Wayne Kinney Posted May 21, 2014 Share Posted May 21, 2014 Hi Guys, Wayne here from British Finescale/fiNetrax. I thought this might be of interest, I am currently experimenting with 3D printed wheel centres to convert RTR N Gauge Loco's to finescale. I have seen a few people like Julia Adams and Damien Johnson using the same technique, so thoughth I would give it a go. I recently purchased one of the new Farish 3F Jinty's so thought this would be a good loco to try finescaling using this method. I have attached some images showing the 3F Jinty centre with tire/rim attached. The 3D printed wheel centre is from shapeways, printed in frosted ultra detail. The material seems strong enough and the wheel also seem to run true - very positive feel. Next to install all 3 axles into the jinty and see what happens. I will post how I deal with the split frame chassis convertion using plastic wheel centres. Please let me know what you think NOTE: The wheel rims have been turned to finer than 2FS, testing for a possible 'S148' track and wheel standards/dimensions. I am currently in the process of testing the following: Track Gauge: 9.7mm Flangeway Gap: 0.4mm Wheel Tread: 0.8mm Flange Width: 0.2mm Flange Diameter: 0.7mm + wheel diameter Back to Back: 9.0mm The above dimensions maintain the same clearances and tolerances as 2mmFS. Link to post Share on other sites More sharing options...
Wyvern Posted May 22, 2014 Share Posted May 22, 2014 Fasiciating development. I think with the split chassis of the modern farish and Dapol models it would probably be best to turn the wheels and put new tyres on. You then retain the benefits of the split chassis - no picks and associated drag. However with older non split frame models, it looks like a very good option. Link to post Share on other sites More sharing options...
Wayne Kinney Posted May 23, 2014 Author Share Posted May 23, 2014 Thanks for your reply, I am trying to explore a way of converting to 2FS without the need for turning. My method is to install 3mm diameter brass tube onto the boss of the plastic centre, and connect to the tire via 0.2mm phospher bronze wire. This allows us to keep the bearing pickup/split frame design. Also, the finess of the 3D printed centre is much better than the farish cast centres. I will show this in a few photos soon... Link to post Share on other sites More sharing options...
bill-lobb Posted May 23, 2014 Share Posted May 23, 2014 Thanks for your reply, I am trying to explore a way of converting to 2FS without the need for turning. My method is to install 3mm diameter brass tube onto the boss of the plastic centre, and connect to the tire via 0.2mm phospher bronze wire. This allows us to keep the bearing pickup/split frame design. Also, the finess of the 3D printed centre is much better than the farish cast centres. I will show this in a few photos soon... This is very interesting. The wheels look very nice. I did have a concern about the apparent need for pickups, but the above answers that. You mention split frame. Are those axles insulated at the centre? I am wondering how possible it would be to incorporate into normal 2mm scale models. I also had a couple more concerns, the first being concentricity. I am not that familiar with the 3D print process, but is it accurate enough to guarantee concentricity to within a certain tolerance? I seem to think that Julia had some issues with that at one point, but it could be that the technology has moved on since then. I understand that quite a lot of checking and turning is involved to ensure that the 2mm Scale Association wheels are concentric. How are the tyres fitted to the wheels? Is there any possibility that forcing a slightly oversize wheel into a slightly undersize tyre could cause the centre to distort? Sorry if I sound as if I am raising difficulties. I think this could be a very worthwhile development and I hope it succedds. Bill , Link to post Share on other sites More sharing options...
modfather Posted May 23, 2014 Share Posted May 23, 2014 these look great, either as an alternative to the society wheels or as a modernised version of the sorely missed Bryant wheels that we can pop straight in. Link to post Share on other sites More sharing options...
