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Compound curves!!!

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Old 12-11-2005, 06:44 AM
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Ispitfire
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Default Compound curves!!!

This is something I have never been able to do very well at all, I dont know why I havn't asked before. How the hell do you get a smooth finish around a compound curve when using iron on covering materials??? I always seem to end up with a mess of different slices of covering in various places which doesn't look neat at all. any help!!
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Old 12-11-2005, 07:15 AM
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Default RE: Compound curves!!!

ORIGINAL: Ispitfire
How the hell do you get a smooth finish around a compound curve when using iron on covering materials???
1. Patience
2. Heat
3. Patience
4. stretching/shrinking/more heat
5. More patience
6. SHARP X-acto knife

Seriously, the covering will take a lot of heat and abuse durring the covering process. You can use a heat gun to stretch/shrink/stretch around a compound curve. If you can find it, check out Faye Stilley's book "Covering R/C Models"

I just did [link=http://www.rcuniverse.com/forum/fb.asp?m=3638232]this cowl [/link] and the orange has only one seam each in the upper and lower halfs.
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Old 12-11-2005, 07:46 AM
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Ispitfire
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Default RE: Compound curves!!!

that is a seriously impressive job! does everyone on this site have a sig somethin extra? iv got one and there are like 100 different posts about it! so i assume you used a heat gun for that job right? I can only dream of getting a finish like that! Where do you start when going round a compound curve like that, can you do it using an iron or is a heat gun absolutely neccessary?
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Old 12-11-2005, 08:56 AM
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Default RE: Compound curves!!!

Actually, I did that entirely with an iron. I started with a piece on the top surface. I used a lo temp covering iron to stick the top to the big flat surfaces. THen I used a detail iron on high heat to stretch the covering over the radius. As I got near the corners, I use the detail iron's heat to shrink up the excess and then stretch it over the compound corner. THe trick is to work slowly over the radius shrinking and stretching. WHatever you do, don't allow the covering to crease by mofing too fast with the iron. When I had that piece wrapped clear over by 1/4", I trimmed off the excess, leaving at least 1/18" for the next piece to overlap. Then I took another strip and centered it at the centerline of the front and worked across the front and down each side, overlapping the top piece. I then took a brand new X-acto blade and cut the upper edge to clean up the overlap and resealed the seam with the low heat iron. From there, it's just a matter of wrapping over the exposed edges. Repeat the entire process for the removable lower half. Each half took me about 1 hour.

Usually, poor results come from rushing the job and creasing the film. Just don't be afraid of shrinking or stretching the covering beyond what you think it is capable of. Take your time and the results will come.
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Old 12-11-2005, 10:08 AM
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Default RE: Compound curves!!!

I think it was Coverite that had an advertisement showing a tennis ball covered with their new film. I figured it was advertising BS so I tried it. Turned out to be fairly easy. I carried the ball out to the field when the MonoKote pro scoffed at the ad and said it couldn't be done. Got a bet with him to see if it could be done with MonoKote, figuring if anyone could do it, he could. And I wanted to learn how he did it. Unfortunately, never heard another word from him. And years later heard second hand about one with MonoKote on it.

It's like darn near everything in our hobby. Often it's technique that solves the "impossible" problems.

krossk, thanks for the "lesson"
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Old 12-11-2005, 11:33 AM
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Default RE: Compound curves!!!

I have found that Ultracote in film coverings and SolarTex in fabric coverings are the best (I have encountered anyway ) for compound curves. Work slowly and use heat.

I do 95% of my covering with a regular iron, about 4% with a trim iron and the remainder with a heat gun. They all have their advantages and disadvantages. I would suggest a regular iron 1st, then a trim iron and finally a heat gun.

If you do not have Coverite irons (built in ACCURATE temperature settings ) definitely get a thermometer to use with your irons.
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Old 12-11-2005, 01:00 PM
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Default RE: Compound curves!!!

ORIGINAL: Campy
I have found that Ultracote in film coverings and SolarTex in fabric coverings are the best (I have encountered anyway ) for compound curves. Work slowly and use heat.
Yea, I forgot to mention that I use Ultracote exclusively.
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Old 12-11-2005, 01:11 PM
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Default RE: Compound curves!!!

I think i am gonna try and get my hands on a heat gun, I saw the videos minnflyer posted in his review of the profile p-38, the heat gun looks quite effective. ufortunately the videos dont show a solid compund curve like an engine cowling. I get the impression it could be trickier. I am also gonna try an get some ultrakote or monokote, I have only ever used solarfilm cos its whats been available to me.
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Old 12-12-2005, 05:55 AM
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Default RE: Compound curves!!!

There was an instructional video that was with a review of a P-38 that showed how to do compound curves. I watched it a few days ago but I can't seem to find it now. You might try looking for it.
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Old 12-12-2005, 05:56 AM
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Default RE: Compound curves!!!

Yes we do all have somethin' extras. I had the ARF now I'm working on the Kit.
ORIGINAL: Ispitfire

that is a seriously impressive job! does everyone on this site have a sig somethin extra? iv got one and there are like 100 different posts about it! so i assume you used a heat gun for that job right? I can only dream of getting a finish like that! Where do you start when going round a compound curve like that, can you do it using an iron or is a heat gun absolutely neccessary?
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Old 12-12-2005, 09:33 AM
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Default RE: Compound curves!!!

I have an Ultra Sport wing which will get covered sometime this winter. I'll shoot a video of the wing tip covering.
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Old 12-12-2005, 10:52 AM
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Default RE: Compound curves!!!

That would be muchos coolos!
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Old 12-13-2005, 01:31 PM
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Default RE: Compound curves!!!

Again, I suppose what works for YOU is what you should use. I find heat guns make the covering shrink very uniformly and looks very nice. However, it does not do much toward sticking it to the wood. I also use an iron about 95% of the time.
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Old 12-13-2005, 01:44 PM
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Default RE: Compound curves!!!

I think on my next attempt im gonna try a combination of using a heat gun to shrink/stretch the covering round the corner then use the iron to finish it off touching it up etc. il let you know how it goes....
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Old 12-13-2005, 02:52 PM
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Default RE: Compound curves!!!

That is the way to do it.

Imagine this:

Let's take the wingtip below. Now, imagine that you have a sheet of thin rubber - like the type a balloon or rubber glove is made from - and you have that sheet glued to the top of the wing.

Now you want to glue the sheet to the wingtip, so you smear some glue on it, and you pull and stretch the rubber over and around the wingtip.

You can see in your mind's eye how easily that would work, and how the rubber sheet would conform to the shape right?

It is exactly the same thing with covering, except that heat is needed to make the covering plyable.

Something people tend to forget is that covering will stretch as well as shrink.

An Iron alone will not heat a large enough area to allow good stretching, so a heat gun makes things go much easier.
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