Post Curing

[Wdshea]

i only use virgin material, i've found that a faster burnout does improve removal of the resin.

for some reason my prints, when heat curing, despite being UV cured for hours, no matter how small they are, seem to crack a little bit. any tips on preventing cracking? i can heat cure for 30min at 170*F-200*F, but once i try to take it up higher (~250*F) they always crack. i don't understand. though, heat curing to 200*F seems to be fine, i'm curious as to why i have that issue.

[Jewelermdt]

If I over heat my models they will crack. I do not UV cure my prints. Only microwave 3min cool at least 15min. I do this 3 times. I use oil. Retains heat longer than water and don't have to worry about boil out.

[rkundla]

Based on the temperature ranges you described, it would seem to indicate there is probably water trapped inside the resin that boils off at the higher temperatures causing the cracks.

You can try holding the oven at 200°F for like two hours and raise the temperature. If it really is trapped inside resin with no microfissues to vaporize out of it will probably still burst.

Makes me wonder what might happen if you put the print in a vacuum chamber? Will the same thing happen at room temperature?

[Wdshea]

Mineral oil? How big of a vessel?

I've been UV curing in a shot glass with baby oil. Might boil out of there...

[Wdshea]

i found that i don't have cracking now that i've been printing at 3000ms at 25z. prints at 2800ms would crack during heat curing despite 8hrs of UV.

if you still have cracking during heat cure, try upping exposure. maybe just another 100ms.

i'm curious to have a definitive answer, but in my mind, this has been proven.

[Wdshea]

my post curing woes (and casting woes) were due to low layer exposure. without enough exposure per layer, my prints could not be cured enough (UV or otherwise).

now that i've turned up my layer exposure, i UV cure all angles for a little, then i can microwave cure. i have yet to have single print crack since i have increased layer exposure.

hope this helps someone.

[M-Williams]

Glad to Hear that.... Is your Casting coming along better.

[Wdshea]

almost no problems, issue now is in the design. very fine lettering has broken off during casting. lessened letter depth 25%, hopefully that resolves that issue.

testing a major focus improvement i made today, i really look forward to those results.

[M-Williams]

Whenever I have anything with lettering or got to cast a class ring I use http://www.stuller.com/products/21-7060/?groupId=118383.

100 % bullet proof.

[Wdshea]

thanks for the tip, i've been resisting PBI due to cost and our luck with plasticast has been satisfactory. i also use 2% boric and 2% calcium nitrate, that makes my investment VERY hard. especially at 36:100. i recommend those additives to anyone.

our drawback is we had zero experience in 3D design or casting a year ago... so we're trying to figure out what will work for us. fortunately, we're about 98% there.

i'll post some pics sometime.