burgundy Posted July 19, 2011 Share Posted July 19, 2011 Does anyone build locos in 4mm scale with split frame chassis please? As noted in another thread http://www.rmweb.co....e-of-a-terrier/ I have struggled unsuccessfully with this arrangement twice now, but hate to give up. Or maybe I am just too mean to leave the rather nice set of Branchlines wheels unused? Any practical experience would be much appreciated. Many thanks Eric Link to post Share on other sites More sharing options...
Weekday Cross Posted July 20, 2011 Share Posted July 20, 2011 Why not tell us what project you are working on - as split frame solutions may differ depending on the prototype Link to post Share on other sites More sharing options...
bertiedog Posted July 20, 2011 Share Posted July 20, 2011 Sadly the split frame in 4mm has a bad reputation from the efforts of RTR makers to use it a few years ago, continued with some Bachmann designs. Split frame it the best electrical pickup system, simple, no special pickups, there are none!.. no drag, no servicing, no pickup parts. But it needs special wheels, and axles, to achieve the system, wheels that are not insulated in any way to the axles,and electrically split axles. The frame changes are quite easy, PC board can replace whole sides or provide area around the bearings that are insulated from the rest of the chassis. One side can be normal, the other side insulated, or both the same, and insulated. Nothing must short the sides, either the body or the valve gear. Wheels remain a problem, none are made to suit, although ex- Bachmann re-used are suitable, but are rather low quality diecast plated efforts with a poor bearing area it is possible to modify the Alan Gibson and Sharman wheels with a wire that runs from the tyre to the axle. This is not too difficult but is precision work, and soldering the tyre is risky to say the least. My own method uses no solder, ,the fine wire is forced into a close fitting hole in the tyre, and then forced into a hole in the axle. The fit must be tight, but not unduly so,and I have had no failures using just this close fit. The next issue is the axle, and this is the big problem....... it is going to involve very careful hand work or work on a lathe. the axle is sawn in half and reconnected with a Muff,, a sleeve of plastic, in a hard grade like Bakelite or tufnol. The other way is to use a smaller axle like 2mm to ease the size of the sleeve, which must be able to take the gear on it to drive the axle. A third way is to use the 1/8th axle and drill out the centre with a 2mm drill, and reassemble on a 2mm glass fibre rod as insulation.In my opinion this is the best way, but needs a lathe to do the driling and preparing the glass fibre rod by machining to exact 2mm. The split is arranged on the glass fibre version to one side to allow quite ordinary gears to be used in the usual central position. Markits ( Romford wheels), can be used , they make uninsulated versions with nickel tyres or you can short the insulation quite easily on old ones by insertion of a wire into the insulated rim gap, But the axles must be made, using the sleeve method, and the squares accurately set to match to make quartering accurate. It is not possible to just drill through the axle and fit glass fibre, but after splitting each half can be drilled to take a short fibre glass rod, as long as the drilling is short of the special squared ends. So not for the faint hearted, there is no off the shelf solution for OO split frame, but there are methods for making in the home workshop, but really with a lathe to make the special axles required to sufficient accuracy. 2mm attracts a lot of split frame designs, the lack of drag and pickups is vital to decent running, and 7mm attracts split frame as solid wheels in cast iron are made, you only have to make the axles. Stephen. . Link to post Share on other sites More sharing options...
Jol Wilkinson Posted July 20, 2011 Share Posted July 20, 2011 Split axle "kits" are available from the S4 Society and EMGS presumably for 18.83 and 18.2 gauges. Branchlines did split axles but their "Blog" website isn't much help as to the current situation. I think soemone elso does them, but not sure who. Jol Link to post Share on other sites More sharing options...
