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

[b1heqh54]

Yes folks, it was absolutely free afterall!

I'll post a link to the iso file once I get it ripped...

...and here's a supplies link that looks pretty good too

www.miapoxy.com/

[b1heqh54]

Every time I go to use this mould and I don't have tighten a hundred nuts and washers onto all those bolts, I'm gonna grin from ear to friggin' ear! Just set the clutch nice and loose on the driver and give those 1/4" bolts hell. These thread inserts are going to save so much time it's not even funny.

[b1heqh54]

These are garage door hinges. I had them laying around from a past project and won't be needing them. I thought this might be a good opportunity to try something new and hinge the two main sections of my wing mould. If it doesn't work out, I will simply remove the hinge pins. I will align their axes with the laser level to give it the best shot at working since they can't simply be mounted flat against the angled back wall.

It's the classic risk vs reward. The question is - are yours big enough to get an angle grinder that close to 3 years work?

I'm not finished cleaning up yet but I needed a break, so here's some pics for today.

[b1heqh54]

These hardwood blocks were $0.50 ea at the woodshop supply store.

Here's their website. They have lightweight ply too...

www.workshopsupply.com

Notice that I've set the hinge pins to level when the blocks are placed on the mould face where they will become part of the finished mould base.

[b1heqh54]

So the hinge pins are level, at the same height, and in the same plane. Hopefully this will work because it will take what is really an awkward two person job and make joining the bulky clam sections a one handed operation. There's still some play in the end because I can shim the hinge plates on the hardwood should need be to get things finalized.

[b1heqh54]

So this is pretty much the mould form completed and ready to cast. I will now go over everything with a fine tooth comb and make sure all the clay is finished off properly.

Once I've laid the main lower section in the formers, they will need to be removed. The clay blocks around the top will just give me somewhere to get between the newly cast mould face and the white board. The formers are very close to the finished plug and we don't want to be trying to force something in the seam to pry the board away from the plug in order to carry on to the second mould section. (main upper) Just dig out the clay and there'll be a nice place to GENTLY pry off these white board formers.

The recesses around the perimeter of the base will also provide a little rigidity but that's not really why I did it.

I've also added two air ports in the wheel bays. They're held in place with clay. Just before laying up a part in the mould I will fill the hole with some clay and glass over them. Once the part has cured I'm hoping that a short blast of air in this location will free the part from the mould. It's the deepest spot in the mould, and it's a flat face at the bottom of a tightly controlled cylindrical form....we'll see....

[b1heqh54]

Almost forgot to fill the wing mounting holes...added cavities in the mould at the aileron trailing edges too. The empty cavity just outboard of the inboard hinge (hmm...clear as mud eh?) will provide a place to feed the control rods from the bellcranks during assembly.

Oh, and a quick pic from the couch of all the pieces that I have moulds for, all duct taped together - motivation....

[b1heqh54]

Once I have progressed to some of the heavier cloth layers in the layup of this main lower mould section, I will lay this straw conduit down on a tacky surface and continue to lay cloth up on top of it. All of the joints have been sealed with clear tape to keep the resin out. I will mould a pipe union into the end faces so that I can screw taps onto each end of the mould.

By running hot tap water through the mould face, I hope to have a means for controlling the time/temp curve for the cure and tool cycles. I should be able to reduce the cure time to some noticeable effect with only tap water to a maximum of about 140 deg. fahrenheit or about 60 Celcius.

To my estimation, this would represent the home hobbiest's best chance of approaching any sort of idealized tool utilization rate while maintaining a moderate capital investment.

[b1heqh54]

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.

[b1heqh54]

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)

store.workshopsupply.com/catalogue/blackjack-track-p-2954.html

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

[b1heqh54]

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.

[b1heqh54]

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!?

[b1heqh54]

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...

[b1heqh54]

[b1heqh54]

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.