Richard Hall Posted May 13, 2016 Share Posted May 13, 2016 Well, I sent off my application to join the 2mm Scale Association, mainly in a fit of rage at the utter hopelessness of Farish driving wheels. On which subject, does anyone know what the maximum tolerance is either side of the reference point for quartering wheels? I'm not talking about the absolute position (normally 90 degrees), more that if you have one wheelset at exactly 90 degrees quartering, how many degrees +/- can you get away with on the others before everything locks up? This is not just idle curiosity: I have been playing around with a design for a quartering tool, initially for old Farish wheels but the principle can be adapted to pretty much anything. The problem is that even with the overscale crank throw on Farish wheels, one degree of wheel rotation from top dead centre equates to less than 0.05mm movement at the crankpin. On something like a J27 with scale wheels, it's 0.03mm. Which raises the question of how accurate a quartering tool actually needs to be. Within one degree, five degrees, ten degrees? My design can probably get the variance between wheelsets down to less than two degrees, if it works... I have trawled the Internet and can't find an answer to this one. Can anyone help? Richard Link to post Share on other sites More sharing options...
Caley Jim Posted May 13, 2016 Share Posted May 13, 2016 I've never used a quartering tool. I set the driven axle to roughly 90 degrees and then set the others to match that one using the rods, turning by hand and feeling for any tight spots. There is an article in the magazine a few years ago. Sorry I'm not at home just now, so can't give you the reference. As to the tolerance, the nearer you can get to an exact match, the smoother the loco will run. Jim Link to post Share on other sites More sharing options...
Richard Hall Posted May 13, 2016 Author Share Posted May 13, 2016 Every modeller should have a dog. Most of my ideas come to me while walking mine, including this one. It occurred to me that the big problem with quartering is that you cannot see both sides of the wheelset at the same time. What allows you to do that? Mirrors.... So - two mirrors set at around 120 degree angle. A Vee-block to support the axle, and a depth stop to support the outside crankpin horizontal with the axle line. Fine lines scribed in line with the axle on both mirrors. And a magnifiying glass. Roughly quarter the wheelset, drop it into the vee block and position the outside crankpin on the depth stop. Then look at the inside pin via the mirrors, making sure all the reflected lines align (you need to be able to keep your head steady, resting your chin on something helps). Adjust the quartering until the scribed line on the rear mirror passes exactly through the centre line of the crankpin. I just tried it, and got perfect quartering (on a 4-4-0 admittedly) in under three minutes. It would have been quicker, except that I underestimated the importance of getting the lines in the mirrors exactly aligned, so the wheels bound up when tested the first time. The adjustment I had to make to get them running freely was tiny, maybe two or three degrees. I think that answers my original question... I then deliberately upset the quartering so the chassis no longer rolled, and reset it again using the same method. Same result, a chassis that rolls as freely as a wagon on pinpoint axles. Some improvements needed: the scribed lines could do with being an inch longer, and i need a much better magnifier than the nasty distorting piece of tat that I have. Also I scribed the lines on the mirrors with a diamond-tipped burr and they are a bit coarse and smudgy. Crisper lines would make things easier. Next question - can it work with 2mm finescale? I think so. It will need a Vee block made from very thin brass (a fold-up etch would be ideal) to fit between the wheels and the outside of the frames. The wheels would need to be inserted into the muffs far enough to get them square, but still allow the chassis to sit inside the Vee block. And you would have to quarter the wheels first, then squeeze them in to the correct back to back afterwards. I'll give it a go with the Jinty chassis and report back. Richard Link to post Share on other sites More sharing options...
Caley Jim Posted May 13, 2016 Share Posted May 13, 2016 ...... you cannot see both sides of the wheelset at the same time......You don't need to see both sides at the same time. After inserting the second set of wheels, roughly quartered, fit a coupling rod onto one side and set the wheels on that side to top dead centre. Hold the wheels in that position with a finger and turn the chassis over. You can then compare the position of the two crankpins on the other side and adjust the non-driven wheelset as required. Inserting a jewelers screwdriver between the spokes and gently twisting it enables you to make very fine adjustments. Having the rod at TDC helps to keep the two wheels on that side in the same relationship. Jim Link to post Share on other sites More sharing options...
