I want to make this following dome shape. I have a couple of options for materials and I would like some opinions/advice for how best to do it


Option 1
Form it out of 1/8 Ali sheet, by far the preferred method, already have materials though my ambition may outweigh my metal shaping skill. Though could make in sections

Option 2
Form it out of 0.9mm steel sheet, already have materials though again my ambition may outweigh my metal shaping skill. Again could make it in sections.

Option 3
Make it out of fibre glass, easily within my capabilities but would have to purchase the material and I don't really want to make it out of GRP

Any advice?

Personally, fibreglass then foam filled for strength.

More or less as above, but I would make the shape first out of polyurethane foam, and then lay glass matt / resin straight over it - moldless construction. You could get to that stage in a weekend.

Applying filler and sanding to get the finish would take a bit longer though.

If you want to make more than one, then glass for sure, make a mold from the first one and you are in business

Cheers

Fred W B

[Edited on 16/3/11 by Fred W B]

That's made from upholstery grade pu foam, high density, with leather or vinyl upholstered to a 6mm mdf base by the look of it

Hi Liam

Nice little project. I think I'd go for your option 2 and use 0.9mm mild steel. 1/8th aluminium would be terribly difficult to form.

The steel will shape quite easily and welding should be straightforward. I'd make a station buck along the lines of the one I made for the Clamshell Wings in the Tools and Techniques section and then decide how many pieces to make the piece in. It is best to have the joins on the curve to avoid distortion when welding. Cut paper patterns and then mark onto the steel allowing 10 to 15mm oversize. You can put the shape in using a bossing hammer and sandbag and then planish with a hammer and dolly. Each piece should fit nicely on the buck. Once you are satisfied, trim so that one part buts up to the next with no gap and then tack every 25mm to prevent distortion when fully welding. Prior to fully welding, using a hammer and dolly make sure the edges of the steel are still flush with each other and that any distortion is removed. Once welded the weld can be filed and planished ready for finishing.

Do hope you taske the metal route and look forward to seeing your progress. Best of luck.

[Edited on 17/3/11 by 2cv]