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Model Forum / General / Railroads / July 2004Expansion gaps
Hmmm. Expansion gaps required in 00 layout, longish runs of track. Is there a reasonable guideline for width and frequency? Guy  SignatureMay contain traces of irony. Contents liable to settle after posting. http://www.chapmancentral.co.uk 88% of helmet statistics are made up, 65% of them at Washington University > Hmmm. Expansion gaps required in 00 layout, longish runs of track. > Is there a reasonable guideline for width and frequency? I can tell you the story about how I got it wrong, if that would help? :-) Regards, Greg.P. >I can tell you the story about how I got it wrong, if that would help? :-) Oh go on then :-D Guy SignatureMay contain traces of irony. Contents liable to settle after posting. http://www.chapmancentral.co.uk 88% of helmet statistics are made up, 65% of them at Washington University > >I can tell you the story about how I got it wrong, if that would help? :-) > > Oh go on then :-D I added a 34' x17' garage to my property - typical cheap/nasty NZ type with wooden frame and steel cladding. The idea was to have a main baseboard across one end, 1' wide baseboards down each side and a removable bridge section across the doors. (Room for 4 cars and workshop space in the middle) My first year discovery was that the internal temperature moved over a range of +/- 10 degrees C of the outdoor temperature range +40/-5 degrees C. In that time I had built eight 4'x1' baseboards and laid a double track main line, a passing station and a short branch-line. The track, including ballasting, all got laid in spring while temperatures were moderate. When summer came those 32' feet of straight track expanded and the wooden baseboards shrank so I spent some time shortening rails to avoid some serious problems. After that I got sidetracked onto various household problems and in insulating the garage walls, so the layout got ignored for a few months. The next time I ran any trains was late autumn - the train ran very well until it got to the passing station, which was situated on the last three baseboards. "CRUNCH". Closer observation revealed a full quarter inch gap between the first turnout and the next length of rail! All my carefully gapped rail joins along the full length of the layout were hard pressed together and the total gap had all arrived at one point. Murphy's law perhaps, or the 1:100 gradient caused all the rail lengths to move down-hill? Regards, Greg.P. > > >I can tell you the story about how I got it wrong, if that would help? :-) > > > > Oh go on then :-D > > I added a 34' x17' garage to my property - typical cheap/nasty NZ type with I sniped a bit . I built one in the cellar hand built soldered track. It contracted all wavy . Story is that the Each summer the VOR had to remove a section from the bottom and add it to the top each winter > > > >I can tell you the story about how I got it wrong, if that would help? > :-) [quoted text clipped - 10 lines] > Story is that the Each summer the VOR had to remove a section from the > bottom and add it to the top each winter LOL! > All my carefully gapped rail joins along the full length of the > layout were hard pressed together and the total gap had all arrived > at one point. Tee-hee! Note to self: superglue the top bits of the incline :-) So, did you cut gaps in the rails, or just leave spaces at the joiners? That does seem like the obvious solution, put a bit of ten thou Plastikard between the rails when laying the track, but I wonder if that is enough? My temperature variation is a bit less than yours but not much, and the layout is 12' square. SignatureGuy -- May contain traces of irony. Contents liable to settle after posting. http://www.chapmancentral.co.uk > > All my carefully gapped rail joins along the full length of the > > layout were hard pressed together and the total gap had all arrived [quoted text clipped - 3 lines] > > Note to self: superglue the top bits of the incline :-) Hmmm, not as silly as it sounds! > So, did you cut gaps in the rails, or just leave spaces at the joiners? Well, on 4 foot long baseboards you end up with: /yard length / 1 foot length / baseboard gap/... > That does seem like the obvious solution, put a bit of ten thou Plastikard > between the rails when laying the track, but I wonder if that is enough? My > temperature variation is a bit less than yours but not much, and the layout > is 12' square. Curves have to help - as on the prototype the track will move fractionally sideways under expansion. Just the compression of the rail fixings sideways has to equal a few millimeters. Calculating my layout: 5 x 4 foot modules = 11 rail joints at about 10 thou = 110 thou Baseboard timber movement in opposite direction would be double the rail movement = 220 thou. 110 + 220 = 330 thou total which equates to the rail gap that derailed my train! Of course, that 330 thou is at the median temperature so the difference between -15degrees c and 50 degrees c could be double that distance. I think a good case is made for screwing pc board sleepers at each baseboard end and soldering the rail ends down! In that case, all the expansion/contraction on each 4 foot baseboard is going to appear between the two lengths of flex track. Greg.P. These are problems I have seen on several layouts. I apply the following rules: 1/ Attach wires to rails at the midpoint of the rail, NOT the ends. This is because the connection acts as a fixing point about which expansion will occur. 