Spitfire wings at AREA-52


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Vapor52
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Post by Vapor52 »

TH, I'd love to build a machine to do that exact process. I have no programming experience, do you think I could learn it? Is it 2 process'? Draw the part, then write a program that drives the router? ------rick
THend
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Post by THend »

Rick, the process gets pretty easy once you overcome some of the hurdles. I will say, it sounds great to have this, but there is some work involved. I've reached a point where it is enjoyable.

You don't have to be a programmer, but you will need patience and fortitude....

You built the cnc foam cutter, the 3D router is a bit more involved.
Vapor52
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Post by Vapor52 »

I'm up to the building part, just don't want to build it and then not be able to use it!
THend
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Post by THend »

Rick, I remember when you built the cnc foam cutter and the phone calls.... You did great!

I know you can build it, I've seen what you can do, and I am dang sure that between the support here, and the support from CNCZone.com we'll get you cutting.

You will dig it, and I will help you as much as I can.
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Post by THend »

Ok, so you shape the "plug", however you can do it.

If you have two halves, try spray painting one half on the flat. Or some way to mark the center of the plug. This will come in handy when setting up the plug later into the parting board.

You can see I joined the two plug halves. Let me tell you, you don't want to be a Messy Marvin and get epoxy all over the place. Infact, next time I may just use Probond type glue. The reason is that the epoxy doesn't like to sand so much.

So, join the two halves, be very careful to align the key areas like the horiz stab and the wing saddle, and depending on your choice of front ends alignment there is real important too. My very fist mold, the Manta fuse, I didn't nail the alignment on the front end, and that would have led to issues with getting the motor alignment. I'll be re-making the Manta mold soon.

Ok, so you joined your two halves, or you just shaped the whole enchilada out of one piece. Now, sand and sand to smooth it out. This plug has some serious 90 degree angle areas, so I sanded in some "relief". Next time, I'll design the plug with fillets etc...

Here is the plug being primed. Some folks like to paint black, but I decided to try white to allow me to see the black parting line I painted on one half. You need to seal the plug, and then sand again. Just when you think you nailed all the rough spots, the paint will really highlight where more work needs to be done.

NOW, I believe this to be a combat plane. Thus, I will only put so much effort into the sanding process. It needs to be smooth enough to pop out of the mold. At least, if you do make it pretty, the results will always be seen in the future fuses you pull. Make it too ugly, and it too will live forever in future pulls.

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Johnny Bravo, the dude with a plan.
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Ed Kettler
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Post by Ed Kettler »

Terry, what are the "pegs" in the cowl area for?
THend
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Post by THend »

I'm trying to devise a way to key in the motor mount, once mounted, the keys get removed and the surface blended. The big deal is to get away from conventional firewalls and motor mounts. Then, if the mount gets damaged, we can remove and replace it.

This will be going down over the next few days, and I will keep you all posted.

There are possibly better ways, so we will continue to work on it.
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Post by THend »

Ok, pushing forward.

Once the plug is shaped to satisfaction, you need to prime and seal it. I used Kilz spray primer and it seemed to work just fine. I think many others seal MDF with polyurethane as well.

After the plug is sealed, it should be sanded smooth... really smooth. I hit the plug with 220, and then finished off with 600. I figured it was OK, it isn't a show room model, it's a combat plane. It just needs to be smooth and clean so it will not show up in every fuse pulled.

Then you need to wax the plug, and wax the plug, and then wax the plug. I must have waxed this plug 6 to 10 times..

Now you need to cut a parting board. The parting board will hold the plug at darn near the center of the plug. Thus, half of the plug is exposed for the first layup. I used Rhino to resize the original profile by just a tad so the plug would fit nicely into the parting board. I screwed up, I resized the drawing in Rhino and didn't do it right. Mental note, always check your changes in CAD. Oh well, we filled the voids and moved on.

Cut the parting board.
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On a good day, the opening in the parting board will be just big enough to set the plug down into it, and with some shiming it will stay mounted 1/2 of the plug sticking out. Butch Abongan looks over the rig.
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I used modeling clay, mold release wax, and later on the PartAll. The clay works pretty good for sealing the gaps around the plug and parting board. However, we mounted the plug in the evening, and by morning the clay dried and cracked to where we had to do it over again. I may see if there is another recommended way to do this. So, if you are going to do this, I recommend sealing the parting board and moving forward shortly thereafter. It only set us back 45 minutes or so, but was a drag.
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Get set up in a well ventilated area. I've worked with epoxy and polyester resins, and you need fresh air for both. I have a respirator as well.

At this time, you apply the PartAll. This stuff will soak into small holes, and seal the surface yet again. I spray this on with an airgun, but I've seen folks brush it on too. Key point is to cover the plug AND the parting board so it will all come apart after the curing. I kinda sprayed too heavy, so take it easy and apply in thin coats. Also, this stuff will "skin up" on you so over brushing is bad. You'll see the first time you do it.

So, spray the parting board and the plug with PartAll, and let it dry before going on.

The first thing you want to mix up is some resin with Cabosil in it. The Cabosil is light weight filler, and it gets packed around all of the hard to mold corners. Basically, where the relief of the mold is tight or straight up and down, use the cabosil to ensure that the area is sealed and will be "modeled" correctly.

Here, E-True Hollywood Starlet Butch Abongan shows just how thick the mix should be. We also added a blue pigment to the cabosil mix, and the first batch of resin to go on the mold. The coloring comes in handy when laying up fuses, it makes it easy to see when the glass is properly wetted out. (soaked with resin)
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Now, we apply layer after layer of glass. Take the time to make sure that no air bubbles are trapped under the glass. I pre-cut most of the glass because once you start, you are on the clock the whole time and the resin is curing to some degree. We weren't pressed for time and it went fairly well. The first two layers were very thin 3/4 oz glass, and it was a pain to get to lay down. I don't recall anyone going that light before, and I won't in the future. So, I say start off with 2 oz or 4 oz glass, and say at least 3 or 4 layers. These initial layers are capturing the shape of the plug. Then we used the fiber mat which adds strength and filler.

