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Author Topic: Sticking ABS Plastic to GRP  (Read 4816 times)

chingdevil

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Sticking ABS Plastic to GRP
« on: June 17, 2006, 06:48:52 pm »

The hull of my Mountfleet Puffer was not moulded correctly and I need to raise the sides on the quarter deck, by 5mm. What is the best adhesive to join GRP to ABS palstic, or can any one think of a better way to raise the edge. I would rather not send the hull back as it took them 6 weeks to send me the correct plan.

Brian
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Daryl

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Re: Sticking ABS Plastic to GRP
« Reply #1 on: June 17, 2006, 09:01:47 pm »

I know its of no help but I have had several people tell me theirs had the same fault, It would not surprise me if ther are other fitting problems. I now have the Caldercraft puffer which I hope goes together withoput to many headaches.

How I fit deck supports and bulkheads to GRP is to roughen the area with corse sandpaper and use slow setting epoxy resin. I have never had  anything fall apart yet.

If your going to Weymouth model boat show in August, there is a chap who exhibits there every year and he builds only Clyde puffers. I intend to study them a bit closer this year than in the past.
Hope this helps
Daryl
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anmo

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Re: Sticking ABS Plastic to GRP
« Reply #2 on: June 17, 2006, 09:56:39 pm »

The hull of my Mountfleet Puffer was not moulded correctly and I need to raise the sides on the quarter deck, by 5mm. What is the best adhesive to join GRP to ABS palstic, or can any one think of a better way to raise the edge. I would rather not send the hull back as it took them 6 weeks to send me the correct plan.

Brian

The best advice I can give you is don't even think about it, forget ABS and build up the sides with P38 body filller, or a similar material. If you're very careful, you can add a couple of layers of masking tape around the outside of the hull, then add filler on the inside of that, removing the tape after it's gone hard. This is a common problem, some manufacturers trim the fibreglass hulls in the moulds, gradually wearing them away, their money saving short cut, your problem. I wouldn't bother sending it back, any replacement hull will almost certainly have the same problem. The things we modellers have to put up with.
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rob

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Re: Sticking ABS Plastic to GRP
« Reply #3 on: June 18, 2006, 04:49:25 pm »

have to agree with anmo there.
If you must glue abs to grp, in my mind there is only one adhesive............ stabilit express.
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White Ensign

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Re: Sticking ABS Plastic to GRP
« Reply #4 on: June 19, 2006, 10:18:04 am »

Forget any connection from ABS to fibreglas, as you will injure a several thermical problems in shap of cracks after a while. The best said method is a fibreglass-filler from the carsection or brass which matches by the shape.

I have had a similar problem and hated myself for doing that. But small mistakes lead to great punishments- though I had stripped it all down and started again......

J?rg
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Stavros

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Re: Sticking ABS Plastic to GRP
« Reply #5 on: June 19, 2006, 06:36:05 pm »

As White Ensign says forget it also forget using filler of even fiberglass paste the only way to do this without the tears is simple
1 Add cardboard to sides of the model on teh outside of the hull taping down properly
2 Wax this card up with a good quality car poolish to stop new grp sticking to it
3 Lay up on the inside of the hull 2 layers of matting over the area you want to enlarge
4 when cured remove cardboard any resin that has run down onto the hull can be removed with teh finger nail
5 Mark new cutting line cut away
6 Sand down hull join to fiberglass and fill as necessary
7 pat your self on the back on a job well done

There is no other way for a stress free outcome I should know been moulding car Spoilers for a living it is the only way to extend a hull line or any other object made of GRP as it bonds to the original and does not crak.
Yes I know what you are going to say my hull is going to be thiker below the joint yes I know that but a bit of filler will soon sort it out and believe you me it is not noticable I hope this is of assisatance Stavros
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kayem

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Re: Sticking ABS Plastic to GRP
« Reply #6 on: June 19, 2006, 09:44:26 pm »

That's not good advice Stavros, White Ensign & Anmo were right, the only way to add an extra few millimetres to a badly trimmed hull like chingdevil's Mountfleet Puffer is with body filler. The only advice I'd add to what Anmo said is that the inside edge of the original fibreglass hull should be bevelled almost to a knife edge, then wiped with acetone before applying filler. Using cardboard as you suggested would be fatal, no amount of release wax would prevent the fibreglass bonding to the card. Your method would take at least ten times as long, and it would never give as good a result as the bodyfiller
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Stavros

