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Old Jan 27, 2012, 11:09 PM
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yea pretty much, just something to make heat and hold it.. Since it'll be summer-time before i get a fuse laid up, i'll just sit it outside in the sun for a few hours this vacuum infusion process for the fuselage is going to be interesting...
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Old Jan 27, 2012, 11:12 PM
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I can't wait to see it! One issue I have had with heat leaving mods in the car is that the parts start to demold themselves.

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yea pretty much, just something to make heat and hold it.. Since it'll be summer-time before i get a fuse laid up, i'll just sit it outside in the sun for a few hours this vacuum infusion process for the fuselage is going to be interesting...
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Old Jan 27, 2012, 11:13 PM
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I can't wait to see it! One issue I have had with heat leaving mods in the car is that the parts start to demold themselves.
LOL.. well that could pose a problem!
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Old Jan 27, 2012, 11:17 PM
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By the way, I use fast curing epoxy that only has a pot life of 15 mins. I have to mix small batches but it cures incredibly fast and rock solid. So I am not even sure if I need post curing. I tried the slower stuff from the same company and the parts were not as hard, even weeks later.
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Old Jan 27, 2012, 11:28 PM
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Ahh ok.. this Adtech resin does really good. I used the USC 635 resin with the medium hardener and it took about a week for it to reach full-hardness @ room-temp. With the Adtech, it reaches full hardness in about 2-3 days @ room-temp.

Even with that said, I've been told by more than one source that it is still highly recommended to post cure to get all of the strength properties as possible.. I'll probably wrap a heating blanket around the molds while the parts are curing.
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Old Jan 27, 2012, 11:31 PM
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Yeah, the USC medium sucks. The fast works great, but you need to really move. Hard to believe there is such a difference between hardeners.

Yeah I have been hearing and reading the same thing. The blanket is probably a good idea. I might look into that myself. Or maybe tomorrow I will make a quick and dirty hot box.

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Ahh ok.. this Adtech resin does really good. I used the USC 635 resin with the medium hardener and it took about a week for it to reach full-hardness @ room-temp. With the Adtech, it reaches full hardness in about 2-3 days @ room-temp.

Even with that said, I've been told by more than one source that it is still highly recommended to post cure to get all of the strength properties as possible.. I'll probably wrap a heating blanket around the molds while the parts are curing.
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Old Jan 27, 2012, 11:33 PM
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Yeah, the USC medium sucks. The fast works great, but you need to really move. Hard to believe there is such a difference between hardeners.

Yeah I have been hearing and reading the same thing. The blanket is probably a good idea. I might look into that myself. Or maybe tomorrow I will make a quick and dirty hot box.
Yeap.. i'll use the USC just cause i have some left over, but this adtech stuff is only $10 more per gallon and much better IMO.. granted i haven't done any tests like the one guy in the composites section...

Have you looked at heating blanket prices lately? We just picked up a king size one for our bed, it was over $200!
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Old Jan 27, 2012, 11:37 PM
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WOW, then I'll just make a hot box haha. Yeah the guy Wyowindworks knows his stuff and does a lot of testing. I asked him about cheaper epoxies and he really likes US Composites. I use the medium hardener for stuff just to get rid of it, like you.

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Yeap.. i'll use the USC just cause i have some left over, but this adtech stuff is only $10 more per gallon and much better IMO.. granted i haven't done any tests like the one guy in the composites section...

Have you looked at heating blanket prices lately? We just picked up a king size one for our bed, it was over $200!
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Old Jan 27, 2012, 11:42 PM
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WOW, then I'll just make a hot box haha. Yeah the guy Wyowindworks knows his stuff and does a lot of testing. I asked him about cheaper epoxies and he really likes US Composites. I use the medium hardener for stuff just to get rid of it, like you.

Well i gotta get my butt back out in the shop.. i gotta get that fuselage finished between tonight and tomorrow so i can start doing parting planes
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Old Jan 28, 2012, 10:44 AM
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Separated the ventral fin and 2nd canopy frame tonight. It was a good learning experience, but I am not satisfied with the outcome...

First off, I used a mixture of epoxy and cabosil to fill in the 90* joints on the ventral fin and around the naca duct since the glass cloth won't go all the way into those corners. I also used this same technique to join the 2 canopy frame parts together. The execution was perfect, Until it came time to remove them from the molds. The ventral fin cracked at the seams and then the mixture between the mounting flange area and the naca duct cracked out.... disappointment #1. So i decided to move onto the canopy frame. The lower half of the mold released well, but in the process of getting it out of the 2nd half of the mold, the epoxy mixture didn't hold well and the bottom portion of the frame basically peeled away from the mixture. The mixture was also extremely brittle.... disappointment #2.

so a few things were learned today... some ok, some very bad

1. Epoxy and cabosil to an almost peanut butter consistency SUCKS for everything.
2. My canopy frame mold somehow developed a few issues. The right rear corner is about 3/32" lower than it should be, which causes the canopy frame to end up high in the back than it should. I have no idea how this happened since it was the last part of the canopy mold to be made... so a few options to fix this.
A: make G-10 routed parts and assemble the frame molding to the frame base plate separately (more work for the builder, but the fit would be extremely tight).
B: Make a new lower canopy frame mold segment
or
C: try and modify the current lower mold segment to fill in the portion that isn't correct. I will probably try this first, if it doesn't work, I will probably do option B, as i'm trying to make this an easy build.
Instead of trying to pry the parts out of the molds, use compressed air.

Get an air nozzle similar to the one seen in the pic and blow air along the edge of the mold and part. The part should pop out on its own with little to no damage.

My air nozzle has a rubber tip. I like it better than the metal one shown in the pic because it won't damage the part or mold.

Dan
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Old Jan 28, 2012, 10:47 AM
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Instead of trying to pry the parts out of the molds, use compressed air.

Get an air nozzle similar to the one seen in the pic and blow air along the edge of the mold and part. The part should pop out on its own with little to no damage.

My air nozzle has a rubber tip. I like it better than the metal one shown in the pic because it won't damage the part or mold.

Dan

Dan,
Good tip! I've used air previously on a few parts (like a composite spinner for a FW-190) and some things on the F-14. But i have found that getting most of the parts out of the molds for the tomcat are fairly simple even with the "new" molds. Once they get a few layups on them i have no doubt they will be even easier to release.

The ventral fin is still the worst b/c of that NACA duct.
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Old Jan 28, 2012, 10:50 AM
ReVolt- Proprietary Insanity
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Yeap.. i'll use the USC just cause i have some left over, but this adtech stuff is only $10 more per gallon and much better IMO.. granted i haven't done any tests like the one guy in the composites section...

Have you looked at heating blanket prices lately? We just picked up a king size one for our bed, it was over $200!
I got my heating blanket for $25 dollars.
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Old Jan 28, 2012, 10:52 AM
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I got my heating blanket for $25 dollars.
NICE! but where?
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Old Jan 28, 2012, 09:25 PM
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I just got one today for $25 as well from Walmart. $25 for a twin. A Queen was $50 I think, and I think a King was $85. I am about to open it now and check it out. Has 10 heat settings. Made by Sunbeam.

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NICE! but where?
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Old Jan 28, 2012, 10:14 PM
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I just got one today for $25 as well from Walmart. $25 for a twin. A Queen was $50 I think, and I think a King was $85. I am about to open it now and check it out. Has 10 heat settings. Made by Sunbeam.
hmm.. interesting, guess i'll have to go look again
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