Making a large composite mold of complex shape. Part 1: Shaping the plug.

[@andreschavarria1450]

Next and last part on mold-making is ready and online: kzbin.info/www/bejne/q5OphWt_f6aSiqc

[@SteveVon7]

Wow, it is so sweet and awesome to see husband and wife, (or bf and gf) working together like that, pretty cool.

[@emrage]

I've been toying with the idea of making a negative mould of interior panels of an aircraft for months. Literally tonight I had the idea of splitting the window panel into several boards and carve them up to the right shape with templates. Then stumbled upon your channel. Thank you for your instructional videos on XPS foam!

[@phani8482]

why isn't this video more famous

[@andreschavarria1450]

Spread the word, and it will get famous! In my opinion, this is one of the few ways to go for small companies and hobbyist.

[@vincentbarkley9121]

Very impressive; you do great work.

[@matthewmoilanen787]

I realize it's been a while since this was posted but your wife has been an awesome help in your videos! Did she get the first flight?

[@andreschavarria1450]

We're still working on the wings. So no maiden flight till now ;-) You find more on the current status on our Intagram account (instagram.com/hortenmicrolight) or on our blog (hortenmicrolight.wordpress.com/)

[@kareemtarek2]

could you please provide me with a reference to learn more about software designs to build a monocoque mold ???

[@isabel6343]

Hi! Is this mold suited for prepreg?

[@rirogamer1]

Gracias por los videos, I will try do use your method to build a shell for a velomobile...I heard Spanish and German in the background, BTW I lived in Stuttgart for four years!

[@andreschavarria1450]

Glad you liked the video. I hope it helps you to make your velomobile.

[@fsxx123]

Thank you for making the video! How thick was the foam you used?

[@andreschavarria1450]

The foam was 10 cm ( 4 inches) thick. The optimal thickness depends on how curved the shape is: The more curved the thinner the foam should be.

[@illiachyrva612]

Hi. Thanks for the video. My concern is how do you control the dimensions of the mold? It is critical for the aircraft

[@andreschavarria1450]

The shape is controlled by using templates. The method presented has a general precision of about 1 - 2 mm at the size of this mold (2300 × 700 × 700 mm). If precision below 1 mm is required, other methods, such as CNC machining should be considered. However: Though keeping a prescribed shape is important for aircraft, usually fuselages, cabins, etc. of light sport aircraft are desgined by their looks. It is more important achieving a wave free and smooth surface than perfectly keeping a shape that was anyway freely desgined in the computer ;-) CNC machined plugs/molds of that size are very expensive, require a perfect 3D drawing (wave free), and modifications of the shape are much more difficult to conduct afterwards.

[@Alhussainba]

@@andreschavarria1450 Wondering if 3d printing will be a good option, the mold can be divided into different parts to be printed separately, internally it can be printed hollow or with little infill to save on cost, time and weight. And the tolerances can be as low as the quality of the 3d printer (which is pretty good even for cheaper models nowadays)

[@andreschavarria1450]

@@Alhussainba 3d printing molds is possible and I've heard of people using them for small pieces. However, the surface quality I've seen from usual printers is far from that what you get with the presented method. Also, you need a very large printer to make parts the one shown, and the mold produced has quality and endurance for a series production. Though good 3d printers have became much more accessible in price, machining block material with a CNC is probably still the better option to make single use molds on the fly.

[@dejayrezme8617]

Thanks for the video! What foam do you use? Is there any place where you can buy hard foam in quantity and CHEAP? Compared to insulation PU foam, the shipbuilding foam is very expensive.

[@andreschavarria1450]

We use Styrodur® CS 3000 from BASF, which is an extruded polystyrene foam (XPS) of mid density. You can buy similar products from other companies, such as Jackon Insulation (JACKODUR). Compared to expanded polysteren (EPS), it can be sanded very well. With 240 grit or higher you can produce very good surfaces. I've heard of people who use thin sheets as a core material. I would myself stick to Rohacell®, AIREX®, etc. for that application. PU foam cannot be cut with a hot wire, tends to "sand" all the time, and is more sensible to mechanical damage. Styordur® isn't really cheap, but the price is ok and is easy to get in quantity, because people insulate complete facades with it.

[@dejayrezme8617]

Thanks for letting me know! I read quite a bit about foams the last weeks. I didn't think XPS was strong enough for these applications? I thought it had the least amount of shear strength, even less than low density PU foam. But this "friability" (crumbling into dust) seems to be the problem with PU foam. There is some formulation of denser PU foam used for truck builds that apparently is more elastic and can withstand the vibration and bending without crumbling.

[@RamaKrishna-kc5mo]

I want to buy rohacell. But I don't whether it can be cut using hot wire and can be sanded using sand paper. Can you please clarify regarding me about rohacell?

[@andreschavarria1450]

I haven't used Rohacell, but from the datasheet I would not expect that cutting with a hot wire will work well. It is temperature stable up to 180 °C, which is roughly twice as high as for XPS. Sanding should be no problem. Usually Rohacell is used as a core material for sandwiches in more or less thin sheets (couple of mm to a couple of cm). You can easily and precisly cut it with a sharp knive. Are you going to use it for a plug? If yes, then I would advice to use XPS instead, which is much cheaper and easier to shape. If you are going to use it for a sandwich core and you have complex shapes, then I would suggest to use a CNC router.

[@andreschavarria1450]

Part 2 on covering the plug should be in a couple of seconds online: kzbin.info/www/bejne/p3PLd6qted6YfqM

[@SuperMarioJustin4]

Am I the only one here who cringes to the sound of styrofoam rubbing?

[@cazadorczdr6788]

1:50 hahahha sorry

[@andreschavarria1450]

If it doesn't hurt, it's not good :)