The hottest material we have casted into porcelite is 2250*f. This was bronze. The mold needed to be fired after printing for it to become a ceramic object. The mold is much like ceramic shell.
For a shell mold, what (approximate) wall thickness would you recommend? Iâm interested in engineering parts - not jewelry.
1 Like
I have a Form2 and I ordered some Photocentric3D Firm Grey due to others on this forum having good success with it.
I was disappointed to find out that it did not work for me with any of these settings:
- Open Mode - Form 2, Grey V2, 0.1mm setting --> Failed print (not sticking to build platform, curing to PDMS)
- Open Mode - Form 2, Grey V2, 0.05mm setting --> same as above
- Modified Open Mode (Grey Cartridge in, filling resin tank by hand manually) - Form 2, Grey V2, 0.1mm --> Partial print failure
- Modified Open Mode (Grey Cartridge in, filling resin tank by hand manually) - Form 2, Grey V2, 0.05mm --> Partial print failure
However, after many resin filtrations and a lot of cleaning and scraping and resetting, this setting is currently working for me:
Open Mode - Form 2, Grey V3, 0.1mm --> printing as we speak, will check quality and post back.
I just wanted to save people some resin and time if they have ordered some Photocentric Firm Grey with the Form2. It makes me wonder how people were printing with V2 before the new PreForm came out with V3 in it⊠Anyone have any ideas, or is anyone experiencing the same as me with V2 settings?
Thank you,
Kevin Yoder, DDS
Update and Photos:
Open Mode - Using Grey V3 0.1mm (default Preform orientation and support generation):
Fresh off the printer
Note the raft lifting from the build plate
The clarity of the edge of this print was distorted
Another shot of the raft lifting from build plate
After IPA rinse and UV cure (did not sand or anythng)
Note the edge distortion again
Warping of thin wall
Another shot of thin wall warp
Thatâs what I got so far, anyone have any ideas why the raft would be lifting or the wall warping? Is that a sign of over/undercuring? I would want to know so I can make an educated guess of what resin to try next instead of just iterating through every single combination of settings.
Kevin Yoder, DDS
3 Likes
Can you measure your wall thicknesses and compare it with the thickness on the digital version?
I tested all settings with different layer heights and the best setting(grey V2) overcured the resin increasing the diameter of diagonal supports from 1mm to 1.4mm. Also test parts were constantly 0.4mm too thick. I tested hard resin as well but itâs too brittle but overcures a bit less. The overcuring causes the warping(itâs sticking too much to the PDMS) and some of the printing errors you are observing. The firm resin is very flexible so it sticks less to the platform.
So far, the only people Iâve seen that reported good results were the ones that made figurines, where supports and dimensions are less of an issue(and the overcuring makes the figurines look more smooth).
The good news is that I managed to make hardware modifications and tweaked the resin a bit and my parts come out very sharp and accurate(almost +/- 0.1mm vs formlabs resin), some more fine tuning and it will be perfect. It will likely work for many resin brands. No need for open mode anymore. 
The photocentric resin and other have however different characteristics(strength, flex, âfeelâ) than FL resin so in some cases you still want to use FL resin.
Are these modifications easy to do? Any chance you could reveal those tweaks so others (and me 
) could start printing without the limits of open mode?
Have you tried the Grey V3 setting yet?
Kevin
Yeah, they are very easy to do. The modifications do not involve opening the machine and cutting wires or such.
Iâll share the details later once I have tested more materials and something more interesting than test cubes to show.
I will be here, patiently waitingâŠ
Feel free to PM me if you need any help with anything!
In the last mailing from formlabs I found a test file they are using to validate their resin.
As I am working with some form 2 tweaks for some time already, I though, why not share my results on these tweaks:
What you are seeing below is a photocentric 3D resin with mixed additions in the resin(price is still really good). It is less brittle than their hard resin, a little bit flexible like FL grey V2 and softer to the touch than FL resin.
Price of this particular piece is roughly 60 cents, versus 98 cents for FL resin(including tray).
Additionally, a machine modification was made(non intrusive, fully reversible and safe) to get a variable laser intensity for different layer heights and resin colors.
*** note: the model in the picture is scaled by almost 50%, so features are much smaller than the original test file! ***
For reference:
The curved pilars are 2.8mm wide.
The only two standing walls 0.5mm(minimum feature size for now) and the slots are 0.5mm as well.
The hex shape below the butterfly is 2.2mm
This is printed at 100um layers. Form 2 machine running with wiper and heater.
Surface quality seems to be very acceptable.
OK @fantasy2 Iâll bite.
- I saw that test object in the mailer as well, but I could not locate it online. Would you mind sharing the link?
- What type of mixtures are you doing?
- Can you talk a little more about the reversible hardware hack you have done?
Results look SUPER detailed for the size, congratulations on an awesome job!
I can only help with number one 
I found the file earlier on this page. As far as I can tell it opens up a 3D rendering app, openjscad.org, where it seems you can programmatically create/edit a 3D fileâŠidk I am not familiar with the site.
I tried uploading the STL file hereâŠthe forum says it is too big (even tho it is 2.2mb and the limit is ~7mb 
)
But you can generate it yourself by clicking here.
1 Like
So what would be some stable resins from Photocentric? I am interested in getting cheaper resins but I donât want to experiment yet.
Can you guys suggest me some stable resins that wonât cause a major headache to work with?
If thatâs the requirement⊠Then unfortunately none yet.
Doesnât have to be 100% stable but if it mostly works then I am willing to experiment with it. Itâs much cheaper than Formlabâs resin after all so it would worth it if it works (and if it doesnât it wonât hurt my wallet 
)
Depending on the type of parts you print, photocentric might work. Donât expect dimensional accuracy or straight walls when printing large cross sections.