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Re: Sticking ABS Plastic to GRP
« Reply #7 on: June 19, 2006, 10:59:34 pm »

Absolute crap Kayem that method that I have suggested is the best method to use I have used it extensivly and guess whta IT DOES WORK it does not fall off if one accidentallt knocks the hull.To add 5mm my way would take approx 2hrs and not give you the grief of filler cracking off please in FUTURE DO NOT CRITISE some one who KNOWS what he is talking about.Having used grp exyensivly for the last 25+yrs dont you think that I know what I am talking about.You should try it some time IT DOES WORK ;)
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kayem

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Re: Sticking ABS Plastic to GRP
« Reply #8 on: June 19, 2006, 11:22:49 pm »

My way works, and it would take about 10 minutes. I'm sure that forum members know enough to be able to make up their own minds.
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rats

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Re: Sticking ABS Plastic to GRP
« Reply #9 on: June 20, 2006, 12:02:04 am »

  I think Stavros is right - if for no other reason than filler has little or no flexibility and in time would crack or chip. Anyway whats a couple of hours compared to the total build time of a model !
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Daryl

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Re: Sticking ABS Plastic to GRP
« Reply #10 on: June 20, 2006, 08:49:33 am »

I too think Stavros is right, I have seen repair jobs done with fillar along with the cracks that result. I also know severla people who have succsessfuly repaired bike fairings and car bodies this way.

Daryl
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anmo

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Re: Sticking ABS Plastic to GRP
« Reply #11 on: June 20, 2006, 09:24:55 am »

We're talking about a simple job here, adding a few millimetres around the top edge of a hull, and once the deck is on, how is that going to flex? In any event, the wood inwales that reinforce the hull/deck joint would take care of that problem. As with most work of this kind, the secret is in preparing the surfaces properly at the outset. I think that most on this forum have worked with body filler often enough to be trusted to do the job properly. Unlike the stavros suggestion, it isn't something that requires 'twenty five years experience of working with GRP'.
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magpie

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Re: Sticking ABS Plastic to GRP
« Reply #12 on: June 20, 2006, 09:48:34 am »

Have you read the puffer thread in Mayhem "Builds" section. Here's a couple of paragraphs covering the problem. It seems that Bradders found the deck marks to be wrong rather than the hull side height. See what you think.
 
I used a sanding drum in the pillar drill with a 'medium' grade drum which smoothed the inner edges effortlessly.
 The frame is the first thing to go in the hull - the position is measured from the top edge of the bulwark down (I used a piece of scrap wood as a gauge and drew a pencil line). After marking out I believe the deck is about 5mm higher than it should be i.e. the angle iron pieces that go on to the inner edge of the deck are actually in the wrong place compared to the outside rubbing strip detail, but I decided to go with the instructions.
 
The top surface of the two outer 'longerons' of the frame needs lots of little saw cuts made in the top of them. this allows the frame to be bent upwards at each end making the deck SLIGHTLY concave (about a 6mm 'dip' in the middle). I Glued with 5 Min epoxy using lots of clamps. be careful not to damage the outside of the hull.
?
 I found a discrepancy in the instructions when aligning up the frame in the hull,? the measurement from the stern to the frame is 270mm but this would leave the Bulkhead 'J' hanging in mid air, I reckon the measurement is nearer 260mm.
(I panicked a bit here as Martin had made the frame and I feared
 
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chingdevil

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Re: Sticking ABS Plastic to GRP
« Reply #13 on: June 20, 2006, 12:16:39 pm »

Thanks to everyone who answered my query, not sure yet which way I am going to go yet. Actually had a crazy thought yesterday about buying a plan and building the hull myself, need to go and get some more pills! this thinking stuff is dangerous.
Magpie Mayhem built a different puffer to my one so the hull is different, measuring off the plan showed me the problems with the hull also just looking at the moulding it was obvious some of the detail was missing.



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Shipmate60

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Re: Sticking ABS Plastic to GRP
« Reply #14 on: June 20, 2006, 10:21:48 pm »

Why not go a slightly different way.
Fit the inwhales into the hull on both sides then the deck, if it is only a few mm either way will do, and will strengthen the deck/hull join too.

Bob
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