is there a way to melt sprues so you can pour them into a mould?ive been experimenting using hammerite thinners and whilst they melt nicely the resulting goo do'snt seem to set. ive seen an article about this which is where i got the idea from but can't remember where i saw it

I should imagine it would have to heated in some sort of electrical heater that would be thermostatically controlled to maintain the correct temperature, would it ever be thin enough to mould without being injected under pressure?

Vinnie

I dip the sprue in Thriclorotoluene and it works...
Ciao

hi , take a half empty bottle of liquid poly and add to it cut up slivers of sprue , leave to dissolve , takes a few days , test the result and add more glue or sprue as the case may be , you want it to stick to a cocktail stick but when held upside down it forms a blob , put into your mould in a thin layer , leave to set hard and then add more melted spue in thin layers till you have the result you want , great if the mould has a flat edge , no good if it is two part mould , cheers ian

The problem with using thinners for polystyrene based plastics in two part molds is that they won't cure properly. The thinner essentially is a "plasticizer" that allows the plastic to be flexible. The problem with two part molds is that enough air can't get to the part to evaporate out all of the plasticizer, and the part stays soft.

If you use pressure and heat to inject the melted plastic into a mold, you don't need to use these plasticizers and when the part cools, it is rigid.

HTH-
Jeff

Watch the fumes when using solvents.... some can be very hazardous.

If you already have the molds....just go buy yourself some resin....alot easier to deal with...and its fairly cheap....you can get a 2lb kit at Micro Mark for like $25, get a little plasitc cup....pour the 2 liquids in even proportions....stir and pour. Alot easier than screwing around with styrene shavings and liquid poly.

hmmmm..... i only need two rocket 'bell' exhausts,i made a mould out of milliput,from one i've got, and was wondering if i could knock something together from stuff i've got to hand. to make the mould i just got the spare part and pressed it into the milliput, leaving a cup shaped hole i could just pour something into, i was going to try two-pack car filler this afternoon but its vanished.i sent an email to someone who might be able to supply a spare today but i'll keep on experimenting anyways #:-)

I saw an article about using a glue gun in place of resin. It was on Raodkill's site. Here's a link. Hope this will halp as an alternative to melting sprue... http://users.pandora.be/ronny.noben/website/index.htm. The way the site is set up you have to go through hoops to get to it. Click the "tips" icon on the left side of the main screen and then look for the reference for the glue gun. It's on the right hand side.

Good luck!

just read the article, thats brilliant! im off to buy a glue gun right now! that should solve my problems with this damn exhaust, this morning i set fire to a peice of sprue and let it drip into the mold........tiny bits of soot were floating round the house all morning and it made a smell like an explosion in a nail varnish factory (oh and the piece turned out totally deformed)

forget about chemically melting plastic and try to use that for casting.
You'll spend lots on time doing things that make your whole room smell and cannot possibly be good for your health, and the result will be lousy.

Plastic that is melted with products like trichlorethylene, take a loooooong way to get hard again (unless you apply it in extremely thin layers). And they tend to shrink while getting hard, which is definitely NOT what you want.

If you can't find resin, why not try plaster ? Some plasters can be made as liquid as milk, and dry perfectly. Since the plaster doesn't get hot (contrary to resin) while getting hard, you can even use it in makeshift molds like plasticine.

Good luck !

Jan

I'm not sure if this is what you are looking for but I was going through the Alpine inmport.com site and they have what they call Easy Cast casting epoxy, and for not an arm and a leg to try. They got an 8 oz. kit that costs $ 7.59 which if you already have your mold this should work on small pieces, of course they have it clear up to by the gallon if you wish.
Hope this helps

i took some pics of my efforts, the glue gun worked brilliantly

i believe that melting sprues will take time and egffort with no good result. as i have tried some times i didnt succed enough