2/ Where a yard of rail is long enough to traverse the entire length of a board, ALWAYS cut the rail in half and lay with a gap in the fishplate joint. Wires are attached to rails as in (1) so that equal expansion is possible. 3/ NEVER solder rails to screws at the ends of boards: it creates a fixed point which means that rail expansion can only occur in the opposite direction across the entire length of the rail and create greate expansion on the far end of the rail than would occur if it was fixed at its mid point 4/ Don't use long lengths of rail - maximum 1M/yd 5/ When laying track, ALWAYS leave a small gap between rail ends - DON'T but the rail ends up together. 6/ ALWAYS use insulating fishplates or similar: simple gaps in rails can close up and cause all kinds of shorting problems, but don't rely on plastic fishplates as a means of maintaining track alignment - they don't have the strength. 7/ Never use breaks in rails at board joints as a means of separating electrical polarity (eg isolating sections, cross V's etc). It causes no end of confusion with wiring and when rails expand, the gaps close up and cause shorts. Of course, these rules apply in environments where significant temperature variations occur. My layout was in storage for a year in a Sydney garage where temparatures could range from 0 degrees to 45-50 degrees. The above rules ensured that there were no expansion/buckling problems at all. BTW: When prototypical CWR track is laid, it is tensioned up. Here in Sydney, I am only aware of one expansion joint on the Meadowbank viaduct across the river. Obviously, tensioning makes expansion joints largely unrequired. Graham Plowman < > 6/ ALWAYS use insulating fishplates or similar: simple gaps in rails > can close up and cause all kinds of shorting problems, but don't rely > on plastic fishplates as a means of maintaining track alignment - they > don't have the strength. NEVER use insulating fishplates.......... Cut the rail with your Dremel tool, insert a small piece of suitable thickness of your favourite plastic sheet, add a touch of AC glue and when dry, file the plastic to the shape of the rail. -- Cheers Roger T. Home of the Great Eastern Railway http://www.highspeedplus.com/~rogertra/ > < > [quoted text clipped - 8 lines] > thickness of your favourite plastic sheet, add a touch of AC glue and when > dry, file the plastic to the shape of the rail. AC glue has little shear strength, particularly under tension. Regards, Greg.P. > NEVER use insulating fishplates.......... We'll have to disagree on that score Roger. Providing you only use insulated fishplates on relatively straight track they shouldn't present any problem(s). John. >> NEVER use insulating fishplates.......... > >We'll have to disagree on that score Roger. Providing you only use >insulated fishplates on relatively straight track they shouldn't present any >problem(s). One thing I discovered on my garden railway, is that Peco insulating fishplates (rail joiners) are pretty awful, because they are incapable of keeping the track in line. However, you've got to do something at an insulating joint. So this is what I have started to do. Cut two three-inch-long pieces of rail. Join them with the aforementioned insulating fishplates, allowing zero expansion gap at all, then stick them to something to keep them in alignment (and curvature if necessary). Join them to the track with ordinary metal fishplates, allowing the usual expansion gap there, and carving the baseboard up if necessary to ensure all fits nice and level. A couple of 1/2" No. 6 CSK screws might help to keep everything in place. The worst joint on my railway is between two points on a crossover, where the insulating fishplates have assumed a Z structure with about 2mm. difference in height between the tracks. Yes it needs fixing. No I couldn't be bothered at the moment. Next year, perhaps. SignatureJohn Sullivan OO in the garden http://www.yddraiggoch.demon.co.uk/railway/railway.html My next project: Extend the layout back up the other side of the garden. John, >Cut two three-inch-long pieces of rail. Join them with the >aforementioned insulating fishplates, allowing zero expansion gap at [quoted text clipped - 3 lines] >baseboard up if necessary to ensure all fits nice and level. A couple of >1/2" No. 6 CSK screws might help to keep everything in place. One thing I am trying out in 7mm scale, where I want an insulated joint and alignment, is to solder a small strip of PCB across the undersides of the two rail ends with a gap cut in the insulation at the rail gap. I've actually used some gapped N scale sleepers which I had lying around from tracklaying many years ago and they seem to work well with sufficient strength to hold Code 125 bullhead in place. If I needed more strength I'd get some heftier PCB to do the job, although cutting that into thin strips might be a bit of a chore. Jim.. > Hmmm. Expansion gaps required in 00 layout, longish runs of track. > Is there a