any advice on molding a BF jet pack.

  1. #1
    mrbungle's Avatar
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    any advice on molding a BF jetpack.

    i have the main body of my jet pack almost ready to mold. i want to use fiberglass to make the mold. because i do not want every detail picked up like RTV does. i am thinking of doing a 2 part mold. needs to be a little flexible so it will be easier to pull a casting of it.

    one mold for the top and front, and one with the bottom and back. kinda like 2 L shaped molds. does this sound right. this will be my first complex mold and i do not want to screw up the pack or the mold.

    if any of you that have done this before, any advice would be nice.
    here's the pack.


    thanks ,mr. bungle

  2. #2
    mrbungle's Avatar
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    Re: any advice on molding a BF jetpack.

    anybody???

  3. #3
    I helped at SDCC '08 987654321a's Avatar
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    Re: any advice on molding a BF jetpack.

    Give it some time, you just posted this. I would suggest, taking your time, because, in my experience, any mold picks up alot of detail. Even fiberglass molds.

    I would also suggest to sand this smooth if you want to be completely satisfied with your work. Molding isnt that cheap with rubbers.

    Here is a list from most expensive to cheapest

    Silicon
    Urethane
    Fiberglass
    Latex


    Enough silicon for the entire jet pack would cost you around $200-400, and Silicon picks up EVERY detail. Just look at my harvey dent coin mold in person and you will see that it picked up every detail down to every fingerprint on there. You would need to build up at least a 1/4" thickness all around for the silicon to not deform while in the support shell. Then we have the support shell which could be plaster, fiberglass or anything hard really, that will set you back about $35, because you can just buy a can of fiberglass resin and some fiberglass mat, from walmart for that. Or plaster of Paris, which is about $15


    Urethane will be much cheaper than silicon, but requires more prep work, such as sufficiently applying mold release to your model since urethane rubber is NOT self releasing as is silicon. These molds will shrink over time and deform.

    Fiberglass molding is my second favorite (First is silicon). FG molding requires alot of prep work but it is worth it in the end, when you have a mold that does not shrink whatsoever, and wont easily deform. Unless you want to make a cheap quality mold, I would steer clear of the walmart brand resin and glass. Get it from professional fiberglass supplier like fiberglast.com . You need Gel coat, which can be sprayed on or brushed on, PVA (Mold release), Carnauba wax, Fiberglass mat, and epoxy resin, which is what I use (I buy all my fiberglass/silicon stuff locally from www.jgreer.com)


    I wont even get into latex molding, as that is not even practical for your application. It is too time consuming, your mold will deform, and shrink beyond belief.


    So it is really a matter of personal choice, whether or not you want to mold it at this stage is your choice.


    Edit- It is really important to mold this professionally because you will thank yourself in the end for doing so.

  4. #4
    mrbungle's Avatar
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    Re: any advice on molding a BF jetpack.

    thanks for the advice. no, it is not ready to mold yet. i still have a lot of prep work to do. more sanding and epoxy .............arrgghhhh....LOL!
    i put the pic up to give an idea of what i am trying to mold.
    but fiber glass seems to be the trick. i have worked with silicon molds and you are right it picks up every detail. good and bad. i was wondering about the release agents and the gelcoat. you answered my question about that , it is a must.

  5. #5
    I helped at SDCC '08 987654321a's Avatar
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    Re: any advice on molding a BF jetpack.

    A mold, I did one time that was supposed to be 2 piece and hollow at the same time was really complicated, since you cannot shrink yourself, go inside the two mold halves and apply the fiberglass, I pretty much applied the gel coat to the two halves while it was open, and once that was semi cured (Soft, but tacky to the touch, and it doesnt lift), I applied about 5 or 6 layers of FG and I bolted the two halves together. The wet fiberglass basically acts like a glue and it stuck together, I then went back in when I pulled the part out, and just secured the parting line with one more strip of fiberglass.

    A Jet Pack mold can be just as complicated because it takes at least a weekend to do all of this. Another option would be to have a pour spout on top of the jet pack, where the rocket is inserted, and do a slush casting method with silicon.

    Ill let the experts chime in, since my mold was my first of the fully enclosed two part molds.



    You can also make a 3 part mold, making it easier to glass the two halves, and the top half and just bolt the top half on.

  6. #6
    CombatBaby's Avatar
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    Re: any advice on molding a BF jetpack.

    i would think it'd be only about $100 to make a decent set of molds for a jet pack

    OOMOO30 silicone rubber and some fiberglass for the mother mold

    about $85 worth of rubbed and $15 for fiberglass resin and matting.


    it doesn't need to be thick, just well supported.

    of course. if he's doing a run, more money should be spent for a very sturdy mold.

  7. #7
    I helped at SDCC '08 987654321a's Avatar
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    Re: any advice on molding a BF jetpack.

