davidmcc3 Posted November 1, 2015 Share Posted November 1, 2015 Good morning all. Are there any structural engineers (or similar) who can comment on the relative merits of supporting baseboards away from the ends ... say 9" to 12" from each end of a 4 foot run ... compared to support right at the ends, the 'traditional' fold-up leg variety? With the loft nearly finished. I'm planning to start designing the layout over Christmas. Thanks, David Link to post Share on other sites More sharing options...
RMweb Gold chris p bacon Posted November 1, 2015 RMweb Gold Share Posted November 1, 2015 So long as the boards are joined with a strong fixing system then cantilevering a foot beyond the legs isn't a problem. I have 2 quarter curved boards at the ends and at the door end of the room there is just a single pair of legs supporting at the mid point and there hasn't been a problem. You just need a suitable system to join the boards........quite where you could get them I'm not sure.. Link to post Share on other sites More sharing options...
RMweb Premium Andy Hayter Posted November 1, 2015 RMweb Premium Share Posted November 1, 2015 The only disadvantage that I can see is that if you are constructing fold up legs (as per your post), then the lags will be shorter than they would be if the legs are at the ends. So if you are setting the legs 12" in from the ends the legs are going to be less than 3ft long with 4ft baseboards. This may be a little on the low side for comfotable operation and construction. Link to post Share on other sites More sharing options...
davidmcc3 Posted November 2, 2015 Author Share Posted November 2, 2015 What prompted the question was the discovery of a high point at the join of two boards on a new club layout, even though it has been leveled up. What's going to make fixing this difficult, is that the two boards have high and low sections... the high level joint is fine ... the low level one isn't! And everything is all very firmly screwed and bolted together. When I put shelves up with wall bars, I never have the supports at the end of the shelf ... always a little way in ... to counteract the natural droop in the middle - and I've seen baseboards with similar problems. I wasn't going to attach legs at the end ... I mentioned that as it seems to be 'normal' practice. I'll have to be innovative with the legs as I need one height in the loft (low) and another (if it ever gets finished) when I take it out. I know I could have two sets, but I was trying to avoid that! Link to post Share on other sites More sharing options...
RMweb Gold chris p bacon Posted November 2, 2015 RMweb Gold Share Posted November 2, 2015 I've come up with a scheme for the club layout that is simply timber beams that join together to create a sub frame this sits on top of some trestles that can be placed wherever the floor allows (within reason) The layout then sits on top of these and is bolted together. Fencehouses (2mm FS) uses something similar. Link to post Share on other sites More sharing options...
RexAshton Posted November 2, 2015 Share Posted November 2, 2015 Any form of leg support whether at the end or set in will leave unsupported baseboard. It doesn't really matter how strong and rigid your baseboards are there will me a tendancy to sag if only by a little amount. Trestles and L girder beams are the only answer as the baseboards are then supported along their full length. They're also generally much quicker to set up. Link to post Share on other sites More sharing options...
RMweb Gold Happy Hippo Posted November 2, 2015 RMweb Gold Share Posted November 2, 2015 I've come up with a scheme for the club layout that is simply timber beams that join together to create a sub frame this sits on top of some trestles that can be placed wherever the floor allows (within reason) The layout then sits on top of these and is bolted together. Fencehouses (2mm FS) uses something similar. Sounds like Iain Rice's 'Ullysses' system from the Finescale in Small Places book. I've used similar on an exhibition layout with great success. Set up the frame, and level it, then just place the baseboards on top. Link to post Share on other sites More sharing options...
Nearholmer Posted November 2, 2015 Share Posted November 2, 2015 David I can't find the maths to demonstrate it, but I would be fairly sure that, with an evenly distributed load, the ideal load-bearing points for a beam supported at two points would be 1/4 and 3/4 along the length, modified slightly, to account for the fact that the centre part of the beam is supported at both ends, whereas the two outer ends are not. If you look at the wheelbase vs over-headstocks of a traditional four-wheeled railway wagon, you will see that it fits this "rule of thumb", so 9ft wheelbase for 17ft 6in wagon. Don't build your house by my advice BTW; I'm not a structural engineer! Kevin Link to post Share on other sites More sharing options...
F-UnitMad Posted November 2, 2015 Share Posted November 2, 2015 Any form of leg support whether at the end or set in will leave unsupported baseboard. It doesn't really matter how strong and rigid your baseboards are there will me a tendancy to sag if only by a little amount..... Only as we're still using such primitive materials as wood for our baseboards. You'd think somebody would've come up with an alternative suitable for the 21st Century by now... Link to post Share on other sites More sharing options...
