The original helmet mold finally gave up too much RTV to be useful, and it was time for a new mold. I have also been working on a back-saving machine to do the rotating for me. For that, I went out and got a welder at Harbor Freight, and here are the results:
And finally, the show off:
Would you mind telling how you made the molds? I love the pictures, but would love to know the process behind it too
I would not mind, but as it it is a long process, it would require more typing than my fingers would allow.
youtube is a good source for demo videos.
That's some great fiberglass jacket work. I made an airwolf helmet that had a jacket and it was such a pain, so I appreciate good jacket work. I also love the roto-cast set up, you wouldn't happen to be in LA somewhere so I can come by and use it?
clonesix said:
Would you mind a phone call or the like?
Wouldn't "Mind," but words without pictures don't tell much of a story.TheFifthSparrow said:
Is there a specific question that you wanted to know?
I would have to search, but I did a write up on case molds a while back. I will look for it and see if I can repost.
The thing that makes it difficult to write on, is that there are so many steps that drescibing it all in writing would be a small novel.
The first thing is to determine your parting line. That is where the two halves meet. You can see it drawn on the model in the photo above. In the top pic, you see half the model burried in masonite. I trace the outline of the model, and cut a hole that fits the shape of the model. That supplies a solid foundation, onto which the mold is constructed.
Don't forget that clay, RTV, and fiberglass have weight, and that the model and its support must be strong enough to stand the weight of the materials piled on top of it.
those look great and the roto machine looks great. It seems once you get to that point ( after the mold, roto macking etc) you are set to make endless helmets.
I guess you have to adjust for the thickness of the masonite for the opposite side ? I need to search for the case mold thread. With back problems myself , that would make it much easier.
great work and better help to others..
One thing I've always been curious about: it seems like everyone does 2 part molds like that. So far I've been using 1 part glove molds... paint on 4-5 layers of super-stretchy silicone, then peel it on/off in 1 piece. That cuts out the parting line, clay, and seams in the finished product.
But, considering I'm really new to this and people who have been doing it a lot longer than me all seem to do it the same way, I have to wonder what I'm missing.
My phase1 clone helmet is just a Hasbro mod, but the general shape is the same, so the glove mold style will work on something that complicated. I'm guessing my mold life is considerably lower from the stress of stretching...
Here is a re-post of a thread I started on another board on the subject. Most of th epictures have disappeared from the explanation, and I will see if I can find them later:
Case molds, also known as Matrix mold, blanket mold, skin mold, etc. are simple a rubber mold that is supported by a ridged shell. You could simply pour a mold with solid RTV and have a fine mold. At $100/gal for RTV, this makes for a very $$ mold. So if one could have a surface coat of RTV, backed up by a cheaper and more ridged material, it makes for a very economical product.
There are two schools of thought on this topic: 1) rubber first; case second. and 2) case first; rubber second. I am a believer in the second school for the reason that the case material, whether it be plaster or fiberglass, always shrinks more than the RTV. Therefore, it makes sense to create the case first and fill it with the rubber second.
This is done by creating a space for the RTV and building the shell over it. The space is made by protecting the model in a layer of saran wrap to protect it from the clay, and then covering it with a 1/2" of clay. Then the case is built over that. Once the case is done, the clay is removed, leaving a hollow space to be filled with the RTV.
This is better visualized with pictures,
Start by mounting the model to a good solid surface such as a piece of 3/4" plywood. Don't go cheap here, whatever you mount it to must support the weight of the model, clay, being fiberglassed, or even plaster. In this case, I took some water clay and wrapped it in Saran Wrap. The clay will form a nice cradle to hold the model and the Saran Wrap will protect the model from geeting the clay on it.
In order to get a good parting line from the masonite, I use a square and a pen to mark the outling of the model. Simply go around the model with the square and mark the outer most points of the model.
When you have maked enough points to connect the dots you will have an outline of the model that can be cut out with a saber saw.
You will notice that the center line is level at 6.5". That is where the parting line will be. I use 1/4" masonite for the parting line, so subtract the 1/4" from the 6.5 and cut some uprights at 6.25"
Use a litle hot glue and glue the uprights to the plywood
And mount the 1/4" masonite on top of the uprights
now you have a good, solid parting line
cover the model in Saran Wrap to protect it from the clay. Slice up some 1/2" slabs of clay with a clay slicer. I have some pictures of this, but I will have to find them later.
A clay slicer is simply a wire stretched between two cariage bolts. The thickness is adjusted by adding or subtracting nuts on the bolts. Two nuts is about 1/2". Add a few washers for thicker slices.
Hear is the model covered with 1/2" of clay + a gasket edge. That is a lip that helps hold the rubber in the shell. the edges slope at 2-3 degrees to lock the rubber in. It also gives the rubber more of a mating surface when the mold is assembled.
You will notice two things here: the shiney surface is lacquer. The water clay MUST be sealed. Polyester resin that is used with the fiberglass HATES moisture. Give it 5-6 good coats of lacquer. Hell, 10 coats won't kill you. The second thing is the little plastic cup that is sitting upside down on the clay. I put that on the high spot to allow for a pour spout for the silicone RTV, to be added later.
Next, you need a GOOD coat of PVA for release for the fiberglass. I prefer to spray the PVA for an even coat, but it can also be brushed if you don't have a spray gun and air compressor.