bertiedog Posted July 20, 2011 Share Posted July 20, 2011 I did mention "no off the shelf " for OO, the Societies offerings are for S4 and EM, and are they a total or partial help?, as it may still require the wheels modified. I had heard of the Branchlines axles, but do not know what wheels it goes with, I assume 1/8th plain, to suit Sharman and Gibson etc. I have never seen commercial axles for Romford axles in an insulated form. With split 1/8th axles there is still the problem of the metal gear straddling the gap if it is in the centre area. It is best to move the gap to one side, no issue at all then, or to fit a larger bored gear on an insulated sleeve. making it a lathe job, rather than a simple one. Split frames makes motor gearbox frames awkward if the gap is within the gear frames, as the bearings straddle the gap, another restriction to bear in mind. This means a lot of popular designs and makes are off limits, unless big alterations are made, like plastic bearings in the gear frame. The simplest way can be the best with split frame, a solid frame in perspex, metal bearings wired together inserted into the plastic, and a carved out space for the drive and motor, but this is a milling machine job, or a craftsman job to make a hand sawn sandwich of perspex sheets sawn and fled to shape. Simplest of all is simply make the frames from PC board, both sides and join with ordinary spacers, but remove the copper they touch. With fibreglass board they are durable, and provide easily for insulating the body and couplings. But after sorting the frames it still leaves the axles and wheels. It is possible to make the axles without a lathe, they must be sawn in half and re-assembled in a V block pair, using a simple drilled plastic sleeve and epoxy, ,...it works, it was the way a friend used to do it in the 1960's, with totally accurate axles, no lathe work at all. But it leaves finding or making the gears to fit, or moving the gear to one side of the muff sleeve. As you can see there are a legion of methods to get around the problems, but worth it in the end as the performance with split pickup is so superior to having wheel pickups. Stephen. Link to post Share on other sites More sharing options...
Darwinian Posted July 20, 2011 Share Posted July 20, 2011 The Branchlines split axle system was described by Alan Sibley in Model Railway Journal Issue 143 (Quite a few years ago now ). If my memory serves me, there was a double split axle onto which a gear wheel/gearbox would mount without making electrical contact. There were also perspex jigs to align the components whilst the epoxy resin holding the axle parts together cured. The axles had to be trimmed to length once assembled although this might be achieved in a small electric drill rather than with a lathe. I've not used the system myself and since Branchlines changed hands I do not know if it is still available. An alternative for shorting out the centres of Gibson/Sharman/Ultrascale wheels are etched shorting wires. These have a central washer with a strip of brass about 1mm wide that can be soldered to the rim. Martin Finney does simple ones and Bill Bedford did ones with a petal arrangement to make contact with the axle although i cannot find these on Eileen's Emporium's lists. I have tried an alternative approach on a Gibson GWR 850 0-6-0T which was to short the wheels on one side (with Finney etched shorting wires) and use sprung plungers on the other. Much to my surprise this seems to work remarkably well . Oh, my models are 00 so fitting in two sets of plunger pick ups is awkward and produces a lot of rolling resisistance to boot. Adrian Link to post Share on other sites More sharing options...
billbedford Posted July 20, 2011 Share Posted July 20, 2011 The OP should think of joining the 2mm Association. Split frames are their preferred method of loco construction. Link to post Share on other sites More sharing options...
burgundy Posted July 20, 2011 Author Share Posted July 20, 2011 Thanks to all for the very helpful suggestions. I should have been more specific with the original exam question, although I had assumed that the back reference to the Terrier article would provide a clue. However, the photo below, showing the main ingredients, may help (with apologies for the quality). Reading from left to right Frames from a Perseverence etched chassis kit Terrier - Dapol body made of plastic, which is what made me think it was a good candidate for the split frame treatment Branchlines wheel (there are another 5) - solid metal (so no need to short the rim to the axle) and, I think, originating from Paul Berntson (sp?) Split axle (although one of the three came out of the jig unsplit) - 2mm diameter so I need to source appropriate gears A half split axle to show the 2:1 ratio in which the axle is split. I think I have got my head around the main bits of the chassis; I can see how you would use PCB or something similar to to keep the two sides of the frames the right distance apart and, with a plastic body, there should be no need to worry about the body bridging the frames. However, the 2mm axles take you down a path of needing 2mm bearings in hornblocks (are they available?) and a gearbox set for 2mm axles. I have a dark suspicion that the original design may not even have envisaged a cradle for the gears, as the split in the axle does not seem to allow space for anything more than the gear wheel itself. As soon as you go down the path of a cradle (far less gearbox) you seem to create a bridge across your split axle (and/or possibly between the frames) and I assume that anything like a muff on the driven axle is going to create a problem in ensuring that the gear wheel is properly concentric. I would be most grateful for any further suggestions, although I am afraid that I do not have a lathe (or the engineering skills to use one!). Many thanks Eric Link to post Share on other sites More sharing options...
