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Widening a GRP nosecone
Beardy_John - 11/12/07 at 11:53 AM

Hi all, supposed to be working from home today, but my mind is wandering on to more intersting things......

Have been thinking about building my chassis 2" wider than Mr Gibbs chassis design (which in turn i believe is about 2" wider than the original book chassis). Problem then is getting GRP for it. Was thinking about getting a standard nose cone, cutting it straight down the middle and using an insert piece of polished Alu or Stainless to span the join, using rivets (to give it an old aircraft style look) and adhesive to hold it. together. Then use the lines of the insert piece up the Alu bonnet and do the same with the scuttle.

Anyone tried this before??


JohnN - 11/12/07 at 12:19 PM

Yes !

I built a McSorley 442, ie 4 inches wider in the cockpit, needing a 4" wider scuttle

I widened my scuttle by cutting it in half and then using a stainless strip to cover the gap. I even used rivets! See picture in my Photo archive.



My nosecone wasn't widened, but I imagine it would be simple to do, and would give you the option to have a tapered gap if that fitted the chassis rails better.

[Edited on 11/12/07 by JohnN]

I assume the archive pic won't display, 'cos the jpg filename has spaces in it??????

[Edited on 11/12/07 by JohnN]


James - 11/12/07 at 12:24 PM

Bit revolutionary I know but what about buying a +4" nosecone.

Cheers,
James


twybrow - 11/12/07 at 12:37 PM

Why not widen and finish it with gelcoat/GRP? No visible join and no reflective stainless bit to put you off when driving!


AdamR - 11/12/07 at 01:30 PM

I have the same job to face up to next year.

GTS sell +4 bodywork, but it's not too pretty in my book. And then there's the inevitable battle to get it delivered once you've parted with the cash.

I'm toying with the idea of making my own custom bodywork but I can see that extending the project by two years!

I quite like the idea of a stainless/ali insert.


sammy - 11/12/07 at 01:36 PM

That's good timing, I have only just got hold of a second hand nose cone that I need to widen for my +4 chassis.

I hadn't thought about riveting a strip down the middle, that might look OK.

I'm just a bit worried about it turning into a mess if I try to use gelcoat/grp as I have never used gelcoat before, and my grp repairs to my race plastics were always functional rather than presentable!

Anyone got any pictures/advice on their efforts?


Beardy_John - 11/12/07 at 01:45 PM

JohnN - Thats exaclty what I was looking for!! How spooky.... Looks pretty nice too

I know there are companies out there who make them, but I get the feeling some of them arent the easiest to deal with. Rather have a proper "locost" solution to it.

I could do a GRP fill-in, but as said above, I have no experience and would probbaly just end up bodging it.

Think I will have to draw one up in 3D to see what it would look like. Does anyone have drawing plans for a standard "book" scuttle and nosecone???


Ivan - 11/12/07 at 02:36 PM

I will be doing something similar shortly.

What I plan to do is to first polish up the nosecone suitably.

Then lay gel coat and fiberglass where I intend to cut

Then remove it

then cut the nosecone and spread it

then bolt on removed fiberglass over empty portion, to use as mould, turn it over and lay fresh gel coat and fiberglass with 50mm overlap, remove mould and sand and fill accordingly.


iank - 11/12/07 at 02:52 PM

Mr Whippy widened some cycle wings with step by step pictures here
http://www.locostbuilders.co.uk/viewthread.php?fid=4&tid=62375

A nosecone would be a bit more awkward due to the shape, but the theory is sound.


twybrow - 11/12/07 at 05:32 PM

Take Mr Whippys technique, but instead of going straight in with the GRP, put a good coat of gelcoat +wax (flow coat) first. Then layup your GRP. Remove the temporary mould surface, fill in any holes, then sand it back flat. Voila!


Dick Axtell - 11/12/07 at 06:01 PM

quote:
Originally posted by iank
Mr Whippy widened some cycle wings with step by step pictures here
http://www.locostbuilders.co.uk/viewthread.php?fid=4&tid=62375 />

Thanks iank, for the thread indicator. Good guide for me to widen a grp bootbox. Came from a W**t****d, but unfortunately, narrow-bodied!

LoL
Dick


mark chandler - 11/12/07 at 08:00 PM

Make sure you cut it in half with a wavy line..... i.e do not cut straight down the middle but in wide S cuts, 2" wide.

This has a few benefits:

Extended edge when bonding
Extends the contors when joining
Relieves the chances of it cracking as no straight line
Much easier to flatten, no unslightly join lines to hide.

Mines got an extra 2" doing this
Rescued attachment small10sept2006.JPG
Rescued attachment small10sept2006.JPG


Ivan - 11/12/07 at 08:50 PM

quote:
Originally posted by mark chandler
Make sure you cut it in half with a wavy line..... i.e do not cut straight down the middle but in wide S cuts, 2" wide.




I specialise in cutting wavy lines - its the straight ones that are the problem


Syd Bridge - 12/12/07 at 11:53 AM

quote:
Originally posted by twybrow
Take Mr Whippys technique, but instead of going straight in with the GRP, put a good coat of gelcoat +wax (flow coat) first. Then layup your GRP. Remove the temporary mould surface, fill in any holes, then sand it back flat. Voila!


Now, Mr.Twybrow, you think I have a vendetta against you. I don't. Just against misinformed BS.

Firstly, the wax in Flowcoat is meant to come to the outer surface, to keep the air off and form a seal and stop the surface being 'tacky' to feel. I've seen this ballsup more than a few times in local boatbuilders sheds. Someone puts Flowcoat on a mould instead of gel. And it's not discovered umtil the hull is released. 40+ feet of rubbish,...then some!!!!

If the job were done as you describe, the gel and grp layup will separate!!! ie. The wax in the flowcoat will not allow the grp subsequently added, to stick to it.

Beardy, put ordinary gel in, then layup onto that, and all should be well. The wax goes on the bit attached on the outside to widen it, and act as a temp mould. Not IN the gel!

Cheers,
Syd.


2b_pablo - 12/12/07 at 01:18 PM

buy 2 nosecones, cut one up the middle, cut the ends off the other one and join the middle section to the two halves?

^^ did that make sense?