Chris Higgs Posted December 19, 2015 Share Posted December 19, 2015 Here's one of my more adventurous ideas I have been trying out with 3D printing. Loco wheels with square axles. And muffs with square holes. Hence self quartering I expected this to be a total disaster but it has worked out so far. Printed using Shapeway's extreme fine detail, they look great and fit like a glove into the Association rims nice and square. I have to do some work to get the muff hole just right for a sliding fit on the axle. Then the big issue is whether the wheel centres can be printed in a metallic material instead. Probably somewhere other than Shapeways as none of their options seem a possibility. I guess this may still prove to be a project a few years ahead of its time. Chris Link to post Share on other sites More sharing options...
Valentin Posted December 19, 2015 Share Posted December 19, 2015 And just yesterday I was wondering who could help me with some 6 mm driving wheels!... Link to post Share on other sites More sharing options...
Chris Higgs Posted December 19, 2015 Author Share Posted December 19, 2015 If this technique could be made to work it opens up a lot of possibilities. For example we could make replacement wheels that plug directly into Dapol split-frame locos, meaning there would be no need to take the chassis apart to finescale it. Which is why I chose GWR Pannier wheels as my prototype. Link to post Share on other sites More sharing options...
RMweb Gold Revolution Ben Posted December 19, 2015 RMweb Gold Share Posted December 19, 2015 Hi there, That looks really interesting. At a recent 3D expo in Birmingham I saw some 3D metal sintering machines that create "3D printed" parts in metal. cheers Ben A. Link to post Share on other sites More sharing options...
RMweb Gold Joseph_Pestell Posted December 19, 2015 RMweb Gold Share Posted December 19, 2015 Chris, you have come up with a fascinating design there irrespective of scale. It gets rid of the ugly screw arrangement of a Romford axle and could even be adapted, with a triangular shaft, for three cylinder locos. One might even put a gear into the outer shaft (muff). Link to post Share on other sites More sharing options...
Chris Higgs Posted December 19, 2015 Author Share Posted December 19, 2015 Chris, you have come up with a fascinating design there irrespective of scale. It gets rid of the ugly screw arrangement of a Romford axle and could even be adapted, with a triangular shaft, for three cylinder locos. One might even put a gear into the outer shaft (muff). Ian Morgan already designed muffs with gears on for the Dapol Terrier. But we are really not sure if the teeth would survivie in real use. As soon as you scale these things up though, they get very expensive to make. Dapol themselves already use such an arrangment to quarter their locos. Except they have it the other way around - the square end is on the axle/muff, and the wheel plugs into it. Link to post Share on other sites More sharing options...
bmthtrains - David Posted December 19, 2015 Share Posted December 19, 2015 I'd be cautious about 3D printing wheels as the friction on them will rapidly wear them down. 3D printed metals aren't actually quite what they seem, as they need something to hold them together so aren't just metal. They are best described as metal-effect prints. If you think about the RPM a wheel does, that's why they tend to be made from cast metal. You could of course 3D print masters that were then cast, but that's a hugely expensive job. David Link to post Share on other sites More sharing options...
John lewsey Posted December 19, 2015 Share Posted December 19, 2015 Clearly an innovator Chris John Link to post Share on other sites More sharing options...
Caley Jim Posted December 19, 2015 Share Posted December 19, 2015 I'd be cautious about 3D printing wheels as the friction on them will rapidly wear them down. 3D printed metals aren't actually quite what they seem, as they need something to hold them together so aren't just metal. They are best described as metal-effect prints. If you think about the RPM a wheel does, that's why they tend to be made from cast metal. You could of course 3D print masters that were then cast, but that's a hugely expensive job. David I think the idea is to print wheel centres which are then fitted into 2mm Scale Association rims, so there is no issue with wear on the wheels. I presume the 'metal' printing is with the idea of conducting the current from the tyre to the frames. My concern is wear where the muff runs in the bearing. Is it the idea that a slice of metal tube be slide over the boss on the inside of each wheel which then runs in the bearing! Jim Link to post Share on other sites More sharing options...
2mm Andy Posted December 19, 2015 Share Posted December 19, 2015 Clearly an innovator Chris John I can think of at least 3 people who have tried 3d printed wheels with varying degrees of success. The problem seems to be finding a way of printing them with sufficient accuracy so that they run true. Aside from Bill Bedford's photo-acrylic wheels in P4, Damien Johnston and Julia Adams both tried 3d printed wheel centres in 2mm a few years ago. Damien had some square-ended axles machined in steel which fitted square holes in the printed wheel centres. I haven't heard of any of these being used in a running model, which makes me a little wary. Julia tried various ways of getting concentric wheels, and ended-up getting wheel centres printed without an axle hole, mounting the wheel centre in the tyres, then mounting the assembled wheel in a collet on the lathe and drilling the axle hole. I'm sure that it is possible to get wheel centres printed so that they run true with minimal work post-printing, but not at sensible prices at present. The idea of lost-wax casting wheels in brass from 3d printed masters has also been done, with significantly better results. It is reasonably cheap (£30ish for getting 8-10 wheel castings which excludes the cost of the 3d printed master) but the wheels still need to be machined. For unusual wheels and one-off models it is a technique worth considering. Andy Link to post Share on other sites More sharing options...