decauville1126 Posted May 23, 2014 Share Posted May 23, 2014 I also had a couple more concerns, the first being concentricity. I am not that familiar with the 3D print process, but is it accurate enough to guarantee concentricity to within a certain tolerance? I seem to think that Julia had some issues with that at one point, but it could be that the technology has moved on since then. I understand that quite a lot of checking and turning is involved to ensure that the 2mm Scale Association wheels are concentric. How are the tyres fitted to the wheels? Is there any possibility that forcing a slightly oversize wheel into a slightly undersize tyre could cause the centre to distort? Although not in 2mm scale, I had a need for some special wheel centres to suit a particular loco. My son drew them in cad and had them printed by Shapeways in frosted ultra detail. We also had another set printed by a firm in Belgium who are not now doing a direct-to-customer service sadly. Not being sure of loading and the ability to withstand pressing onto axles he made the axle bore dead 2.00mm and the outside diameter a dead fit for Gibson 10.5mm diameter tyres. When received they just pushed straight on and ran true and concentric. The chassis was connected by gear drive, and it was for P4/18.83mm gauge. After a quick spray some of the layering became evident but not of concern. The only issue was that repeated removal of a wheel did eventually lead to a slightly 'eased' fit on the axle that needed a spot of superglue to cure - strangely loctite didn't work even though the axle was steel. The wheel centre bosses were very small and I think that any kind of heavier force fit might have split them. Which does lead to the question of on a steam loco with rods whether the quartering might go askew, but perhaps with a largish centre boss a couple of thou under nominal diameter might give enough grip. Link to post Share on other sites More sharing options...
Chris Higgs Posted May 24, 2014 Share Posted May 24, 2014 I believe that some people have experienced curved spokes if you try and twist the wheel on the axle e.g. for quartering. So best to make it a loose fit and get the quartering right first time. I tried a similar experiment with true scale dimensions for 2mm wheels many years ago. It worked fine enough for the width based measurements (flange width 0.2mm, flangeway 0.3mm) and the trackwork looked great. But turning down the flange depth to scale (0.17mm) left you with something that would not stay on the track - a days running at an exhibition could easily leave you with a depth of crud greater than that and so in effect flangeless wheels! You know, you really should only call something S148 if that is what it is - all dimensions directly reduced to 1:148 of their prototype size, as for example is the case with S4. Chris Link to post Share on other sites More sharing options...
Nigelcliffe Posted May 24, 2014 Share Posted May 24, 2014 Rapid prototyped wheels are an interesting idea, and I expect we'll see more of the general approach. One issue for Wayne to think about - return cranks for outside valve gear. With a plastic centred wheel and a brass crankpin, the traditional way of assembling a return crank (solder) won't be safe/reliable/possible for most people. So, if the wheels are to be useful on locos with outside valve gear, a solution for the return crank is needed. For locos with inside valve gear the issue doesn't arise. And, I agree with Chris about the "S148" badging of a scale; S implies dead scale, which is known specialist niche at 7mm, extremely rare at 4mm (P4 isn't S4...), and bonkers much below. - Nigel Link to post Share on other sites More sharing options...
Wayne Kinney Posted May 25, 2014 Author Share Posted May 25, 2014 Hi Guys, Thanks for your replies. I certainly welcome all insight and advise on potential issues with this, since this is an experiment on the feasibility of the material/method/approach. I have a few loco's to convert including a Royal Scot which would have the most chance of showing issues (large diameter drivers, outside valve gear) so hopefully this will give us at least some information. The only thing I can't easily test is reliability over time or exhibition running. Regarding the labeling of 'S148', I would like to make it clear that the dimensions in my first post are totally my own, using 2FS as a guide and starting point. It has no connection to the 'Scale 148' modelling group. It is not my intention of finding/publishing a set of standards recommending for others to use - this is purely for my own personal use for a possible layout if I choose to use them. I should not have used the word 'standards' in my original post, I believe. My only reason for mentioning is to explain why the tire is a slimmer profile. Link to post Share on other sites More sharing options...
Wyvern Posted May 25, 2014 Share Posted May 25, 2014 Could you solder the return crank to the crankpin before gluing it in place? Guy Link to post Share on other sites More sharing options...
