Brittle K&L chairs

Discuss the prototype and how to model it.
njggb
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Brittle K&L chairs

Postby njggb » Sun Jun 11, 2017 5:05 pm

Hi,
I am trying to use up some twenty year old plastic two bolt chairs. I am aware of the interregnum as regards C&L so cannot order more.

Is this turning brittle a known problem? What about the chairs that I have used as functional chairs?

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Tim V
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Re: Brittle K&L chairs

Postby Tim V » Sun Jun 11, 2017 5:25 pm

I think the ones I had were brittle a long time ago. I've not noticed any failures on completed track.
Tim V

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barrowroad
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Re: Brittle K&L chairs

Postby barrowroad » Sun Jun 11, 2017 10:00 pm

I'm not sure about K&L chairs but I stopped using a batch of C&L chairs ( red plastic ) as they were extremely brittle and would not cut for use as cosmetic chairs. I believe there was a problem with the quality of the plastic used. Ever since I have only used Exactoscale chairs.

Robin

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Re6/6
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Re: Brittle K&L chairs

Postby Re6/6 » Mon Jun 12, 2017 6:51 am

When we (DRAG) inherited Mike Casey's 'Bodmin' for restoration, many of the K&L chairs had become brittle and broken allowing loosening of the rail in places.

Also the old steel rail has become severely corroded in many places so much so that the all trackwork now will have to be replaced.
John

njggb
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Re: Brittle K&L chairs

Postby njggb » Mon Jun 12, 2017 11:19 am

Hi,
Thanks guys. Some unused chairs are ok, but I guess I will have to wait for C&L's successor to be back in the stream. I may have enough to finish this test track.
Thanks.
James

Knuckles
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Re: Brittle K&L chairs

Postby Knuckles » Mon Jun 12, 2017 1:46 pm

Is there anything they can be soaked in for a night to revitalise them?
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Martin Wynne
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Re: Brittle K&L chairs

Postby Martin Wynne » Mon Jun 12, 2017 2:54 pm

Knuckles wrote:Is there anything they can be soaked in for a night to revitalise them?

A long soak in (very) hot water may work. The last time this topic came up I suggested a few minutes in boiling water, but users reported no improvement.

Higher heat may help, e.g. in a low oven, but there is obviously a risk of melting them if you are not careful - and no guarantee it will work. The longer you can leave them there the better. Experiment with a few first.

Martin.
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njggb
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Re: Brittle K&L chairs

Postby njggb » Mon Jun 12, 2017 6:19 pm

Allan Goodwillie sugested that the problem could be exposure to UV light and careful coating in solvent might form a surface repair. I am going to try that on some that I know are brittle, not all are. Where these were "stored" they could been exposed to UV. Allan cited the problem that you get with plastics in greenhouses.

My Dad worked for a plastic injection moulding company and they had trouble with nylon 66 becoming brittle. That material is hydroscopic and if maintained in a humid atmosphere the problem did not arise. In a dry atmosphere it was more brittle.

Richard Hollingsworth, of Parkside Dundas fame, had said sometime ago that recycling some plastics resulted in poorer performance. You see Richard I was listening.

I can see many possible mechanisms, I just wondered if others had encountered the problem and what fix was available.

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Will L
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Re: Brittle K&L chairs

Postby Will L » Mon Jun 12, 2017 10:28 pm

njggb wrote:Allan Goodwillie sugested that the problem could be exposure to UV light ...


Alan was right that the problem is due to UV exposure, but as the result is the breakdown of the polymers chains that make the plastics what they are, once affected the process is not reversible. The only solutions is prevention. The manufacture can minimise the problem by using a plastic which isn't so sensitive to UV but small items, like chairs, will suffer more than big bits of plastic. The user should keep them in the dark before use and paint the built track so the plastic has the minimum exposure to UV.

njggb
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Re: Brittle K&L chairs

Postby njggb » Fri Jun 16, 2017 11:03 am

Thanks Will. I will hide away future stocks.

James

Enigma
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Re: Brittle K&L chairs

Postby Enigma » Sat Jul 29, 2017 7:45 am

As reported elsewhere (the Double Slip thread) I found a lot of my older stocks of K&L chairs were brittle - and they had been stored away from light in an old shoe box. I did use them on the DS (fitting the halves from either side of the rail once the position of the rail had been secured with strategic rivets) provided they broke cleanly across the jaws which most seemed to do.


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