Starship Modeler Discussion Forums

Always! I figure it this way....anything that's designed to coat something else is NOT something I want in my lungs!

Just my 2 peso's

Carry on....

I know that this is a little off topic for this forum...but I gotta give it a try....nothing ventured, nothing gained so they say. After recieving a Wierd-oh kit for Christmas ( Leaky Boat Louie) from my daughter, we've decided that she and I will do some fun modifications. One thing we want to do i...

FYI...the link that Linda has supplied is not the type of foam we've been discussing.....it's better! :shock: Her link shows you a urethane foam that is similar to RenShape board used by pattern makers as well as others. It's a much denser material which will give you a crisper edge when machined an...

I use plain old ( inexpensive ) WED clay for my beds...tin cure silicone ( mold max series ) Loves the moisture in it and cure a bit quicker. It's also MUCH easyer to clean off the master! Lay the stuff down quick and wait a bit for it to firm up...then tool it up to the master for a nice clean part...

Rigid Polystyrene Foam Board. Commonly used for housing insulation. Dow Corning is one manufacturer Cuts easly, glues with epoxy and spray contact cements , sands well, polyester ( fiberglassing ) resin melts it, Bondo melts it, urethane resins do not melt it,found in 2-3 thicknesses 1/2"- 2&qu...

There's another technique for creating a part like your saucer. I'll try to be brief..... The process starts with a standard 2 part mold formed from your master. next, paint some urethane over the entire cavity covering all that nice detail with a thin coat of plastic ( you'll see why in a moment ) ...

Empireman...I tried a rotary grater and it did'nt work that well...the silicone just rode over the "teeth" and never really shredded. The cast iron style meat grinder really works the best. The only thing that might work better ( I'm told by a fellow engineer) is a set of intermeshing gear...

Empireman....Yup. Should work fine. How would you go about shredding the silicone ? Another thing about adding old silicone to new...it tends to speed the cure of the new silicone as well as making it thicker. I usually have to pressureize the mix to prevent air traps near the master. I typically re...

I ran into problems when I just cut the silicone into chunks.....the edges of the chunks would show themselves in the mold and cause issues with the castings. Perhaps it was the slightly differing hardnesses that created the problems ? Since I started grinding it into small chunks ( 1/8" sq. or...

Meat grinder for me as well.....the silicone beats them up pretty well tho....

Guess I'm glad that I can get them at a local flee market for 2 or 3 dollars each !

Modelnutz 8)
"the name sez it all"

Trek...if the parts are thin, it should work OK....Bondo's kinda' brittle though. You may end up with a fragile pc. Give it a try though..I don't want to stop the joy of experimental learning ! :) Darkov...If I understand you correctly....you used automotive fiberglass resin without the fiberglass ?...

One word.....shrinkage.

If you make a massive part..the stuff gets real hot...and the more mass you have, the more it shrinks.

Don't let me stop you from using it though...it's a great modeling material.

Just build up to your shape slowly in thin layers and it should work fine.

Modelnutz 8)

From the "For what it's worth, works for me" Dept........................... When I was still building guitars and wanted to get the best finish in the laquer............I would wet my sandpaper then rub it on a bar of soap. The soap reduces the friction and drag of the sandpaper as your s...

When dimentions are really critical....using slow cure urethane helps.
What really helps is using platinum cure silicones which tend to have minimal shrinkage.

As for polyester resins ( the standard fberglassing resin ) they shrink a TON!

Just a few cents worth for ya'

Modelnutz 8)

What size pc's. do you need ?
How about a block of urethane ?
Easy to pour to a near net shape and quite machinable.
Glueable as well.

Modelnutz 8)
"I'll admit it..I too am a resin addict"

I might advise that you use a fairly fast setting resin such as Smooth-on's SC-300 or SC-320 ( or similar ). I also find ( via roto-molding experience) that a bit of filler ( such as Smooth-on's Ure-fill )should be considered. This increases the thickness of the coating and reduces the chance of a m...

Darkson, you have a PM

Modelnutz 8)
"the name sez it all"

Have you considered Roto-Molding ?
Saves on resin and is likely the best way to produce something too large for pressure pots. When done correctly, it can produce a very nice casting.

Modelnutz 8)
"watch this space"

Smooth-On's ease release 800 for silicone to silicone works very well.
Follow directions and it works quite well.
I've also used the vasalene cut with mineral spirits.

Modelnutz 8)

Isn't Envirotex a form of E-Poxy? That would explaine the adverse reaction with fresh silicone....alcohol leaching from the silicone.
Alcohol thins epoxy

Modelnutz 8)

I've used Smooth-on...and Industrial Polymer's. CC-202 CC-200 real nice but tricky to work with...heating molds works well SC-300 and 320 300 for small detail parts because it snap cures. Best stuff in the universe IMHO 320 is my standard casting material....real user friendly..very forgiving Task 9...

Used to use GI-1000
Changed over to Smooth-On Mold Max-30 and 40
Much better pricing. Works pissa ( that's masshole for real good)
I'm hooked and will never go back!

Modelnutz 8)
"does it show?"

Smooth-On has a nice one...Crystal Clear 202. This one's pretty quick tho...9 minute gell time. They have a slower one...200....20 min. gell time. It's kinda pricy but IMHO worth the price. Polishes up really nicely after a few days post curing. You will need to de-gas any clear materials before loa...

Yup....it's just another form of vacume forming.
Big problem is in getting enough pin holes in all inside corners of your mold to draw the air out from all the details.

What type of mold material were you going to go with ?

Modelnutz 8)
"the name sez it all"

I'll second the recomendations for the Smooth-On materials. I use Mold Max 40 all day long and it works great. As for a very nice, mold friendly resin, you can't go wrong with SC-320 It kicks to a cream colored plastic and cures with a low temp.and is paint friendly as well. Another trick you might ...

One thing that I can tell you is that using a hot wire cutter is a no no on urethane foams....I'd suppose that holds true for solid urethane as well.
Personally, I'd advise against it...better safe than sorry.

Modelnutz 8)
"could it be the fumes?"

As far as I can tell, the only thing that will touch cured urethanes is a material called RIM Mold cleaner . A very nasty solvent. Not sure what it would do to a plastic tho. Try a google search for a company called Michaels Engineering. They supply plural guns to the urethane casting companies. The...

Contact Smooth-On ( 800 ) 762 - 0744 and ask for their teck dept.
I'm sure they have a simple to use low durometer plastic or rubber that will work fine for what you're doing.

Modelnutz 8)
"the name sez it all"