Chris Higgs Posted January 5, 2016 Author Share Posted January 5, 2016 (edited) Interesting, Chris. Would the frames need to be assembled in a jig (as the etched chassis are) or is the printing accurate enough to allow the frames to be located by some other means? I assume that you could also produce a gearbox that is supported on both sides (as the printed material is non-conductive). Obviously there would need to be slots to allow the gearwheel and worm to be assembled, but it should be quite a bit more rigid than the cantilever arrangement in theory. Andy I am certainly hoping no jig is needed. The prototypes look accurate enough and the bearings are a tight fit in the holes, so everything should be nice and square. If it isn't, there is no scope for adjustment! I really am looking here for something that represents a leap forward in speed and ease of assembly. I could produce an up and over gearbox design, but this has issues. Normally there is a spur gear on the side opposite where the cantilever is, so it would be more slender that side. And then there is the issue of how to get the gears and muffs in and out. The design as it stands requires the wormwheel to come in from to the side/above. A much weaker chassis block would result if it had to be inserted from below. An alternative is to make a plug-on gearbox similar to that seen (in brass) on the milled Manor chassis for example. You could adjust the mesh on this one using shims. Another is a gearbox that attaches to the chassis at one side and the front. Given the very constrained space in a 2251 firebox I decided that the cantilever was the way to go on this one, and also took little design time - I only had an hour free to design it last week. Given the chassis will be in my hands a week from submitting to Shapeways, I can always have another go. I will look at other options for other locos in due course. This week's design time is allocated to producing a set of detail fittings for my 3mm scale version of the Class 08 kit. Something I had been putting off for years. Chris Edited January 5, 2016 by Chris Higgs Link to post Share on other sites More sharing options...
Tim V Posted January 5, 2016 Share Posted January 5, 2016 Could this technique be used for outside cylindered locos? Building outside cylinders in 2mm is a fiddly exercise. Link to post Share on other sites More sharing options...
Chris Higgs Posted January 5, 2016 Author Share Posted January 5, 2016 (edited) Could this technique be used for outside cylindered locos? Building outside cylinders in 2mm is a fiddly exercise. It's certainly possible to 3D print the cylinders, and has been done for example on John Birkett-Smith's Star Saint (sorry, wishful thinking!) https://www.shapeways.com/product/4TJWUEZU5/gwr-2-cylinder-block-x2-2mm-fs?li=search-results-1&optionId=57305424 In FUD as they need to be fine resolution. But I think the slidebars and valve gear have to remain as metal. I intend to do cylinders for some of my locos. Chris Edited January 6, 2016 by Chris Higgs Link to post Share on other sites More sharing options...
RMweb Premium Ian Morgan Posted January 10, 2016 RMweb Premium Share Posted January 10, 2016 Not so enthused that apparently the Terrier and J39 are not selling too many in the Association shop :-( Chris I have the first one of mine running nicely now. I had to resort to pickups wiping on the rail tops, though. The 'Simpson spring pickups' bearing on the axles did not seem to work very well, so I added some wipers bearing on the tops of the wheel treads, but that did not help either. It seems the wheels just would not make proper contact with the rails. https://www.youtube.com/watch?v=IDyOgHuYR8M Two more to go Ian Morgan Hampshire Link to post Share on other sites More sharing options...
RMweb Premium nick_bastable Posted January 11, 2016 RMweb Premium Share Posted January 11, 2016 I have to many unstarted / unfinished projects so a terrier is on hold, for interest how did you fix the motor ? I have the first one of mine running nicely now. I had to resort to pickups wiping on the rail tops, though. The 'Simpson spring pickups' bearing on the axles did not seem to work very well, so I added some wipers bearing on the tops of the wheel treads, but that did not help either. It seems the wheels just would not make proper contact with the rails. https://www.youtube.com/watch?v=IDyOgHuYR8M Two more to go Ian Morgan Hampshire Link to post Share on other sites More sharing options...
