Quickly dissolve filament

[precisionpete]

I need some help quickly dissolving a filament build.
I am currently using PLA and trying to heat to evaporation temperature but having trouble since it's inside a sand mold.
I can't get it hot enough because the sand insulates too much.
I was looking at MEK or Sodium Hydroxide but neither looks like they give decent results.
Also just saw filament called PVA which dissolves in water.

Just looking for some tips and suggestions from people who have done this with success.

Thanks,
Pete

[Captain Starfish]

Pop the sand box into a furnace and crank it up to 450º, your PLA will vanish.

[precisionpete]

Must not have gotten it hot enough, 525 deg F for 1 hour didn't touch it.
I then poured molten metal into the mold and the pla STOPPED the molten 2000 Deg metal
Was looking at something I could run through the mold.
Presents another problem then to dry the mold.
Will crank the heat up more and wait longer. Still a R&D project.
Thanks,
Pete

[Polygonhell]

I don't think you will find a chemical that will do what you want.
Even HIPS which is usually what's used for dissolvable support is usually removed inside an ultrasonic bath (on commercial printers) because otherwise it just doesn't dissolve very fast at all.
The only accounts of lost PLA casting I've read about use heat to remove the material.

[lordbinky]

There was a pretty nasty chemical that dissolved PLA. Might be worth a look into since you likely have the controls and PPE to do it safely if you're already playing with molten metal.

[precisionpete]

There was a pretty nasty chemical that dissolved PLA. Might be worth a look into since you likely have the controls and PPE to do it safely if you're already playing with molten metal.

What was the chemical? Edit, I searched for nasty chemical and found this: Miller-Stephenson’s MS-111 Stripping Agent. It dissolved the PLA in an hour or two. That chemical is very nasty, it will even dissolve cured epoxy.
Is that what your referring too?

Mixed up some sodium hydroxide today and put a fan shroud made from pla immersed into it, sat all day and didn't even soften.

Tomorrow will make a small test mold and crank up the heat to 1000deg F on that puppy, I just like instant satisfaction

[Captain Starfish]

Sorry, I meant 450 real degrees (ºC)

850ºF or more.

And yeah, if there's enough cold PLA in the sprue to slow the metal and allow it to cool, it'll jam.

[precisionpete]

Sorry, I meant 450 real degrees (ºC)

850ºF or more.

And yeah, if there's enough cold PLA in the sprue to slow the metal and allow it to cool, it'll jam.

Your hired, when can you start? We play with everything here Every day is new and fun. OKay sometimes frustratingly s l o w.

[Captain Starfish]

Sadly, I've not put the theory into practice yet. But lots of reading, lots of reading.

And one day my Gingery furnace will become a reality.

[Ricky_Spanish]

This guy seems to have his system down. https://www.youtube.com/watch?v=WWVVSZP3Au4 Looks lioke it just has to get REALLY hot.

[precisionpete]

My guess is you did not intend to post Def Leppard - Me and my wine?

Pretty sure the video is of a guy melting al in the snow? Yep saw that one. saw that video after I had the idea.

Slow day in the shop today, got the mold poured but took longer than expected and won't bake out till tomorrow, might pour metal tomorrow but Monday for sure. Did I mention things take longer than expected? Probably should just crank the temperature to 1100F which is supposedly the high point for the plaster/sand mixture. Let it sit for couple hours to make sure the PLA is really gone.

[Ricky_Spanish]

My guess is you did not intend to post Def Leppard - Me and my wine?

oops. fixed...

[precisionpete]

Update: Mold looks good, 1050 degrees F for 40 minutes and poof. Just some ash where the PLA was.
Baked it for 4 1/2 hours with a slow ramp to final temp to make sure everything was dry.
Monday we pour metal

[Demolishun]

Is there any way we can document what you are doing with metal molding? This is really good info and I would love to learn more. Being able to pour metals using PLA as a mold maker is really good stuff.