How do i smooth pla?


#1

Hi guys, i wanted a quick and dirty way of smoothing PLA without harmful chemicals and XTC 3D, any help is greatly appreciated!


#2

Pure PLA won’t do it, but there are some mixes of the material that do soften with Acetone. Above and beyond that, most of the things that smooth PLA are pretty nasty chemicals that you don’t want to mess with. Since PLA is organic, many of the solvents that melt it will also melt you :slight_smile:


#3

ouch… that would be painful…


#4

is there anyway to sand it and get some gloss?


#5

Yes start from a heavy grit to fine and finish with wet sanding. Some people use body filler also (bondo).


#6

thanks alot, will try that


#7

Several coats of a filler primer spray paint will help, too.


#8

Can you cover PLA in resin? For example to ensure something is waterproof?


#9

Polymaker makes a special smoothable PLA and has a polishing machine for it:

http://www.polymaker.com/shop/polysmoothpolysher/

The machine is not cheap, but the PLA cost is only fractionally higher than regular PLA and the results are pretty amazing. Especially with transparent PLA that can come out looking like glass.

They are in the final stages of shipping their Kickstarter orders. The campaign is here: https://www.kickstarter.com/projects/polymaker/polysmooth-and-polysher-3d-prints-without-layers


#10

The Polymaker machine is just using IPA, their trick is in the filament, but I don’t like being locked in to a brand like that.

As Jim said, there is no easy chemical method, THF is probably the safest but the results will not be as good as that with acetone and ABS. IMO that always looked kind of ‘melted’ anyway.

With PLA, the general rule of thumb I use is if I am going to sand it, then I am committed. When it comes to PLA, there is no such thing as just ‘a little sanding’ and calling it good. It’s all or nothing, as once the grit hits the plastic, it is going to go chalky on you. It seems tedious, but it really is faster to work up through the grits i.e. 240, 320, 600 as each one will knock off the peaks of previous layer lines. From there, a low-build filler/primer if you are going to paint. Or another 600 -> 1200 wetsanding if you want to leave as is with a clearcoat.

XTC-3D really does work though if you can get it and want to try it. It’s crazy expensive to have shipped overseas so we’re out of luck over here.

Other options are two-part resin coatings, those work too. It all depends on the piece and what the final use will be.


#11

I found this but never tried it!
Krylon Clear Sealer Gloss 312g can. Krylon Clear Sealer is an acrylic spray which provides a hard and clear GLOSS coating to almost any surface. Krylon Crystal Clear can be applied to wood, plaster, clay, metal, glass, and more. Suitable as an effective barrier for sealing porous surfaces prior to applying rubber mold making compounds to patterns. Dries in 12 minutes or less to a gloss finish. Part can be handled in one hour. Coverage : Up to 25 sq.ft. per can on a non-porous surface.


#12

yes, but its much more expensive than regular PLA. :frowning:
not a fraction of the price. ill try to try that PLA out, thanks for the help!


#13

You can readily find aerosol polyurethane resin for coating a print, but that only minimally hides the layers; you’ll have to put in the work to smooth the print, whether with sanding down the layer lines or filling the gaps between and sanding the filler flat, before you apply the urethane coating.


#14

cool! will try that out.


#15

I have done gassing with ethyl acetate, it smooths the pla, but I do this in my workshop.


#16

I’ve been trying hard to find that here. Finally found one lab that had it, for about $100 US for 500ml…

Not sure I want it that bad. XTC-3D after shipping comes out to about $80 US for 24 ounces though…

So now I’m back to looking for THF again. Seems to be safest and easier to find.

Funny thing is, I can buy dichloromethane all day long, which will smooth and/or weld PLA but is really kind of toxic and is very touchy between ‘hey that worked great’ and ‘crap, my print just turned to rubber’ so I don’t even bother with it. Just not worth the risk/reward at all.

The Polysher/Polysmooth/Polywhatever just seems like a gimmick. I joined the FB group to see what all the hype was about. You need their machine, although you could really use any nebulizing vaporizer and build a housing; Isopropyl Alcohol, and their special filament, which is kind of pricey. Personally, seeing the results, I am not impressed. They look melted and lack detail.


#17

I found this article online:

He uses Automotive Filler / Primer made by Rust-oleum to fill-in gaps and sanding.


#18

thanks alot! just what i was looking for!


#19

This is a problem that’s going to be part of any smoothing method; you’re evening out the surface by either filling in discontinuities in the surface or melting the surface to make the high spots run down into the low spots. But neither process knows whether a particular surface feature is a printing artifact that needs to be smoothed, or part of the object’s surface detail that needs to be preserved, so you’re going to be removing detail along with the artifacting.


#20

hi, after much more research online I found out that you can use a heat gun to smooth pla, not a hair blower ;), personally I didn’t try this out because I couldn’t get my hands on a heat gun :frowning: .