Laminating The Nissan R89 C Part 1

LAMINATING THE NISSAN R89 C by Alan C Paterson Step by step to making the Nissan R 89 C Model Slotcar Body. Part 1

Adding on the Erlo's previous article on laminating a body, this is my personal "step through" with pictures, of the process involved in making this Awesome Nissan R89 C body for use in the LEGENDS series. Ampreg 21 Epoxy laminating system Ampreg 21 has been optimised for the manufacture of large composite structures using hand layup, and vacuum bagging techniques. The relatively low initial mixed viscosity of Ampreg 21 allows easy wet out of heavyweight reinforcements. It has been formulated to provide excellent Health and Safety. Ampreg 21 has been designed to give excellent mechanical and thermal properties from both ambient temperature cures, and moderate temperature post cures (50°C). This system is available with a range of non-pigmented hardeners, from Fast to Extra Slow. Ampreg 21, and Moldmax Silicone plus other laminated products are all available from John Soper at AMT Composites. Ok, there's going to be some repeats from Erlo's article, but the general topic of discussion, is how to go about making your own Body for use in Model Slot Car Racing. Laminating a body for Slot Car use is the art of reproducing a body using Fibre Glass and Resin. This is achieved by moulding the original car body in silicone and then layering fibreglass and resin into the mould to produce a replica of the original. For this article, we're already assuming you've made your Silicone Mould, as covered in Erlo's article. We start ready to do the whole laminating process. The first step is to mix up your Epoxy for both the Gel-coat (top covering of the body), as well as "laminating" or "laying-up" the fibre matting which gives the body it's strength. My product of choice is using small, paper cupcake holders, very cheap for a pack of 50 at your local grocery store. Using your accurate Digital Scale, pour out 10 grams of Ampreg 21 Epoxy Resin, followed by 3.3 grams of Fast Hardener. About half a teaspoon of White Pigment, especially formulated for use with Epoxy resins, and it helps to produce an almost pure white body, ready for cleaning and primer before painting. Lastly, about two teaspoons of fine white powder, all obtained from AMT, and this is used to thicken up the mixture. Then, using a long matchstick, mix this concoction up until it's a smooth, lump-free runny gel. It actually has the consistency of thick white house paint at this point, and total weight of this first "Gel-coat" mix is approximately 15 grams. HOUR 1

Next step, we take a small paintbrush, and we "paint" the mixture into the prepared, clean, and slightly waxed up mould. This is a kind of polish, very similar to floor wax, and is a good release agent to help get the Ampere-cured body out the mould at the end of the process. Being very liberal with the brush and resin, simply paint up the entire inside of the mould, and flow over the existing base of the body in the mould, so that there's a consistent thickness of the product all over the body going well below it's actual bottom line, or window edges. This excess will be ground away with a dremel in the Body prep later on. Finish the entire dish of Epoxy resin in this first process. I'd guess there's a good 1mm of "thickness" throughout the body.

The powder you mix into this mixture is to help keep the resin in the mould, including on all the high surfaces, so it doesn't ooze down and pool in the lower areas. It stays on the sidewalls and high points, and looks like, ermm, thick cream, white paint, as you can see below. Also make certain you get the product under all the small crevasses like vents, and body lips, ledges, etc. The other advantage of making the pigment white besides a good base colour is you can see how well you've covered the Pink Silicone Mould.

You can clearly see the A frames and side windows are almost completely laminated closed. This is needed later on when you dremel out the windows, to leave a small "ledge" about 1mm of surface material which the vac-formed windows can be glued on to. So you always laminate over the exact bodylines and edges. Now, I place the entire silicone mould into the oven, just on 50 degree's, for about 30 to 40 minutes. It needs to be slightly tacky to the touch, to help hold the matting in place. Next, I get my fine glass matting, and cut a sheet about half an A4 page in size. I guess it's around 60 to 80 g/cm, it's VERY fine, and has the texture of woman's stockings etc. very light and fine, and bends and conforms easily to the edges and lumps in the mould. I then cut this into rough rectangles, about 2 x 1 cm in size, not 100% accurate, but small pieces which we will then lay-up in the mould.

I then mix another identical weight portion of epoxy as before, and then take the mould out the oven, it will be slightly warm to the touch, and the gelcoat is on it's way to setting up hard, but still slightly tacky. Now you start layering the squares inside the mould by hand. The Gelcoat should not be sticky that it's sticking to your fingers, because then the matting just disintegrates. HOUR 2

There's no exact science here, just make sure each piece overlaps by 1 to 2 mm's over the other piece. What you're attempting to do is completely cover the entire gelcoat with glass mat, which will give the body the strength needed. I do this process once, then let it cure, and then do it again around the front, sides and back of the body, so it's double layered for added strength.

Eventually, the entire body will be covered. Now you need to "laminate" the matting with the next mixture. Take your brush, and gently but firmly "dab" the mixture onto the matting. You are now impregnating the mat with the resin, or "wetting up" the matting. You’ll be able to "paint" in the resin in certain parts, but sometimes it starts picking up the matting and disturbing your layup, that's why I dab the epoxy all over the matting, completely covering the sheets with the entire mixture.

Eventually, you'll have the entire body covered again, and you'll only just be able to see the matting. I'd hazard a guess the thickness is between 1 to 2mm thick at this point, and the mould already feel rigid, it's no longer flexible. The Gelcoat is already curing now, and the second layup coat with the matting now needs to cure onto the first coat. HOUR 3

At this point, it's back into the over for another 45 minutes. Essentially, that's it. If we add up the two total pot mixes of resin, we've used approximately 28 grams of Resin, (2 x 14 grams of mixture), and the total weight of the matting is around 4 to 6 grams. So the body weight in the mould, before we grind off the excess, is around 30 to 32 grams. In my opinion, this is strong enough for model car racing, but, you can still strengthen it further by adding a third, half-coat of about 7 grams of mixture and some more matting around the nose, wheel arches, and the rear of the body. This makes the bottom, front and rear of the body extra strong to withstand crashes in racing. I then leave it in the oven switched off now, overnight, for

around 12 hours to fully cure and go hard. The heat helps keep out any possible humidity and moisture, and the Ampreg product cures stronger with gentle heat processes.

Reproduced with the author`s permission – John H Green