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Molds to be reworked.

 
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jegner
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Joined: 30 May 2003
Posts: 2144
Location: Texas, USA

PostPosted: Tue Oct 31, 2006 10:24 am    Post subject: Molds to be reworked. Reply with quote

Well, I pulled a suit over the last couple of weeks and realized my molds have had it. The all need major repairs, and some need to be resculpted completely. Looks like my Fall and Winter are going to be spent in the workshop.

The chest mold needs the most work as a resculpt. My version is too flat, and needs more of a round body. Shocked

The thighs need more 'meat' and the ends need to be reworked to be more screen accurate.

The biceps are breaking apart, and just need a total rebuild. The shoulders have too steep of a curve, and need to be rebuilt with a better taper.

The shins need some fine tuning, and the collars need to be resculpted this time with arches.

Oh, by.
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dman
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Joined: 09 Oct 2006
Posts: 34

PostPosted: Tue Oct 31, 2006 11:26 am    Post subject: Reply with quote

LOL I hear ya. I've been thinking about making a new mold. My lights are selling pretty good and if my molds screw up, I'm in bad shape. I think I read that fiberglass molds are the best. Is there a decent way to make a fiberglass mold exactly like my mdf ones or do they need to be made from scratch?
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jegner
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Joined: 30 May 2003
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Location: Texas, USA

PostPosted: Tue Oct 31, 2006 11:55 am    Post subject: Reply with quote

pull a sheet of .060 or even .040 HIPs over your mold, then lay up some fiberglass resin [be sure to use mold release] and once that sets, then do up the glass mat, and do this in several layers. Remove the .060 or .040 HIPs and volia!
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knightshade
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Joined: 19 Jun 2005
Posts: 123
Location: Rochester NY

PostPosted: Tue Oct 31, 2006 12:04 pm    Post subject: Reply with quote

I've converted a few of my molds to fiberglass....

Basically - I made pull of my existing mold using styrene
Coated the inside of that pull with vaseline..
Fiberglassed the inside (~1/4"-1/2 thick)

My experience is that the styrene slightly bonds to the fiberglass, but will seperate without to much effort.
The surface of the new mold is somewhat pitted - and needs a very good sanding.

If you had any air bubbles, you may need to fill them in. (Bondo or fiberglass resin work well.)

Hope that helps!


So far, I've not had any of my fiberglass molds damaged - but I haven't given them that much of a workout yet.



(LOL - Jim posted as I was typing)
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TK 109
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Joined: 11 May 2007
Posts: 712
Location: Galena, Ohio

PostPosted: Mon May 14, 2007 4:53 pm    Post subject: Reply with quote

i pulled my suit, and realized i looked like a mutant football player...
i'm trying to rework the molds to make me look better, and to conform to the new stuff, ie the boots...
the calves are really "kicking my butt!" (quote from Jim), the contour is so confusing... maybe i'm thinking too hard... Embarassed
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jzawacki
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Joined: 12 Jan 2007
Posts: 70
Location: Illinois

PostPosted: Tue May 15, 2007 7:26 am    Post subject: Reply with quote

Try gelcoat on your pull when setting up the fiberglass. This is the release agent I have read the most about when working with fiberglass, and is what was on my professional ground effects for my car.
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drcrash
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Joined: 04 Sep 2006
Posts: 705
Location: Austin, Texas

PostPosted: Tue May 15, 2007 8:02 am    Post subject: Reply with quote

jzawacki wrote:
Try gelcoat on your pull when setting up the fiberglass. This is the release agent I have read the most about when working with fiberglass, and is what was on my professional ground effects for my car.


Ummm... gelcoat isn't a release agent. It's a layer of unfilled resin that you put on the mold before laying up the cloth, so that you have a layer of solid plastic on the outside.

The normal thing for fiberglass parts is that you put mold release on the mold, then paint a layer of gel coat on, being careful to get rid of any bubbles before it sets. Then you wet it with more resin put on cloth, wet that out, and repeat until you have as many layers as you want.

For making vacuum forming bucks (molds) this is a bit tricky---which is one reason I haven't actually done it yet and am talking out my ass. If you don't have a perfect mold and intend to sand and fill the cast buck, you may not want to use conventional gel coat---unfilled resin is really hard to sand. (That's why Bondo has microballoons in it---so that it won't be solid plastic, and is lighter and easier to work.)

