mark chandler
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| posted on 26/5/06 at 02:15 PM |
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Bonnet edge
Hi All,
I,ve now reached the bonnet stage.... Looking at the archives it looks like everyone has merely cut the bonnet to the scuttle and nose cone, has
anyone bothered to turn the edge back on itself for a neater finish ?
If so what problems did you encounter.
Cheers Mark
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shortie
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| posted on 26/5/06 at 02:19 PM |
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If this is an MK bonnet you shouldn't have to cut anything, it should fit exactly between the scuttle and nose cone.
Rich.
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02GF74
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| posted on 26/5/06 at 02:32 PM |
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what can be neater than a cut straight edge?
I suspect with bending the edge, you may make a mess unless you have a sheet metal folder and it would need to be done before the bend so it may not
fit if you get it wrong. How do you propose to bend it once curved? pliers and the such will mark the metal so read the first sentence 
as someon who has recently spent a load of time on a bonnet, it ain't worth it.
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Hellfire
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| posted on 26/5/06 at 02:38 PM |
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As you're building an MK... the bonnet is fibreglass. DON'T BEND IT!!! It is made to size and adjustment of scuttle/nose cone is required
for it to fit properly...
If you're referring to manufacturing your own aluminium one - good luck!
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DarrenW
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| posted on 26/5/06 at 02:39 PM |
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Fibreglass bonnets sometimes need trimming. The edge then covered with u trim 9 i got mine from Mac#1). Gosforth VOSA require the edge trim to be
bonded on.
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mark chandler
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| posted on 26/5/06 at 03:23 PM |
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Scratch built so I,m making as much as I can.
The reasons for wanting to turn the edge are two fold
1) no sharp edges.
2) It will make the ali more rigid when bent to shape around the scuttle.
I do have access to a sheet metal bender but I do not think flattened out the edges would be straight.
Anyway is no-one else has bothered then neither shall I.
Cheers Mark
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Ian Pearson
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| posted on 26/5/06 at 03:34 PM |
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I did! Mainly for rigidity. Took it to a metal shop who used a sheet metal folder. The only problem was that despite careful measurement, and marking
the edge of the fold, the guy got it wrong. The edge is a couple of mil out. Having made too many bonnets to mention, I've accepted this one as
the final one!
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pajsh
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| posted on 26/5/06 at 03:58 PM |
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In Exterior Projections SVA manual says sheet metal edges must be folded back 180 degrees on themselves (13.3.e). It doesn't really say if this
is an exposed edges or any edge.
To be sure I put 5mm beading on all exposed edges (suspension holes etc) including the bonnet front and rear even though it is flush with the scuttle
and nose cone.
How long it will stay on after SVA I'm not sure
FRP panels must have a radius not less than 1.5mm. (13.3.k)
[Edited on 26/5/06 by pajsh]
I used to be apathetic but now I just don't care.
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Fozzie
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| posted on 26/5/06 at 04:17 PM |
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Mark, all edges of my bonnet have a return!
Fozzie
 
Rescued attachment 1aFozzie.jpg
'Racing is Life!...anything before or after is just waiting'....Steve McQueen
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GeoffT
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| posted on 26/5/06 at 08:05 PM |
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My first attempt at a bonnet was going to have 180 degree returns at the back and front edges. It's actually very difficult to form these, as
the edges are not straight lines, meaning you have to lose or gain metal as you fold it. You can't put a 'snip' in the return
either, as when you try to form the curves it will always 'give' where the cuts are.
Eventually I gave up with this, and just fitted some U-trim over the plain edge, which gave a perfectly good result. My advice is, unless you're
highly skilled in sheet metalwork (like Fozzie....!) and have the right equipment, forget the returns.
Geoff.
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