Zeta's Roto-casting machine build

Rotational molding, also known as rotomolding, is a molding process for creating many kinds of mostly hollow items. The info is not specific to Classic Cylon Centurions, but SURE can be helpful for them and many, many others projects. Here you'll find various threads with great info from our members for the hobby of costuming.
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groupleaderzeta
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Zeta's Roto-casting machine build

Post by groupleaderzeta » Sat Aug 27, 2011 4:45 pm

My next big project is a roto-caster.

My inspiration...



I will be making a 24 inch machine from wood.
Bearings, large pulleys, and bolts (shafts) came from my local tractor supply store.
The small plastic idler pulleys are from the hardware and are for screen door repair.

It will be hand crank at first, I can add a motor later.
Attachments
bearings.jpg
drive pulleys.jpg
Idaler pulleys.jpg
shaft.jpg


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Re: Zeta's Roto-casting machine build

Post by Cylon-Knight » Sat Aug 27, 2011 5:44 pm

DUDE!
Remember - I said it should play "Cotten Eye'd Joe" ... *face palm*

I hope youre build plays the right music. :twisted:
"All Baseships are now in range to attack the Colonies."
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Re: Zeta's Roto-casting machine build

Post by SiR-ROUND » Sun Aug 28, 2011 4:05 pm

Good, I have thought about building one for ages...

Make it happen.

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Re: Zeta's Roto-casting machine build

Post by Big Al » Mon Aug 29, 2011 1:32 pm

:cylon: Awesome Zeta!!!! I asked around on some of the other forums mostly trooper sites and met alot of good guy's and got a couple of methods for calculating the resin amount for a hollow casted helmet. ...and I will be posting this up on the rotocast page as well plus I found 2 more great case mold / matrix mold making tutorials...One of them they had to restore all the pics on the site because the article goes back a few years and links go bad and pic accounts get closed!.



:cylon: Here are the methods they suggested


:arrow: Method 1

By Stormtrooper Guy

Trial and error

I do mine in multiple coats. I've found that 8oz combined of resin with 4 oz of filler is good for a coat. I typically do 3-4 coats depending on how it works out. I use a filler from Smooth-On called Urefil 3. It's a ground up ceramic powder. It makes them a bit stronger and makes the coats of resin build up better.

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:arrow: Method 2

By EVO3

Hey Alan, sorry to reply so late. I also use the trial and error system. However, at this point in the game, there is less error in my estimations. LOL THere are always minor adjustments to be made in volume but not by much. You will want to put enough resin in each coat to just cover the surface of the mold. I do mine a but different than Brian. I use between 6 and 7 coats. It depends on the temp outside. I use Smoothcast 65D for the first 4 layers and Smoothcast 320 for the last 2 or 3 layers. I mix in ATH powder to all my coats with the exception of the first coat. You can get ATH powder at Smoothon as well. The ATH powder expands the resin to help build up the thickness of the helmet. We all have our own ways of doing things. Its just what you find that works best for your style. Hope this helps.

Ive been in the hobby retail business myself, going on for about 18 years now. Its really an advantage to work in a hobby shop when building armor is your real hobby. The strange look i get from regular customers is priceless. Not to mention the little kids that come in asking where all the SW helmets are. LOL

As for helmet thickness, that really varies from helmet to helmet. Although i have about the same volume of reson in every helmet, it doesnt always spread on the helmet evenly. Some areas may have more thickness than others. And from one helmet to the next, one helmet may have more thickness it the bottom, others may havve it on the top. Its just not an exact science. After doing this for the last few years, its like playing an instrument by ear. You just kinda feel it out as you go.

I found my avitar a few years back from some website and it just kinda stuck. I like the disturbing image, and i guess some people relate it to me now, so it follows me wherever i go.

