Perspex track support

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kingmi53
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Perspex track support

Postby kingmi53 » Fri Oct 13, 2017 2:12 pm

I have decided that rather than have a scenic lift out section I would like to "suspend" the individual tracks that span the opening by fixing them to clear Perspex which would just be the width of the track (oo Gauge). My query is that I don't know what thickness of Perspex to use so that it won't bend under the weight of the loco and it's own weight. It seems that it could be quiet expensive to test so I wondered if anyone had any ideas? The span of the track would be approx. 550mm.

b308
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Re: Perspex track support

Postby b308 » Fri Oct 13, 2017 2:23 pm

I'd be tempted to build them as a bridge so making them more ridged, that way you can use thinner materials. If I understand you right they trains will go across a gap looking like they are "flying through the air"? Very nice but only a slight nudge and your train ends up in pieces on the floor! If I am misunderstanding your idea please ignore!

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TimberSurf
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Re: Perspex track support

Postby TimberSurf » Fri Oct 13, 2017 3:53 pm

We are talking real structural calcs here! :D You need someone with stress element software analysis tool! :lol:

As a very rough guess, I would imagine even 10mm to 12mm thick perspex would flex several millimeters at the centre!
Flat material has no strength against bending/flexing.

Either consider two side walls glued to the sides (So U shaped cross section) or a central stiffener glued underneath to make a tee shaped cross section (with either you could get away with 4mm or 6mm)

Or just use a girder bridge!
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Bufferstop
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Re: Perspex track support

Postby Bufferstop » Fri Oct 13, 2017 5:49 pm

Except that once you start talking about 10mm thick perspex it isn't going to look as though the tracks are suspended in mid air, the refractive index is so different to air that you can't miss seeing the perspex as you just can't see "straight" through it*. If your want to be a bit posy go for a perspex tube with the sleepers sitting in the tube with a slight gap beneath their centres.

*I know if you look at it perpendicular to the surface the light should not get bent, but the accuracy of alignment needed is just too precise for it to be achieved.
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kingmi53
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Re: Perspex track support

Postby kingmi53 » Sat Oct 14, 2017 12:48 am

I had thought of a Perspex tube to bridge over the staircase if my wife ever let me have the adjoining room to expand into!!
Although it would not seem invisible, the option could be to have 10mm high Perspex sides (taking up Timbersurf's comments), this would make the structure more rigid (reducing the base thickness) and potentially stopping the trains falling off the edge as b308 suggested.
I should also have said that these tracks are at base level and above the are likely to be two girder bridges on inclines to the upper level. This is my first attempt at building a layout and I'm finding things very difficult to visualise but I'm sure it'll turn out fine.

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SRman
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Re: Perspex track support

Postby SRman » Sat Oct 14, 2017 1:20 am

I was thinking roughly along TimberSurf's lines, but with a T-section instead of two risers. The vertical leg of the 'T' would be centred under the tracks, below the flat strip, so should be nearly invisible.

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Bufferstop
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Re: Perspex track support

Postby Bufferstop » Sat Oct 14, 2017 10:32 am

I'd make the side walls at least 20mm high, 50mm would be even safer. Definitely a case where Murphy's law prevails.
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Forfarian
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Re: Perspex track support

Postby Forfarian » Sat Oct 14, 2017 11:45 am

Perspex is not for the faint hearted, it really has no strength in the flat, it also is subject to temperature changes.
If you go down the Perspex road, put masking tape on where you want to cut it this will stop it reforming in the cut behind a jig saw.
For a lightweight lift out section why not use aluminium angle toe to toe this will also give the safety sides as suggeted by timber surf
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