Platform10 Posted February 19, 2012 Share Posted February 19, 2012 Hi folks, I'm building my first pointwork for my future EM gauge layout and I'm a bit stuck for a dimension. Can anybody tell me, please, what is the EM standard dimension for switch blade opening? Strangely I cannot find reference in either the EM Society manual nor for P4 in the Scalefour Society manual. Link to post Share on other sites More sharing options...
Andy C Posted February 19, 2012 Share Posted February 19, 2012 I have always used the same dimension as the check rail guage, although have at times had to open them out slightly. Link to post Share on other sites More sharing options...
Tequila Sunrise Posted February 19, 2012 Share Posted February 19, 2012 You need to make sure that the width across the 2 point blades does not exceed the recommended width over check rails. Using a check rail gauge will not necessarily ensure that, especially if you joggle the rails on your points. Link to post Share on other sites More sharing options...
Platform10 Posted February 19, 2012 Author Share Posted February 19, 2012 Andy and Tequila, If I follow you correctly, you are suggesting a gap no less than the check rail flangeway? I was thinking it ought to be a bit more than that, the prototype standard flangeway is 41mm and the switch opening is 108mm. So my simple tells me it ought to be a bit more than a check opening, but how much more? I'm not joggling the stock rails, merely putting a set on the curved stock, so at the point tip the stock rails are at gauge. Link to post Share on other sites More sharing options...
Tequila Sunrise Posted February 19, 2012 Share Posted February 19, 2012 Reading my response again I realise that my fingers were not typing what my brain was thinking. If your points are not joggled, the gap at the tip of the point blades needs to be slightly larger than the normal checkrail gap as you don't want your point blade to act like a checkrail. In EM this will be quite different to the scale dimensions because of the wider-than scale wheel flanges etc. Link to post Share on other sites More sharing options...
Grovenor Posted February 19, 2012 Share Posted February 19, 2012 Look at your prototype numbers, a rule of thumb is a little over double the check rail flangeway, the result should be that the narrowest part of the gap between switch and stock rail (near the switch heel) is a little bigger than the check rail flangeway so that the backs of the wheels are not hitting the switch blade at this narrow spot. Regards Keith Link to post Share on other sites More sharing options...
Platform10 Posted February 19, 2012 Author Share Posted February 19, 2012 I'm using a flangeway of 0.8mm in the wing rails and my check rail flared openings are 1.5mm. Looking at my model, I had already thought that 2mm switch opening was too big and 1mm too small. So it seems 1.5mm would not only look about right but also fit in with both the suggestions above. Mind you its not far off dead scale. Grovenor, your point about the gap being a bit bigger than a flangeway is well made - the minimum prototype gap at the end of the planing is 50mm (i.e. bigger than a 41mm flangeway). What surprises me is that this doesn't seem to be set in tablets of stone. One would have thought even the P4 people would have had a standard to work to... Link to post Share on other sites More sharing options...
RMweb Premium t-b-g Posted February 19, 2012 RMweb Premium Share Posted February 19, 2012 I had used a normal check gauge gap for years until I saw a dimension of 4 1/2" on a prototype drawing. Since then I have used 1.5mm as the gap and found it to be totally satisfactory with wheels from every manufacturer from Hornby/Bachmann to Sharman. Link to post Share on other sites More sharing options...
Platform10 Posted February 20, 2012 Author Share Posted February 20, 2012 Thanks for your thoughts everyone. Looks like its going to be 1.5mm then. Link to post Share on other sites More sharing options...
Miss Prism Posted February 22, 2012 Share Posted February 22, 2012 One would have thought even the P4 people would have had a standard to work to... They do. Link to post Share on other sites More sharing options...
Platform10 Posted February 22, 2012 Author Share Posted February 22, 2012 Well, don't keep us in suspenders then! Link to post Share on other sites More sharing options...
Miss Prism Posted February 22, 2012 Share Posted February 22, 2012 Here Link to post Share on other sites More sharing options...
Platform10 Posted February 22, 2012 Author Share Posted February 22, 2012 That's a really good bit of info there, albeit P4, but thank you anyway. My Scalefour Society digest sheets have somehow missed the inclusion of this amended sheet. Link to post Share on other sites More sharing options...
Flymo748 Posted March 9, 2012 Share Posted March 9, 2012 That's a really good bit of info there, albeit P4, but thank you anyway. My Scalefour Society digest sheets have somehow missed the inclusion of this amended sheet. That is actually on the CLAG website, which is an enormously useful source of information for everything from trackwork to the mathematics of Continuously Springy Beams. If you are missing any Scalefour Society Digest Sheets, then members can download anything from a single one to the full set from the Members' Area of the Society Website. You'll also find a full library of all published issues of Scalefour News as well for download, if ever (no matter how unlikely) RMWeb runs dry of interesting things to read... HTH Paul Willis Scalefour Society Deputy Chairman Link to post Share on other sites More sharing options...
Grovenor Posted March 9, 2012 Share Posted March 9, 2012 That's a really good bit of info there, albeit P4, but thank you anyway. My Scalefour Society digest sheets have somehow missed the inclusion of this amended sheet. You can get the official version here, better should you want to print it out. http://www.scalefour.org/downloads/P4-standards.pdf Best regards Keith Link to post Share on other sites More sharing options...
Platform10 Posted March 11, 2012 Author Share Posted March 11, 2012 Thanks to both Paul and Keith for the P4 digest sheet info. As my original post was about EM trackwork, I can now say I have used the received wisdom of allowing 1.5mm for the switch opening on my B7 crossover and am happy to say it works well. So thanks everyone who replied. Bob Link to post Share on other sites More sharing options...
micknich2003 Posted March 11, 2012 Share Posted March 11, 2012 The throw or travel of a standard mechanical switch is 4,1/4ins. I set mine for 4mm/EM Gauge using the shank of a 1.5mm drill as a gauge, it works OK and also looks right to the eye. From memory, and without checking, I think in modern work (Clamp Locks etc) the above dimension can be increased. Mick Nicholson. Link to post Share on other sites More sharing options...
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