Classsix T Posted November 2, 2015 Share Posted November 2, 2015 So long as the boards are joined with a strong fixing system then cantilevering a foot beyond the legs isn't a problem. I have 2 quarter curved boards at the ends and at the door end of the room there is just a single pair of legs supporting at the mid point and there hasn't been a problem. You just need a suitable system to join the boards........quite where you could get them I'm not sure.. I'll bite "Chris": http://www.rmweb.co.uk/community/index.php?/topic/104454-baseboard-joiners-for-the-21st-century/ I shall quite likely regret letting the link out of its own box of Pandora...C6T. Link to post Share on other sites More sharing options...
RMweb Gold chris p bacon Posted November 2, 2015 RMweb Gold Share Posted November 2, 2015 Sounds like Iain Rice's 'Ullysses' system from the Finescale in Small Places book. I've used similar on an exhibition layout with great success. Set up the frame, and level it, then just place the baseboards on top. Haven't heard or seen of that but I'll keep an eye out. I approach things from "Building houses" point of view, it can work sometimes although club chairman is not convinced that a 12" petrol cutter is a good way to cut track. Link to post Share on other sites More sharing options...
brigo Posted November 2, 2015 Share Posted November 2, 2015 David I can't find the maths to demonstrate it, but I would be fairly sure that, with an evenly distributed load, the ideal load-bearing points for a beam supported at two points would be 1/4 and 3/4 along the length, modified slightly, to account for the fact that the centre part of the beam is supported at both ends, whereas the two outer ends are not. If you look at the wheelbase vs over-headstocks of a traditional four-wheeled railway wagon, you will see that it fits this "rule of thumb", so 9ft wheelbase for 17ft 6in wagon. Don't build your house by my advice BTW; I'm not a structural engineer! Kevin Technically the distance between the supports (S) is known as the Airy points and for a beam length (L) is given by the formula :- S = L / square root* of 3, which is approximately S = 4/7 L, or for a 48 inch baseboard, about 27.5 inches apart. Brian * For some reason a square root symbol got changed to a question mark when I posted it, although I still see the correct symbol in edit mode !! Link to post Share on other sites More sharing options...
F-UnitMad Posted November 2, 2015 Share Posted November 2, 2015 I'll bite "Chris":http://www.rmweb.co.uk/community/index.php?/topic/104454-baseboard-joiners-for-the-21st-century/ I shall quite likely regret letting the link out of its own box of Pandora...C6T. I suspect that's exactly the thread "Chris" (who's name we know is not "Chris") had in mind, as did I (who's name is not "F-Unit", but 'mad' is debateable...) Link to post Share on other sites More sharing options...
Nearholmer Posted November 2, 2015 Share Posted November 2, 2015 Brian, Brilliant, many thanks. Now more reading to do, because although it is "blindingly obvious" that the distance between the two points will be "slightly greater than L/2", because of the support at both ends, I now want to know why it is L4/7....... In short, I think I want to see Mr Airy's proof. Bound to be on the web somewhere, and I reckon that catenary curves must come into it somewhere. Kevin PS: OK, found it. Main conclusion: when returning to "proper" maths after a 30 year break, it might be wise to practice a bit on easy stuff before diving in! Link to post Share on other sites More sharing options...
RexAshton Posted November 2, 2015 Share Posted November 2, 2015 Only as we're still using such primitive materials as wood for our baseboards. You'd think somebody would've come up with an alternative suitable for the 21st Century by now... Fair point but until we do trestles and beams work - and I suppose they'll work in the future even we have some new wonder material which we almost certainly will. It's not that long ago that we had to wind locos up but look now. Link to post Share on other sites More sharing options...
F-UnitMad Posted November 3, 2015 Share Posted November 3, 2015 It's not that long ago that we had to wind locos up but look now.Oh I don't know.... a frightening number of locos I've seen at recent Exhibitions need a push to get them moving.... /coat+hat=gone!!! Link to post Share on other sites More sharing options...
RMweb Gold Phil Bullock Posted November 3, 2015 RMweb Gold Share Posted November 3, 2015 Fair point but until we do trestles and beams work - and I suppose they'll work in the future even we have some new wonder material which we almost certainly will. It's not that long ago that we had to wind locos up but look now. Yup - now the locos wind up the operators! Especially those Bachmann class 40s.... Phil Link to post Share on other sites More sharing options...
davidmcc3 Posted November 4, 2015 Author Share Posted November 4, 2015 I suppose carbon fibre might be the ideal material for lightness and stiffness, but would probably need a 2nd and 3rd mortgage! Link to post Share on other sites More sharing options...
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