Gluing 'Hard' plastics

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DaveHarris
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Gluing 'Hard' plastics

Postby DaveHarris » Wed Mar 01, 2017 12:56 pm

I am not sure if this question has been asked before, but here goes! I have broken off the steps on a Heljan Class 14 loco. I am looking for some advice on the best type of glue to reattach the steps? I have tried an epoxy and a superglue. Both intialy seem to work but the slightest pressure and the joint breaks! Any advice would be appreciated :?:

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Tim V
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Re: Gluing 'Hard' plastics

Postby Tim V » Wed Mar 01, 2017 4:30 pm

Try a solvent on a non visible part of the model - to determine which one to use.

ABS solvent may work?
Tim V

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Noel
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Re: Gluing 'Hard' plastics

Postby Noel » Wed Mar 01, 2017 5:04 pm

It isn't possible to offer any informed suggestions on solvents without, as Tim implies, knowing what sort of plastic is involved. However, either epoxy or superglue [or both] would usually work, so I wonder just how much contact area is actually involved here. Modern steps are commonly fairly thin, resulting in a small contact area, so it may be necessary to use some form of reinforcement behind the break.
Noel

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RobM
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Re: Gluing 'Hard' plastics

Postby RobM » Wed Mar 01, 2017 5:12 pm

I'd epoxy a piece of fret waste over as much of out of sight area. As Noel says, reinforcement is necessary.
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Philip Hall
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Re: Gluing 'Hard' plastics

Postby Philip Hall » Wed Mar 01, 2017 5:48 pm

A useful idea, if the steps are thick enough, is to pin the two parts together. Drill a small hole, 0.45mm or 0.3mm, in one side of the break and another in the corresponding place on the other part. It might be difficult to judge so as to get the holes in exactly the right place. The parts are then glued together in the usual way.

For difficult plastics, I always give a coating of Deluxe Materials Tricky Stick which somehow prepares the surfaces and superglue and epoxy seem much happier to stay put.

Philip

DaveHarris
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Re: Gluing 'Hard' plastics

Postby DaveHarris » Thu Mar 02, 2017 2:15 pm

Gentlemen,
Many thanks for all your replies. I must admit i was a bit shy of trying the pin and glue method on such a small part, but having seen the replies and given it more thought, I will give it a go as it seems to be the most logical way around the problem, maybe with some small re enforcing strips behind the steps as well.

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RobM
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Re: Gluing 'Hard' plastics

Postby RobM » Thu Mar 02, 2017 5:30 pm

Belt and braces........ :thumb
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Updated December 2016

billbedford
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Re: Gluing 'Hard' plastics

Postby billbedford » Fri Mar 03, 2017 9:44 am

Cors you could always try welding the bits of plastic.....


Bill Bedford
Mousa Models
http://www.mousa.biz

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jim s-w
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Re: Gluing 'Hard' plastics

Postby jim s-w » Fri Mar 03, 2017 10:45 am

Having glued a lot of Lima side frames to things I've found evostick first then thin zap (the pink bottle) gives a good solid result. Let the evostick dry first.

HTH

Jim

DaveHarris
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Re: Gluing 'Hard' plastics

Postby DaveHarris » Fri Mar 03, 2017 11:13 am

Thanks for the subsequent suggestions. I'm not sure about the 'welding' idea, having watched the 'film' it would appear to leave a very 'coarse weld', and the steps need something very fine just on the mating surface, with maybe some re enforcement on the rear which would not be visible. I'm leaning towards the 'pin and glue' idea which should be strong and not visible, with maybe a couple of re enforcing strips on the rear..... if i'm accurate enough with the drill and economic with the epoxy!

billbedford
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Re: Gluing 'Hard' plastics

Postby billbedford » Fri Mar 03, 2017 12:03 pm

You don't have to use the 2.5mm rod used in the video, you could use something much finer, like 1mm, though you would have to keep it short to ensure that it could be forced against the substrates.

Probably the best solution to broken steps is to glue short lengths of angle brass behind the plastic step. Or even better substitute a whole built up step arrangement for the plastic mouldings, but of course you would have to replace all the steps on your loco.
Bill Bedford
Mousa Models
http://www.mousa.biz

DaveHarris
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Re: Gluing 'Hard' plastics

Postby DaveHarris » Fri Mar 03, 2017 12:40 pm

Doh! Why didn't i think of brass angle behind the steps! Thanks Bill

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Mike Garwood
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Re: Gluing 'Hard' plastics

Postby Mike Garwood » Fri Mar 03, 2017 2:10 pm

Dave

You aren't the first person to mention the fragility of the steps on the Class 14. Rod Hall and myself paid a visit to Dean Forest railway and measured up the steps to form the basis of an etch :

Teddy bear steps V3.dwg
Teddy bear steps
(48.75 KiB) Downloaded 53 times


Justin Newitt had them etched for me and Rod has since fitted them to the 14. These rely on the pin and glue method. I gave Justin the file, which he was - at some stage - going to add to his website. You could always ask him if he's prepared to get another set etched.

Teddy bear steps V3.dwg
Teddy bear steps
(48.75 KiB) Downloaded 53 times



D95 steps 2.jpg


D95 steps 1.jpg



regards

Mike

Edited to add photos

DaveHarris
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Re: Gluing 'Hard' plastics

Postby DaveHarris » Sat Mar 04, 2017 9:34 pm

Mike , thanks for the suggestion


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