Any Polycast users out there?

Hello,

I am a new member to this forum but not to casting. I have been running a Sovol S3 3D printer for a year now and just received a roll of Polycast filament for doing investment casting. I have done a lot of lost wax, slurry investment but would like to try the 3D printed patterns rather than silicone molds and injected wax patterns.

So if any of you have some helpful information about 3D printing and or burn out (I have a PID controlled burn out oven that I built for lost wax) I would enjoy hearing from you on this thread. Thanks, John Gaertner

 

I've had success with standard PLA for investment castings. Polycast is supposed to be polish-able with their proprietary "polysher" machine, burn out cleaner than PLA similar to wax.

The process is the same as wax if you've already done it before, it just requires a little higher temperature for the "melting" phase and a little more time (due to the viscosity) before you burn out the residue. Just follow the pdf they have, do things like you have with wax and you'll be fine.

 

I can't help with PLA, DavidF has some experience as well as others.

What are the shells in the photo? The lower portion looks like magneto switch housings?

 

They are mag switches I make for Curtiss Jennies and a lot of other WWI era american planes. See attached.

 

Hello Forum, I finally am able to break the seal on my vacuum bag of PolyCast. I am running my very first test that I always use on new filament.

In the booklet that came with the PolyCast it recommends a 0.100 Layer Height. Has anyone tried using a larger layer height? I have a .600 nozzle.

Thanks, John Gaertner

 

I've used larger layer height at 0.2. They just need to smoothed longer. You'll lose detail with the larger nozzle diameter depending on your part.
The skull was printed at 0.2 with a 0.4 nozzle. The bottle is acetone smoothed ABS.

 

Thanks for the reply! I am running a part right now at the .1 setting. I guess I will see how it comes out?
I had zero problems with my simple test print this morning which is very encouraging. I will report back
to the forum when I get this casting pattern printed, some time late, tomorrow.
J Gaertner

 

Hello Forum, Finished my first PolyCast print and it came out fantastic. The "core" support came out very easily. Part is better than the PLA sample I printed several months ago. Starting a different part with longer print time, right now.

 

Nice work! You might want to consider a multi-part assembly. PVB sticks to itself very well with a little IPA. Printing in multiple parts and then gluing would eliminate the supports and give you a smoother interior finish.

What infill are you printing at?

 

Hello Mach, I was thinking about printing the next handle that way, as you suggest. The interior is smoother than the interior of the PLA print I did. But it also is a good bet if there is a print fail, in my absence of babysitting the printer, only loosing 1/2 of a part/pattern. I am printing the part shown below in segments, right now and will glue them together. I used a 20% fill per the instruction manual. Any suggestions?

 

No, 20% is good. Less is better but that's a large surface area.

 

First "half" of the pattern I am trying to PolyCast print came out really nice. 18.8 hours print time. I have not attempted to remove the internal supports yet but if its as easy as the handle pattern I printed, early, it should be OK. I will try the second half of the large pattern, soon. I did notice that when I started the PolyCast 3D print there was some popping of the filament. I expect, there was some moisture there? I just opened the vacuum bag on Saturday. What are other people doing to keep their PolyCast filament dry between prints? I cut the filament above the print head and put the reel back in its foil bag for now. Thanks.

 

I store it in an air tight container with desiccant. PVB will absorb moisture quickly. Not as bad as nylon but enough to affect print quality.

 

No PolyCast experience - I'm watching this thread as the parts I want to make soon are well suited to lost wax. PolyCast may be a viable option.

I keep my filament in plastic totes with a bag of crystal type cat litter.......the same stuff you can use to make sodium silicate.
Even with 20% humidity being on the high side here I have trouble with water absorption occasionally if I leave a spool on the machine for more than a few days. A couple of hours in the oven takes care of that. I'm too cheap to buy a dedicated food dehydrator.
Popping means there is a lot of water. If I suspect high humidity I extrude about 1/4 meter manually and inspect for bubbles in the extruded filament.

 

I have used Polycast and had the poping when printing. I just reduced the extruder temperature and it went away.
I have one of these now and will use it before printing in future, actualy durring printing.
SUNLU FilaDryer S1 I added a link but it was rejected.

 

Hello Myfordboy, Thanks for the reply. I just finished a 16 hour and a 18.6 hour 3D polycast print. Its a 2 part pattern that we have discussed off this forum. The first half was started from a unopened reel of Polycast. Worked great. Second part, started the next day had gaps and popping on the first layer so I dried the roll at 60C for 4 hours in my mini oven and started over. No gaps or popping on the first layer. I just tried starting a new part, same roll, not removed and dried and I got popping and even bigger gaps on the first layer. So the reel in is the mini over, as I type this. I may look at buying a drier but I already have the mini oven with a digital temperature control.