I didn't get photos of us putting the glass down. It is important to start from the mid line of the plug, and dab your brush (stipple?) up and down to wet out the glass. The resin was mixed in 2 oz batches, and I know we mixed several of them. At some point, you can apply the glass "on the bias" which just means that you apply the glass at 45 degree angle to the midline of the plug. This adds strength.

So, once everything has been made bubble free, and wetted out, it is time for the EZ bake oven. I decided to use the EZ bake because the temperature in the garage in winter gets down to a "crazy freaking bone chilling, take your breath away" 55 degrees. The EZ bake with a 100 watt bulb settles in at a cozy 98 degrees. All temps are in Farenheit...LOL..
The lamp gets clipped onto the parting board, and pointed toward the back of the box. I have a little temp guage in there, ask the wifey if you can borrow the turkey temperature probe..!
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So, now it is just a waiting game. I will let the mold bake through the night, and will pull it out the next day. I don't have a hard and fast time for this. Still learning too..

Have a cool beverage and relax. Head stippler Butch relishing in the moment.
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The shop needs some cleaning! Ever notice you clean it up, and it looks like a bomb went off the next day?
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More to follow! [:D]
Vapor52
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Post by Vapor52 »

TH, looking good all the way. I have a mold for 1/12th ME 109 that I made the plug from foam all the way and glassed. What CAD/CAM software are you using?------------rick
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Post by crash_out »

You do have your priorities straight...looks like the beer is on top of everything else and easily accessible....

I wish it was 55 degrees here....
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Post by THend »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by crash_out</i>
<br />You do have your priorities straight...looks like the beer is on top of everything else and easily accessible....

I wish it was 55 degrees here....
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

The beer didn't last long, and the temp has crashed all the way down to 50....[:p]
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Post by THend »

Well, I just couldn't wait any longer and had to see if the plug and mold were ready. So, after poking around for a bit, I decided to go for it.

Take a putty knife, I would have used a plastic one if I had one, and work around the parting board and the flat portion. Take your time, go easy, and you can get a feel for if it wants to go. At this point, I am just trying to get the whole enchilada off the parting board. So far so good.

Here the wife is giving me a hand...
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Now the tricky part, getting the plug out of the mold without damaging anything. I was not too happy about the clay, but in reality it wasn't bad at all. Just need to go slow, take your time and clean out the interface between mold and plug. Then, I usually work from the aft fuse and see if I can get it to POP. Really go easy, and slowly work on getting it to cut loose. Then, migrate more forward, and keep an eye on everything and eventually it will come out. Gladly, the plug suffered no damage.

Now, I am not so sure I was supposed to take the plug out, but I knew I needed to clean up the interface area a little bit, and well the plug will drop right back in.
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You can see where the clay and the parting lines were. It didn't come out as clean as I'd like, but it is still very workable. Hit the bandsaw and sand down the sharp edges, wash with warm water and soap.
Not looking too bad for a combat plane! [:)]
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Now to clean everything up real good. Wax the plug again, and get it seated into the first mold half.

Stay tuned...
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Post by THend »

Ok, plug re-waxed, first half mold cleaned up and waxed. Install plug, and coat edges with PartAll and then spray entire fuse and mold flats with more PartAll. The PartAll is a release agent that will allow the carcinogenic taco to come apart. It is a very thin film. I've seen folks brush it on, and or spray it on. The material will run together and create a smooth finish.

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Here, stipple master Butch shows us that he can stipple faster than the camera can focus. Man, he IS good! Basically at this point we have laid down about 4 layers of 4oz glass with two layers on the bias. We are now laying down the chopped fiber mat that will add volume and strength to the mold. It really can suck up the resin.

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Well, after about two hours it is time to head back into the EZ bake for the night. Whew... time for a beverage.

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Tomorrow, I'll pull the whole mess apart, clean it up and let it set until Friday when we lay up the first fuse. Keeping my fingers crossed that this turned out sweet.

More to follow... [:p]
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Post by THend »

Well it is done. I pulled it apart tonight, and the results are OK, not great, but OK. We had some air bubbles at the wing saddle area, so I'll have to do some minor repair work to the mold, or leave it and sand out the blem every time a fuse is popped out.

The front end has some geometry that I was concerned about due to the multiple angles etc.. just prior to applying the PartAll, I realized I could use some surfboard wax to add relief to the areas where the muffler will be...kinda round out the area more than I had done originally. It worked VERY well, and I am happy with the result.

Had we caught the air bubbles at the saddle I'd be happier, but at least I learned now. When we do the 2610 Spit, we want that mold to come out perfect.

BTW, the SSC Spit and the 2610 Spit use the same wing. NICE!

We have a SSC Spit mold now!
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Here you can see what air bubbles do to a mold. Look in the saddle area just where the saddle becomes the fuse side. Bummer, but not a deal breaker.
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Here is a shot of the front end, and it came out perfect. Man, I was sweating this area.... In the image, I have not cleaned up the area yet, so what you see is surfboard wax residue, partall residue, and even some mold release wax....
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The plan is to layup a fuse on Friday, pull Saturday, and maybe layup fuse #2 ritht away. Butch really wants to roll this out for the Pearl Harbor Classic..
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Ed Kettler
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Post by Ed Kettler »

The results look very good. I can't wait for the next chapter!

Happy Thanksgiving!
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