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Composite Warbird Build 1/7th P-40E Warhawk

Old 06-15-2011, 04:47 AM
  #126  
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The lowest cost solution seemed to be a hose repair kit. It cost me just under $5 for both the male and female brass fittings. I now have a couple of spare 1/2" gear clamps in the top drawer of my tool chest.

I've positioned the hose hookups on the rear face of the mould section so that the potential exists to hook the upper and lower sections together in a series configuration during final assembly with two small lengths of hose.

Normally I would wait an additional 24 hrs to demould the joined wing assembly. With heat to aid in reducing cure times and improving wing rigidity, I'm hoping to take a mould cycle from a tiresome 3 day operation to an easy 2 days per wing.



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Old 06-15-2011, 04:58 AM
  #127  
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Originally Posted by wilmracer View Post
I like that idea, but I would be worried about the integrity of the straws over time. Perhaps a single piece of thin copper pipe? they have cheap hand tools to allow easy bending and shaping of the pipe and you wouldn't have to worry about leaks. You also would get better heat transfer from copper vs. plastic, although at this size it would be minimal...
Well, you're a thinker - I like that. But you're also a human who likes to complicate things; why? well only you can answer that... After the epoxy in which the straws are embedded has set, the presence of the straw is incidental.

Copper pipe or anything else will create an expansion differential across your lamination resulting in strain concentrations in your mould, and ultimately surface fracture.

LOL - I told you, I'd given much thought to arrive at what seems an idea that's just too easy to be optimum. (it's genius in a dirty straw disguise...lol)
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Old 06-15-2011, 05:28 PM
  #128  
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One of the first places to wear on a multi-piece mould like this, is the edge along which you trim semi-green parts just prior to joining. As a result, it's a very slow and tedious process to try and freehand.

This aluminum insert in the mould face will help to provide a nice durable trimming edge face. Notice the external grooving to aid in bonding with the tool surface coat.

It will also form an overflow channel to give excess resin during joining a place to go.

It might also provide a calibrated groove in which a custom trimming blade jig might ride...

Here's a source link (for future reference, 36" weighed in at 205 g)

http://store.workshopsupply.com/cata...ck-p-2954.html

...and here's the idea...



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Old 06-18-2011, 10:35 PM
  #129  
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OK, first of all - thank you for your patience - I know that this takes forever, and now I've gone and switched things all around on you....

We still have the semi-spherical registration keys - but there are fewer of them. Fewer means less effort in keeping them clean and free from build-up. In an effort to maximize their effect however, they are placed at the extremes of the mould sections.

We still have the 1/4"-20 thread inserts for joining. There are a couple new ones. You can also see that I've countersunk the two on the end faces so that they will not interfere with removing the leading edge section.

The new bits are the extruded aluminum T-slot ways. I've filled them with clay, and then screwed them down to the parting board.

They will provide a nice flat, and wear-resistant face to trim against.

They will also act as an overflow channel during assembly.

But mostly, they give me the option of speeding things up considerably if needed at some time down the road. By vacuum sealing across the flange face and controlling resin flow into each of the nine overflow channels, while drawing vaccum from the underside through the gear bays it will be possible to infuse parts rather quickly.

I left the conduit for the heating circuit on top just for the sake of the picture: of course it will be embedded in the layup.












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Old 06-21-2011, 09:52 PM
  #130  
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These bright white LED's will provide some light in the cavities where the control rods will extend past the trailing edge during final assembly.

(...because I'll be sure to be an old grey man with bad eyes by the time this thing's done!!)


How do you like my scale bullet holes in the wing skins in this first close up shot!?



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Old 06-23-2011, 02:09 AM
  #131  
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Alright, it's been 8 weeks setting up the first section of the wing mould. But it's good news / good news: I'll be starting the layup this evening / the next sections will be much quicker.

I've added some artwork that will be cast into the end faces of the mould (just for a little fun) and I've also updated the tool ID tag.

Stay tuned, there'll be ongoing pics, and so without further adieu...