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:arrow: Method 3

By Freedo

I guess the formula would be surface area, [including any part of the casting you plan on removing] X the thickness you want. I chose to cast a known volume of wax, then measure the wall thickness of the casting and adjust from there.... I have a 1/2 gal. wax pot that melts wax and maintains a set temp. so that's what I used..... Lacking that I would have found something else, probably a cheap casting resin. Once you know what a certain volume equals in wall thickness, then you can adjust the volume for whatever wall thickness you want, with a fair degree of accuracy................Fredo

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:arrow: Method 4 (The Rice Method)

By Jdougn

For what I do trying to calculate surface areas would be nearly impossible. You could just line with the right thickness of clay then pull it all out pound into a cube & calculate. Or, rice & clay would work also. Fill the mold with dry rice & measure the volume. Line the mold with clay the desired thickness. Fill the balance with rice & measure the difference in the volume of the rice. Just an idea.
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Re: Zeta's Roto-casting machine build

Post by groupleaderzeta » Mon Aug 29, 2011 1:41 pm

vary kool ideas, I will have to give them a try.
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Re: Zeta's Roto-casting machine build

Post by Big Al » Mon Aug 29, 2011 2:12 pm

groupleaderzeta wrote:vary kool ideas, I will have to give them a try.
I Like the rice Idea....and these guy's have poured alot of helmets from what it sounds like.

EVO3's Method is very practical as well.

These are tips that would get you around a complicated formula.

Although the smooth on people had a pretty good one it sounded like the most complexed.

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Re: Zeta's Roto-casting machine build

Post by groupleaderzeta » Mon Aug 29, 2011 6:02 pm

caster started. frame is done.
just need to cut off bolts, seal wood, and get the drive belt on.
Attachments
Inner frame.jpg
outer frame.jpg
upright show bearing.jpg
upright with pully attached.jpg
frame together.jpg
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Re: Zeta's Roto-casting machine build

Post by Big Al » Mon Aug 29, 2011 6:25 pm

Go Zeta ! Go Zeta! Go Zeta! :cylon: :cylon: :cylon:

Your Jammin! Keep it up!...are you going to make it electric?
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Re: Zeta's Roto-casting machine build

Post by groupleaderzeta » Mon Aug 29, 2011 9:01 pm

probably after I get used to how it works
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Re: Zeta's Roto-casting machine build

Post by Cylon-Knight » Mon Aug 29, 2011 11:30 pm

Looking NICE, Zeta!
Why not strap yourself to it and make us a demonstration video of how it spins? :twisted:
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Re: Zeta's Roto-casting machine build

Post by Big Al » Mon Aug 29, 2011 11:40 pm

If you spin em up fast enough .....you can open a black hole! :wtf:
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Re: Zeta's Roto-casting machine build

Post by groupleaderzeta » Thu Sep 01, 2011 7:47 am

The caster is nearly done. second coat of paint and counter weights and its done. :byyourcommand: :cylongold: :cylon: :salute:
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caster machine.jpg
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Re: Zeta's Roto-casting machine build

Post by Big Al » Thu Sep 01, 2011 8:50 am

groupleaderzeta wrote:The caster is nearly done. second coat of paint and counter weights and its done. :byyourcommand: :cylongold: :cylon: :salute:

Great Job!!!! What did you use as a drive belt?
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Re: Zeta's Roto-casting machine build

Post by groupleaderzeta » Thu Sep 01, 2011 11:53 am

Its a round Rounthane Belt 1/4" dia. sold by the foot. Ordered it from Stock drive products.
the belt is like a tube, cut it to what length you need and use a metal connector to make it a endless belt.

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https://sdp-si.com/eStore/PartDetail.as ... roupID=510
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Re: Zeta's Roto-casting machine build

Post by Big Al » Thu Sep 01, 2011 12:10 pm

groupleaderzeta wrote:Its a round Rounthane Belt 1/4" dia. sold by the foot. Ordered it from Stock drive products.
the belt is like a tube, cut it to what length you need and use a metal connector to make it a endless belt.

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https://sdp-si.com/eStore/PartDetail.as ... roupID=510
Very Cool!!! :cool:
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