Chris Higgs Posted May 25, 2014 Share Posted May 25, 2014 Track Gauge: 9.7mm Flangeway Gap: 0.4mm Wheel Tread: 0.8mm Flange Width: 0.2mm Flange Diameter: 0.7mm + wheel diameter Back to Back: 9.0mm The above dimensions maintain the same clearances and tolerances as 2mmFS. Drawing on the experience with 2FS, one of the next questions to ask is how would diesel loco and wagon/coach wheels be produced to such a standard. Certainly anyone modelling to such a set of standards would need rather more of the latter than they would need loco wheels. The total thickness of the wheels is now very thin at 1mm, and consistent concentric and wobble-free assembly of such wheels requires good quality components and diligent and careful procedures using jigs. Of course, it would also need track components, but Wayne knows how to do those as he has already shown us! Chris Link to post Share on other sites More sharing options...
Chris Higgs Posted May 25, 2014 Share Posted May 25, 2014 Hi Guys, Thanks for your replies. I certainly welcome all insight and advise on potential issues with this, since this is an experiment on the feasibility of the material/method/approach. I have a few loco's to convert including a Royal Scot which would have the most chance of showing issues (large diameter drivers, outside valve gear) so hopefully this will give us at least some information. Yes, this will prove an interesting test. Previous experiments by Bill Blackburn using the methods used to construct the 2mm Scale Association diesel replacement wheels which he himself developed, showed that they did not work sufficiently well when applied to a 13mm diameter steam loco driving wheel - eliminating wobble proved impossible. That is not to say you will not succeed, and I wish you the best in your attempts. Chris Link to post Share on other sites More sharing options...
Wayne Kinney Posted May 29, 2014 Author Share Posted May 29, 2014 After reading feedback, I am going to try a slightly different approach. I beleive that the 3D printed frosted ultra detail (acrylic plastic) will be fine for pony & tender wheels under 8.5mm diameter. For drivers and/or bigger wheels, or any wheels that require split frame bearing pickup, and/or are connected to coupling rods - 3D print in wax and cast is brass. I think this is similar to how the 2SA wheels are manufactured, and indeed will need after machining/turning. I use this technique to cast the frog crossing in the fiNetrax range. I am going to try an experiment with a 13mm diameter spoked driver, seeing how well it will cast and if I can turn it to run true. I will keep you updated Link to post Share on other sites More sharing options...
Horsetan Posted June 4, 2014 Share Posted June 4, 2014 ....S implies dead scale, which is known specialist niche at 7mm, extremely rare at 4mm (P4 isn't S4...), and bonkers much below. Yes but, as long there are sufficient numbers of bonkers people to push the scale envelope, why not? As Chris Bonington reputedly said when asked why he wanted to climb a mountain, "(b)ecause it's there." Link to post Share on other sites More sharing options...
Chris Higgs Posted June 6, 2014 Share Posted June 6, 2014 Yes but, as long there are sufficient numbers of bonkers people to push the scale envelope, why not? As Chris Bonington reputedly said when asked why he wanted to climb a mountain, "(b)ecause it's there." Actually it dosen't really matter how bonkers they are, its whether it would actuallly work. These things don't come to pass simply by willpower. Chris Link to post Share on other sites More sharing options...
RMweb Gold 2mmMark Posted June 7, 2014 RMweb Gold Share Posted June 7, 2014 I have actually seen some US N scale stock with wheels to P-160 standards, i.e. exact scale width & flange. I felt the flanges were so delicate that they could be subject to damage if mis-handled. Even if that can be avoided, there's then the need to lay track to very close tolerances. I'm content with the 2mm Association finescale standards. They are a good compromise between appearance and practicality. Mark Link to post Share on other sites More sharing options...
Wayne Kinney Posted June 13, 2014 Author Share Posted June 13, 2014 Even if that can be avoided, there's then the need to lay track to very close tolerances. I'm content with the 2mm Association finescale standards. They are a good compromise between appearance and practicality. Mark Hi Mark, The dimensions I set out in my first post actually result in the same tolerences and clearences as 2FS, so it should be just as practical. Link to post Share on other sites More sharing options...
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