Guest Natalie Graham Posted July 20, 2011 Share Posted July 20, 2011 Alan Gibson do hornblocks in 2mm diameter. I think the bits the bearings slide in are plastic too (they certainly were when they first came out) so you could build your chassis with metal spacers just as you would for insulated wheels and the hornblocks would provide the insulation. Link to post Share on other sites More sharing options...
Michael Delamar Posted July 21, 2011 Share Posted July 21, 2011 this is something Ive wanted to try for a while now as pickups really frustrate me. the axle is sawn in half and reconnected with a Muff,, a sleeve of plastic, in a hard grade like Bakelite or tufnol. is this done once the frame is made or done first then the frame built around it? and what if an axle is to be compensated? Link to post Share on other sites More sharing options...
meil Posted July 21, 2011 Share Posted July 21, 2011 Suggest you look at this article: http://www.mmrs.org.uk/technical/Langan%20articles.htm Link to post Share on other sites More sharing options...
Adam Posted July 21, 2011 Share Posted July 21, 2011 2mm square bearings can also be had from High Level and MJT (via Dart Castings). Most of the High Level gearboxes can be had with a final drive gear to suit a 2mm axle if you ask Chris Gibbon nicely. 1/8" to 2mm reduction bearings (available from Gibson, Branchlines, Markits...) should sort out the gearbox itself: I've done this myself once, for a Judith Edge Sentinel 0-4-0 and this works fine. Adam Link to post Share on other sites More sharing options...
bertiedog Posted July 21, 2011 Share Posted July 21, 2011 this is something Ive wanted to try for a while now as pickups really frustrate me. is this done once the frame is made or done first then the frame built around it? and what if an axle is to be compensated? If muff sleeves are used over the axle, and 1/8th axles are in use,, then the increased diameter will mean you can't easily assemble the frames, axles, wheels, and bearings, except by assembling the lot as a unit and dropping into a slotted conventional chassis as per the real thing, and adding a keeper plate or keeper wires to retain them Using a chassis with plain holes would be out, or lead to a complex assembly order. Split frame does not affect any springing method within reason, all should work with due allowances made to ensure the insulation is not straddled due to movement etc., of the bearings The issue of the gearboxes straddling the split can be cured in P4 and EM , as there is extra space, by making the split at one end of the axle, allowing just enough uninsulated axle to run in the bearing, then the insulated gap, and then back to steel. This suits an axle made by sleeving over fibre glass, or a plug ended axle, where the loger part is drilled out and the shorter has a pin of reduced diameter, and the insultion is made from epoxy, with the axle assembled in a jig., It will also work in 00, but clearances are very tight, and a non gearbox solution may be better, a traditionally mounted motor and gear. Springing is more difficult, but as it is usual to have a rigid axle even on a sprung loco, this may not be a problem. Stephen. . Link to post Share on other sites More sharing options...
bertiedog Posted July 21, 2011 Share Posted July 21, 2011 Thanks to all for the very helpful suggestions. I should have been more specific with the original exam question, although I had assumed that the back reference to the Terrier article would provide a clue. However, the photo below, showing the main ingredients, may help (with apologies for the quality). Reading from left to right Frames from a Perseverence etched chassis kit Terrier - Dapol body made of plastic, which is what made me think it was a good candidate for the split frame treatment Branchlines wheel (there are another 5) - solid metal (so no need to short the rim to the axle) and, I think, originating from Paul Berntson (sp?) Split axle (although one of the three came out of the jig unsplit) - 2mm diameter so I need to source appropriate gears A half split axle to show the 2:1 ratio in which the axle is split. I think I have got my head around the main bits of the chassis; I can see how you would use PCB or something similar to to keep the two sides of the frames the right distance apart and, with a plastic body, there should be no need to worry about the body bridging the frames. However, the 2mm axles take you down a path of needing 2mm bearings in hornblocks (are they available?) and a gearbox set for 2mm axles. I have a dark suspicion that the original design may not even have envisaged a cradle for the gears, as the split in the axle does not seem to allow space for anything more than the gear wheel itself. As soon as you go down the path of a cradle (far less gearbox) you seem to create a bridge across your split axle (and/or possibly between the frames) and I assume that anything like a muff on the driven axle is going to create a problem in ensuring that the gear wheel is properly concentric. I would be most grateful for any further suggestions, although I am afraid that I do not have a lathe (or the engineering skills to use one!). Many thanks Eric On the basis of the parts, the wheels are just right, solid, the axle will be intended to have the split over to one side, so a conventional gear frame can be fitted with care, adding insulted washers to the insulted gap side to prevent any chance of the gear frame bearings straddling the gaps. 2mm gears are available as are bearings, are the Branchlines axles 2mm outside diameter? The best way with the chassis would be simple plate glass fibre PC board spacers used in the same positions as the nickel etched ones. If you have only got the sides it is quite easy to determine the positions one front flat to bolt the body to, one flat at back to bolt the body to, and a vertical plate just ahead of the gearbox or gear frame position. SRB(paxolin) PC board will also work , but is not quite so robust as glass fibre, so if it is used pick a thicker grade. After they are soldered in to place run a fillet of superglue along the other side of the joint, it strengthens the joint a lot. The copper is split down the middle, (file away), and any area of metal on the body taped and insulted from it, although in this case the body is plastic. The PC board provides handy attachment points for the motor leads. Stephen. Link to post Share on other sites More sharing options...
