Edit 12/29/12 - As this might get searched in the future and someone make these mods, I wanted to post some additional advice I had based on further work this morning. Be sure to read all the way to the end of this note if you plan to make this modification.
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Remote Thomas running around our tree was a monster hit this Christmas: my three-year old grandson stayed glued to it. My five-year old granddaughter loved to run it too, when she could get the remote away from her brother. My sons (36, 32, 30) and I also thought it was cool to have around the tree . . . . except . . . three-year olds can operate the remote. And a five-year old can even re-mount the cars after the inevitable derailment due to trying to load and unload animals in the cars while the train is running. But young kids cannot master the couplers. Grandpaw, uncles, and Daddy, all got very tired of jumping up from the dining room table to, once again, put things right. Very, very tired.
So, before putting our Christmas remote Thomas away until next year, I modified it with wooden-track (Bio and Thomas and Friends) magnetic couplers. I know a three year old can handle those unaided!
This was a quick-and-dirty-but-gee-it-worked-okay project. I cut apart five wooden Thomas cars (we have more than we could possibly ever need - they will not be missed), and cut the couplers off. Then made swivel-type couplers from 1/8 inch model plywood that would attach with the original screws so the cars and loco aren't modified at all - I can reattach the original couplers if need be. I glued the magnets on each coupler in a position so it would have the same net swing radius as the original.
First thing I learned: these magnets are just strong enough. I worried I would need stronger magnets, which would have hugely complicated this project. But these are barely strong enough (see the video, the train has run for twenty minutes with no decouplings, although I can force a decoupling by running thetrain at full speed backwards and then slamming Thomas to a stop.).
Second thing I learned: don't make swivel couplers. In the video they are as originally made, swiveling like the original couplers. This works fine going forward - the train apparently will run all day this way. But they bunch sideways to a sharp angle when pushing (when the loco is reversed) and cause problems . So I glued them all straight forward and they work okay when not swiveling (just like they do on the wooden railway). They'd work a bit better if I shortened the coupler so they cars are a bit closer together but they work okay. They have to be absolutely level with one another by the way (see photo, the coupler on the right is not and had to be fixed, the one on the left is). Also, if the magnets were to be too weak, or grew weaker, a small neodymium magnet ( I have some about the size of a dress-shirt button) positioned right behind the coupler increases its coupling force noticeably). The coupler on this loco - which has more tension on it than any of the other couplers, can pretty reliably pull the four cars shown in the video but I doubt it could pull any more. I mounted a "button" there to assist it in staying coupled.
I painted the couplers black and after they dry will put Thomas away until next year. hen, we can hopefully talk and relax while the kids play, and not have to get up every two minutes.
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I was not entirely happy with how smooth Thmas ran yesterday so I went back and worked on the couplers some more this morning. I spent fiv e hours trying a variety of things. What I wanted was smooth running, not decouplings, and no derailments. From the beginning, Thomas-with-magnetic-couplers ran smoothly forward, but disaster would happen upon backup up - the two swivel couplers would jackknife and then cars would derail.
I fixed this, almost good enough, be making all the couplers fixed straight forward. This worked okay forward, and almost okay backward. But not quite.
What works well is this: make the coupler on the locomotiv, and the rear magnetic coupler on every car fixed, so it does not swivel side to side.but leave the front couplers on each car swiveling so they do swing side to side. Then, augment the magnetic pull of the fixed couplers by mounting a neodymium magnet behind them. See photo below.
This results in a train that will nicely pull four to five cars over rough track and bumps without decouplings, and back up, with no derailments. More than four cars (three is best) and derailments seem to happen if one backs up fast, but I noticed the same happens with the normal (factory provided) couplers, so I think it is the cars.