    Thats true. But Oomoo30 is good for 1 time use applications, unless he likes alot of prep work that doubles each time he casts a new piece. My suggestion is go to Jgreer.com, his 10:1 mix silicon is perfect for any application including yours and it is much much cheaper than smooth on.

  8. #8

    Re: any advice on molding a BF jetpack.

    PM sent..

  9. #9
    mrbungle's Avatar
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    Re: any advice on molding a BF jetpack.

    thanks for that site!! they prices are much better than smooth on.
    someone asked me if i was going to do a run and at this point ,no. but i do want a good mold in case i change my mind.

    the 3 part mold you talked about seems to me to be a good route to go. it would be much easier to fiberglass in with a bolt on top.



    987654321a said: View Post
    Thats true. But Oomoo30 is good for 1 time use applications, unless he likes alot of prep work that doubles each time he casts a new piece. My suggestion is go to Jgreer.com, his 10:1 mix silicon is perfect for any application including yours and it is much much cheaper than smooth on.

  10. #10

    Re: any advice on molding a BF jetpack.

    CombatBaby said: View Post
    OOMOO30 silicone rubber and some fiberglass for the mother mold

    about $85 worth of rubbed and $15 for fiberglass resin and matting.
    heh... i used $150 of oomoo on 1 gauntlet... i'm not sure how you'd do a whole jet pack that cheap. the oomoo tears really easily when its thin.

  11. #11

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    Re: any advice on molding a BF jetpack.

    ok I know I am new at this - but part of the prep work I heard with FG has to do with FG resin itself - ie toxic, temperature conditions, out door use. Heard it once or twice now abt a water based resin which should make things easier (although it is also more expensive)

  12. #12
    mrbungle's Avatar
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    Re: any advice on molding a BF jetpack.

    well here is after sanding till i have lung cancer. ready for molds i think. i am going to use the fiberglass 3 part mold plan. already have the gelcoat and release agent stuff ordered.
    any critique would be nice.



  13. #13

    Re: any advice on molding a BF jetpack.

    just an fyi for the oomoo series of silicones. they are low wear silicones. for the mold that will be used a whole lot use moldmax series. if you want a rigid but flexible mold you can use the vitaflex series. we use moldmax with our pen castings and for our poly screws and handles. it is expensive but worth it.

  14. #14
    CombatBaby's Avatar
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    Re: any advice on molding a BF jetpack.

    stormtrooperguy said: View Post
    heh... i used $150 of oomoo on 1 gauntlet... i'm not sure how you'd do a whole jet pack that cheap. the oomoo tears really easily when its thin.
    I was more stressing the fact that if he's not doing a run he might be able to get away cheaply making a mold. if he layers it correctly and it careful I'd think he'd get at least 2 good packs before the mold deteriorates. Figuring that a jet pack can cost anywhere from $150-500 I'd say it'd be worth it.

    if he chooses to put more money into it and make a very solid mold then it will last longer, but if he's not making the additional casts anyway then what's the point?

    When I molded my WOF jet pack i only used $85 worth of silicone (5-1 pound kits w/ my student discount). I made a mother mold out of fiberglass and paper mache and it's still in great shape even after 3 pulls.


    I took my time and did several coats, which i think helped not waste any. I don't like the box method a lot of people use for molding as there is so much void that most of the silicone is just wasted. Mother molds are supposed to be the real support. A little thickness on the mold itself is definitely a plus, but as he's not going for mass production i'm sure he can make a decent mold for around $100 or so, especially if he goes with the jgeer gallon kit at just around that price.

    good luck.


    Please take into account I did not mold a rocket or thrusters. Those do take a lot of silicone....so that could throw off my original "quote"

  15. #15
    mrbungle's Avatar
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    Re: any advice on molding a BF jetpack.

    i am trying to do a very good fiberglass and tooling gelcoat mold. the rocket and thrusters are molded out of RTV. i am taking my time and trying to do the best job possible. i do not want to destroy the master copy.

    i do plan to do a run , a very short run. 5-10 at the most.

  16. #16

    Re: any advice on molding a BF jetpack.

    What would you cast the jet packs from? a rigid foam,silisone,hard plastic,fiberglass resin/tigerhair combo?


    Thanks
    CCM

    mrbungle said: View Post
    i am trying to do a very good fiberglass and tooling gelcoat mold. the rocket and thrusters are molded out of RTV. i am taking my time and trying to do the best job possible. i do not want to destroy the master copy.

    i do plan to do a run , a very short run. 5-10 at the most.

  17. #17
    formerly old_jedi_mind_trick Bobby Fett UK's Avatar
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    Re: any advice on molding a BF jetpack.

    Interesting. I am around the same place, but hope to do a run of 10 - 20 depending on demand. I was planning on a two part silicon mold with a fg mother. I was going to build it up, brushed on (with thickener) to about 10mm.

  18. #18
    mrbungle's Avatar
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    Re: any advice on molding a BF jetpack.

    the jet packs would be fiberglass and gelcoat.

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