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PET-G (PolyEthlene Terephtalate Glycol)

PET-G is of course a clear rugged platic that is also used widely in commercial products and packaging that we use everyday!

Displays

[attachment=4]Pet g display.jpg[/attachment]

Food Covers

[attachment=7]petg_food_cover_1.jpg[/attachment]

Universal book/ catalog stand

[attachment=6]Pet -g stand.jpg[/attachment]


It is also widely used by hobbyists like myself to make parts that require clear plastic.

These are some examples I found on the net and you can see why we use it
One important reason we use this plastic is because it has great Detail Retention.

I think this is a canopy for a B-17 ...hard to tell because the pic is there but the site is gone

[attachment=5]pet g canopy.jpg[/attachment]

This is a Huey Helicopter body with doors
Notice the rivet details

[attachment=3]Pet G Heli 2.jpg[/attachment][attachment=2]Pet G Heli.jpg[/attachment]

And here is the finished Heli with paint

[attachment=0]Pet g Heli 3.jpg[/attachment]

Pet G has great properties and pulls just about the same as ABS. it is also very good for deep pulls.

[attachment=1]vacuum-draw deep pet-g.jpg[/attachment]

Pet G Forms at temps between 260 to 300 degrees and can withstand a continuous temp of only 150 degrees so in R/C modeling we can't use it for cowlings on gas powered aircraft or anything else that will be exposed to high heat. Heli bodies and canopies are a perfect aplication for this plastic and would make great Cylon parts!

It works great with one stage and or low vol vacuum machines and comes in clear, translucent grey and bronze tints and I think you can custom order other tints, IE Amber or yellow.

Pet G heats rather quickly and begins to sag almost immediately and will keep on going so it is very important to watch this closely as it will sag right to the floor if you let it!

Pet G is very tolerant of a cold mold but it seems to like to stick to things more than ABS or other plastics so it's a good idea to use use a light coat of petrolium gelly on your plug or mold and your rubber seal.


Here is the Bio spec sheet from Polymerplastics.com

PETG also known as Vivak (Trade name for Sheffield Plastics)

PETG, glycol-modified polyethylene terephthalate, is a copolyester that is a clear amorphous thermoplastic. PETG sheet has high stiffness, hardness, and toughness as well as good impact strength.

Unstressed PETG exhibits good resistance to dilute aqueous solutions of mineral acids, bases, salts, and soaps. PETG also has good resistance to aliphatic hydrocarbons, alcohols, and a variety of oils. Halogenated hydrocarbons, low molecular weight ketones, and aromatic hydrocarbons dissolve or swell this plastic.

PETG does not contain a UV inhibitor and it is not suggested for use in applications involving continuous long-term outdoor exposure.

Properties:

High gloss
Transparency
Toughness
Fast forming cycles
Ease of forming
Sterilizable with gamma rays
Resistance to stress whitening

Applications:

Blister Packaging
Medical device packaging
Face shields
Display racks
Bottles for soaps, detergents, oils

Availabilities:

Sheet: .020" to .250"
Standard Colors: Clear, custom colors available

Next Up: Polycarbonate

I don't recall what Alsa product it is called, but it was made to chrome on the back side. It was reflective on both side, so you could made armor pulls, and spray the inside, and not worry about scratching the top side. So this Pet-G looks like it would work for that method on chroming a clear Cylon with a chrome finish.

GoldCylon wrote:I don't recall what Alsa product it is called, but it was made to chrome on the back side. It was reflective on both side, so you could made armor pulls, and spray the inside, and not worry about scratching the top side. So this Pet-G looks like it would work for that method on chroming a clear Cylon with a chrome finish.

Yes Pet G and Polycarbonate are both excelent for this app.
and I was going to talk about painting from the inside of clear after I covered plugs and mold but I'm glad you brought it up because it's one of those tricks that is so important when making parts....it works great and let's you achive an apperance of high gloss even if you use a white or a flat color of any kind.

Polycarbonate is even tougher and more scratch and impact resistant and this is what we use to make car bodies with.

I have never used the product you mentioned, but I do know about it because my Friends have use it when painting car bodies. Car bodies are all painted from the inside.....

Glad someone getting somthing from these posts I have tried not to get to complicated but the info I have posted is important to the process and making great parts.

Thank you very much for your imput

Big Al

I was of course thinking along the same lines with clear plastic. It would be great to mirror the inside so that the entire helmet would be like a visor. No more crappy vision! The only thing to get in the way would be the scanner.

I think the chrome I am thinking about is called "Mirror Chrome" thus the name. It reflects from the inside out like a mirror.

