Stirlsilver's Disco Ute Project

First off great work I love the whole disco ute concept !

You can use regular polystyrene as your mould plug, all you need to do is wrap it in glad wrap and tape over any possible exposed areas. I use this method for making carbon ram air tubes/airboxes for race bikes as well as for various fairing parts.
It's cheap and you can shape the foam with a plaster "sponge" sanding block.

It looks as though you've settled on your winch box design. If it where me I'd be lapping those little gusset doublers over the chassis extention rather than corner to corner. I think the biggest issue you will have is twisting from the top (as the first model shows) possibly some ribs (25x5 flatbar on edge) on the outside of the 8mm plate and then under the large angled plate? It wouldn't really triangulate it but would make it a lot harder to twist it.

Ash.

Alright, I'm back... For now.

I spent another night in the workshop. But first thing is first. I got hold of of a back wall and rear window of a 2001 Nissan Navara. Nice and flat panel which should be a bit easier to work with:

https://www.aulro.com/afvb/images/im...12/02/1264.jpg

I have come up with the idea that I will use a high density 2 part Polyeurathane Foam. I will form a rough shape of the roof using MDF sheets and the ribs I cut out previously and pour in the foam and get it to expand and take up the rough shape I need. Then I'll profile the roof down to the shape of the ribs and glass over the top.

So I started by bonding in the ribs and then mounting a back plate wrapped in cling wrap (so that the foam doesn't stick to the board). The plate was held in with wire off the ribs:

https://www.aulro.com/afvb/images/im...12/02/1265.jpg

https://www.aulro.com/afvb/images/im...12/02/1266.jpg

Various small gaps were sealed with silicone. The plan is to now go around the outside with some sheets to form the rough outer profile. I only got to the stage where one was mounted before it was 11pm and time to go home:

https://www.aulro.com/afvb/images/im...12/02/1267.jpg

https://www.aulro.com/afvb/images/im...12/02/1268.jpg

Next time i'll continue installing the outer panels and doing the tricky corners. Then maybe I'll be ready to pour some foam!

Well I am finally at the stage where I need to buy the polyeurathane foam mix it and pour it in to form the roof! Exciting times!

https://www.aulro.com/afvb/images/im...012/02/565.jpg

https://www.aulro.com/afvb/images/im...012/02/566.jpg

https://www.aulro.com/afvb/images/im...012/02/567.jpg

https://www.aulro.com/afvb/images/im...012/02/568.jpg

https://www.aulro.com/afvb/images/im...012/02/569.jpg

Should be interesting next weekend.

First of all, I love your work and the CAD drawings are fantastic.

I've tried to follow it when I can but haven't had a look in a while.

I don't know if you have covered this already but why did you just not use steel and weld it in.

Much quicker and easier than what you are doing there.

You may have had to do it in 3 sections but the roof is steel so it wouldn't have been a problem to stitch it together with the MIG and then a bit of filler to clean it up.

You will now have the problem of matching the glass down to the roof level and trying to make sure you get a reasonable finish from the matting surface as it wont be like an out of the mould finish with gell coat.

You will still have to use filler to get a good finish in the end.

Cheers Casper.

Thanks for the feedback Casper.

I know I could have used steel to do the roof and I have seen a number of people who have done these sorts of modifications graft on parts of roof sections to get the profile they need.

Because I am going with a customized shape for the roof onto the rear wall, it would be very difficult for me to find pieces of steel which were close to the profiles I would need. So that would mean I would have to shape up the steel and I don't have access to the sort of equipment needed to do that.

So... basically my only option was to go with Fibreglass. I know I am going to have a few hours of sanding coming up, but with the ribs embedded in the foam, at least I have some profiles already there so all I need to do is take the mid section down to the rib profile and then shape the corners. After fibreglassing I agree I'm going to have to do a fair bit of work to get a nice smooth surface, but that will come with working it.

Ok, an update from the work over the last couple of weekends:
I mixed and poured the foam into my mold. Below is the result after I pulled the mold off:
https://www.aulro.com/afvb/images/im...012/03/909.jpg

The inside didn't expand to the point I was hoping it would so it means I'll need to spend some time adding more foam until I get it up to the roof. It shouldn't be difficult to do this though:
https://www.aulro.com/afvb/images/im...012/03/910.jpg

After spending some time with a strip of ply wood and some 80 grit sand paper I got the profile down to what I wanted it:
https://www.aulro.com/afvb/images/im...012/03/911.jpg

https://www.aulro.com/afvb/images/im...012/03/912.jpg

https://www.aulro.com/afvb/images/im...012/03/913.jpg

For the coating of the foam I was considering perhaps not bothering with layering the foam with fibreglass but instead just running a few coats of epoxy over the top. Does anyone have any thoughts on this? I'm just not sure if I do it this way, if the surface will be hard enough to handle minor knocks.

I would use some glass cloth otherwise it will not have any strength and will crack when knocked. Without the fiber the crack will keep running and want to peel off in chunks.

Nice work, haven't stumbled across this thread before. Have you fitted crush tubes to the winch extension?

Quote:

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Originally Posted by slug_burner

I would use some glass cloth otherwise it will not have any strength and will crack when knocked. Without the fiber the crack will keep running and want to peel off in chunks.

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What he said. Glass over it or it will crack like crazy - especially where steel meets foam.

I have seen panelbeaters make up shapes like you have there using minimal tools - hammer and a couple of blocks of steel as dollys.

Bog hides a lot of imperfections....

Thanks for the input guys, I'll glass over it then. I can see how it would be very easy for the two materials to separate at the joint if I leave it this way.

Isuzu - on your comment about crush tubes. I'm assuming you are talking about the SHS I added in behind the winch mount as spacers?

When I welded them in, I thought about the crushing scenario and I figured that given that it is 3mm thick steel and tha the SHS is only 40x40mm, it would be very hard to crush. But on thinking again, why risk it, it's easy enough to add them, so I'll do that.

Quote:

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Originally Posted by stirlsilver

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Isuzu - on your comment about crush tubes. I'm assuming you are talking about the SHS I added in behind the winch mount as spacers?

When I welded them in, I thought about the crushing scenario and I figured that given that it is 3mm thick steel and tha the SHS is only 40x40mm, it would be very hard to crush. But on thinking again, why risk it, it's easy enough to add them, so I'll do that.

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Yes... Try rerunning your FEM with the SHS added - plastic deformation for sure. Won't be catastrophic, as it is in compression, but the bolts will work loose, etc...

I would use at least 6mm wall for the crush tubes as they will have most of the load.