The basic idea seems right, though. You could put on a layer of bondo, maybe thinned with a little extra resin to make it easier to get the bubbles out. (But not too much, because you don't want the result to be unsandable.) Then you could lay up cloth... or maybe just slather on Bondo-Glass, which is Bondo (polyester) resin plus short glass fibers rather than microballoons. The glass fibers make it way stronger than regular bondo, so you may not need to lay up glass cloth at all. (Or you could do a layer or two of cloth, a thickish layer of Bondo-Glass, and another layer or two of cloth.
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jzawacki
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Joined: 12 Jan 2007
Posts: 70
Location: Illinois

PostPosted: Tue May 15, 2007 10:31 am    Post subject: Reply with quote

Hmm.. I thought the gelcoat was the reason the paint wouldn't stick. I guess it must have something else on it.
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drcrash
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Joined: 04 Sep 2006
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Location: Austin, Texas

PostPosted: Tue May 15, 2007 11:19 am    Post subject: Reply with quote

BTW, if you're content with a plaster-or-something cast buck, and only getting one or two copies, an easy and moderately-priced way to copy an existing buck or a new clay sculpt is using alginate, like lifecasters use.

Alginate is not exactly cheap, but it's a lot cheaper than 2-part silicone. It's made from seaweed, and is like super-Jello. You mix it with water, smear it over your thing, and then make a plaster bandage mother mold around that, like you would with silicone. It sets up to a rubbery consistency in a few minutes.

The downsides are that

1. you have to use it right away, because it's full of water and starts shrinking. You can usually pour two, maybe three copies in it, and that's about it.

2. you can't cast resins in it. (But it works very well for plaster or water putty or gypsum cements like Hydrocal or Ultracal.)

Alginate captures incredibly fine detail, much like silicone.

My wife uses it for copying face casts and modeling clay mask sculpts. For a normal face-sized mask, you need about $5 worth of slow-setting alginate. (Which is less than the cost of the water putty she usually casts in it, and a fraction of the price of silicone.)

My wife's got some nice pictures of this process that I can post when I get ahold of them.
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Tired of buying cheap plastic crap? Now you can make your own! www.VacuumFormerPlans.com
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gobler
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Joined: 23 Mar 2007
Posts: 30
Location: So Cal

PostPosted: Sat May 19, 2007 6:28 pm    Post subject: Reply with quote

drcrash wrote:

The downsides are that
2. you can't cast resins in it. (But it works very well for plaster or water putty or gypsum cements like Hydrocal or Ultracal.)


drcrash, you are spot on with the description and uses of alginate. I must point out there is one urethane that does set up with alginate. BJBs TC1630 works wonders. It makes a great surface coat for vac bucks. I use it for loads of other things as well so it fills lots of uses. Very Happy

Cheers,
Jeff
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drcrash
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Joined: 04 Sep 2006
Posts: 705
Location: Austin, Texas

PostPosted: Sun May 20, 2007 3:22 pm    Post subject: Reply with quote

gobler wrote:

drcrash, you are spot on with the description and uses of alginate. I must point out there is one urethane that does set up with alginate. BJBs TC1630 works wonders. It makes a great surface coat for vac bucks. I use it for loads of other things as well so it fills lots of uses. Very Happy


That's VERY interesting. There may be other urethanes it works with. I might be confused because it doesn't work with two peculiar urethanes we've bought but haven't tried yet. One has water in it, and after you cast it, it shrinks, so you can use it to scale stuff down. The other is hygroscopic, and after you cast it, you can soak it in water so that it swells up and scales stuff up. (Then you generally cast a new mold from the shrunken or enlarged thing, and make the final version in whatever you want.) Of course, those urethanes would be sensitive to the water in the mold alginate.. But if one urethane works, maybe there are others. Cool!

I'll check out the TC1630.
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Tired of buying cheap plastic crap? Now you can make your own! www.VacuumFormerPlans.com
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drcrash
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PostPosted: Mon Jun 18, 2007 12:56 pm    Post subject: Reply with quote

I did a little googling, and found some people saying that alginate molds generally do work for fast-setting urethanes. Cool.
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Tired of buying cheap plastic crap? Now you can make your own! www.VacuumFormerPlans.com
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