how to obtain custom RC car bodyshell in Lexan

Customized Lexan bodyshell

Every week, I receive requests from enthusiasts who want to make bodies of their favorite model for their chassis at various scales.

I am happy to reply by e-mail, but it seems to me useful ,since begining,  to present the technique (and the economy) of the manufacture of a car bodyshell or a scale  car model .

Technical solutions

There are 3 methods I use to make a miniature car.
A fourth: the traditional body by forming sheet metal would please me but I do not master it yet. (Some examples are on the forum:  Erik, Pigno or John Elwell..)

john elwell shortnose jaguar d type 02

Fiberglass / carbon, a technique used for racing cars at 1: 1, Thermoforming, the most common technique for radio controlled cars and 3d printing, which is becoming more democratic, making it possible to produce very beautiful bodies and Models.

The common feature of stratification (fiber) and thermoforming is the necessity of producing a mold, which has a cost, to be damped on a series of bodies of varying size.

Design of the master shape

The methods are the same for both techniques, only the shape of the mold changes.

The simplest will be to sculpt or model a model (master) by hand, using plans and photos, and the actual model if you have it  in garage!

An example made in wood (medium) by Claude

Claude @ RCCCB.be

Another in foam concrete by Christian

Cobra by Christian

We can also use Clay / Clay as here Franck Killam

Corvette killam mold 07

The technique I use is the 3d computer design

Renault megane trophy 15 03 jpg

Then machining a block of resin by a moulder (I can do it internally now that I bought a CNC at the end of 2016)

Renault megane trophy 15 13 jpg

The fiberglass body

This automotive technique, but also used for boats or aircraft, has the advantage of being able to be implemented without specific tools.

Once the master realized it will make it possible to make a mold of production. The parts of a mold can be machined directly with a CNC milling machine.

The master is painted, polished and waxed

Then the mold is produced in several parts if necessary for easy demolding.

The mold is waxed, prepared with a special finish that acts as a finish or undercoat paint (Gelcoat), then the body is laminated. The layers of fiberglass or carbon fabrics are impregnated with resin (polyester or epoxy).

The body when polymerized is removed from the mold

Then cut

If you want a painted finish, you need an undercoat, a primer.

Then auto paint

Lexan bodywork

The mold for the Lexan has been machined is ready to serve.

Renault megane trophy 15 14 jpg

If one starts from a master of material not suitable for thermoforming (200 ° C) a mold of the same type as that for fiberglass (negative) can be used to cast resin to make the production mold.

Rod5 lexan forming

The thermoforming can start once the mold is fixed on a metal plate, the setting takes time, which is why we always produce series for thermoformed bodies.

Rod5 lexan cutting

The Lexan sheet is trimmed a first time to reduce the size of the body.

5 axis body trim

Then according to the models the bodies can be trimmed by hand on a cutting template or as shown in this picture using a 5-axis CNC milling machine.

The bodywork printed in 3d

Technische Universitaet Berlin, TUB, Fakultät V, Verkehrs- und Maschinensysteme, Institut für Strömungsmechanik und Technische Akustik, FG Experimentelle Strömungsmechanik, Untersuchungen im Windkanal an einem Automodell, dass im 3D-Labor des Instituts fuer Mathematik ausgedruckt wurde. Im Bild Dipl.-Ing. Dirk Wieser und Hanns-Joachim Schmidt (Mütze)

This technology that has more than 20 years is growing more and more. If amateur printers are really cheap their use is limited by quality (FDM fused wire) or by size (SLS polymerization of resin by led or laser). Professional online printing services allow access to a much better quality and size ,at a price that further limits their distribution.

I reserve this technique for accessories and models.

Economy, manufacturing cost

In conclusion, it is often the price that prevents an enthusiast from having his bodywork. Molds, which are necessary for manufacturing, must be amortized (their price is divided by the number of parts and added to the cost of material and labor) and on a small series the price of a piece is difficult to accept.
One solution is to provide me with a master made by hand or other, in order to have “only” the mold production to manufacture.

That’s why I’m working on single pieces.

The customized production of a body is always possible for a company, a club or a group that wants a series of bodies. Having all the necessary tools on site, you only have to choose the model!

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