loud!

When finished with this, the part will look pretty dirty and not resemble its final appearance at all... I use a clean hose to spray as much excess dust off as I can and then go to rinse the piece off.  Rinsing the piece off with water makes it look instantly like it is back to being glossy, but as it drys it will magically turn matte in front of your eyes.  It will generally take about an hour from this point to reach its final appearance and texture.  Please feel free to comment or make suggestions on any improvements that can be made...  The entire process for these pieces was about an hour total with 45 minutes of it being waiting time...  Here are pictures of the before, glossy, and matte of a few pieces to show a comparison...  All of these pieces were printed at .1 mm resolution with the black and red vase being the exception.  It was a failed print a .3 mm, turned successful.

yoda from thingiverse...


similar to original print, can't find pre pic


glossy yoda


matte yoda

... Here is a vase from thingiverse


original print


per Ian's suggestion, I tried to tape off a section to do layered textures...


I think it came out as a pretty cool and unique look...

Ganesha from thingiverse...







And finally the dragon from thingiverse!


original at 2 heights


gloss and now a few mattes





Re: DIY Smoothing Station II

Great post!

I prefer the gloss look and I think you and Ian have inspired me to design an Arduino controlled acetone vapor finisher when I finish my current project.


Re: DIY Smoothing Station II

I like this, appears nice and easy to get extraordinarily professional results.


Re: DIY Smoothing Station II

Nice post, I will be trying this out for sure.


Re: DIY Smoothing Station II

Great post! I especially like that with the acetone you set it up, let it sit for a fairly short period of time, and then you're done.  I, too, like the gloss quite a bit.

6 (edited by cckens 2012-11-02 16:32:55)

Re: DIY Smoothing Station II

Wonder if instead of the kapton, you could use a square (or circular, but that may be harder to accomplish) plate of glass to rest on the bottom of the basket.  This would level it out and you wouldn't have to worry about the bolt heads used to raise it off the bottom of the heated acetone.  Shouldn't be too expensive an addition to do this and the glass wouldn't be affected by the acetone.


Re: DIY Smoothing Station II

I wonder if heating while drying would make a difference.  My oven does a minimum of 170F with convection, which is above boiling for acetone.  I wonder if it would cause bubbles, or if it would just dry quickly.  On the other hand, the smoothing action continues after you pull the print out of the vapor until the acetone is gone, so you might get better results with the slow dry anyway.   If you have more finishing to do and it looks smooth enough already, then some heat would probably be what you want. 

Maybe a space heater fan would be just enough.  I wouldn't worry about fumes at that point, there just isn't that much acetone in the plastic.  Put the print on a rotating turntable, or inside the blasting cabinet with the fan so there is airflow going all around.

Lawsy, what would you use the arduino to control?

8 (edited by jooshs 2012-11-02 17:29:51)

Re: DIY Smoothing Station II

I have tried using a spaceheater with a fan and it dried it out a little quicker, but it is hard to get an even finish then...  I really think that the extra half hour helps since the melting plastic smooths out more as it finishes its job without eating much more away.

Running the part under very hot tap water also helps if it is smooth already...  I wouldn't do this for 20 minutes though since the piece is still soft enough the water pressure could actually deform the surface... Maybe dunk it in a tub of hot water?

I'm curious what you would be controlling as well Lawsy?  The whole process if so fast that you literally don't have time to do much of anything besides turn it on, turn it off, take off the lid, and remove the basket...  I actually would be a little careful about the acetone vapors being exposed to the arduino as well... I'm sure nothing would happen, but those pins actually can get very hot and I don't know if something could happen with them?  But I do love arduino projects, so I'd love to see what your'e thinking.

I am surprised everyone likes the glossy look so much more... It may be something you have to see in person since the pictures really don't do either of the finishes justice.  The glossy finish is super shiny and feels almost tacky...  The matte finish is still more glossy than it looks in the pictures and has almost a spackled matte look under the gloss... the texture is also more appealing...

The one thing I didn't make a big deal about was how well this dealt with .3 mm layers.  I didn't expect it to work well, but the layers completely disappeared and looks smooth as can be.  Good to know that for anything without lots of surface details.


Re: DIY Smoothing Station II

cckens wrote:

Wonder if instead of the kapton, you could use a square (or circular, but that may be harder to accomplish) plate of glass to rest on the bottom of the basket.  This would level it out and you wouldn't have to worry about the bolt heads used to raise it off the bottom of the heated acetone.  Shouldn't be too expensive an addition to do this and the glass wouldn't be affected by the acetone.

Yes I wanted to use glass, but my 6x6 piece was too big to fit in the basket and I didn't find any glass circles... I almost stole the mirror from one of my gf's little handheld mirrors, but I didn't think she would appreciate it. I would still use the bolts because it allows the vapors to flow in that space... Plus the bolts come with the pot.


Re: DIY Smoothing Station II

I'm going to have to make a trip to Walmart for that pot, it looks perfect.  It's out of the way since this is very much Target country, and Kmart is selling the same pot for $44.  However my wife is easily convinced to go to Walmart even if it is for a printing project.


Re: DIY Smoothing Station II

I meant that the bolt heads on the inside of the basket could skew the smoothing due to melting and creating a small divot in the bottom of the print, but hey, it's not the end of the world.

I'm looking at getting the cooker to use as a smoothing station, but I think I'm going to see about altering the design to use ice cubes on the lid as I have very little freezer space to fit the lid.  Not quite sure how just yet, but I'll work it out.


Re: DIY Smoothing Station II

cckens wrote:

I meant that the bolt heads on the inside of the basket could skew the smoothing due to melting and creating a small divot in the bottom of the print, but hey, it's not the end of the world.

