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Old Dec 09, 2009, 08:04 PM
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How much does it weigh?
Hi Kevin,
the fish scale says the entire assembly weighs 2oz. Half of that weight is the round stock I haven't parted off yet. I knew as soon as I posted the picture I'd be hearing from you on the weight. You're a man of your word.

Dan Eaton
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Old Dec 13, 2009, 12:56 PM
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The $3,000,000 nose cone

I needed a nose cone for the F-18 so I set out to build one and learn something along the way. The costs:

50 pound bag of Hydrocal...................$26.30
West System resin, hardener, brushes....$57.05
3.6 oz cloth and pumps......................$73.59
Partall Mold release...........................$00.00 donated from a friend
Composite Molding Made Easy DVD.......$39.00

The results:
Check out the pictures. I ended up with a FG nose cone that looks pretty good for my first try. It weights .4 ounces which I can probably improve on. I didn't even try getting off any excess resin by blotting with paper towels. The cloth was slipping around a lot so I decided just to let things be and see how it turned out. I used two layers of 3.6 ounce cloth which is what Steve Neill settled on back in his old build threads. If it's good enough for Steve, it's good enough for me.

Was it worth spending all that time and money just to get this nose cone? Nope, but the knowlege gained was more than worth it. Plus I got all these left overs now and plenty of ideas. Mr. Cox, you need to get busy.

Dan Eaton
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Old Dec 13, 2009, 01:01 PM
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Great looking build Dan,hope to see if fly when you get it finished!!!
Hi Joe,
my goal is to have this flying by the Phantom Flyer's E-flyin in July. There's lots of interesting EDF projects going on in Saint Louis this Winter so there should be some good stuff to see at that meet.

Dan Eaton
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Old Dec 13, 2009, 01:09 PM
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Skunk Water, Rhode Island
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Hi Dan! Good to see you discovering Hydrocal. As a young teen, I used it for scenery on my HO train layout. Latex rock castings, Zip=texturing, yada.. The casting variety, when fully cured, 1/4" thick will support 150# weight. I used to walk on the scenery. Now I still use it for moldings. Mixing it with chopped glass will make the casting last forever. And you can add RIT dye to make lay-ups more visable. Black makes bubbles show great. Add the dye and chopped glass before the water. I use distilled water. Helps the cure with no chlorines/ammoniates or flourides, depending on local injection practices.

And she's lookn' great!

Fuzz
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Old Dec 13, 2009, 01:25 PM
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Dan,

I've never heard of Hydrocal, how does it work? You just put your positives on a board, make a box around it and pour straight on the waxed/pva positives?

Finish quality good on the molds?

Is it mixed with epoxy or it's own solution?

Good for bigger parts or just small stuff?

Sorry for all the questions, just looks interesting. Keep up the good work.
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Old Dec 13, 2009, 02:24 PM
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Add the dye and chopped glass before the water. I use distilled water. Helps the cure with no chlorines/ammoniates or flourides, depending on local injection practices.

And she's lookn' great!
Hi Fuzz,
Thanks. I've known of Hydrocal for years but always thought of it as just like Plaster of Paris but different. My mistake, big difference although you wouldn't know it until it sets up.

I've added chopped twine to Plaster of Paris molds to increase the strength. I never thought about adding glass but it makes sence. Good idea on the dye too.

Interesting comment about the water. I used tap and had no issues. What kind of problems with the cure do you see?

Dan Eaton
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Last edited by eatond; Dec 13, 2009 at 02:39 PM.
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Old Dec 13, 2009, 02:38 PM
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Hi Arbo,
no problem with the questions. This stuff is new to me too.

Quote:
I've never heard of Hydrocal, how does it work? You just put your positives on a board, make a box around it and pour straight on the waxed/pva positives?
For a start, go take a look at the Super Bandit thread. That's what got me fired up to give this a try.

Quote:
Finish quality good on the molds?
Kind of depends on the surface quality of your plugs, but when I pulled my plugs out of the mold what I was staring at really reminded me of marble. Way different than the plaster surface I was expecting. Not that things are rough but I actually lost surface smoothness when I sealed the hydrocal with epoxy.

Quote:
Is it mixed with epoxy or it's own solution?
Nope, use the Hydrocal to make the molds and then seal the surface with epoxy. I did that with the molds heated up and the epoxy just ran like butter.

Quote:
Good for bigger parts or just small stuff?
I don't know yet but a 50 pound bag will go a long way and I have some big projects I want to try. I don't see any reason why it wouldn't work.

Dan Eaton
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Old Dec 13, 2009, 03:11 PM
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I'm getting close to trying some molds with some urathane that is aluminum filled. I have some cured samples and it machines really good, is self sealed and polishes awesome. So the hydrocal looked interesting. I'll keep watching, thanks for the info.
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Old Dec 13, 2009, 05:01 PM
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Dan,

Nice work on the gear and the nose.
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Old Dec 13, 2009, 06:54 PM
Big gov never Works
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Skunk Water, Rhode Island
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I had issues with the cure time, Dan. Possibly only because I was in Fla(WPB) at the time and they inject ammonia in the water system, every 3 days. So I never took the chance again. The cure would not happen till the ammonia evaporated.

Hydrocal is a Gypsum. 10x stronger than plaster of paris, but same family. It comes in casting and lay-up varieties. Smaller amounts can be had(1/2 gal) at hobby shops that deal in model railroading. Comes in a 1/2gal milk container, yellow.
It cures as does all gypsum/cement products. There is a working time, depending on viscosity of blend. Clean work tools immediately. After cure water does not harm it, like plaster of paris. With this in mind, waxing the hydrocal mold and spraying with PVA is all that is needed. I learned long ago not to epoxy Hydrocal. I wish I could have known you were doing this, Dan. The epoxy may not remain permenant. Not too much sticks to this stuff for long.

Dan, keep that 50# bag well sealed. Wrap it in double plastic bags. With you living in the south, the humidity will cause it to cure, like cement. By..buy..investment.



Fuzz
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Last edited by St. Martin; Dec 13, 2009 at 06:59 PM. Reason: added coments
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