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Author Topic: Fixing Bulk Heads  (Read 1431 times)

Dave Cook

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Fixing Bulk Heads
« on: June 03, 2014, 08:47:27 am »

Hi All , Please can some advise me on the best method of gluing the plywood bulk heads to the GRP hull on my 1/24 scale Perkasa . I have tryed all the common Epoxi glues on bits of scrap GRP and plywood only to find i can brake the joint by hand . P.S i also sanded the GRP to give it a key.
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TailUK

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Re: Fixing Bulk Heads
« Reply #1 on: June 03, 2014, 08:53:58 am »

You may want to consider reinforcing the glued joints by using glassfibre. Get as close a fit as possible, epoxy the bulkhead in place and then use light GRP matting pushed into the corners on each side of the bulkhead.  The resin should bond the ply to the inside of the hull.  HTH.
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SailorGreg

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Re: Fixing Bulk Heads
« Reply #2 on: June 03, 2014, 09:18:10 am »

Hi Cookie, I'm not sure what you mean by the common epoxy glues.  All epoxies are not born equal, there are definitely good and bad out there.  Unfortunately, I have found that the easier the glue is to use, the less effective it is.  Anything that is a one-to-one mix I distrust.  The "professional" epoxies are usually 5 to 1 ratio - harder to get right but bulletproof once cured.   That said I have had good results from this http://www.easycomposites.co.uk/products/epoxy-resin/epoxy-coating-resin.aspx   2 to 1 mix.  It it called a coating resin but with some thickening it makes a good glue and filler

To fix a bulkhead in a GRP hull I have followed full size practice - edge glue the bulkhead in place then add a fillet of thickened epoxy along the joint.  Once cured (and that might take a couple of days) you will break the bulkhead before breaking the joint.  If that sounds confusing, google "epoxy fillet" and you'll find more info than you really need!

Greg

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Re: Fixing Bulk Heads
« Reply #3 on: June 03, 2014, 09:18:59 am »


Yes, I would say Epoxy, I've had good results with Delux or Zap 20 / 30 minute Epoxy.
Also allow good ventilation inside the hull as the fumes / vapors maybe lingering inside the
hull thus preventing the epoxy 'going off' correctly.

Also try car body filler, e.g. Isopon P38
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Tug-Kenny RIP

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Re: Fixing Bulk Heads
« Reply #4 on: June 03, 2014, 10:59:46 am »


Reading between the lines i notice you say  'on bits of scrap'.  This test really is severe because normally the wood will be wedged between the sides of the hull and held mechanically whilst sitting in epoxy which is setting.

As long as the piece does not move, then the initial  'break out' forces will have to be quite severe. The wood is then secured in place by it's own mechanical stability and the retaining action of the epoxy.

Hope this helps

ken


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Dave Cook

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Re: Fixing Bulk Heads
« Reply #5 on: June 03, 2014, 11:13:08 am »

Thanks Lads , Paul T over on Model Boat also recommended Isopon , I will use blobs of this and then a thick 5:1 bead of Epoxi resin and as Kenny says it will be restrained by the hull anyway , I never thought of that ( What a mump nuts i am )  :-)) :-)) :-)) :-)) :-))  Cookie
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essex2visuvesi

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Re: Fixing Bulk Heads
« Reply #6 on: June 03, 2014, 06:53:05 pm »

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Re: Fixing Bulk Heads
« Reply #7 on: June 03, 2014, 07:09:32 pm »

 %) I glassed mine on the huntsman and that was many years ago and is still solid,just got to make sure that the bulkhead is in the right place and you are happy with it, as once cured it's nearly impossable to move,Ray. %)
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Dave Cook

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Re: Fixing Bulk Heads
« Reply #8 on: June 03, 2014, 08:05:53 pm »

Thanks Lads , got some isopol p40 today as Dave M over on Model Boat said , done a test and ( solid as a rock) just with P40
Thanks Dave M  %% %% %% %% %% %% %% %%




 
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Stavros

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Re: Fixing Bulk Heads
« Reply #9 on: June 03, 2014, 09:41:58 pm »

P40 is the stuff to use ANY form of Car Filler is usless as it does not have any structural strength at all....car filler is for filling dents...A dent doesnt have to be structural...........P40 is a Glassfibe paste in it's nature has shrads of glass fibre fragments in it.........Thats why it is so strong and ideal for fixing bulkheads/Bow thrusters and even sticking a deck down....I often shudder when I see a bowthruster fitted with car filler as this is most definatly a recipie for DISASTER... O0 O0 ....and GLUG GLUG springs to mind...........................
 
 
 
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