Richard Hall Posted May 14, 2016 Author Share Posted May 14, 2016 You don't need to see both sides at the same time. After inserting the second set of wheels, roughly quartered, fit a coupling rod onto one side and set the wheels on that side to top dead centre. Hold the wheels in that position with a finger and turn the chassis over. You can then compare the position of the two crankpins on the other side and adjust the non-driven wheelset as required. Inserting a jewelers screwdriver between the spokes and gently twisting it enables you to make very fine adjustments. Having the rod at TDC helps to keep the two wheels on that side in the same relationship. Jim Thanks for the tip about using a fine screwdriver through the spokes, easier to get fine control that way. i've never had much luck with the "fit then fiddle" approach but I think that was because i hadn't realised just how little movement between the wheel rims represents one degree of quartering adjustment. On a 4'7" driver in 2mm it's about 0.08mm/degree. From what I have found so far it looks like the tolerance is only a couple of degrees either way, and my hapless flailing around has probably been shifting the quartering between five and ten degrees each time. So hitting the "sweet spot" has ended up purely a matter of luck. Anyway, my tool is now getting a proper test. I have an old set of Farish drivers where one wheel has become so loose on the axle that they cannot be quartered by trial and error. The reason being that every time you fit them to the chassis and put the rods on, or try turning the wheels, the quartering shifts. Even picking them up disturbs the quartering. There is no grip at all between axle and wheel centre. So I'm going to "trust the tool". I've applied slow setting epoxy to the axle end, checked the quartering on the tool, removed them to set the back to back, rechecked the quartering (it had shifted again about five degrees when I set the back to back) and I'm now leaving them exactly where they are, sitting on the vee block, until the epoxy sets. If this tool does what I think it does, they will come out perfectly quartered (unless I accidentally breathe on them before the glue sets). Whether they run true is another matter. Link to post Share on other sites More sharing options...
justin1985 Posted May 15, 2016 Share Posted May 15, 2016 Having struggled and failed to get the knack of doing this as Jim describes, and rendered two etched chassis useless in the process, I swear by the Association quartering jig/press! Link to post Share on other sites More sharing options...
Richard Hall Posted May 15, 2016 Author Share Posted May 15, 2016 Having struggled and failed to get the knack of doing this as Jim describes, and rendered two etched chassis useless in the process, I swear by the Association quartering jig/press! Quartering is one of the hobby's black arts. There are rumoured to be people who can do it, but I have never met one. I'm probably being a bit optimistic trying to turn the job into something my dog could do, but it's more fun than mowing the lawn, washing the car etc. For now, results of the first test are inconclusive. I don't think there's anything wrong with the quartering tool, but there's an awful lot wrong with the wheels, and with the home-made chassis they are sitting in. So far today I have made my own crankpin washers out of brass wire (made six, dropped two on the floor and lost them), come up with a technique for punching nice round tiny holes in Rizla papers to sit between said washers and coupling rods so I didn't solder the rods to the crankpins, tried about twenty times to square up the trailing wheelset so that the wheels don't waggle around, decided that wiper pickups bearing on the wheel treads are a bad idea (I had to scrape the crud off them with a scalpel blade), flattened the battery on the digital caliper through endlessly measuring stuff, and fiddled around with my quartering in an attempt to get the little heap to run, each tweak making it steadily worse. This is turning out to be an excellent apprenticeship for 2mm chassis construction: proper metal wheels and crankpins have to be easier than this rubbish. Rant over, and back to work for one more go. I'll make a new axle for the trailing wheelset as I now suspect the one on it is bent. Take the rods off, requarter the wheels, tighten up the clearances on the trailing axle and if that doesn't work, the whole lot can go in the bin. Richard Link to post Share on other sites More sharing options...
Quarryscapes Posted May 15, 2016 Share Posted May 15, 2016 I've always managed well with quartering, but I cannot for the life of me get wheels straight and true, even pressed on in the lathe one or more invariably end up wonky. How doest he Association quartering jig work? Link to post Share on other sites More sharing options...