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Old 06-24-2011, 11:55 AM
  #132  
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Old 06-24-2011, 01:01 PM
  #133  
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That's the first coat of tool coat applied, with particular attention to over hangs. Generally I mix up about 100 grams and put it into tight corners like where the part meets the parting board first while it still flows like no tomorrow. Once it starts to get a little thicker I move onto vertical walls, overhangs and the like.

I'll let this set up for an hour or two, and then I'll give it a second coat of tooling epoxy. I'm shooting for about 1/16" thick and complete coverage.

Haha - my tool ID tag fell off, but both bulldog tags stayed put - can't win for losing. I'll stick the tool ID tag on later I guess.

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Old 06-24-2011, 01:43 PM
  #134  
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Maybe this will be of use to someone else too.
Attached Files
File Type: pdf
Wing Mould Layup Record.pdf (6.1 KB, 137 views)
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Old 06-24-2011, 04:01 PM
  #135  
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2 of 2 coats applied tooling epoxy

Attached Files
File Type: pdf
Wing Mould Layup Record.pdf (6.4 KB, 135 views)
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Old 06-24-2011, 05:07 PM
  #136  
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People might not be commenting, but I'm sure there's a quite few watching.
I find this very informative. I'm learning a lot.

Paul
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Old 06-24-2011, 05:30 PM
  #137  
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This is very light cloth. Mostly it's scraps of 1/2 and 3/4 oz/^yd
that I've set aside when covering other models in the past. I haven't laid any epoxy on it yet, just put it down on the tacky surface coat.

This is what you won't see a lot of others doing: they should.
I've placed it into all of the tight corners. What you do not want are air bubbles and voids. A heavier cloth will show through the tool coat over time and the surface veil will not stay in the tight corners.

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Old 06-24-2011, 06:19 PM
  #138  
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I've wet out the light cloth ensuring that it's into all the tight spots.

OK - I've now been working for 8hrs straight (can you say morphine) and I'm just about to start putting down surface veil. I hope you can see that this is something for which you need to set aside a couple of very long days and nights. Once you start, you don't want to stop or you'll need to sand the entire thing before continuing. (it never works out...)

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Old 06-24-2011, 06:50 PM
  #139  
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This would be a typical first cloth layer. This is continuous strand surface veil or mat. It will stop the heavier weaves yet to come from showing through your surface coat over time. No need to apply it to the flanges: just the part.

You may be tempted to use a chopped strand mat, but the binder in it will react negatively with epoxy resins.

I will now wet this out with laminating resin.
Aeropoxy 2032 with a 30 minute hardener.

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Old 06-25-2011, 12:38 AM
  #140  
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I double dog dare someone to try this on their own! lol

1st layer of 9 oz/yd^2 almost 15 hours into things - I haven't stopped for a coffee yet....


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Old 06-25-2011, 03:06 AM
  #141  
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So now it's just 7 more layers....still haven't managed to eat...as soon as I finish at one end, it's time to start at the other again...

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Old 06-26-2011, 09:37 PM
  #142  
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Well, everything seems to have turned out quite well. The only thing that I'm not overly happy with is the sealer on my wooden registration keys didn't handle the job. Next time I'll use some Kermit the frog eyes from the craft store probably. This time, I'll use the back up plan around the perimeter.

Anyway, here are some early shots. I still have a lot of clay to clean etc., but hey, pictures are cool on a Sunday afternoon too...I'll have more to say later, but I need a coffee.










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Old 07-04-2011, 05:47 PM
  #143  
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Alright, I've had a nice little rest so I thought I should document some things here while I've got a moment.

Since making the fuse mould in 16pcs that each contained 13 layer laminations, at about 3 hours each, I decided that I needed to explore methods for not only speeding things up, but also reducing material costs. As a home hobbiest, you know that the further you can stretch a buck, the better. And afterall, we're building model airplanes here....

The first thought, as silly as it sounds was to go to a bigger brush. Well, that means mixing larger batches, which means a new scale. It also results in using about twice as much resin, but that's another story.

