Trouble in Casting Paradise

[MobiusJewelryDesign]

@wawatobi - I appreciate that. Someone from another casting house told me that. He told me he really doesn't know why I bench cured the flasks for so long and that if I were to just bench cure for two hours at 280 for two hours.....it would basically be the same thing. I actually did this too in the beginning. I like Mark's(archem) logic in his technic and I am applying it now.....I just still get pitting here and there on every one of my casted pieces with the b9 resin. I cure over nite and microwave as everyone suggests. I've tweeked burnout cycles and bought other investment powders but still haven't found the sweet spot. It's a process for sure. I would really hate to go to platinum investment, but we'll see. I still have a few more factors to look at before I do. I appreciate the two cents. Thank you !

[nillard]

Do you have air coming in the oven?

@wawatobi - I appreciate that. Someone from another casting house told me that. He told me he really doesn't know why I bench cured the flasks for so long and that if I were to just bench cure for two hours at 280 for two hours.....it would basically be the same thing. I actually did this too in the beginning. I like Mark's(archem) logic in his technic and I am applying it now.....I just still get pitting here and there on every one of my casted pieces with the b9 resin. I cure over nite and microwave as everyone suggests. I've tweeked burnout cycles and bought other investment powders but still haven't found the sweet spot. It's a process for sure. I would really hate to go to platinum investment, but we'll see. I still have a few more factors to look at before I do. I appreciate the two cents. Thank you !

[MobiusJewelryDesign]

Yes, There is hole in the top of my oven for ventilation. My castings have been perfect with solidscape models for customers, so I know that I must be doing something right. I just want to be able to cast models from my solus. I have used the yellow and green....and I am so envious of those that can cast it. I loupe my pieces and it looks like the surface of the moon! I am thinking of trying ProCAD but it's a $100 a jar. Here is some pictures of my latest casts and burnout procedure.

Print
Alcohol bath - no longer than 1 minute
I rinse the models through a strainer with alcohol a few times then I dry
I put the models in dish soap in the ultrasonic for 5 to 10 minutes
Dry and cure in a UV oven overnite
I microwave my models for 3 x 3min cycles in distilled water
Dry
Sprue
Invest - Plasticast - 38/100 mix
Bench cure 6 hours

Burnout
800 degrees at 1000 degrees per hour
800 degrees for 3 hours
Ramp full to 1450
Hold for 3 hours
Drop to casting temp
Hold for at least 2 hours
Cast
(Usually I leave the oven over nite with programmer)

[rkundla]

Solidscape wax models are just like wax, they melt out at 300°F and make life so much easier. Too bad those printers cost $$$ and the resolution isn't all that great.

Resin doesn't melt, it burns. You need as much atmospheric oxygen as possible to facilitate the decomposition of the resin and minimize ash. People with gas furnaces don't have the same kinds of problems those of us with electric furnaces encounter.

Your pictures look a lot better. It appears you have some ash or broken investment causing the negative defects and those can be fixed with a laser or plasma arc welder if you have access to them. One way to combat that is to add another riser off the model connected to the flask rubber base to create a vent that allows you to use a shop vac to suck the residue out of the cavity before you pour the metal.

[Archerm]

Did you do any grinding or sanding on the inside of the rings? If so you probably went through the cured top layer and exposed uncured resin. I really dont think you are getting a full cure on your pieces. Mark

[Gtg330]

I noticed they you cured the investment for 6 hours you want to cure max of three hours. For satin cast I put in 1 hour after investing. All investments have explicit directions on that particular investment. I have good results with plasticast and also Optima investment.

[Jewelermdt]

That looks like bubbles in the investment process that got trapped so it caused a void. I get that from time to time. No big deal to me. Sands away easy. You might want to try the Optima investment from Stuller. I have been getting great results and not a pain as plasticast.

[samatheang]

Again, I think the problem here is you didn't do the 212 for two hours and 350 for two hours to harden the investment like I always do. Also, I don't see the need of holding it at 800 since it is resin and not wax. You can learn more from reading here: http://3dcadjewelry.com/forum/showthrea ... ht=casting

Good luck!

Yes, There is hole in the top of my oven for ventilation. My castings have been perfect with solidscape models for customers, so I know that I must be doing something right. I just want to be able to cast models from my solus. I have used the yellow and green....and I am so envious of those that can cast it. I loupe my pieces and it looks like the surface of the moon! I am thinking of trying ProCAD but it's a $100 a jar. Here is some pictures of my latest casts and burnout procedure.

Print
Alcohol bath - no longer than 1 minute
I rinse the models through a strainer with alcohol a few times then I dry
I put the models in dish soap in the ultrasonic for 5 to 10 minutes
Dry and cure in a UV oven overnite
I microwave my models for 3 x 3min cycles in distilled water
Dry
Sprue
Invest - Plasticast - 38/100 mix
Bench cure 6 hours

Burnout
800 degrees at 1000 degrees per hour
800 degrees for 3 hours
Ramp full to 1450
Hold for 3 hours
Drop to casting temp
Hold for at least 2 hours
Cast
(Usually I leave the oven over nite with programmer)

[MobiusJewelryDesign]

I appreciate all the advice! Thank you! I sanded out most of the ugliness and repaired the pin holes. The rings are looking.....better. In the end, I believe it's the curing. I believe my curing station is not strong enough to penetrate the models I am printing on it's own. It's the 36w Salon whatamagig that I got last year....no wait the year before that. The green is not translucent and don't quote me on this, but I believe it probably needs a little more TLC to cure because of it. I could be wrong...::Shrug:: I will still use it to cure the models over night with it but I am getting the melody susie to cook those bad boys! 60w 400nw, WOO HOOO........on a 60 sec timer! Not looking forward to that wonderful feature LOL. More updates to come!

I got almost a full box of plasticast......I ABSOLUTELY hate plasticast in all it's nasty, bubbly glory! .....but I gotta go with what works. I am eager to try Prestige Optima after the tyrannical occupation of plasticast has gone! Then me and my Solus can dance together in a field of Daisies with perfect casts and happy customers! Yay! Sorry.....I'll come back down to normal now.

[rkundla]

Again, I think the problem here is you didn't do the 212 for two hours and 350 for two hours to harden the investment like I always do. Also, I don't see the need of holding it at 800 since it is resin and not wax. You can learn more from reading here: http://3dcadjewelry.com/forum/showthrea ... ht=casting

All running at 212/350 does is melt the wax and dry out the investment. It is not hot enough to cause the chemical change within the investment to convert cristoballite from the alpha to beta phase which resists the heat of the molten metal.

Kerr's documentation for Satin Cast 20 described their stages of burnout as follows:

300°F - Initial Wax and Water Elimination - 1 to 2 hours
700°F - Trapped Wax Elimination - 1 to 2 hours
900°F - Thermal Expansion of Mold - 1 to 2 hours (thicker flasks (3-1/2 and 4") only)
1350°F - Complete Elimination - 2 to 4 hours

With a slow ramp rate of 540°F per hour