bertiedog Posted July 21, 2011 Share Posted July 21, 2011 The drawing shows the axle arrangement for a gearbox axle, where the gap, shown in red, is placed between the gearbox and the bearings. The gap has to have an insulating washer added to the axle to ensure side movement will not cause a short. The arrangement will work in 00 but it is a tighter fit all round.. The same arrangement applies to 2mm if the axle is flush, A outside muff is not possible with this arrangement, the split would have to be in the middle, and the gear frame back insulted, with a split PC board supporting the motor. Link to post Share on other sites More sharing options...
bertiedog Posted July 21, 2011 Share Posted July 21, 2011 For those with access to a lathe there is a simple design to be able to short out the standard wheels, if you can get the "spiders" that were done as etchings or cut out you own from thin phosphor bronze sheet, sharp scissors will do it. The spider is made with at least three spoke sized legs that bear on the wheel rim back just short of touching the rim where the rail can reach. The centre is drilled 1/8th inch, and new axles are made from 4mm steel rod, with 1/8th spur ends. The back to back dimension has the total thickness of the bronze spiders subtracted and the axle machined to match. Then unmodified Gibson or Sharman wheels will push straight on and press the spiders into contact with the axle at the correct back to back. Absolutely no soldering is required, and the wheels are unmodified in any way. Quartering is unaffected in any way. The 4mm axle will need the appropriate gap made before the machining of the ends, either in the centre or offset. In this case with obe side holoow and the other iserted into insulation inside or epoxy cast in place. The bearings on the loco must now be drilled out to 4mm or new ones made. 1/8th gears can be drilled or bored out to 4mm holes. Similar spiders can be used on tender wheels, just drill the centre to match the axle,and assemble with two stub axles, the plastic muff centre being made to back to back, less the thickness of the spiders. To prevent the axle stubs touching a scrap of paper is out in the hole before pressing home, This all assumes outside bearings on the tender, one frame will need insulting, and leads provided to take power to the loco. Stephen. Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted July 21, 2011 Share Posted July 21, 2011 Sadly the split frame in 4mm has a bad reputation from the efforts of RTR makers to use it a few years ago, continued with some Bachmann designs... Just for the sake of completeness, not wholly a bad rep in OO. Bachmann deploy a version of split chassis current collection in many of their recent introductions, the class 105 DMUs and Met-Camm Pullmans for example, Hornby use it in their class30/31 chassis, (and probably other bogie diesels in their range) and if the Dapol OO diesel spec is delivered as described these will have it too. And it functions very well indeed, being much easier to arrange with outside bearings; fingers crossed that one day it occurs to Hornby that if they are to persist with current collection on loco tenders they will do away with the draggy wipers and use this technique. Likewise with Bachmann: I have a good number of their split chassis bogies and trucks 'transplanted' onto wiper pick up chassis, to augment current collection on larger locos. There's probably now a reluctance among the manufacturers to use the term 'split chassis' to descrbe this method of current collection, because of the problems with the low cost implementation on the Mainline/Bachmann OO steam (mostly) models. It's a shame that a poor implementation of a good technique casts such a long shadow... Link to post Share on other sites More sharing options...
