Successful castings from clear resin using ceramic shell

#27

Thanks Frew, I will await future developments with interest. The problem I have is that to get good results with castable takes a huge amount of time. 8 hours of curing along with a much longer burnout (almost twice as long as wax) plus letting flasks set for 8 hours and that means it takes several days to cast Formlabs resin whereas wax can be done in one day. Wax needs no curing, just 2 hours for plaster to set and an 8 hour burnout. So all the extra time involved to make resin work makes it less viable and less competitive than wax and the end result is still not as good. So I am really hoping that Formlabs will come up with a new and better formulation for castable soon.

#28

I have been using the bluecast resin. Have had perfect castings. Took a little while to get the burnout schedule correct. But no curing! I go from alcohol to alcohol to drying. 5 minutes each and do it 3 times. Then using r and r plasticast with an 9 hour burnout i have had great results. I can send the schedule if interested.

art

#29

Hi art, I would love to see that schedule, I would like to be able to use FL product, but I also need to have some decent castings, my email if needed is paul.bensel@yahoo.com
I appreciate it very much,
Paul

#30

I have tried the clear for investment casting with poor results. We tried two methods of burnout, one in the using the std burnout process, this cracked the shell. We also tried to use the autoclave, the part went like crazy paving and didn’t burn out at all…

A new resin that can be used for investment casting of engineering parts, wax like if possible for burnout in the auto clave please :slight_smile:

#31

HOw do you people know how much UV exposure has been adequate?

For example with High Temp, out of the bed pieces are pale yellow, but once cured they get a strong pale orange presence…

What about the Castable?

Yesterday we cured a piece for quite some time and the top of it was getting…brownish!? Is that overcuring? How do you determine castable has been cured “enough”?

#32

FL published a whitepaper on curing times, temperatures and UV wavelengths: https://formlabs.com/media/upload/How-Mechanical-Properties-of-SLA-3D-Prints-Are-Affected-by-UV-Curing.pdf

One thing to notice is how important heat during the cure is. Not only does the cure go faster, but in many cases, the final part strength will be 50-100% higher if cured at the recommended temperature (rather than room temperature / 25 C).

#33

I will talk for my business dental lab…
For my point of view, Formlabs cartable isn’t good because it’s way too complicate for a business to use on a daily process, takes too much time for poor casting results. Not to say the fit of the produced part isn’t good.
I have made a lot of trials with cartable, and compared with grey.
The fit and weight of the part is different. ( castable comes out thicker)
Dental framework or crowns are different from grey to castable and won’t fit on the model with cartable when they are just perfect with grey.
I cast about 4 to 8 flasks daily in my lab, all with grey.

#34

Paul

I experimented for months until i got this schedule which works for me. It is a combination of the quick bluecast burnout and the longer one. Have had no issues since i went to this
Ramp 1 230
Temp 1 300 F
Hold 2 hour
Ramp 2 1050
Temp 2 1375F
Hold 4 hour (very important for this long!)
Ramp3 -450
Temp 900F
Hold 2 hour
I start the flask heat up when the temp gets to 900. Takes about 25 minutes till casting temp
I put the flask in sideways in the oven to allow the gas to escape.

#35

Art , thank you very much , both you and @katkramer have been extremely helpful, I’m not sure how FL is going to handle this issue, I’m glad that I don’t have the dissatisfied clients they have, they will at some point understand that they are simply another tool in our tool box, and if the tool doesn’t function for jewelry manufacturing, we are going to find one that does. In the mean time I’ve got a client that I need to… ,LOL, satisfy or they are going to go somewhere else.
When I get done with this gal I’m going to begin using the Bluecast resin in my FL printer.
Thank you both very much for sharing, I will post the results.
paul

#36

Paul

Just cast this using the burnout schedule i posted. Bluecast resin, no uv post cure . tru silver casting grain from hoover and strong. No pitting or issues and a 41 dwt casting.

art

image

#37

Thank you Art, that’s beautiful , I ordered the Bluecast the end of last week and hope I get it by tomorrow , I’m ready for it either way. I cast a couple flasks using FL castable over the weekend to check myself, had to do something with these prints, I followed the recommendations to the letter and it was terrible. I’m looking forward to some kind of success, I appreciate it!
Paul

#38

Here we go Art , this is a taste of the results of the weekend :

Casting pic 13
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![Casting pic 14|375x500](up
Casting pic 16
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Casting pic 12
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)

#39

I’ve made I don’t know how many of these for this group, I’ve been milling them in green wax like matt wax, I have rarely had a problem, out of say 30 final pieces, you can see where I put the sprue on the side there , I know that’s why I got the break down in the lettering, I was desperate for a good casting and was trying to get some air flow up there was my thought, so this is where I’m at with all this,
as I’m writing this I found out that I need to make 30 badges for a local police department, I hope this issue is resolved soon or I’m going to be in real trouble
Paul

#40

Let me know how the other resin works for you. Parts look good but too much extra work. I did have a couple of small minor issues when i started cleaning up, but nothing major. Hope it works out. I mill rings in the green was . I have been mixing some flasks with milled and grown parts. Using the plasticast i am getting about a 95% success rate… Had to play with times and percentages with the plasticast aslo. Can send tat info if you want. The times and rates on the sheet that came with the investment were too long and the investment started to get clumpy. Kept playing until i got mixes that worked for me

#41

I hear the stories about cracking ceramic shell- have any of you guys tried making the print hollow with a very thin wall?
I am wondering if this would allow the resin to swell internally without applying pressure to the ceramic shell?

#42

That would be very cool Art , Id like to see what your doing with the plasticast , I haven’t struggled this hard for a long time, thank you, Ill let you know how things go
paul

#43

Interesting thought…on the hollow shell.

#44

Look up Tetrashell
It’s been done for years.
http://www.materialise.com/en/manufacturing/3d-printing-technology/tetrashell

#45

since long before that…
hollow wax patterns have been used since ceramic shell first was developed… allows for faster burnout because you don’t have to worry as much about the expansion of the wax pattern prior to it reaching melting point.

#46

Has anyone succeeded with ceramic shell and the purple castable wax? Im interested in a cast that is larger then a jewelry foundry I use locally can do and would rather use my form then PLA as I have in the past. I would be using a foundry whose had success with PLA using bronze casting for larger pieces.