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Old Mar 13, 2012, 06:03 PM
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central illinois
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J,
was that hot glue on the vertical/parting plane only, or on both vertical and parting plane/plug ?
david
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Old Mar 13, 2012, 09:42 PM
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J Morgan's Avatar
Chapel Hill, TN USA
Joined Apr 2001
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David,
I used low temp hot glue (didn't want to harm my foam plug with hi temp) to glue the horizontal parting plane where it meets the vertical plane. That was a wood/wood joint so I wasn't worried about the hot glue. Then I squeezed some glue out of the gun and used a matchstick to scrap it up and deposit on the horizontal plane/foam plug juncture at the rear. Didn't use much and was very careful when handling the whole thing. Tomorrow I won't have to worry about that, the horizontal planes come off. I'll just need the vertical plane for tomorrow and don't have to worry about it till I drill out the dowel holding it..

Guys,
I don't pretend to be an expert here on fiberglasssing. In fact I know just enough to be dangerous. But we will all learn to do this better by jumping in and trying it.
The proper way as I understand it would be to give the whole thing a thin surface coat. That is epoxy mixed with a substance that makes it thicker. Dumping some graphite in it makes it easier to see what you are doing too. Then when that thin coat gets tacky to the touch, another thin surface coat is applied and given time to get tacky too. When it does it is time to start laying up glass.
I used small pieces up at the nose of the cowl. The turn down into that vertical parting plane was really difficult with the 3 and 5 oz glass. So I used smaller pieces that are easier to "tuck down in those crevices.
I put layers on until I ran out of epoxy for the third time. Don't even know how many layers i put on it but it is several.
Tomorrow the other side and start the wing cores
Did a little Polaris flying this afternoon and that slowed me down too.

J
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Old Mar 13, 2012, 10:11 PM
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thanks, J.
just learned a little more.
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Old Mar 14, 2012, 01:59 AM
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FlyDave's Avatar
Svizzera, TI, Bellinzona
Joined Oct 2005
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For those interested, this is a pdf document explaining exactly what John say, showing how to make a mold out of a plastic cowl :

http://www.cstsales.com/tutorials/fiberglass_mold.pdf
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Old Mar 14, 2012, 12:42 PM
Now in TN!
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Chapel Hill, TN USA
Joined Apr 2001
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Finished the cowl mold this morning. Has a few air bubbles but they are in the upper layers and shouldn't affect it.
You don't see a lot of molds made for one-offs( hope I only need one cowl) but I planned this for practice for a much larger project later this year. And I think I am learning some good things here.
I remembered something though. On the vertical plane( across the cowl opening) I pre-waxed it before mounting the parting planes. But I did forget to put any mold release on it. So I hope the wax does a good enough job.
Tomorrow morning I will find out and also how good the inside is. If it isn't up to snuff, I will have add'l work on it to get a good inside surface. We'll see.

J
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Old Mar 14, 2012, 12:51 PM
DELTAS RULE
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tehachapi, CA
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impressive work mr moldsman! wow!

maybe i missed it, but i take it this is a bungee bird? LOL
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Old Mar 14, 2012, 12:58 PM
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Chapel Hill, TN USA
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Unfortunately it will have retracts Nut.

J
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Old Mar 14, 2012, 01:05 PM
Dr John
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Lake Placid, Florida
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John

A few years`back when I was making molds for Warehouse Hobbies all we used was wax.

John
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Old Mar 14, 2012, 02:11 PM
No Hangar Queens!
Maryland
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Quote:
Originally Posted by J Morgan View Post
it will have retracts
Well, there is your problem. I know they are not your favorite considering your last battle. One day though, you will get it right and you will love them.

Bigger project? Any hints so we can start guessing?
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Old Mar 14, 2012, 04:16 PM
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Chapel Hill, TN USA
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Quote:
Originally Posted by Willsonman View Post
Well, there is your problem. I know they are not your favorite considering your last battle. One day though, you will get it right and you will love them.

Bigger project? Any hints so we can start guessing?
No, it's way too soon to be guessing. Besides with my fickled R/C mind I can change at any time.

John,
Wax might well do fine but Partall over it guarantees no problems.

If you've seen any of my builds, then you know that I have very little patience. So I put the mold in my warming oven( 75 degrees outside and hot in the sun!) for about an hour. Worried about it getting too hot so I brought it in and cooled it and then did it again. It is cured. I decided to trim, drill the alignment holes, and popped it off the plug. To my amazement the plug was fine and there seems to be a pretty smooth surface on the mold halves.
So now it needs washed to remove the release and wax and then I will primer it so that I can check for blemishes. All in all, I'm pretty happy with it and hope I can pull a cowl soon.
So while I was waiting on the mold to cure I pulled out of my storage the crappiest piece of 2" white foam that I have ever seen. It was left here when I bought the house. Dusty and a rough surface but since I'm short of foam and didn't feel like running to Lowes, I cut it up and glued together to make 4" wing blanks.
Good thing that I'm hot wiring it because it is butt ugly but will do the job. I have to do each wing panel in two pieces because my bow isn't quite long enough to cut it.
I have the blanks cut and just need to make an add'l rib template for the middle cut.
Maybe cutting wings tomorrow.

J
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Old Mar 14, 2012, 05:48 PM
Addicted to building...
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Omaha Nebraska
Joined Feb 2006
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Nice. Love the huge scale in foam! thanks for this thread and sharing.

Fred
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Old Mar 14, 2012, 06:04 PM
I don't do Normal
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Old Mar 14, 2012, 07:27 PM
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Man a lot going on there John! I bet that foam is really good!!! Aged ya know! w
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Old Mar 14, 2012, 08:58 PM
No Hangar Queens!
Maryland
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It has me wondering if its like wine... better with age, or like cheese... stinkier the better.
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Old Mar 14, 2012, 09:23 PM
Now in TN!
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Chapel Hill, TN USA
Joined Apr 2001
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Thanks Fred

That foam is the roughest I've ever seen. No telling how old it is. It has those hard chunky spots in it where it seems the machine wasn't working too good. Maybe it's a second but I'm going to use it. It is still light weight, 1 lb/sq ft.
I primered my mold so that I could check the surface. It's not commercial quality but isn't bad and will do for my cowl. I did have a problem with a few little voids in the corners on one side. The other side has nice crisp corners. I'll show some pics and explain what happened there tomorrow. It's all a learning experience and I've already learned a lot.

J
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