Starship Modeler Discussion Forums

You may have better luck if you heat the mold first. E-Poxy is a catlyzed reaction...meaning that it requires heat to cure correctly. Silicone is a real good heat sink. Another issue could be alcohol leaching from the silicone...but this typically makes for a cloudy casting. Heating the mold in an o...

Do you have a cat ?

Their wiskers work really well for small scale antenna.

Anytime

You're trying to glue polyproplene(sp?)( milk jug ) to styrene....very tough to do.
The poly has to be roughed up with sandpaper and the best glue to use is a type called methylacrylate...3M carries it.
Nasty glue...don't get any on your skin and do not breath the fumes.
Works pretty well though.

My suggestion..( backed up by more than 30 years of woodworking) ..take some rubbing alcohol and dampen the original glue...if it turns white ( or cloudy ) then it's likely a PVA glue and White glue will work fine. Carpenter's glue ( the yellowish colored stuff ) is a bit stronger. If the glue doesn...

The vacume chamber I'm using is just about that size and the top is one inch thick plexi.
The unit is an industrial grade unit....I'd recommend going with that thickness for saftey.

Go visit your local sign making shop....you know...the ones that make big exterior signs. Ask about scrap urethane foam board.....find out if they ever use it and would they consider saving some larger scraps for you? They usually throw away enough scrap in a single job to last an average modeller f...

A sample kit from Smooth-on should be more than enough for this job.
I would suggest Mold Max 40 and for the resin...SC300

My tip for you would be to look for sign makers in your location ( yellow pages ) they use urethane foam ( best stuff on the planet for scratch building ) and ask if they have any scrap or small pieces to sell/give away. I have a full years supply ( for free ) stored,which I found in this way. Anoth...

Does making my own Roto Casting machine count?

As an industrial prototyper..I've made dozens of specialty and production tools to fit the job at hand.

If the mix ratio is one to one..it's probably urethane. If the mix ratio is 10 to 1 it's probably epoxy. If the ratio is "a few drops per ounce" it's polyester. If it's polyester, you want to use the smallest amount of catlyst required for a cure...any extra and it will fog up. Mix and pou...

Ti Raven wrote:Cool technique, thanks!

You're more than welcome

The above posters mentioned doing multiple layers. How is this accomplished? My thought is that if you put resin in a mold, slush it, there will be a solid shell coming out of whatever you cast. Then how do you do a second coat on the inside without ruining the detailed exterior of the cast? Jimi, ...

Best advise I can give..... Heat the molds in a low oven for half hour..... Warm the seperate components of the resin as well....not super hot...just warm Mix the resin compoments..and get it in to the mold and under pressure quickly. One bonus to this technique is the thinning effect on the resin...

What type of finish did you use last ?

Dang Kylwell...that was a quick reply.....don't you sleep?

I had heard that you could speed the cure some by using a little extra of one part ( not sure...A or B )

I'm going to give the alcohol a try tomorrow.....I'll report back when the results are in.

A question for you Aves users....
Can you speed the cure ?
Can it be thinned? ( I know that alcohol will thin epoxy...would it work with Aves? )

Modelnutz

My experiances taught me that Platinum cure silicones shrink the least.
As for shrinkage in the resin...totally variable...depends on type.
Smooth-On's site includes shrinkage factors for all thier silicones and urethanes.

Hope that helps...

Modelnutz

I use a vacume chamber to de-gas my silicone before I pour a mold. This removes most of the air in the silicone so that when I cast under pressure ( in the pressure pot ) I will not get distortions in the casting due to air bubbles just under the mold surface. So...vacume for the silicone...pressure...

The small pressure pots from Harbor Freight are the ideal starter pots. If you have a Harbor Freight Store near you, they sometimes offer a discount ( not too sure 'bout the deal.. may be if you buy online and pick it up ) certainly worth the price. Everything you'll need 'cept the moisture trap is ...

How much did I ues it? Oh, pretty much every day...4-6 hours a day. Yea, I guess you could say that I was doing production mass casting (with a spraybrush comp..... :oops:) Guess I learned the hard way :D The pressure you're trying to achieve may not be the issue...the volume of the pressure pot may...

I started casting years ago with an airbrush comp. but I burnt it out after only a few months. What you really need is a decent sized paintshop style compressor. Consider getting a small contractor's portable comp. ( I got mine at Home Depot...~ $300.00...been going strong for 3 years now) You want ...

Yes Sir !
Correct you are Sir !


Sorry...too much eggnog (and rum )

End of the air line....air in the line cools as it travels to the end releasing moisture as it travels.
That's why pro's install air lines with a downward slope from the compressor to the trap.
If you can find a Grainger's catalog, I believe they show the details of setting up an airline.

On an unrelated topic, I've just seen the first parts of the project we've been discussing, and they are looking great! I never would have guessed that a Thompson gun would look soooo cool in 1/6th. [/quote]

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What I have currently are dimples.
They do OK to represent RCS thrusters....But....I was kinda hopin' fer a stellar idea to take them to the next level.

The detail is cast in place and is flush to the surface ( not like an Apollo era thruster....)

on fabricating small scale RCS thruster details on a master for a resin kit. I've tried a few ideas, but I'm not really satisfied yet. I turn to the scratch kings out there for ideas. I believe that the scale I'm using is 1:500 so their pretty small. I await your suggestions... Modelnutz :8) "t...

You might try pressing your fingers all over the glue side of the Dymo tape before you stck it down. The oil in your fingertips will gradually reduce the "tack" of the adhesive. Trial and error here as to how much is enough. You want the take to stick a bit..right ?..got a similar surface ...

Smooth-on has a release called ease release 200 Great stuff...a can will last a looooong time. You could use the "old school" release....vaseline thinned a bit with naptha. Works every time. OT...I've heard a rumor ( not tested yet) that Coca-Cola or Pepsi will wash off the vaseline. If yo...

QC, you may have a point there about the cure time. How quickly will your compressor bring the pot up to 40 Lbs of pressure? I pressure cast stuff all day long using SC-300 and I rarely run into issues. I'm certain that the details will be reproduced fine. If you find that your pot takes too long to...