Re: Sway backed cars

Bob Friddle
 

I haven’t tried this, but a plastic car side is going to be highly resistive to oven sagging. Think of it as a beam, either steel or 2 x1 2 wood; the deeper it is the more stiff and resistant it is to bending (steel beams have webs on the top and bottom to resist lateral forces and warping from side to side, but their spanning ability and bearing strength comes from the depth). Within the beam, or car side, a downward force at the center of the span causes tension (stretching molecules out) at the bottom and compression (pushing molecules together) at the top. Steel and wood handle both of these forces well, especially when they are uniformly distributed along their lengths, as opposed to single point loading in the center. Plastic handles compression well, but thin plastic sheet will warp to the side without the reinforcement of a car top and bottom. Plastic does not handle tension and bending well, it will de-laminate and/or snap after bending just a little. If you think of it as a beam, it is the equivalent of a ten foot high beam that is only a few inches thick. Softening it in an oven does not easily override these characteristics. Even a wetted thin wood side will warp from compression or split from tension. Cattle cars should work best for this, they are much more flexible. For box cars it would be a lot easier to cut the curve into the side at the top and bottom and then apply decals on a slight curve to match. For passenger cars you could try cutting from the top of each window to the roof and press together to close the knife-width cuts. Remember it doesn’t take much sag to notice.

Bob Friddle

Gabrielle Lines

Minneapolis

 

From: GandD@groups.io [mailto:GandD@groups.io] On Behalf Of Russ Desmond via Groups.Io
Sent: Tuesday, June 04, 2019 8:17 PM
To: GandD@groups.io
Subject: Re: [GandD] Sway backed cars

 

Randy: I am sticking with HO gauge cars so the width is not a factor. I do not have a toaster oven so I could try the oven instead, the question then would be regular or convection heat? I use oven thermometers in my baking so the temp can be closely monitored. The magic number of 347 F has been unknown by me so thank you for sharing that piece of information. As for paint I usually buy un decorated cars cause my railroad is a concept railroad and it has it's own custom paint job and decals.  The more I rethink on this subject I believe the best way is to separate the cars into their 4 main components. The reason for that is a box shape is a structurally interconnected and intrinsically a strong shape as opposed to flat sheets of plastic which would be much more malleable when properly softened . I can understand the reasoning behind keeping the floor as straight as possible for the trucks to track properly and not become a rolling derailing nightmare. I'm surprised no one has mentioned car weights as they obviously will have to be replaced with two separate and equal weights and concentrated in the ends of the cars. Again I thank all who responded to this thread as it gives me many different points of view to ponder and experiment with.

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