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Author Topic: 1st WW battlecruiser (LION) questions  (Read 8839 times)

TCC

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Re: 1st WW battlecruiser (LION) questions
« Reply #25 on: May 13, 2009, 05:45:03 PM »

A couple of tips on white metal casting -
The first is to use a large pour channel in the mould, this gives a large volume of metal to apply weight and to increase the time it takes the wetal to cool so it will flow all the way into the corners of the mould.

The second is if a corner or raise detail does not come out, drill through the mould with a 1/1.5mm drill at the area the mould does not cast properly. If this is done grip the mould in a couple of pieces of 18th plywood the size of the mould.

[My bold] Is this for air channels Niall? Yes, I've been doing them. My 'making a big void' is sorta the same principal.

I try to keep my air-channels cut into one of the mould halves as when I've drilled through the mould, you may have just introduced a wm rod that's deeply undercut and thus blocking the direction of you extracting the casting, if you follow.

Cheers
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dreadnought72

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Re: 1st WW battlecruiser (LION) questions
« Reply #26 on: May 14, 2009, 09:09:06 AM »

The plate is solid on the Warspite. Plans tend to show only the outer frame. If the attachment works, this is the view from the AoTS Warspite book.
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Colin Bishop

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Re: 1st WW battlecruiser (LION) questions
« Reply #27 on: May 14, 2009, 09:50:34 AM »

This is interesting because I think that paravanes were invented during WW1 which would have been after Warspite's completion. I can't see a plate like that being introduced into the stem casting subsequently. Maybe it isn't dead central and is actually alongside the stem. Same would apply to merchant ships too which were also retrofitted with paravane gear. It would have needed to be a strong fitting as the forces imposed by a couple of paravane otters would have been quite high although I seem to remember there was a relatively low speed limit imposed when streaming them. Looks like more research needed!

Colin
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dreadnought72

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Re: 1st WW battlecruiser (LION) questions
« Reply #28 on: May 14, 2009, 09:59:24 AM »

Hi Colin,

I agree that the original stem casting for this class was paravane plate-less. I think what we're seeing in this picture is a (not perfectly drawn) pair of plates overlapping the casting and attached to the hull plates.

TCC, I think you need to fill the gap in.

Of course, there are plenty of photos of capital ships of this era in dry dock - does anyone have bow shots of Lion, Warpsite or others during the war? My Burt book has (at least) Neptune in dry dock from the bow, I'll check that out tonight.

Andy
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Niall

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Re: 1st WW battlecruiser (LION) questions
« Reply #29 on: May 14, 2009, 10:13:56 AM »

A couple of tips on white metal casting -
The first is to use a large pour channel in the mould, this gives a large volume of metal to apply weight and to increase the time it takes the wetal to cool so it will flow all the way into the corners of the mould.

The second is if a corner or raise detail does not come out, drill through the mould with a 1/1.5mm drill at the area the mould does not cast properly. If this is done grip the mould in a couple of pieces of 18th plywood the size of the mould.

[My bold] Is this for air channels Niall? Yes, I've been doing them. My 'making a big void' is sorta the same principal.

I try to keep my air-channels cut into one of the mould halves as when I've drilled through the mould, you may have just introduced a wm rod that's deeply undercut and thus blocking the direction of you extracting the casting, if you follow.

Cheers

The drilled hole is to allow the air out. If it is drilled reasonably close to vertical it is not a problem on removing the part from the mould. I've got 30-40 castings of 1/300th scale vehicles from a mould I've used this technique on. I learned this from a manufacturer who uses centrifugal castings.
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TCC

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Re: 1st WW battlecruiser (LION) questions
« Reply #30 on: May 16, 2009, 02:29:26 AM »



Sorry about that, not having much luck with the old image linking. If it doesn;'t work, it's the image of INVINCIBLEs 2 halves sticking out of the sea at Jutland.

If you could find the image of NEPTUNE, I'll look in in a few days, cheers.

Yes, I too am leaning towards a 'solid' frame.

Where ships built per-war built with it? I think I can prove the negative. The paravanes needed the chains, right? They went through the 'stem plate' and they also had a 'fairlead' type fitting just aft of the jackstaff that carried the chains. Pre-war LION photos don't have this fairlead, but war-time shots of her show it, with or without the chains going through it.

Therefore, I think when they fitted the stem frame, they also fitted the fairleads. But if this 'frame' is a war-time addition, why put the solid centre in it? Surely a solid (read:strong) frame would be better than having the same frame but with the area enclosed where wave pressure has more area to stress against? It seems to me that if you have 2 of the same frames, 1 'open', the other 'enclosed', that the open one would have any wave pressure to deal with.

Something elsethat struck me, it's only 'Ram Bow' ships that need this frame. (like duh!)


Niall, I had pretty good success with casting my radial davits... at least I'm happy with them. The davits concerned have a left and right versionm What I did was make 1 but put both sides pulley wheel on and I'll just remove 1 side. But they all came out great... I even got very decent casts of very small pulley wheels. I found the secret is to pour into the mould above them so they get the hottest metal.... and I'm also filling the 'well' up more than I was (after your reminding me of its importance, I tended to not give this bit due prominence but these last castings have been really successful). I had a image lined up but I've got gremlins (in more than one sense ;-))

I'll keep the vertical drill thing in mind.
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dreadnought72

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Re: 1st WW battlecruiser (LION) questions
« Reply #31 on: May 16, 2009, 04:10:44 PM »

If you could find the image of NEPTUNE, I'll look in in a few days, cheers.

I was wrong - it's HMS Monarch, and difficult to tell quite what's going on. Possibly the original plate would say more, but I can't blow the version I have up and convince myself either way.

Quote
Where ships built per-war built with it? I think I can prove the negative. The paravanes needed the chains, right? They went through the 'stem plate' and they also had a 'fairlead' type fitting just aft of the jackstaff that carried the chains. Pre-war LION photos don't have this fairlead, but war-time shots of her show it, with or without the chains going through it.

I agree with this. It's not really a surprise response to the many thousands of mines dumped in the North Sea and elsewhere after hostilities began - witness the loss of HMS Audacious off Northern Ireland in October 1914, and near-loss of HMS Inflexible in the Med in January 1915.

Quote
But if this 'frame' is a war-time addition, why put the solid centre in it? Surely a solid (read:strong) frame would be better than having the same frame but with the area enclosed where wave pressure has more area to stress against?

I disagree - you stream paravanes when moving, and vectors being what they are, the bulk of the force on the paravane holes (along with effective pressure on the plates covering the gap behind them) is going to be along the axis of the hull, aftwards. I think the plates make a lot of sense. (Though they don't look so cool as a curvy ram bow!)

Andy
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