JeffP Posted September 13, 2012 Share Posted September 13, 2012 Hi, looking at one of my "to do" loco kits today, (I'm getting very close to starting one now, LOL...), I saw that it seems made to build rigid, but has markings to cut out for sprung hornblocks. It's a Dave Andrews Peppercorn A1 4-6-2, in 7mm. So: Can it be made with, say insulating hornblocks, to pick up off the wheels, using split axles? I already have Slater's wheels. Would anything else need to be modified? if so, what, please? And why? Would anyone recommend another method of suspension, NOT sprung hornblocks? If so, what, please? CSB? I've been thinking of a Slaters (Tower??), DJH, or ABC motor/gearbox combo. Any comments? Any one in particular? (The loco is unliklely ever to go very fast). Lastly, if using Slater's insulating hornblocks, are they set as soldered ones, using the rods and simple jig, (axles with tapered ends etc), and Araldited (etc, or ??) in place? Thanks for any help, comments etc. Link to post Share on other sites More sharing options...
Buckjumper Posted September 13, 2012 Share Posted September 13, 2012 When building sprung tender locos I leave the loco itself electrically dead and pick up using split axles from the tender only. I use insulated hornguides with brass axleboxes from Slaters (cat.7960) - the hornguides are glued in place using Alraldite (blue tubes) or Devcon and then drilled and tapped 14BD (belt & braces approach) at the centreline ride height which helps with setting up the appropriate ride height later. I've got some brass offcuts which I slot into the hornguides while they're being glued and bolted in place to keep the legs parallel as they have a habit of turning inward slightly until firmly fixed in place, effectively inhibiting the travel of the axlebox (which should be no more than 0.5mm - 1.0mm up or down - you're not going to drive over matchsticks are you?). Care of Steph Dale, this is what needs to be done to the axles and wheels and you'll need to solder some pickup wires (the thin multi strand stuff used for DCC wiring is perfect) to each axlebox before you slot them into the hornguides. I have a pair of copper clad busbars feeding power to the axleboxes and simple socket and pin connectors from Maplins leading to the motor in the loco. Link to post Share on other sites More sharing options...
ozzyo Posted September 13, 2012 Share Posted September 13, 2012 It's a Dave Andrews Peppercorn A1 4-6-2, in 7mm. So: Can it be made with, say insulating hornblocks, to pick up off the wheels, using split axles? I already have Slater's wheels. Would anything else need to be modified? if so, what, please? And why? Would anyone recommend another method of suspension, NOT sprung hornblocks? If so, what, please? CSB? I've been thinking of a Slaters (Tower??), DJH, or ABC motor/gearbox combo. Any comments? Any one in particular? (The loco is unliklely ever to go very fast). Lastly, if using Slater's insulating hornblocks, are they set as soldered ones, using the rods and simple jig, (axles with tapered ends etc), and Araldited (etc, or ??) in place? Thanks for any help, comments etc. Hello JeffP, I don't see why the loco can't be made with insulating horn blocks (Slater's), if your using the Slater's horn blocks they are designed to be sprung. But you can adapt them for other forms of suspension. With split axles on the loco you will have to think about keeping the squares on the axle ends in line. Along with how the gearbox is going to be fitted on the driven axle so that it does not bridge the insulation. For fitting the Slater's horn blocks, you would just fit them as you would brass ones, axle jigs etc. but instead of solder using an epoxy glue. A lot of the people that use them will also drill and tap them 12BA. If all you want to do is get rid of pick-ups, why not have the loco picking up on one side and the tender the other side. This way you don't have to split the axles. All you will have to do is to figure out how to get the electric from the axle to the motor wires. Don't forget that you will have to short out the wheel from the rim to the brass centre as well. OzzyO. Link to post Share on other sites More sharing options...
Miss Prism Posted September 13, 2012 Share Posted September 13, 2012 Please shout me down, but in 7mm, there would not seem to be a friction problem with conventional pickups, and I would have thought the case for split axles, bearing in mind the work involved, was a marginal one? Link to post Share on other sites More sharing options...