Nigelcliffe Posted May 16, 2016 Share Posted May 16, 2016 I've always managed well with quartering, but I cannot for the life of me get wheels straight and true, even pressed on in the lathe one or more invariably end up wonky. How doest he Association quartering jig work? There is a description on the 2mm website products page. - Nigel Link to post Share on other sites More sharing options...
Richard Hall Posted May 16, 2016 Author Share Posted May 16, 2016 I have a running 2P! Very stiff at first, but after three hours going round in circles it's now nice and sweet, controllable down to a scale 15 mph at which point the shortage of pickups makes progress a bit hesitant. I do wonder how people manage to run in new mechanisms without a test oval: I tried one of those rolling road thingies but wasn't impressed. 2mm Jinty chassis next, once I've ordered some new wheels to replace the ones that went rusty in storage, and a smaller motor. I found 12 volt 7mm coreless motors from China at £2.50 for four including postage which will be great if they actually work. I'm determined to get it to cope with 12 inch curves which will require a bit of fiddling. Been thinking about gauge widening, I have a question and will start a separate post for that. Richard Link to post Share on other sites More sharing options...
2mm Andy Posted May 16, 2016 Share Posted May 16, 2016 I found 12 volt 7mm coreless motors from China at £2.50 for four including postage which will be great if they actually work. Richard Richard, Those sound interesting and useful for smaller 2mm locomotives. Do you have any more details? Andy Link to post Share on other sites More sharing options...
robin2247 Posted May 16, 2016 Share Posted May 16, 2016 Richard, Those sound interesting and useful for smaller 2mm locomotives. Do you have any more details? Andy Hi Andy just search for 'micro motors' or 'coreless motors' on eBay there are pages of them in all sizes and a lot of them include postage and packing.Robin Link to post Share on other sites More sharing options...
2mm Andy Posted May 16, 2016 Share Posted May 16, 2016 Hi Andy just search for 'micro motors' or 'coreless motors' on eBay there are pages of them in all sizes and a lot of them include postage and packing. Robin Thanks. I regularly keep an eye on Ebay for small motors (and indeed have ordered a couple of packs recently) but hadn't spotted any matching Richard's description. For others who might be interested I presume these are the ones that Richard referred to; http://www.ebay.co.uk/itm/4pcs-NdFeB-magnetic-716-coreless-motor-DC-12V-24V-Micro-DC-motor-17500-35000-RPM-/111995148610?hash=item1a136e5942:g:32QAAOSwcL5XNENc Andy Link to post Share on other sites More sharing options...
Richard Hall Posted May 16, 2016 Author Share Posted May 16, 2016 Thanks. I regularly keep an eye on Ebay for small motors (and indeed have ordered a couple of packs recently) but hadn't spotted any matching Richard's description. For others who might be interested I presume these are the ones that Richard referred to; http://www.ebay.co.uk/itm/4pcs-NdFeB-magnetic-716-coreless-motor-DC-12V-24V-Micro-DC-motor-17500-35000-RPM-/111995148610?hash=item1a136e5942:g:32QAAOSwcL5XNENc Andy Yes, those are the ones. I've ordered a tenner's worth (sixteen motors!) so I can sacrifice one, strip it and see whether the bearings are likely to cope with end loads from a worm gear. I have doubts about that. 12v motors this size are not common, I'm guessing these are surplus stock from somewhere and probably won't be available for long. I also ordered some of these - same size as a Mashima 1015 but with the brushgear at the shaft end, and £7.40 for ten. I'll have more motors than the Farish factory at this rate. http://www.ebay.co.uk/itm/111949144445 Link to post Share on other sites More sharing options...
RMweb Premium Ian Morgan Posted May 17, 2016 RMweb Premium Share Posted May 17, 2016 There was a lot of discussion and experimentation by members of the 2mm Scale Association a few years back, and it seems that the 'no load speed' of a motor is important. There are tables somewhere (the Yearbook?) giving the speeds of common motors. 17500rpm and 17000rpm stated for the 12V motor on eBay may be a little high, compared with the 11500rpm of the Maxon 10/17. Ian. Link to post Share on other sites More sharing options...
