1. 3d printing for glass casting

10. Containing glass… open shape = open mould

11. A closed shape needs a closed container…
Original
Plaster mold, add wax
Wax model…
Invest in refractory plaster…
Steam out wax…
Add glass and fire
Final object…

13. Testing testing…
To make clean, lightweight, accurate casts in glass from 3d printed objects using as little resource as possible – heat / power, filament, plaster, glass, cold-working…

14. Three broad types of 3d print…
‘Tank’ of powder or liquid, hardened by jet of glue or multiple laser beams
SLA+DLP (Stereolithography + Digital Light Processing)
SLS (Selective Laser Sintering)
Metal Sintering
Pros – great surface detail, complex shapes
Cons – expensive, sensitive
Filament or thread, heated and squeezed through a nozzle
‘FDM’ = Fused Deposit Method
‘CFF’ = Continuous Filament Fabrication
Pros – accessible, relatively robust
Cons – limited shapes, ridged surface
And…‘Jetting’ – fine drops of material like an inkjet printer, also called ‘polyjet’

15. Variables… Shape and orientation of print file…
maximum angle 45 degrees from ‘bed’
continuous ‘pathways’ or vectors minimise ‘threads’ or trails as nozzle moves between elements
internal forms are extremely fragile after burn-out
hemispheres are tricky…
Placing several objects in the build allows the filament to cool down, reducing warping on sharp corners and tips

16. Quality of plaster / investment -
Ready-mixed ‘Crystalcast’ gives most reliable result
Drying time is critical – forcing process makes fragile molds
Using reservoirs reduces contamination
Vermiculite box reduces volume of plaster – speeds up process

17. Type of filament
PLA (Polylactic Acid) – biodegradable, brittle, poor surface quality
ABS (Acrylonitrile Butadiene Styrene) – synthetic, brighter colours, can be treated with acetone for smooth finish, contracts when cooling, so tends to warp if print bed is not heated
PET (Polyethylene) – food-safe, much stronger than PLA, does not warp on cooling, not biodegradable but reclaimable
Nylon – excellent strength and flexibility, takes dyes well, but sensitive to moisture / can warp

18. And… Conductive, magnetic, ceramic, steel, jelly, felt… and hybrids -

19. So far, have focused on ‘standard’ PLA
All seem to burn out between 260 and 320 but some make much more smoke / smell than others
Big variation in surface quality, even at the same slice thickness – range from ‘wispy / crusty’ to incredibly smooth – big difference in detail and cold-working
Clear / transparent much ‘cleaner’ than coloured or white - fluorescent dye left lots of crusty powder on the shelf
‘Filamentum’ seems to be the cleanest of all – relatively little smoke and almost no powder – reduced need to clean out the mold – time / dust creation plus risk of breaking fragile internal elements

20. Best results so far…
Simple / stable forms with no raft, two in each build
‘Crystal clear’ PLA from ‘Fillamentum’
Investment using ‘Crystacast’ specialist glass casting plaster
Reservoirs to reduce contamination
Drying cycle – 80⁰c for 24 hours
Burn-out cycle – 50 ⁰ c to 500, 30 minute soak, end