After some thought about rigidity of the tool, I came to the conclusion that what was needed, was much the same thing that's needed in a wing; a spar to take the bending moment produced along the length of the wing, and something to resist twist.

In the end, by using an integral fibreglass outer shear flange around the tool perimeter, and also incorporating the aluminum extrusions at acute angles in the tool face, I was able to cut the 13 layers down to 6 in the tool face and only 4 around the vertical perimeter shear flange.

More substantially, in terms of cost, I went from 2 gallons of laminating resin down to under one. In ballpark figures that's about a 60% savings in the material cost of this tool. The labour savings, although I will not quantify it here because it would require me to assign some certain degree of value to my skill level, was priceless to a guy who couldn't feel his legs after laying down each layer.


What does General Bugsy think of our new toy?
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Old 07-08-2011, 01:15 AM
  #144  
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edit

Last edited by Slow & Low; 07-29-2011 at 03:59 PM.
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Old 08-02-2011, 09:56 PM
  #145  
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Well, the trial epoxy from my newest trial source has arrived. Online ordering and shipping from within Canada was just too much to resist. The price reduction helped out too.

Now let's see what this stuff does. It took a month to get here (maybe longer, I don't care to try and recall - I needed a break anyway), but now it's time to get back to work!

I may use this gallon with the slow hardener to make a few fuselages to sell before I get to the next upper section of the wing mould. This is a good way to cover the costs of the project. If I'd known then, what I know now, I'd have made the canopy and cowl moulds first, sold a few, and then I'd have needed less money to put in up front on the Two Bulldog P-40

...well, here's what it looks like...







...and here's where I got it http://www.miapoxy.com/p-26-miapoxy-...tem-clear.aspx
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Old 08-17-2011, 08:07 PM
  #146  
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Over the course of the next several days, I hope to layup another P40 fuselage in the mould. This revision will incorporate a 1/4 inch ply firewall, and also a flange on the tail section to ease assembly for whomever should get their grubby little hands on it. lol

I'd like to end up with a sheet metal template for producing future firewalls as well.

I got these two sheets of ply for under $5 each at a local woodworking supply outlet. Oh yes, one sheet is 1/4" and the other is 1/8": both birch.



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Old 08-18-2011, 04:17 PM
  #147  
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Oh boy, my old friend is back...you know, this is one of those pictures that is hard for me to believe - yep I'm that guy!! lol

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Old 02-13-2012, 06:11 AM
  #148  
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...now let's see...where was I ?? Oh yes, let's build a fuselage !!

It often seems that life has a way of pulling us away from things. This is exceptionally true with a project of sufficient scope to impress. lol
The trick, is to make your way back home....

I've been to the local school supply store in my ongoing efforts to stock my shelves with goodies that I can use to itch my constructive itch from time to time. I came away with I think what you will agree is the cheapest method for pigmenting your epoxies.

Now, as regards effectiveness, this test will serve to establish a rather subjective pass, or fail grade to the candidate in question. In support of my somewhat educated guess, I will attempt to attach supporting documentation of related adhesion test results for various common pigmenting approaches; one of which I was rather impressed to discover was tempera powder.

If I'm unable to attach the aforementioned article, I will suggest that a google search of the terms "West Systems, tempera, adhesion, results" will also provide a quick link.

For this one, I intend to incorporate a 1/4" 5 ply firewall and I also have what I think you will find to be an interesting idea for applying camouflage in the mould with my new tempera powders.





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Old 02-13-2012, 06:45 PM
  #149  
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First things first; we're gonna need patterns for our camouflage design. I've taken a few liberties in the name of artistic impression here with regards to symmetry and the like, but hey, it's my fuselage afterall isn't it. (??)

I've used an old pair of pants here to drape and tape. Taped in place with duct tape, and marked with a sharpie.







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Old 02-13-2012, 09:54 PM
  #150  
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...and we're gonna need a firewall...
- don't forget to take a minute to identify your templates for later when you don't know what the heck it was anymore
- and don't forget to cleanup and put your tools away as you go (took me a good 40+ years to learn this one, but building in your kitchen helps...)









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