Michael Delamar Posted July 21, 2011 Share Posted July 21, 2011 thanks for your reply Stephen, I was going to ask about the gearbox which you answered. going back to what you mentioned about the perspex chassis, thats interesting. but I was wondering, and dont laugh, how about a wooden chassis block? not sure how well it would work or last but wondering if anyones ever tried it. or maybe a hard resin chassis block? Mike Link to post Share on other sites More sharing options...
Michael Delamar Posted July 21, 2011 Share Posted July 21, 2011 that led me on to think about having brass frames with a resin block or wooden middle, ie sandwich, but then thought itd be no different to the pcb option which would be better. so ignore that one I think Link to post Share on other sites More sharing options...
bertiedog Posted July 21, 2011 Share Posted July 21, 2011 For block chassis, milled and filed and sawn to shape, then Boxwood, Lignum vitae or Canadian White Maple will work.......they are extremely dense, stable, and hard enough and do not warp significantly, but are expensive and hard to buy in solid block. You can drill and tap them with course threads or fine threads in the case of Lignum Vitae. All take threaded woodscrew with a pilot hole, you will not be able to screw ordinary screws into these hardwoods, it is just too hard. More seriously, Paxolin, Tufnol, or Synthetic resin bonded board is the next best for availability and durability, and ease of cutting and working. Takes drilling and tapping with ease. These are resin products bonded with wood, sawdust, fillers or paper, or cloth in the case of Tufnol. There are dozens of types and grades. Some Tufnol does not glue well, it is too slippery, and all Tufnol should be de-greased before glueing. Tufnol is usually used for gears in specialist gearboxes. Approximately the same applies to Acetal plastic (Perspex), which also glues well with chloroform....(!!).takes drilling and tapping with ease, must be slowly machined as it has a low melting point, hot tools will bind with perspex. With perspex it is mostly the same grade due to the nature of the material. Polycarbonate, (Lexan), with also behaves much the same as Perspex, takes drills and tapping, but is not so easy to sand and still get a good surface. Some Polycarbonate is filled with additions to make it harder etc. ABS sheet can be used, it is made in thick sections, but is softer than Perspex and is more difficult to get a "finish" on sawn or cut surfaces. The best "plastic" of all is still Bakelite, which is still made in sheet form, and can be obtained in 1 inch sheet and blocks. Do not confuse with moulded items in Bakelite, these might be cut up and used but older items may contain asbestos as a filler, and should not be sawn up and you come into contact with the dust. Modern Bakelite is safe, used in sheets for insulation in radio aerials, and other tough environments, it lasts indefinitely. Bakelite saws and machines well, surfaces can be polished and sanded, and it drills and taps perfectly. It glues well with epoxy glue. Sheet Paxolin is often mistaken for Bakelite sheet, and vice versa,....... the Bakelite has a distinct smell when sawn or heated. Paxolin will burn, Bakelite smoulders.but does not usually burn. For all split chassis uses any of the above will work for our uses, with brass outer frames screwed and glued to the insulated core. Stephen. Link to post Share on other sites More sharing options...