RMweb Gold queensquare Posted January 11, 2016 RMweb Gold Share Posted January 11, 2016 (edited) I have the first one of mine running nicely now. I had to resort to pickups wiping on the rail tops, though. The 'Simpson spring pickups' bearing on the axles did not seem to work very well, so I added some wipers bearing on the tops of the wheel treads, but that did not help either. It seems the wheels just would not make proper contact with the rails. Two more to go Ian Morgan Hampshire Congratulations Ian, looks to be running well. I don't have a lot of luck with Simpson springs, I find they loose their tension and are impossible to adjust once the chassis is built. I tend to use top acting wipers bearing very lightly on the tops of the wheels.I wonder if your pickup problems are due to your making the chassis too accurately if that makes sense. I find that a bit of 'controlled slop' in the bearings makes a world of difference. As for Nick's question, I glued the motor in on my Terrier and I seem to remember you had done the same when you showed me it at Portsmouth Jerry Edited January 11, 2016 by queensquare Link to post Share on other sites More sharing options...
Chris Higgs Posted January 11, 2016 Author Share Posted January 11, 2016 I wonder if your pickup problems are due to your making the chassis too accurately if that makes sense. I find that a bit of 'controlled slop' in the bearings makes a world of difference. As for Nick's question, I glued the motor in on my Terrier and I seem to remember you had done the same when you showed me it at Portsmouth Jerry So Simpson springing without the springs? Just drill the hole out to 1.6mm? I must get around to trying the motor mount I have 3D printed. It should work here and the holes to fix it are already marked on the chassis etch. Chris Link to post Share on other sites More sharing options...
RMweb Gold queensquare Posted January 11, 2016 RMweb Gold Share Posted January 11, 2016 So Simpson springing without the springs? Just drill the hole out to 1.6mm? Chris Sort of, I use top acting wipers as they can be retro fitted and are easy to adjust. My Terrier has Simpson springs one side and top acting wipers on the other. It did have Simpson springs both sides but one side failed so I replaced them. Jerry Link to post Share on other sites More sharing options...
Tim V Posted January 11, 2016 Share Posted January 11, 2016 So Simpson springing without the springs? Just drill the hole out to 1.6mm? I tried just drilling out the holes, negligible improvement, but the Simpson springs made a vast improvement. Link to post Share on other sites More sharing options...
RMweb Gold Donw Posted January 11, 2016 RMweb Gold Share Posted January 11, 2016 The must be a wide variation is how much pressure is applied by the springs. I have never heard of anyone setting up the springs to a set pressure. It would be easy enough to measure the pressure but trying to adjust it would be a real pain. I presume that is one reason why people report different degrees of success. Don Link to post Share on other sites More sharing options...
RMweb Premium CF MRC Posted January 11, 2016 RMweb Premium Share Posted January 11, 2016 With the mileages that our locos do, I am not convinced that Simpson springs would last long enough. However, we have used skids under our 0-6-0s for years. They work very well and are hard to spot if chemically blacked. The running gets better and better of course as the track gets cleaner and cleaner. The only down side is that they are bit vulnerable in storage, but can be easily tweaked. Axles need a bit of slack in their bearings, but over do it and CF will soon wear them out! Tim Link to post Share on other sites More sharing options...
RMweb Premium Ian Morgan Posted January 11, 2016 RMweb Premium Share Posted January 11, 2016 for interest how did you fix the motor ? I used Milliput to seat the motor in place, and this holds the motor quite well too. See my blog here: http://www.rmweb.co.uk/community/index.php?/blog/779/entry-17042-terrier-chassis-episode-5/ Ian Morgan Hampshire Link to post Share on other sites More sharing options...
Chris Higgs Posted January 23, 2016 Author Share Posted January 23, 2016 Encouraged by the prototypes, I have sent off a new batch of 3D printed chassis blocks to Shapeways. Here's my latest take on a GWR 2251, complete with as cantilever gear box which should prove to be much less prone to flexing than the etched version. Chris GWR_2251.png GWR_2251_2.png Having got back this desgin printed in WSF, I have come to the conclusion there are issues with the accuracy of the holes in certain orientations. Those for the axles were fine, but the ones for the cantilver gearbox were oblong. I think the print orientation caused this, but another would have been even worse. So I have redesigned the block to print in FUD, leaving more gaps to cut down the volume, and hence the cost. This looks like it has the advantage that there are places to add weight now, perhaps brass strip cut up or lead. I have started a new job this week, only 20 minutes from home, and so perhaps I will have more time to devote to this project. Chris Link to post Share on other sites More sharing options...
pod909 Posted January 24, 2016 Share Posted January 24, 2016 (edited) Following this with interest and very keen to hear your learnings and guidance for anyone looking to do similar Chris Edited January 24, 2016 by pod909 Link to post Share on other sites More sharing options...
