Talk Composites - The Forum for Advanced Composites

Accurate double curvature techniques

http://www.talkcomposites.com/Topic21157.aspx

By Ian Mantula - 4/28/2016 11:44:37 AM

Hello pattern making experts.
I am trying to make a series of plugs for some new engine bay parts for my Marcos Mantula. I'm really hope to get some advice on the best techniques for creating complex shapes with some double curvature. While I'm getting close to the shapes that i want it's still not 100% perfect. I seem to be a perfectionist without the skill to achieve the results that I am looking for. Are there any special tools available from anywhere that make it easier to shape, for example, a concave curve with a varying radius? 
I am building the plug using an MDF structure with expanded 2 part foam for the curvy parts then covering that with polyester bodyfiller. After that Easy Composites Pattern coat primer and top coat.

I'm using Permagrit tools to rough-out the shape, then various home made sanding blocks after that.

In the photo below the box with the lid is for the air-conditioning system. In front of that there is the internal mud-guard. The double curvature is essential due to the shape of the Marcos bonnet. I'll be doing a mirror-image for the other side of the car.

Perhaps the only answer is years of practice...
http://www.talkcomposites.com/Uploads/Images/ed893c8a-2c9b-4570-b0e4-d465.jpg


Thanks for any suggestions.
Ian
By Hanaldo - 5/4/2016 1:03:57 PM

Yeh panel beating is another skill of its own. You need to sand the panel as a whole, not concentrate on getting one area smooth before moving on to another area. And this definitely needs to be done with a block, there is absolutely 0 chance of getting a flat surface if you are sanding by hand. 

A trick the panel beater I work with taught me is to rub a piece of glass before you feel your part, and then close your eyes when you do. This really sensitises you to the ups and downs of your part. It also helps, once you think your surface is close, to spray a light coat of primer over the surface just so that the surface is all one colour. Varying shades of body filler etc can all mislead your eyes, so a uniform colour helps. Once you've done that, rub the primer off again using your sanding block. This will reveal any high/low spots etc.