bertiedog Posted July 21, 2011 Share Posted July 21, 2011 Just for the sake of completeness, not wholly a bad rep in OO. Bachmann deploy a version of split chassis current collection in many of their recent introductions, the class 105 DMUs and Met-Camm Pullmans for example, Hornby use it in their class30/31 chassis, (and probably other bogie diesels in their range) and if the Dapol OO diesel spec is delivered as described these will have it too. And it functions very well indeed, being much easier to arrange with outside bearings; fingers crossed that one day it occurs to Hornby that if they are to persist with current collection on loco tenders they will do away with the draggy wipers and use this technique. Likewise with Bachmann: I have a good number of their split chassis bogies and trucks 'transplanted' onto wiper pick up chassis, to augment current collection on larger locos. There's probably now a reluctance among the manufacturers to use the term 'split chassis' to describe this method of current collection, because of the problems with the low cost implementation on the Mainline/Bachmann OO steam (mostly) models. It's a shame that a poor implementation of a good technique casts such a long shadow... Where Kader's, (and others) engineers and designers went wrong was the wheel and stub axle being combined in one cast by the die-cast process. Thw whole Mazak zinc alloy casting was then copper coated and finally hard chromed with a nickel content. The actual wheel done like this was accurate, and it is the method still used.to make wheels for most Chinese production, where sintered metal wheels are not specified. There is no machining of the wheel, it is used from the die-casting moulding process. The issue with Mainlines method was that the cast on stub acted as the axle, with a chromed cast surface running on a cast Mazak chassis. The chrome wore due to the castings not taking the copper well, and flaked , making a chrome based grinding compound that wore away at both the stub axle and the chassis. It was frankly the method that a toy maker would use to save mony, cast unmachined parts trying to be used where precision machned parts should have been used in dissimilar metals to act as bearings. The change done by Kader, and Hornby with their contract makers s to bore the wheel centre and fit a steel stub axle, which runs in a brass bearing, this works 100% in RTR terms,but it took 25 years for Kader to get around to altering to this for production for the UK.. It had been dealt with for the US market almost at once, but UK was in the period of the change to the Chinese makers and simply did not specify or design the requests to the Chinese factories, who given all their faults, bless them, make what you ask for!! ..cheap model railways. The UK makers did not ask, most of them barely had the knowledge to assess the earlier mechanisms supplied to sell the UK, if they had, I apologise, but they must have been away on holiday. Most ranges took what the Chinese offered, and as we all now know, most was complete rubbish. It's quite different now, the specs are better, the Chinese engineering has improved, and in the case of current split frames works well. ......... and by the way, an old mainline can be rebuilt to cure everything, even using the existing wheels, but with steel axles and brass bearings added, but then there are issues with the gears and motors as well.......curable but lots of work if you are unlucky and have a bad example. Stephen. Link to post Share on other sites More sharing options...
Michael Delamar Posted July 21, 2011 Share Posted July 21, 2011 weight I think should be considered, I remember my dad years ago converting a triang jinty to finescale and replacing the motor with a mashima I think, new bearings and romford wheels, it ran extremley well, wasnt split, same way as designed, but the weight I think made a big difference. Link to post Share on other sites More sharing options...
burgundy Posted July 21, 2011 Author Share Posted July 21, 2011 Thanks to everyone who has contributed to answering my query and in particular to Bertiedog for his detailed explanations. In fact his sketch/end view provided the clue that, I think, has allowed me to see a way through this one. The Branchlines axles are actually 26mm long, whereas an EM axle should not need to be more than about 22mm. Therefore by taking more material off the shorter part of the axle, it should be possible to bias the join so that it falls as close as possible to the frame. This should leave the maximum space for the gearbox to fit to the other part of the axle without bridging the insulation. As various contributors have pointed out, hornblocks and gearsets are available to match a 2mm axle, so, with a bit of careful shopping, a solution should be possible. It looks as though I am running out of excuses on this one now.................. Again, many thanks Eric Link to post Share on other sites More sharing options...
RMweb Premium Dave Searle Posted July 22, 2011 RMweb Premium Share Posted July 22, 2011 Hi Eric, I used split frames for my Belgravia tender (in P4). I used PCB to hold the frames apart, London Road Models axle boxes, and shorted out the Sharman wheels on 2mm Branchlines split axles (and sprung it with CSBs). See: Starting to Build "Carisbrooke" blog I chickened out of doing the same on the loco, due to the added complexity of outside frames. I really must get round to finishing it off. Cheers, Dave Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted July 24, 2011 RMweb Premium Share Posted July 24, 2011 and by the way, an old mainline can be rebuilt to cure everything, even using the existing wheels, but with steel axles and brass bearings added, but then there are issues with the gears and motors as well.......curable but lots of work if you are unlucky and have a bad example. Stephen. I bought 3 Mainline split chassis models when they first came out. I did not use them but packed them away until I had a suitable layout. A few years ago I got them out and tried to run them. One would not run at all - the chassis sides were warped and brittle, when I dismantled it, it virtually fell apart - definitely not curable. The second one did run, very badly - all the wheels were wobbly due to the plastic muffs all being cracked, again the chassis had deteriorated, not as badly as the first, but not worth persevering with. The third one was relatively OK and has been DCC chipped and is still running. Keith Link to post Share on other sites More sharing options...
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