Buckjumper Posted September 13, 2012 Share Posted September 13, 2012 Please shout me down Well I wouldn't be that rude Miss P... When building chassis with fixed bearings (often in 0/F, never in S7) I always use wipers bearing down on the tender wheels, but you'd be surprised that even 0.33mm pb wipers not set up properly can have a significant braking effect on a free-running chassis in 7mm, particularly noticeable if spur & helical gears are being used with a flywheel to promote inertia. As for plungers - of the various types available I've never been able to set them up without imparting some brake force. Maybe it's just me. The extra work for three split axles using the method I describe above is no more than an hour of actual modelling time, yet gives immeasurable peace of mind in the long-term; once done, 'tis done with no need to fiddle or de-fluff or adjust tensions. Link to post Share on other sites More sharing options...
JeffP Posted September 13, 2012 Author Share Posted September 13, 2012 So if you pick up from the tender only, doesn't that limit the running somewhat? I mean, the loco won't get any power until the tender goes into a live section, not the loco, or doesn't that matter? Does brakegear not short it out, especially on something like a Gresley pacific tender where the wheels are sandwiched between brake pull-rods? I suppose the same applies to the loco, unless brake blocks were made from plastikard etc? That was what I meant about anything else needing changed. Link to post Share on other sites More sharing options...
Buckjumper Posted September 13, 2012 Share Posted September 13, 2012 So if you pick up from the tender only, doesn't that limit the running somewhat? I mean, the loco won't get any power until the tender goes into a live section, not the loco, or doesn't that matter? Not sure I understand your query; if you want a train to move from A to B then you set the power for that route, surely? You don't drive into a live section from a dead section, but from live section to live section. If you want to stop a loco in a dead section - say a section within an MPD siding, then you plan each dead section to accommodate a full loco, but that dead section has to be live at the time the loco drives into it, you only isolate it once the loco is in. Does brakegear not short it out, especially on something like a Gresley pacific tender where the wheels are sandwiched between brake pull-rods? I suppose the same applies to the loco, unless brake blocks were made from plastikard etc? Brake blocks: They'd only short if the brake blocks touched the wheels, and you don't want that whether they were live or insulated. Pull rods: Limit sideplay. In the grand scheme of things, Gresley tenders have a fairly short wheelbase, and require very little sideplay. I'd suggest none at all on the front and rear axles and a little on the inner axles - but obviously not enough to touch the pull rods. To be frank, if the tender was electrically dead you still wouldn't want the pull rods to touch the wheels as they'd exert a braking force upon them and they'd skid around curves. Whether the tender is live or dead you decide upon the extent of the sideplay of the middle axles, then position the four pull rods xx thou away from the extremes both inwards and outwards. Current won't jump the gap, so things can be pretty close. One of the locos I'm currently working on is an A3 in Finescale and have an Andrews tender to go with a Finney engine so this is all very much current stuff for me. That was what I meant about anything else needing changed. It's a fair question, but in this particular case, as long as nothing touches the wheels, the answer really is nothing. Link to post Share on other sites More sharing options...
JeffP Posted September 14, 2012 Author Share Posted September 14, 2012 Many thanks for that. Do you ever have problems with the loco stalling since it has a short wheelbase to pick up from? Has anyone experimented with picking up from the drivers too? And what of the front bogie wheels for pickup? Link to post Share on other sites More sharing options...
ozzyo Posted September 14, 2012 Share Posted September 14, 2012 Hello JeffP, about the smallest loco that I've built in 7mm is the L & Y 0-4-0ST. That's OK going through Peco points and I can't put any more pick-ups on that. So if you pick-up from all eight wheels on an L.N.E.R. tender with some springing or compensation you should have no problems as the wheel base is longer than my pug. If you wanted more pick-ups just fit them to the front drivers. The only down side to having all your pick-ups on the tender is when you only want to test the loco. But that's the same with the loco picking up one side and the tender picking up on the other side. OzzyO. Link to post Share on other sites More sharing options...
Miss Prism Posted September 14, 2012 Share Posted September 14, 2012 Jeff - in 7mm, typical loco weights are such that there is rarely a problem in getting (enough) wheels to pickup. Picking up off the drivers would seem to be the norm for most 7mm modellers, and is the only option with tank engines without carrying wheels of course. Picking up from bogies/ponies is very unlikely to be necessary, but a 2-2-2T say is an extreme exception. There are no hard and fast rules. The key is ensuring the pickup wheels are making sufficient contact with the rail. Hence BJ's use of sprung axles on his tenders. Link to post Share on other sites More sharing options...
JeffP Posted September 14, 2012 Author Share Posted September 14, 2012 Thanks to all who have responded. Link to post Share on other sites More sharing options...
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