GoldCylon wrote:I think the chrome I am thinking about is called "Mirror Chrome" thus the name. It reflects from the inside out like a mirror.

thats what i used for the t-800 skull . you are supose to paint on the inside if the clear vac parts for the reflection and that way you dont have to seal it... but if you spray on the out side you need a good gloss black and spray on top of that... it is durable if you let it set for a few months and you cant seal it... at tleast i havent found anything that works yet

There are plenty of chrome clear coats on the market. I used Alsa Clear for Chrome a lot. Good stuff if used correctly.

One secret to any good paint job is stick with the same brand name from primer to paint to clear.

You are assured that all the chems are compatable.

If you use one brand of paint and another brand of clear and they are not compatable, ...things can get real ugly real quick

Different Companies use different solvents in their paints and they can have a reaction resulting in destroying your part.

Big Al

I mostly agree with that statement, but some companies don't make a clear coat for like the shaker cans and you need a coating on that if you are trooping around.

GoldCylon wrote:I mostly agree with that statement, but some companies don't make a clear coat for like the shaker cans and you need a coating on that if you are trooping around.

You are absolutly right! and I wasn't thinking about rattle cans,,, and that is the very reason We use air brushes and fill guns for everything! you can mix and blend your own colors and shades and when you buy paint, you can get the clear in the same brand.

Just remember that you cannot use solvent based paints on PET G and Polycarb as it will attack the plastic.

Water based and latex work great and dry quickly!

Pactra (I believe is made by testors) is a brand of paint that is designed for Polycarb and PETG Plastic.
It comes in rattle cans as well as bottles.

Here is a link Tower Hobbies

I know I bosted earlier about Keep it simple stupid...(Meaning myself) but I never do anything easy! LOL another advantage of airbrush is that you can control the Paint flow, amount of air and the fan thickness from a super fine line to a wide fan.

Of course you can only get these features on a med to high end brush such as an IWATA

These are the guns and brushes we use

This one is a general use gun and is very adjustable

[attachment=2]IWATA HP-CH240w.jpg[/attachment]

This one is a detail brush[attachment=0]Iwata HP-SB-Plus600w.jpg[/attachment]

This one is a fill gun[attachment=1]Iwata G3-AB-GUN_240h.jpg[/attachment]

One interesting thing is that pactra makes a silver metal flake and a gold metal flake ....Wonder how that would look on a Cylon

Polycarbonate

Once again Polycarabonate is of those very universal plastics and is used in thousands of our modern day objects and products.

[attachment=4]Polycarbonate_Film_Polycarbonate_Sheet_PC.jpg[/attachment]

Polycarbonate is Very Very Tough and difficult to form and is the most expensive. Polycarbonate is however the most impact resistant Plastic you can form and is most commonly used in unbreakable windows and signage.

It will withstand Continuous temps up to 250 degrees and for these reasons is exactly why we use it to make 1/10 scale R/C Car bodies

[attachment=3]Poly Carb Car.jpg[/attachment]

[attachment=2]Poly Carb Bodie 3.jpg[/attachment]

[attachment=0]Poly Carb Body 2.jpg[/attachment]


Polycarbonate is alot harder to form in that you need higher heat starting at 350 - 400 degrees and some brands even higher 450 or more. The book recommends that you start at 400 and increse if needed.

You need quite a bit of vac for this one because Polycarbonate cools so quickly and Single stage vacs do not work very good on Polycarbonate. The 2 stage high vol is the only way to go here because the High Vol provides the BIG SUCK FAST!!.

This plastic comes in clear and tinted colors from .005 to 1/2 inch in thickness.

When heating and pulling Polycarbonate you may have to pre-dry it first and this can be done at a temp of 200 to 225 degrees for about an hour. Polycarbonate begins to sag at 250 so keep the pre dry lower

The sag starts at about 250 but if you poke it with your finger it will still be hard.

Polycarbonate is one of those plastics that cools and hardens fast! so you have to work quickly! If you are using a large plaster plug they tend to be on the cool side and your Polycarbonate will set almost on contact so with a plaster plug, you can pre heat your plug at about 200 to 225 at the same time you are pre drying your plastic. Use a cookie sheet to set your plug on the inside of your oven before you make your pull.

Polycarbonate sags at a moderate rate and is almost the same as PET G. You can use this to your advantage as you can pre stretch your plastic for deeper pulls. But be careful Polycarbonate speeds up as it sag so you have to watch it closely

A quick note: Though Polycarb is used in unbreakable windows, It can indeed crack! I have seen many car bodies crack after a crash or run away car into the wall. Not that this would be a problem in a cylon suit but I think the reason this happens is because way it was cut. If you have a nick or a chip from an unclean edge or in the case of a car, a drilled hole for a body post and then it is impacted hard it will crack!


Trade names for Polycarbonate

Lexan
Tuffak
Makrolon
Polygal
Polycarb

[attachment=1]Polycarbonate.jpg[/attachment]


That about wraps it up for the plastics, the rest is trial and error so if you plan a project, be sure to buy extra sheets as you will need them


There is one more plastic I did not cover that might be of some use when making a Cylon Suit or other costume and that is KYDEX.