Chris Higgs Posted December 19, 2015 Author Share Posted December 19, 2015 I can think of at least 3 people who have tried 3d printed wheels with varying degrees of success. The problem seems to be finding a way of printing them with sufficient accuracy so that they run true. Aside from Bill Bedford's photo-acrylic wheels in P4, Damien Johnston and Julia Adams both tried 3d printed wheel centres in 2mm a few years ago. Damien had some square-ended axles machined in steel which fitted square holes in the printed wheel centres. I haven't heard of any of these being used in a running model, which makes me a little wary. Julia tried various ways of getting concentric wheels, and ended-up getting wheel centres printed without an axle hole, mounting the wheel centre in the tyres, then mounting the assembled wheel in a collet on the lathe and drilling the axle hole. I'm sure that it is possible to get wheel centres printed so that they run true with minimal work post-printing, but not at sensible prices at present. The idea of lost-wax casting wheels in brass from 3d printed masters has also been done, with significantly better results. It is reasonably cheap (£30ish for getting 8-10 wheel castings which excludes the cost of the 3d printed master) but the wheels still need to be machined. For unusual wheels and one-off models it is a technique worth considering. Andy I think I wanted to have a go because we now have an even higher resolution from Shapeways so perhaps something can be made accurate enough to not need extra work afterwards. In the pre 3D printing world I always had issues with separate axles pushed into wheels (diesel wheels were what I tried and failed at) and I put that down partially to there just not being enough thickness in a 2FS wheel to get it in square and stop it wobbling. Making the boss on the back as thick as possible would help - this could be done on a wheel for a N gauge chassis conversion for example. But the current Association wheels have the axles integral with the wheel and there are good reasons for that aside from the value it has for split-frame construction. Really if the printing mechanism has high enough resolution it should be possible to get axle and wheel concentric and as good as old-fashoned analogue (aka a lathe). One day it surely will be, even if not yet. The design I have could still be turned if need be as it has a conventional circular surface where it passes through the bearing. That is if it can indeed be transformed into something metallic, either by printing or casting. Link to post Share on other sites More sharing options...
John P. Posted December 30, 2015 Share Posted December 30, 2015 I like this design as the axles are part of the wheel, thus preventing the "wobbly wheel" syndrome. The only real problem I can see is providing a good bearing surface. The Tube idea would be worth trying. Does this make my wheel quartering press redundant? ( the best tool I have ever bought too! ). Link to post Share on other sites More sharing options...
Chris Higgs Posted December 31, 2015 Author Share Posted December 31, 2015 I like this design as the axles are part of the wheel, thus preventing the "wobbly wheel" syndrome. The only real problem I can see is providing a good bearing surface. The Tube idea would be worth trying. Does this make my wheel quartering press redundant? ( the best tool I have ever bought too! ). Well, if it can be made to work (and it's a big if) then yes. I am looking around for ideas to make assembling steam loco chassis easier and less costly. And buying a quartering jig is certainly the latter. Link to post Share on other sites More sharing options...
Quarryscapes Posted January 4, 2016 Share Posted January 4, 2016 When it first came out I printed some Bagnall wheels in What is Now Shapeways's Gold Plated Brass option (it was the only option then) complete with 2FS flanges. They worked just fine, though the plating and polishing killed off the fine embossed line running around the balance weight and made them look odd. The rest of the loco was never built though. I have plenty of FUD wagon wheel centres in Association rims too, though occasionally they suffer Gibson wheel syndrome and separate! I am about to do some more driving wheels but this time using the rims from the Association (they weren't available separately back then) with the centres made slightly oversize in raw brass for turning down true, I'm even toying with steel axles but still undecided there. Link to post Share on other sites More sharing options...
Caley Jim Posted January 9, 2016 Share Posted January 9, 2016 Then the big issue is whether the wheel centres can be printed in a metallic material instead. ...... I have just remembered that it is possible to copper plate any solid object if it is first coated in colloidal graphite. The technique was, and still may be, used in dental laboratories to make copper plated models on which to construct crowns and bridges, before the days of hard wearing plaster materials. A wax or composition impression in a copper ring was painted with colloidal graphite and then placed in a plating bath. The lower the current, the smoother the surface. Admittedly, there is nothing to bind the plating to the wheel, but if the whole wheel was plated then the plating would be held on by virtue of fully covering the wheel. The printed wheel centre could then be fitted to an Association rim and the plating would provide electrical continuity. Am I thinking too far out of the box? There may be some technical issues to be addressed, such as how you attach a wire to the printed wheel centre. Maybe that could be done via a steel collar fitted onto the half axle to form a bearing surface. Tim might be able to comment as it's a long time since I was in a dental lab. Jim Link to post Share on other sites More sharing options...
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