reasonable guideline for width and frequency? My layout is in a insulated loft room and wherever possible I lay my track in the summer, and use a 10 thou piece of sheet plastic to keep the track ends apart. Despite quite significant changes in temperature I've never had any problem with track expansion. John. > My layout is in a insulated loft room and wherever possible I lay my > track in the summer, and use a 10 thou piece of sheet plastic to keep > the track ends apart. > Despite quite significant changes in temperature I've never had any > problem with track expansion. Spot-on, John, as always. Thanks. This is exactly my situation (the loft does get seriously hot, and I had track wandering all over the place because it was all laid butted tightly in winter - d'oh! So, 10 thou at the joiners it is. Should give a nice "diddly-dum"[1] as well :-) [1] Not to be confused with dum-di-dum-di-dum-di-dum... SignatureGuy -- May contain traces of irony. Contents liable to settle after posting. http://www.chapmancentral.co.uk "Just zis Guy, > > My layout is in a insulated loft room and wherever possible I lay my > > track in the summer, and use a 10 thou piece of sheet plastic to keep [quoted text clipped - 10 lines] > > [1] Not to be confused with dum-di-dum-di-dum-di-dum... Or Do wha diddy, diddy dum, diddy do. -- Cheers Roger T. Home of the Great Eastern Railway http://www.highspeedplus.com/~rogertra/ > Or Do wha diddy, diddy dum, diddy do. Manfred Man would have liked that! ;-) John. >> Hmmm. Expansion gaps required in 00 layout, longish runs of track. >> Is there a reasonable guideline for width and frequency? > >My layout is in a insulated loft room and wherever possible I lay my track >in the summer, and use a 10 thou piece of sheet plastic to keep the track >ends apart. It's also worth investigating the Peco sliding expansion joints (assuming they're prototypical for the layout). Although they're only supposed to be for aesthetic purposes, they actually do the job well and are used to good effect on an HO garden railway I'm involved with. SignatureSpyke Address is valid, but messages are treated as junk. The opinions I express do not necessarily reflect those of the educational institution from which I post. > Hmmm. Expansion gaps required in 00 layout, longish runs of track. > Is there a reasonable guideline for width and frequency? > > Guy Interesting thread this. Made me think. Has anyone tried soldering long lengths together in hot weather to emulate the modern prototype tensioned track? Ken. > > Hmmm. Expansion gaps required in 00 layout, longish runs of track. > > Is there a reasonable guideline for width and frequency? [quoted text clipped - 4 lines] > lengths together in hot weather to emulate the modern prototype tensioned > track? "Tensioned"? I understood the theory was to weld at average temperatures and to ensure that the rails were restrained under expansion/compression. Is the system in Britain different to New Zealand? Regards, Greg.P. NZ >> > Hmmm. Expansion gaps required in 00 layout, longish runs of track. >> > Is there a reasonable guideline for width and frequency? [quoted text clipped - 8 lines] > to ensure that the rails were restrained under expansion/compression. Is the > system in Britain different to New Zealand? Ah, looks like I may have misunderstood. Anybody else out there know what the process is? Ken. >>> Interesting thread this. Made me think. Has anyone tried soldering long >>> lengths together in hot weather to emulate the modern prototype tensioned [quoted text clipped - 6 lines] >Ah, looks like I may have misunderstood. Anybody else out there know >what the process is? Looks like you are not getting an answer to this, the average situation is sort of right. The track has a design temperature at which the rails should be stress free, ie not in tension or compression. this will mean that the rails go into tension in the colder weather when the rail attempts to shrink and into compression in the summer when it tries to expand. This design temperature is usually above the mean temperature as the track structure can cope with tension more easily than compression.Tension is mostly contained by the tensile strength of the steel and the risk area is generally poor welds that may pull apart. Compression has to be constrained by the weight of the sleepers and the ballast shoulders preventing a buckle. This is the reason we sometimes get summer speed restrictions as any disturbance to the ballast from maintenance action or train dynamic forces makes a buckle, or 'sun kink' more likely. Note that new rail has to be welded in at the design temperature or lower as it can be hydraulically tensioned to the correct length but there is no way it can be shortened if too warm. Keith Make friends in the hobby. Visit <http://www.grovenor.dsl.pipex.com/> Garratt photos for the big steam lovers. > Hmmm. Expansion gaps required in 00 layout, longish runs of track. > Is there a reasonable guideline for width and frequency? > > Guy Seeing as we're into expansion gaps, solder track on curves, cut expansion joints on straights. Never - NEVER - use plastic rail joiners. They are the Devil's spawn. Oh, check two other things: 1. Temperature range in the layout room, and 2. Is the