I'm looking at getting the cooker to use as a smoothing station, but I think I'm going to see about altering the design to use ice cubes on the lid as I have very little freezer space to fit the lid.  Not quite sure how just yet, but I'll work it out.

The bolt heads actually sit in a depression in the basket so that laying the tape or glass over the gap doesn't affect the print... The lid really doesn't need to be frozen either... It seems like you should theoretically, but I didn't notice a difference between the smoothing in frozen lids and non frozen lids.  I got impatient and just kept going since I didn't want to wait to freeze it again... It might have helped that it was 40 F out, but I won't know till next summer.  smile


Re: DIY Smoothing Station II

I'm in Southern California, so we have some even temps this time of year (normally, but we're supposed to be in the 80s beginning of next week). I'll see what the end result would be and report back, say in 2 weeks time after I get the package and get it dialed in.


Re: DIY Smoothing Station II

I like how you are able to retain a lot of the details even after smoothing.


Re: DIY Smoothing Station II

@Ian and @Jooshs

I think my design would have a peltier element for cooling the top with maybe one of those flexible heating elements at the bottom for warming the acetone. http://www.soliforum.com/topic/168/sili … -1-minute/

Arduino would be used to control these (probably with decent power supply) as well as a simple LCD screen that gave temp feedback and perhaps a timer counting down with a buzzer at the end. I would be looking for a seal-able container to use as the body and then mount the power supply, arduino and underneath.

16 (edited by driggers 2012-11-03 04:37:25)

Re: DIY Smoothing Station II

Those smoothings look beautiful, and I am about to make an acetone vapour bath.  My thought is that you could heat the acetone vapour chamber by setting it (stabilized) in a basin full of hot water.  Just control the temp of the bath with a thermometer and pouring hot water in.  It should be easy to achieve 130 degrees or so.

Also, I was shocked to find so much information about making drugs when I looked up cooking acetone.  blech! (and a gross waste of talent too).

edit:  I read Ian's blog post and I see this has been done, but I didn't understand why the condenser was essential.  So what if some acetone vapour escapes?


Re: DIY Smoothing Station II

new idea new post.

What about acetone in a spray bottle?  Just spritz some into the chamber...


Re: DIY Smoothing Station II

I tried acetone with a Preval sprayer.  It's like a spray paint can, but you attach a jar full of the thing you want to spray.  It always seemed like the acetone evaporated before it could really do anything.  The vapor gives consistent coverage, and seems to get into the surface in a way that applying liquid doesn't seem to.

The condenser is overkill.  Like Josh, I have been skipping it.  In his setup, the cool lid seems to be more of a gauge for when the pot is full of vapor.  It is practical in keeping it contained, so if a breeze blows over the top of the pot, it doesn't stir things up too much.


Re: DIY Smoothing Station II

Yeah, fair enough.  Glad to hear about the condenser, because I was going to skip it anyway.  I scraped together a setup from odds and ends in my little workshop.  That dish is sitting on little pop can things because I've wanted to make these ever since I saw them used in pop can stoves.  We'll see how long this needs to cook for...

Pictures are of my setup.

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Re: DIY Smoothing Station II

First mistake with the smoothing station...  It was caused by my own sloppiness, but do not heat any parts with acetone on them... The acetone will boil and you will not be pleased with the results.  I accidentally spilled a little acetone on this part and still went ahead with it and a few others at the same time.  They came out great again, but not the one I spilled on...



Re: DIY Smoothing Station II

Well I tried it and it works great, even though I have never tried anything else before.  I told my dad I was going to do this before I went home and he started to precaution me and I just said no no no stop a guy had already tried it and it is safe, lol.  But I also tried to debunk the warning of explosion and fire but could not.  I tried pouring in acetone while the pot was hot and it instantaneously vaporized.  I also poured some on the connector that goes into the pot and nothing happened.  By the way these pots have a nice magnetized connector that removes easily in case of emergency.  Since these things are designed for hot oil which is flammable it was a great choice for this.  I didn't use anything on the bottom, I just put it on the aluminum and it did fine.

I will say to anyone who tries this that you can pull the part right out of the strainer and it wasn't sticky or anything, but it is still very soft.  I know you guys were talking about letting it dry and that's a great idea.  I would recommend wearing a form of breathing apparatus because this stuff is potent, if you already didn't know.  I did not but I tried not to breath it so much.

Now I printed the two things I did at .3mm layers.  I am sure it would yield a nicer finish if you had a higher resolution print.  Also it will not take away those knobs of plastic.  Make your piece nice and smooth before you do this and it will come out looking great.  Now I am not a photographer and don't claim to be but hopefully you can see what a great job it does.



Re: DIY Smoothing Station II

I'm becoming very concerned with the percentage of people here that print my little ponies as soon as they get their machine. smile


Re: DIY Smoothing Station II

cmetzel wrote:

I'm becoming very concerned with the percentage of people here that print my little ponies as soon as they get their machine. smile

And of those printing them, how many of them have little girls who Squee with joy when they see the toy that Da has made from them smile wink


Re: DIY Smoothing Station II

Or run over to the printer every time it's moving to see if it's making something for them.


Re: DIY Smoothing Station II

IanJohnson wrote:

Or run over to the printer every time it's moving to see if it's making something for them.

My 3 year old daughter does this, I have a couple "boats" and some spinning tops that I've printed that I give her when she asks me and then I find them and put them back in the box when she's done. 

I get it, I was just making a joke.  Someone said "bronie" in a previous post and I made the mistake of looking it up and reading the urban dictionary result.