Ready to try resin

[chappy]

Well I have been playing around with tires now for quite a while . And vacuum forming shells too.
I would like to give resin pours a try as in pouring bodies.
I understand the 2 methods,,, using 2 part molds and ,,,,, slush casting.
Would slush casting be the way to start. If so and I have my silicone mold made of the body, What should I know about slush casting , ie tools and ammounts and techniques.
Do I need a brush for some areas?
How do I determine the right amount of resin for the slush casting process ?
Any way as a new project , ilike to get my research in order before I go messing things up.
Any helpful hi ts would be appreciated.
These will be 1/32 scale pours.
Thanking you in advance of my mistakes.
Bob. :text-thankyouyellow:

[Dangermouse]

must be an evolution thing - I have been reading up on this as well.... did you catch that article over on SF - I think Marlon authored it.

I shall follow with interest - some of the resident casters may be forthcoming with some tips.....

What body are you doing? That is probably the main reason I haven't started I haven't worked out a body I want to produce :)

cheers
David

[mattb]

Here's something I put together back in the late 80's after I first made a few slush cast bodies.

http://hodrags.com/EntpCasting.html

It is much easier to make an inner mold and just pour one time and get a uniform thickness, but this will get you started.

[chappy]

Hi David, I'm not sure body wise yet but was looking toward the 60s and 70s sports cars .
Although I want to get I to some of the dirt trackers too. Since my basement flooded and is now bare again, I am going to put 2 tracks in . One a big oval, but of plastic Artin . Then I will build another road course out of wood, so I can keep my resin options open really.
Just caught your post Matt , thanks.
Bob

[strangebrew]

[mattb]

Legos make a fine, adjustable mold box, as does cardboard and masking tape. No mold release is required for the silicone to the mold box or to your original pattern. It is good for spraying inside your finished mold when you are ready to pour your plastic. It is especially nice spray the areas where your body is undercut, this makes removing it much easier. If you are doing a 2 part mold then it is critical to use the rubber to rubber release before you pour your second batch of silicone. Two coats.

I find it helps with a lot of problems if your pattern is raised from the floor of your mold box. By having a border area/shelf around your body cavity, you have something for your inner plug to lay on so it doesn't push too far into your outer mold. I like to use an exacto and cut a nice ledge around the bottom of the body opening. Another benefit of this 1/2 or so of extra rubber at the top (side you look at) is the ability to cut holes into the bottom of the mold that allow resin to fill an area much easier as the holes make a vent that allows the resin to push air out the top of the mold. This is really nice if you find after making a body or two there is one area that seems to not get enough plastic into it.

One trick to keep from making two part molds on many small parts is to completely surround your master with silicone and then partially cut it open so you can remove the master while keeping the mold basically intact. When you pour your part, you can spread the mold open, pour the plastic and slowly allow the mold to close or use a toothpick and fish out air bubble if you have to. I find gently bumping the mold against the counter top usually dispels any air that is trapped. For me that is always the drivers nose! This mold method works pretty good for drivers. It is also possible to glue a thin piece of plastic sheet to your master and pour rubber completely around the master and but leaving the plastic exposed. When cured you can open the mold where the plastic exits the box and remove the master. You now have mold that you can open, but it covers all sides of the new part.

I know it is hard to grasp some of this, as I am not good at writing descriptive instructions. I can post some pix if needed.

This forum has more guys into casting than any where else on the web not dedicated to the hobby. There are plenty of "experts" on here for casting the stuff we like. The guys on here are a great resource.

[HomeRacingWorld]

Indeed, a lot of great folks here willing to help.



The General has been sneaking me a few items here and there for my journey as well.

I am making Sportsman models from altered Revell, Scalextric, Carrera, and assorted Snap-Tite/RC kits. Between myself and the efforts from RMS & Shotgun, our oval series will be just fine. Not to mention the cool 3D castings I just got from nymodifieds.

Doc, Shotgun, Mr. Brew, and Btaylor have helped a lot helping me choose the right material. Dixon John just dropped by some Smooth-On as well.

On hold as I work on the new Show-Me, but soon...very soon.

[chappy]

Guys this is great. I really appreciate all the input, and the little tricks of the trade youhave offered up.
All these things will make it easier for me to take the jump into bodies.
Having made thousands of tires may help me somewhat but the resin is a very different animal to work with.
This is one of the big additions to my aspect of the hobby, and I suppose like everyone else , I want to get the best help and advice possible. So again my thanks.
Once I get going I will post some pics so you can judge if the grasshopper is learning.
All my best
Bob

[VTECFOUR]

Hi Bob,

I keep it simple and just slosh cast.

