dpgibbons Posted October 20, 2017 Share Posted October 20, 2017 I have just bought my first item of 7mm rolling stock - a Slaters GWR open wagon. The instructions suggest adding weight to match other wagons of which I have none, so could somebody suggest please what an average wagon should weigh? Link to post Share on other sites More sharing options...
Simond Posted October 20, 2017 Share Posted October 20, 2017 Dependent on your metric/imperial preferences, you could have a gram per millimetre of length, or an ounce per inch... Or 50g per axle Or “a bit” Or not worry about it til you do have other wagons. Personally, I’d add some weight to a plastic wagon kit, to get into 50-100g range. Don’t use lead shot and PVA glue. This works really well, but months or years later, expands due to a slow chemical reaction, and ruins your model. Lead shot can be used with resin glues / epoxies / bluetack / plasticine, alternatively, stick-on wheel balance weights, or lead trimmings from flashing are useful sources of mass. In a van, just about anything glued down firmly inside will do (and drill a couple of holes in the van floor to let the fumes out, if it is not otherwise ventilated). Best Simon Link to post Share on other sites More sharing options...
hartleymartin Posted October 20, 2017 Share Posted October 20, 2017 If memory serves me the GOG technical manual recommends 1 gram per 1 millimeter of vehicle length, measured over the length of the buffers with no vehicle weighing less than 125 grams. Link to post Share on other sites More sharing options...
N15class Posted October 20, 2017 Share Posted October 20, 2017 I go with Simon. A gram per mm length over buffers. Link to post Share on other sites More sharing options...
Tricky Posted October 20, 2017 Share Posted October 20, 2017 With Slater's open wagons for instance, I have gone with squeezing as much lead sheet into the spaces in the underframe as I can. Add a splodge of epoxy to hold it. Not very scientific but seems to work. Next question, though, do you bother with compensation..?! Some of mine have it and some don't - I can't tell the difference in performance. Link to post Share on other sites More sharing options...
hartleymartin Posted October 20, 2017 Share Posted October 20, 2017 I (primarily) model NSWGR which tend to have slightly larger wagons than found in the British Isles. I found that 9'0" wb wagons in 7mm finescale generally don't need any compensation or springing as long as they are built straight and level. 10'0" wb wagons are also generally fine. When you get to 11'0" wb then they must be built very accuratly in finescale, and scaleseven would absolutely need springing/compensation. The longest 4-wheeler I ever tried to build was a 16'0" wheelbase 4-wheel coach (from the Coal Mining Railways) and despite being built on a sheet of plate glass to ensure perfect levels, it would leave the track the moment you looked at it the wrong way. Eventually, I figured a general rule that if the fixed wheelbase is more than 3 inches long, it will need some sort of compensation or springing. Link to post Share on other sites More sharing options...
jim.snowdon Posted October 20, 2017 Share Posted October 20, 2017 Unless you are intending outdoor operation, there is no actual need to add extra weight. The notion that wagons have to be given additional weight is something of an O gauge myth and legend. Jim Link to post Share on other sites More sharing options...
Simond Posted October 20, 2017 Share Posted October 20, 2017 I think I covered that option Link to post Share on other sites More sharing options...
jim.snowdon Posted October 20, 2017 Share Posted October 20, 2017 I think I covered that option That's alright, I simply added weight to the proposition. Jim (beats hasty retreat behind parapet) Link to post Share on other sites More sharing options...
duncan Posted October 20, 2017 Share Posted October 20, 2017 I have used antimony hardened lead shot & PVA for 20+ years and never had any problems, but always open to the air so no chemical build up. Turn the wagon upside down & pour the shot into the "boxes" in the underframe, add glue & wait for the mass to harden. Do not use a cover & don't use inside a van or loco (without good ventilation). The antimony coating might be the factor &/or leaving the mixture open to the air. Anyway, wash hands after handling the shot ! Link to post Share on other sites More sharing options...
Simond Posted October 20, 2017 Share Posted October 20, 2017 Duncan I suspect that leaving it open to the air on one side is enough to stop it breaking its way out. The antimony might make a difference, but I believe the culprit is lead acetate, which will happen, eventually. Hoping you don’t have problems eventually Best Simon Link to post Share on other sites More sharing options...
hartleymartin Posted October 21, 2017 Share Posted October 21, 2017 The requirement for weight in wagons is more that on curves you don't have very light wagons pulled off the tracks by the drag of heavier ones. This is much less of a problem on shelf layouts with only short curves. The issue here is that some wagons or coaches might be built from heavier materials such as whitemetal/pewter or brass. The requirement for additional weight came about with the advent of injection-moulded plastic kits which were significantly lighter. The same problem of weight occurs even on the prototype. There is more than one story about a train separating in the middle of a curve only to later discover that one or more wagons were missing because they were unloaded and rolled down the embankment! Link to post Share on other sites More sharing options...
duncan Posted October 22, 2017 Share Posted October 22, 2017 Simon, I agree, keeping the mixture open to the air is the secret, stops any build up of fumes & if there is any expansion, the mixture can fall off the bottom of the wagon, plus the antimony coating should keep the pva & lead separate. Some of my wagons are 30 yrs old now with no problems. I have some vans with the mixture inside in a tray, but large holes in the floor to let fumes out. Link to post Share on other sites More sharing options...
Simond Posted October 22, 2017 Share Posted October 22, 2017 I don’t believe it’s the open air, it’s that there is room for it to expand, if it’s open on one side. The horror stories all concern things like tank wagons and loco boilers that were pretty much full of the stuff. When it reacts, it expands, and like a tree growing in a pavement, eventually bursts through. I had a professionally built Slaters milk tanker where the end popped off, and I was lucky that I read about the problem in time to save the boiler & tanks on my Acorn 57xx - boiling water weakened the stuff so I could prise chunks out, despite the fact that it was open at the firebox end, it was reacting & swelling. You may well have no problems at all, but I’d still avoid mixing lead shot with PVA, especially as it is a known issue. It mixes fine with epoxy, or casting resin. Best Simon 1 Link to post Share on other sites More sharing options...
Fastdax Posted October 22, 2017 Share Posted October 22, 2017 You may well have no problems at all, but I’d still avoid mixing lead shot with PVA, especially as it is a known issue. It mixes fine with epoxy, or casting resin. Another vote for mixing a batch of lead shot with epoxy. I found that "diver's lead ballast" is quite fine-grained lead balls and cheaper than the stuff sold specially for weighting models. Link to post Share on other sites More sharing options...
RMweb Premium Dava Posted October 22, 2017 RMweb Premium Share Posted October 22, 2017 If you add a wagonload that can provide the weight you need. 'Ten Commandments' and Skytrex both do a range of assorted wagonloads which for £5 provide all the weight you need. Dava Link to post Share on other sites More sharing options...
Simond Posted October 22, 2017 Share Posted October 22, 2017 If you do want lead shot, it’s about £3.50 per kilo in gun shops. I bought a plastic bottle of it YEARS ago, and still have most of it left! Best Simon Link to post Share on other sites More sharing options...
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