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Very Nice molding. À self made body or maybe other spares is very interesting. : y:

stingray-63 wrote:

Very Nice molding. À self made body or maybe other spares is very interesting. : y:

Thanks Stingray! I'm hoping to be able to make other parts as well, thats one reason I chose a smaller size to start with as I didn't think it would go to waste.

the Escort front end I plaster cast has two problems. Basically I mixed the plaster too fast, and didn't make enough, and ended up pouring it in layers. Layers is fine when done properly, but not done properly it can weaken the plaster. Also mixing too quickly and not taking care will introduce bubbles, of which I had a lot of!

So I decided to practice on something smaller to see if I could improve my plaster making skills. The other thing I needed to try is giving the body more support, so there is no movement and distortion. I had tried to plaster cast a damaged Audi Quattro body earlier and found that the shell moved quite a lot with the weight of the plaster. Looking into options I ended up making a basic version of greensand. Using bentonite clay (ground up kitty litter clay), river sand and water, you can make a semi-sticky sand for metal casting.

Here is the setup, using a rally cockpit



formed, dried (the seat tops gave me lots of issues and broke off). I got a lot less bubble this time and the consistency of the pour was a lot better.


This was going to be interesting to vac form with all those deep areas. I didn't expect it to be perfect!


and a side by side comparison. Left is the original, middle it the plaster cast and right is my vac form attempt. There is a fair bit of detail loss. So I might re-do this, casting it in reverse, drilling holes in the deeper recesses. However for a basher it'll be fine.



I'm also doing tests to remove the wrinkles with vac forming the front. I'm almost there and will post once I've sorted that out. One thing I have learned is that I can't adequately can form 1 mm polycarbonate, I just don't have enough sucking power. However 1 mm is overkill for an RC body.

Polycarb also has a narrow temperature range between is Glass Transition temp and its melting temp, about 9C difference. To form properly, the plastic has to be above its glass transition temp, for polycarb that is 145C, but it melts at 155C So another problem I have is that I might be over heating the polycarb I am testing on as its forming bubbles on the surface. Pic below is the best I've been about to do with 1 mm polycarb. Tomorrow the plastic supplier I use should have re-opened (here in Australia pretty much all suppliers shut for at least two weeks over christmas), then I can order some 0.5 mm sheets.

You have good results for "samples". That's awesome

thanks Stingray, I ended up with a lot of test samples! They are all high impact polystyrene though and wouldn't be suitable for a runner.

I had to work out how to avoid wrinkles on the parts of the body I need to keep and finally today I worked that out.




and these are all the test samples I made.



next step is to get some 0.5 mm polycarbonate and to make a new plaster casts of the Escort and I should be ready to make a copy for a runner. I've got a TA02 chassis to mount it too, just have to choose a paint scheme.

I love the escort mk1. more with the mexico arches. for the color, why not a pure white with rothmans sponsors a top runner: a ta02 under an escort mk1 body

stingray-63 wrote:

I love the escort mk1. more with the mexico arches. for the color, why not a pure white with rothmans sponsors a top runner: a ta02 under an escort mk1 body

yeah, I'm undecided at the moment. Although I was considering a copy of Hannu Mikkola and Gunnar Palm's 1972 East African Safari rally car.

yes yes yes. lights could be grasshopper ones

only a minor update. My quest for some 0.5 mm polycarb has been fruitless. The one supplier that stocks it isn't fully open after the christmas shutdown yet, so I am hoping next week will be better. Still I did manage to get some black 1 mm ABS plastic to try, which gave average results. It was shrinking a fair bit when heated (although seems to come back a little after awhile), so I needed to add more clamps to the frame.



Still, I couldn't get the front to vac form very well.


If I want to vac form thicker materials I am definitely going to have to improve on the design. Obviously more vacuum power is needed, but I think I will also need to warm the buck to stop the plastic cooling too quickly.

I think this would be good to make parts like the bonnet if I want to have an opening version. I'm also thinking if I made a mold of a chassis or floor plan that the ABS would work very well.

Re having to put extra bits next to the wheelarches to avoid folds - I'm wondering if the original was formed vertically, possibly with two front end bucks back to back & nose in the air ...