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Sheerline Type VII

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Sheerline Type VII

Postby Polycell » Sun May 23, 2010 7:28 am

My Sheerline type VII has just come to the top of my 'get opn and do 'list. It got shelved cos I was having troubles minimising the gap, when joined, of the two halves of the hull.
So come on someone how the hell do | fill the gap?
I have tried all sorts. I tried cellotape on one half of the joint joining the two halves making secure and then putting filler in the gap. It worked!!! but taking the two halves apart and taking the tape of the gap magically reappears. Grrrr
Now I am beginning to wonder if its something to do with the fact that the two halves are flexible ie easily flexed when squeezed.
So my next plan is to reinforce the the two haves by building frames from fibre glass matt.
Question anyone got any good ideas. Please.
Thanks Fred
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Re: Sheerline Type VII

Postby Wheelerdealer » Sun May 23, 2010 8:09 am

Will the 2 halves come together with light pressure? How are the two halves joined together? Sometimes using 2 screws to hold the top and bottom halves will exert enough pressure to close the gap.
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Re: Sheerline Type VII

Postby Polycell » Sun May 23, 2010 12:35 pm

Wheelerdealer wrote:Will the 2 halves come together with light pressure? How are the two halves joined together? Sometimes using 2 screws to hold the top and bottom halves will exert enough pressure to close the gap.

The two halves when in place are kept together with a 'device' at the forends, a 4mm bolt at the after ends and a set of ultra strong magnets(three each side) down the sides.
Yes I can almost squeeze the gap out of existance.
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Re: Sheerline Type VII

Postby JWLaRue » Sun May 23, 2010 3:38 pm

Can you post some photos? It's hard to understand where and what the problem is without them....

-Jeff
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Re: Sheerline Type VII

Postby Polycell » Mon May 24, 2010 12:56 pm

Image
Piccy of the gap!
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Re: Sheerline Type VII

Postby Sub culture » Mon May 24, 2010 1:11 pm

I've seen a lot worse to be honest. Looks like you just need a bit more glass in there if you want the gap a hairline width.

I'd sand those rivets off whilst I was at it- never liked those, way over scale.
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Re: Sheerline Type VII

Postby Wheelerdealer » Mon May 24, 2010 1:18 pm

That really is a small gap. Looks like you may already have filled some with filler. Looks like just a little more will do it. Otherwise, I think a couple of bolts screwing the top hull to the bottom and tightening will do it. As the WTC is in the way you will need to come up with a way to get around it (eg a bent semicular brass bar attached to the bottom hull, that goes over the WTC; screw the top hull on to this bar)
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Re: Sheerline Type VII

Postby JWLaRue » Mon May 24, 2010 1:47 pm

That gap isn't too bad (as others have said)....but for the anal modelers amongst us.....

You could install some tabs on the upper, inner lower surface so as to force the two edges together when the upper is locked down to the lower. This would eliminate the almost certain problem where the hull will want to slowly open up over time.

-Jeff
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Re: Sheerline Type VII

Postby Polycell » Mon May 24, 2010 2:10 pm

Sub culture wrote:I've seen a lot worse to be honest. Looks like you just need a bit more glass in there if you want the gap a hairline width.

I'd sand those rivets off whilst I was at it- never liked those, way over scale.

I've done the little bit more glass trick it gets worse!"
I have tabs fitted on the lower hull that pulls the upper hull into place and strong magnets that pull the two halves together.
Sorry to be 'anal' as you call it but whats the point of doing it if it just looks krapp!
I shall continue if all else fails the dust men come on Thursdays!
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Re: Sheerline Type VII

Postby Sub culture » Mon May 24, 2010 2:29 pm

Then you're doing something wrong. What that is, is difficult to surmise without being able to witness your building technique.

I see you've been given some good advice on the mayhem forum so follow that and see how you go.
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Re: Sheerline Type VII

Postby Polycell » Mon May 24, 2010 2:58 pm

Sub culture wrote:Then you're doing something wrong. What that is, is difficult to surmise without being able to witness your building technique.

I see you've been given some good advice on the mayhem forum so follow that and see how you go.

Yes it didn't take long to realise I am doing something wrong ! As for taking the advice already given.....Oh I will !! Thanks!
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Re: Sheerline Type VII

Postby Sub culture » Mon May 24, 2010 3:26 pm

Composites shrink as they cure, and move over time. Epoxies shrink very little, but polyester shrinks quite a lot. This isn't a problem providing you are aware of it.

In your case, you may have go over the same ground a few times to get the required result, and then still be prepared for the resin to shrink further over time and the gap widen again.

If you want a tiny gap that maintains integrity with a composite hull, the best solution is to glass the hatch in place, and split the hull radially (think Robbe U47 or Engel Type VII) then use either metal or G10 epoxy sheet for bulkheads either side of the split. That won't move in a month of Sundays.
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Re: Sheerline Type VII

Postby JWLaRue » Mon May 24, 2010 4:34 pm

Sub culture wrote:Composites shrink as they cure, and move over time. Epoxies shrink very little, but polyester shrinks quite a lot. This isn't a problem providing you are aware of it.

In your case, you may have go over the same ground a few times to get the required result, and then still be prepared for the resin to shrink further over time and the gap widen again.

If you want a tiny gap that maintains integrity with a composite hull, the best solution is to glass the hatch in place, and split the hull radially (think Robbe U47 or Engel Type VII) then use either metal or G10 epoxy sheet for bulkheads either side of the split. That won't move in a month of Sundays.


....which is exactly why I suggested using a series tabs. I've done it for a 1/48th and 1/32nd scale Type VII to 'fix' the gap at the saddle tanks. Done properly, it works fine. the trick is to make sure the that tabs are curved with the same radius as that particular area of the saddle tank.

-Jeff
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Re: Sheerline Type VII

Postby Polycell » Tue May 25, 2010 7:37 am

JWLaRue wrote:
Sub culture wrote:Composites shrink as they cure, and move over time. Epoxies shrink very little, but polyester shrinks quite a lot. This isn't a problem providing you are aware of it.

In your case, you may have go over the same ground a few times to get the required result, and then still be prepared for the resin to shrink further over time and the gap widen again.

If you want a tiny gap that maintains integrity with a composite hull, the best solution is to glass the hatch in place, and split the hull radially (think Robbe U47 or Engel Type VII) then use either metal or G10 epoxy sheet for bulkheads either side of the split. That won't move in a month of Sundays.


....which is exactly why I suggested using a series tabs. I've done it for a 1/48th and 1/32nd scale Type VII to 'fix' the gap at the saddle tanks. Done properly, it works fine. the trick is to make sure the that tabs are curved with the same radius as that particular area of the saddle tank.

-Jeff

Sorry its an age thing can you explain what you mean by 'tabs' and are there any piccies around of what you mean by 'glass the hatch in place. Sorry confused and old Limousin!
Fred
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