Getting the master ready for the mold is really the bulk of the work and it's key to quality re-pops.

Once I clean up the mold of flash (Smooth On Mold Max 30 silicone)that can block the flow of the resin, I'm ready to go with my simple molding process and set up.



Materials:
resin - Smooth On Smooth-Cast 321 in off white color. Easier to see body features and imperfections than plain white.
kitchen scale - to measure weight of mixing batches of part A and part B. Purchased at Lee Valley
silicone gloves - to keep hands clean
small chop stick - to stir part A and B and to push out air bubbles and force resin in small crevices and crannies. The one piece ones that snap into a pair from fast food Asian take-outs
small paper or plastic mixing cup - for mixing resin
paper towel - eight small squares cut from one towel to clean up dripping material from containers and wiping excess resin
newsprint - to cover table top from inevitable spills

I like making my bodies with as little excess resin as possible, so mine come out pretty thin and light.



My latest, a Lola T160, took 11g of part A and 11g of part B with very few heavy areas. If thin in some spots, I just reinforce with two part epoxy after.
You'll notice a standby mold, usually wheel inserts that I do first then the body.

As mentioned, the resin does cure in about eight minutes, so I spill the resin in the mold to get coverage in the top of the body, moving it back and forth and then spend the rest of the time sloshing the resin along the sides, front and rear. All along I'm poking the resin into the voids and crevices with the chop stick.

You'll know when you've got to move really fast as the transparent mix quickly becomes opaque. If you think you've got too much in some spots just remove the excess with the chopstick, wiping it on to the paper towels.

As it comes to the end of solidifying, I turn the mold upside down for the excess to run down the sides, front and back and accumulating. I then remove any excess with the stick.

I try to leave it alone and within 20 minutes, it's already solid. I usually wait a couple of hours and pop it out, ready to do the next one.

If you like doing tires, you'll really like molding bodies.

Have fun!

Dan

P.S. My casting and molding materials are Smooth On products purchased locally and online from Sculpture Supply, a Toronto area Smooth On dealer. I just use the starter kits.

[mattb]

Alumilite products are available at Hobby Lobby and with the 40% off coupon on their website you can buy material cheaper than anywhere else and there is no postage. You are allowed one coupon per visit.

Making an inner mold is really no big deal and you can make your body with one pour and with nice uniform thickness. No re-inforcing, doing a second pour, etc, Granted you may just want to slush cast your first body, a two part mold really does make it easier and faster.

[dreinecke]

All very good tips here.

Be aware - some folks have had issues with some resin products not doing well in normal temperature situations. A person I know purchased numerous kits from a caster and they were all twisted before he got them in the mail. Those can be fixed, but just be aware that different resins have different properties.

[Kemtronracer]

[mattb]

No problem with leaks, but I do tape the bottom edge all the way around. Actually I have more trouble with leaks when I make a mold box from cardboard and it has seams along the bottom and at all corners. I have learned to be more particular about how I tape all those seams and that eliminated any leaks. You can't be too critical about any of this stuff. Close attention to all detail is needed to not have mistakes and do overs.

Another mold release some guys use is baby powder. They dust the mold and shake out excess. I haven't tried that, but am told it leaves a nice surface for paint adhesion and you have no problems with any left over mold release, which can really mess with your paint.

Harry showed the Alumilite 3 in his picture above. I can't say too much about how good this stuff is. It is so flexible that any undercuts are no problem at all. This stuff is so soft that it can easily stretch to allow your part from the mold. I have cast Cox Chaparral full figure drivers with the head glued on in this stuff. I eas able to cut a slit about 1 inch long and push the new part out of the mold.

Using it for a body, I have found that a big mold, like a 1/24 car body, it helps to have a small piece of wood the same size as the long sides of the mold. I put a piece of wood on both sides of the mold and then a rubber band around the whole thing to keep the side in line and not allow them to bulge a little.

If you use a harder rubber, like the Alumilite quick cure, it doesn't have those stretching abilities. You may need to cut your mold in half to remove your new body. That is ok. Just cut in an irregular pattern so both have can be "locked" back together. You just put them together with a rubber band to hold them tight, pour, remove the band and open your mold.