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Here's an update on the Bentley...



most of the shut lines are on and bonnets vents are done...



rear windows sorted out....

but it was the grille that has taken a lot of time. Due to its shape - curved in two directions I had to try several ways of producing a pattern for it and finally (three moulds later) came up with this....



The original pattern is on the left, the other two pieces are castings from the first two moulds. The pattern was made by using air drying clay for the shape and fit into the body, this shrinks so some resin filler and cling film was subsequently used to get the final size. This shape was then covered with double sided tape and the grilles were applied using fishing line (I first used card strips but these were too thick) ....



The problem with the first two moulds was the that the grilles were breaking when releasing the casting from the mould as you can see in the 1st picture. After a some time head scratching
wondering why this happened it finally dawned that the silicon was getting under the fishing line because its circular in cross section. So coated the pattern in PVA to blend the transition between the grilles and now I've got a decent looking grille for the Bentley....





If anyone knows an easy way to do grilles like these please let me know
 

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Alan Tadd
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4,029 Posts
Excellent Marlon.

A very good solution to a very difficult problem. The car is really looking something very special now. Congratulations.


Regards

Alan
 

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As always it is a thrill to watch you work. Thanks for taking time from the project to share it with us.

My lack of knowledge, experience, and skill will only permit questions. Once you've crafted a pattern for this type of complex curve, would it be easier to vacuum form it rather than try to cast it?

Would it be easier to work in wood? I think that even small sign companies have the capability to do precision cutting in wood with laser tools. Once the shape is crafted, could the ridges in the grill could be cut by laser?

Last, since the grill piece could be precisely modeled in a 3-D modeling program, I wonder if it would be possible to take the software model to a machine shop for cutting in metal, wood, or plastic? Or perhaps the clay prototype could be measured by lasers that then control machines that do the forming. Maybe that's too expensive now but something the future might hold.

Just casting about in a probably vain attempt to brainstorm - no reply necessary or expected!

Paul
Circuit TrustChrist
 

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Fab Marlon! You win the prize for dedication and ingenuity!
It's looking really wonderful and well worth all your excellent efforts.
Inspirational!
 

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Administrator
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Beautiful work Marlon. With the amount of time and effort you've put into this car you must be living, eating and sleeping Bentley.

David
 

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Discussion Starter · #9 ·
Thanks for all your comments, really appreciate it.

QUOTE (pault86 @ 7 Jan 2005, 08:49)Once you've crafted a pattern for this type of complex curve, would it be easier to vacuum form it rather than try to cast it?

Would it be easier to work in wood? I think that even small sign companies have the capability to do precision cutting in wood with laser tools. Once the shape is crafted, could the ridges in the grill could be cut by laser?

Last, since the grill piece could be precisely modeled in a 3-D modeling program, I wonder if it would be possible to take the software model to a machine shop for cutting in metal, wood, or plastic? Or perhaps the clay prototype could be measured by lasers that then control machines that do the forming. Maybe that's too expensive now but something the future might hold.

Circuit TrustChrist
<{POST_SNAPBACK}>

Paul, a vacuum form wouldn't give me the detail I need for this piece but I am going to try a vacuum form window piece. If I had the funds and was going to make many of these the production method I would choose would be a photo etching for the grille. The etching would be flat but a former could be made to press to the correct shape afterwards, that would look really good then
and is fairly common in die cast kits.

Marlon.
 

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Hugely impressive. Makes me want to just give up on my own crappy projects and get another hobby like R/C or binge drinking or something!


Coop
 
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