Chris Higgs Posted January 30, 2016 Author Share Posted January 30, 2016 (edited) Just in case anyone thinks this thread has just turned into blue-sky thinking, here are some photos of a real chassis built up using 3D printed blocks. The block is WSF, which I do not intend to persist with, but it shows how I see it working out. The etched sideframes have had their bearings soldered in, and they will then be superglued to the block, perhaps holding in a vice to ensure they are firmly seated. From then on everything will have to be glued, so make sure you have soldered on what ever you deem necessary (sandboxes etc.). I have left the tags which would have been soldered to PCB spacers as extra places for the glue to hold, and to which the motor wires can be attached. On this design I have left the cantilever gearbox in place, as the motor needs to be mounted back behind the spur gears so I am reasoning the worm shaft will need some support at the far end. Also, here is a new design for a GWR 42XX. My idea is that existing etch sideframes from a kit could be used - in this case the Worsley Works one - onto such a block. All you have to do is drill out the axle holes to take the Association bearings, and the bearings for the wormshaft plug directly into the block - no need to acurately mark and drill the shaft in the sideframes. Edited January 30, 2016 by Chris Higgs 7 Link to post Share on other sites More sharing options...
Branwell Posted January 31, 2016 Share Posted January 31, 2016 What's the 'real' one for Chris? Link to post Share on other sites More sharing options...
Chris Higgs Posted January 31, 2016 Author Share Posted January 31, 2016 What's the 'real' one for Chris? All will be revealed in due course. You can guess if you like. Chris Link to post Share on other sites More sharing options...
RMweb Premium DavidLong Posted January 31, 2016 RMweb Premium Share Posted January 31, 2016 All will be revealed in due course. You can guess if you like. Chris Looks like an 0-8-0 of some description, which narrows it down to any number of classes! An 'Austin Seven' would be nice . . . David Link to post Share on other sites More sharing options...
richbrummitt Posted February 19, 2016 Share Posted February 19, 2016 Coal tank, presumaby? Link to post Share on other sites More sharing options...
RMweb Premium DavidLong Posted February 19, 2016 RMweb Premium Share Posted February 19, 2016 richbrummitt, on 19 Feb 2016 - 14:27, said:Coal tank, presumaby? You may be right, Richard. I'd sort of edited out the rear guard irons. Not the usual thing on 0-8-0s of the tender engine variety! David Link to post Share on other sites More sharing options...
Chris Higgs Posted March 28, 2016 Author Share Posted March 28, 2016 (edited) A rainy Easter Monday has finally seen the test etch of the GWR 51XX under construction. Pretty much everything is as I intended. The cylinders do build, but are quite fiddly and I for one will be using the 3D-printed cylinders that I will supply with the etch. I'm sure someone is going to ask about the lack of a rear truck (pony or radial). I've done the maths, and with the frames narrowed to 7mm at the rear and sufficient sideplay of 0.35mm in all axles (not just the rear one) the design should go around 2ft radius curves. The 0.35mm total sideplay can come from a combination of the wheels in the frames, plus the wheel flanges on the rails. Edited March 28, 2016 by Chris Higgs 3 Link to post Share on other sites More sharing options...
Tim V Posted March 28, 2016 Share Posted March 28, 2016 I like the look of those continuous slide bars, when will the etches be available? Link to post Share on other sites More sharing options...
Chris Higgs Posted March 28, 2016 Author Share Posted March 28, 2016 Next up is the M7. This is in the 0-4-2-2T arrangement recommended by TIm Watson. The etch also allows you to build it as a classic 0-4-4T. Good luck with getting the weight balance in that case though. 4 Link to post Share on other sites More sharing options...
RMweb Premium nick_bastable Posted March 28, 2016 RMweb Premium Share Posted March 28, 2016 Next up is the M7. This is in the 0-4-2-2T arrangement recommended by TIm Watson. The etch also allows you to build it as a classic 0-4-4T. Good luck with getting the weight balance in that case though. DSCF0795.JPG DSCF0796.JPG DSCF0798.JPG now I want two of these little beauties Link to post Share on other sites More sharing options...
RMweb Gold 2mmMark Posted March 29, 2016 RMweb Gold Share Posted March 29, 2016 Looks like an 0-8-0 of some description, which narrows it down to any number of classes! An 'Austin Seven' would be nice . . . David The little known GER "Octopod"? Link to post Share on other sites More sharing options...
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