Now you are ready for a fiberglass shell.get two layers of 1.5 oz matt on and let set.
Here is a tip: If you wait until the resin gels (gets firm, but not completely hard) you can run a utility knife along the edge and trim a nice clean edge. If you wait until the fiberglass is completly hard, you will need to grind the edge with a belt sander to get a clean edge. GRINDING FIBERGLASS IS MISERABLE- AVOID AT ALL COSTS
After the first two layers have cured, add additonal layers as needed. IN this case, I added 3 more layers of 1.5 oz matt to get a 1/8" lay up. 1/8" is strong enough for a mold of this size. Large (heavier molds may require additional thickness.
Once gel-trimmed, and cured, you can flip it over and remove the masonite, and repaeat the clay/seal/PVA process for the other side.
Once you have both sides doneyou should end up with everything encased in fiberglass like this.
You are now ready to open up the case and remove clay from one half or the other, it doesn't matter which, but not both. Once open, you have the model sitting in the clay half and you need to use a tool to smooth out your parting line in the clay. Sorry that I don't have a picture for this, but the cleaner your parting line, the smaller the smaller the flashing and easier the cleanup.
Once you have a nice clean edge tooled into the clay, add some keys so the rubber registers back into the same place each time. I use acrylic hemispheres, but you can also poke depressions into the clay with a drill bit. It works the same.
Back to the fiberglss shell - clean out any remaining clay and sand out any rough or gummy spots. ( if the water based clay wasn't completely sealed from moisture, some of the fiberglass resin might have not completey cured - not a problem)
Be sure to drill 1/16" holes in all the high spots of the case. this is to let air escape as it fills up with the RTV.
Now you can add the RTV.
NOTE: If you save the clay from the case, you can pound it into a block and measure the dimensions. Why? Because the volume of the clay = the volume of RTV. This is where METRIC rules! Cubic centimeters = grams of RTV (approximately) At $100/gallon, I don't like to waste any.
Do you see the tall funnel I have? This is because height = pressure. Fill the cone (keep it slender. A fat cone wastes RTV) with RTV and as it fills, it will bleed out the holes that you drilled in the case. Once they bleed out a little, pluge the hole with a ball of clay. Add enough RTV so that the entire case fills and the is an inch or two left in the funnel.
NOTE: Be sure to check on the pour every once in a while until cured. If the unthinkable happens, and there is a blow out (or even a small leak) you will come back to the garage in the morning to find a VERY expensive mold of the floor.
Once cured for 24 hrs, remove the second half of the case and clean out the clay. Add a layer of Vaseline to the surface of the RTV and return the case (with the same 1/16" holes drilled for air) and pour the remaining RTV.
This should give you a good case mold that will produce many clean parts.
Last edited by clonesix; Mar 25, 2010 at 12:11 AM.
stormtrooperguy: There isn't much difference in the molds. The difference is in the part. The helmets I have molded have a smaller neck opening, and therefore smaller mold space to "Peel" back.
I have tried to continue all my molds into the interior of the neck, as I feel this gives a cleaner product, that requires less sanding afterwards.
Last edited by clonesix; Mar 24, 2010 at 11:18 PM.
great information. When you get the picks up i will be take many notes for future use.
That makes sense, and is definitely food for thought.clonesix said:
Here's a video from the 405th site. Not fiberglass but he makes it look pretty easy. I can't find the videos before this one but if you look at his related vids they are there somewhere. He's good.
Wow, that is a lot of pictures to go through. It'll take a while...
Maybe you said this already but I'm going to ask anyway.
Edit: Oh I see after taking a closer look it spins both directions.
How fast or slow would you move that in a cast.
i have added pics to my flickr page and I think they match the words. I am too sick of looking at it to care. let me know if it makes sense.
My eyes...
My eyes...
my eyes.
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I appreciate you undergoing the "pain" because it's actually quite a fascinating read. I've never seen a mold created in this way. Thank you.
Yes I will echo what webchief said. Thanks for posting this up. This should get stickied so that it won't drop off. Thanks again.
Yeah, I've read about that style, but I usually go the "silicone first" route... brush on 4-5 layers then do the shell.
I'm also waffling on the shells... I like fiberglass, but hate working with it
I've used Smooth-On's plastipaste twice now, and it's clean, neat and easy, but much heavier.
It's always cool seeing other ways to approach a problem!
That is how many do their molds, and in most cases will work fine. That method works well if your master is locked in place, or too big, such as a architechtural detail or that is too big to move around easily.stormtrooperguy said:
Yeah, I've read about that style, but I usually go the "silicone first" route... brush on 4-5 layers then do the shell.
I'm also waffling on the shells... I like fiberglass, but hate working with it
I've used Smooth-On's plastipaste twice now, and it's clean, neat and easy, but much heavier.
It's always cool seeing other ways to approach a problem!
Yes, I hate fiberglass and polyester laminating resin, but when you need it, you need it. I have also done this with plaster case, and it is cheaper, but heavy and messy.
So, no one has even commented on all the helmets on the shelf? C'mon guys, that is a pretty impressive display!
True that!clonesix said:
I actually didn't stop to think that you had all of those copies finished in the same place at the same time!
Insane, thanks for sharing the mold write up. Youd idnt have to but you did, good on ya!
As for the helmets on the shelf...that my friend is insane. Thank you!
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