Most of us have seen post war Lionel F3 shells that warp giving them a hump back look. Has anyone been successful at straightening out humped shells? I have some I would like to keep if I can straighten them out. I thought about a heat gun and some forms to press it back in shape, then I thought about turning a shell into a puddle of plastic and stopped. 😜😜

Any ideas or is the best way to just replace them?


Original Post

Shells warp to relieve internal pressures created in the plastic casting as the item was cooling in the mold. These pressures are released gradually over time producing the warping.  Most of that warping with the Alco shells happened fairly soon after the item was produced by Lionel.

In fact, they changed the mold back in the day to include pressure release areas in an attempt to stop the warping. They only had limited success with these revised molds.

If you heat the item now, all those pressures will be relieved quickly, producing even worse warping.

You can see those areas under pressure by viewing a clear plastic item with polarized light. The different color areas are different stresses. If heated, the plastic will deform to reduce those areas under stress.

Thin plastic items can be straightened with heat if done gradually and if you only wish to flatten an object or produce a simple curve. But a 3 dimensional object like a shell has too many surfaces under stress to correct, unless you could put it back in the original mold.




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I was thinking of making a form for the inside and outside of the shell, clamp it tight and heat it up to say 180 degrees Fahrenheit, then let it cool for 4 hours or so before releasing the forms. If that doesn’t work I am thinking of cutting out the warped part and splicing in some styrene. I realize if repainting is involved it would be faster to buy a good junker shell and repaint it, I guess I just want to try. 😜😜


There’s boat loads of PWC shells on the bay....I’d just get a pair of them, and paint them however I like....they’ll be straight as an arrow....I’d think any success you have at straightening would be minimalistic at best, and hardly worth the fight....if you did get them to move, surely the paint ain’t gonna move with them, so you’d be looking at repainting anyways........Pat

The Water Level Route.......You Can Sleep

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