layout room air conditioned? You may need to watch shrinkage in timber caused by the dehumidifier action of the A/C unit. The track stays the same length, but the baseboards shrink a little under it, giving exactly the same result as expansion of track in hot weather. I know this one... :-( Steve Newcastle NSW Aust Getting a little away from track expansion, but on the subject of rail joint noise (clickety-clack), has any one ever filed little nicks in the railhead at scale 60 or 45 foot lengths, to give the effect of full size rails. Nicks would only need to be made in one rail, not both. I've thought about doing this, but have been too lazy to try it out. I'm talking, of course, of the period before long welded rail came into general use. Regards, Bill. > > Hmmm. Expansion gaps required in 00 layout, longish runs of track. > > Is there a reasonable guideline for width and frequency? [quoted text clipped - 20 lines] > Steve > Newcastle NSW Aust The message <40fe2223$0$16106$afc38c87@news.optusnet.com.au> from "William Pearce" <ben_issacs@optusnet.com.au> contains these words: > has any one ever filed little nicks in the > railhead at scale 60 or 45 foot lengths, to give the effect of full size > rails. Works OK if your stock has metal wheels. I tried the idea on an early development of my current layout - it worked but I didn't extend it to the whole layout. The length of rail I used is now in a siding where it produces an interesting sound as wagons are shunted in, providing I'm not playing something loud-ish on the CD player... SignatureDave, Frodsham Hi William, > Getting a little away from track expansion, but on the subject of rail > joint noise (clickety-clack), has any one ever filed little nicks in the > railhead at scale 60 or 45 foot lengths, to give the effect of full size > rails. Nicks would only need to be made in one rail, not both. I've thought > about doing this, but have been too lazy to try it out. I'm talking, of > course, of the period before long welded rail came into general use. A problem with that idea is the we generally remember hearing the clickety clack from beside the track or from inside a carriage. In that situation we heard ONE clickety clack, whereas with an HO model and nicks at 45 scale feet we would hear ALL the clickety clacks for the entire train at about equal volume. > Regards, > Bill. [quoted text clipped - 26 lines] > > Steve > > Newcastle NSW Aust >> Getting a little away from track expansion, but on the subject of >> rail joint noise (clickety-clack), has any one ever filed little [quoted text clipped - 9 lines] > and nicks at 45 scale feet we would hear ALL the clickety clacks for > the entire train at about equal volume. Since many 1930s and 1950s coaches were roughly 60 feet long, the clickety-clacks with 60 foot rails would be almost synchronous. I have re-wheeled all my rolling stock with the latest Hornby steel wheels, and find they make very little noise over rail joints, and not much more over points (where I have reduced the depth of the flangeway through the frogs with plasticard). SignatureMartin S. > >> Getting a little away from track expansion, but on the subject of > >> rail joint noise (clickety-clack), has any one ever filed little [quoted text clipped - 12 lines] > Since many 1930s and 1950s coaches were roughly 60 feet long, the > clickety-clacks with 60 foot rails would be almost synchronous. A rake of 57' coaches on 60' long rails is going to make a real cacophony of sound! > I have re-wheeled all my rolling stock with the latest Hornby steel > wheels, and find they make very little noise over rail joints, and not > much more over points (where I have reduced the depth of the flangeway > through the frogs with plasticard). You should find the build-up of crud on the treads is much reduced too! :-) Regards, Greg.P. > You should find the build-up of crud on the treads is much reduced too! > :-) This shouldn't be an issue Greg - I always recommend cleaning all loco & stock wheels at the same time as your track. This may sound onerous, but in effect I find I only need to clean my track once or twice a year, and with all metal-wheeled stock, I don't have much of a dirt problem. John. >> You should find the build-up of crud on the treads is much reduced too! >> :-) [quoted text clipped - 3 lines] >effect I find I only need to clean my track once or twice a year, and with >all metal-wheeled stock, I don't have much of a dirt problem. On my garden railway, it is a good idea to clean the track once a week, or even more frequently. Can I have some volunteers to clean the wheels of my rolling stock? SignatureJohn Sullivan OO in the garden http://www.yddraiggoch.demon.co.uk/railway/railway.html My next project: Extend the layout back up the other side of the garden. > Hi William, > [quoted text clipped - 11 lines] > and nicks at 45 scale feet we would hear ALL the clickety clacks for > the entire train at about equal volume. I can well remember hearing the interrail gap/wheel interaction of a train on Southend Pier, horrendously loud! >> Regards, >> Bill. [quoted text clipped - 26 lines] >>> Steve >>> Newcastle NSW Aust --- Outgoing mail is certified Virus Free. NAV BSoDs XP! |
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