KYDEX is a very thick and heavy Black plastic with a orange peel like texture that is used for making form fitting holsters for pistols.

from what I have read, it forms pretty good.

I have never used KYDEX so I can't give you all of the details. and when I did google searches on this plastic, all I got was How to make holsters....go figure

Next Up: Plug Making!

Plug and Mold Making

This one is a little involved and I will try to be as precise as I can be without being to long winded.

This is the part of the process where your you will need your craftsmanship and artistic abilities as well as ingenuity. Being a little clever helps too! I call it (The MacGyver Mode!) well maybe not that extreme.

The only reason I say that is because you will use a variety of materials, tools, and machines to achieve your plug! The MacGyver part is the home brew implements you can make, in order to construct your home brew plug!

It seems every specialty tool or machine I would like to have,...is usually out of my price range so I seek alternatives like building my own! Ergo MacGyver! And the reason for this thread.

Plugs and molds can be made from a lot of things. Plaster, Wood, Fiberglass, Foam, Cast resin, Metal, and just about 10 million other materials you can think of!

Blue Foam (Extruded PolyStyrene)

Blue Foam is an insulation product and is called Bluecor Styrorfoam and is a trade name of Dow Chemical and is the exact chemical make up as Styrofoam (White Foam) also a Dow Chemical trade name.

[attachment=9]Dow%20Blue%20Foam.jpg[/attachment]


Blue and pink foam comes in different thicknesses and if the desired thickness is not available, you can stack and glue just like with balsa.

I didn't post any source links for the Blue or pink foam, although I'm sure you can find an internet source. The reason why is, you can get this from any local insulation company and some times you can find it at a local Home Depot or Lowes or any home center you might have in your town.

Expanded Polystyrene (Styrofoam) beads

[attachment=8]Styrofoam Beads.jpg[/attachment]


The difference is that the common Styrofoam we all know that is used to make everything form coffee cups to packaging, is made from (Expanded Polystyrene) these are the little foam balls that fly everywhere like a dandelion when you break a molded piece apart!

Expanded Polystyrene, are little foam balls that are filled with air and are placed in between a 2 piece mold (male and female), Heated with steam or other heat sources sometimes heating the mold itself.

Then the air in the balls expand against each other and are formed and pressed with a great deal of pressure to create a part.

Expanded polystyrene,

Rigid Polyurathane Foam

This foam has been around a long time and shapes similar to blue foam and capable of retaining great detail. It can also be used to create plugs and molds.

Ridgid Polyurethane Foam
[attachment=1]rigid-polyurethane-foam-757006.jpg[/attachment]

This foam is also available from local suppliers and comes in many different thicknesses and sizes.

This next example is a stunning photo essay of Sean Bradley's ODST actual working Back pack build
and how to achieve a highly detailed plug from plaster or resin with a Male to Female to Male process.

He starts by making a detailed master plug from a polyurethane block , Then pulling a thicker plastic to make to make a female mold and pouring plaster or resin in the mold cavity of the plastic, creating a highly detailed, perfect plaster replica slave of the foam master.

This project could have as easily had been done in blue or pink foam with the same results.

The next step is to use the Plaster slave plug to pull your part and you have created a plug that will withstand a med to large production run.

This is a great artical and is right up our Cylon alley! One thing I found interesting is that He discusses different ways he could have done things for certain reasons to achive different results as well as his process and outcome.

Here are some pics from his web site Blue Realm Studios, Sean Bradley's ODST

[attachment=0]ArticleCoverImage.jpg[/attachment]

Please visit this site and read his artical it's a treasure trove of info on the subject and takes you from the making the master plug to the finished product!


Next Up: Tools

Huttman wrote:
if i were to do it again, i would build it using all steel frame. the bottom that holds to two square frames is steele, but the actual frames are aluminum. its sturdy and holds the 25 pound molds, but i have sculpting helmets on the horizon, im hoping it holds well.

Its a learning experience for sure, it would be nice to have seperate speed controls but that is a whole different ballgame, and costly.

Are the frames completely driven by gears or are you using a dirve motorfor the entier machine and then use a secondary motor on the big frame and driving the inner frame with gears and shafts? and if it is the latter, does the machine have some sort of electrical swash plate that feeds the secondary motor?

Also I don't know if you seen my other post's about the plans? and I hope you don't think me as some Know it all guy butting in on somthing I don't know about and if I offended you I am sorry. Building Home brew machinery gives me just as big of woody as does the the hobbies I love. Especialy when they Work!

I enjoy very much discussing my hobbies and projects with people who share my interests and maybe I was just alittle over stimulated.

I guess building the machinery is also one of my hobbies but I never thought of it that way.

I do think your machine is fantastic and when I'm finished with this thread, I intend to do some serious research on this subject.


Big Al