2mm Andy Posted May 17, 2016 Share Posted May 17, 2016 There was a lot of discussion and experimentation by members of the 2mm Scale Association a few years back, and it seems that the 'no load speed' of a motor is important. There are tables somewhere (the Yearbook?) giving the speeds of common motors. 17500rpm and 17000rpm stated for the 12V motor on eBay may be a little high, compared with the 11500rpm of the Maxon 10/17. Ian. 17000 rpm is lower than a lot of the 'no load' speeds of the motors listed in the 2mm yearbook tables, eg. Mashima 9/16 (25000rpm) and Faulhaber 1016 (18400rpm). Even the little flat can motor sold as 3-257 in the shop is quoted at 20000rpm. Andy Andy Link to post Share on other sites More sharing options...
RMweb Gold queensquare Posted May 17, 2016 RMweb Gold Share Posted May 17, 2016 There was a lot of discussion and experimentation by members of the 2mm Scale Association a few years back, and it seems that the 'no load speed' of a motor is important. There are tables somewhere (the Yearbook?) giving the speeds of common motors. 17500rpm and 17000rpm stated for the 12V motor on eBay may be a little high, compared with the 11500rpm of the Maxon 10/17. Ian. I remember reading all that and deciding to take little notice if it, as with many things it seemed to me to be over complicating things again. The Nigel Lawton motors are lively but at the moment I use them almost exclusively. So long as the mechanism is sensibly geared the loco will be controllable, if I want it to go slower I just turn the controller down a bit! The advent of high quality chips such as CT and Zimo has added another level of controlling lively motors. Likewise end thrust from a worm drive. I have numerous locos running like this with a variety of coreless motors and never had a problem. I don't think the torque required for 2mmlocos is likely to be an issue. I've ordered four of the 7mm coreless motors, they look remarkably like the Farish ones to me. Jerry Link to post Share on other sites More sharing options...
Richard Hall Posted May 17, 2016 Author Share Posted May 17, 2016 I've ordered four of the 7mm coreless motors, they look remarkably like the Farish ones to me. Jerry The Chinese must be wondering what is going on. They've shifted over a hundred of these motors since yesterday morning. Lot of loco building out there. Link to post Share on other sites More sharing options...
£1.38 Posted May 17, 2016 Share Posted May 17, 2016 Just to clear things in my mind, does the 10pcs mean 10 motors for £3.70, or am I dreaming? Link to post Share on other sites More sharing options...
2mm Andy Posted May 17, 2016 Share Posted May 17, 2016 Just to clear things in my mind, does the 10pcs mean 10 motors for £3.70, or am I dreaming? No, you're not dreaming, it is £3-70 for 10 motors. Whether they will be any use is another matter, but at that price I'm happy to give them a go. Andy Link to post Share on other sites More sharing options...
£1.38 Posted May 17, 2016 Share Posted May 17, 2016 No, you're not dreaming, it is £3-70 for 10 motors. Whether they will be any use is another matter, but at that price I'm happy to give them a go. Andy Me too! Link to post Share on other sites More sharing options...
Richard Hall Posted May 17, 2016 Author Share Posted May 17, 2016 Just to clear things in my mind, does the 10pcs mean 10 motors for £3.70, or am I dreaming? Sorry, I said £7.40 for ten, I forgot I had actually ordered 20 That's a lifetime's supply of 1015s if they work. Link to post Share on other sites More sharing options...
£1.38 Posted May 17, 2016 Share Posted May 17, 2016 The gentleman who said he ordered four is actually getting 40 then, so he has to live at least twice as long Link to post Share on other sites More sharing options...
RMweb Gold queensquare Posted May 17, 2016 RMweb Gold Share Posted May 17, 2016 The gentleman who said he ordered four is actually getting 40 then, so he has to live at least twice as long No I've ordered the little 7mm coreless motors which are £2.50 for four. Jerry Link to post Share on other sites More sharing options...
RMweb Gold 2mmMark Posted May 19, 2016 RMweb Gold Share Posted May 19, 2016 Just a reminder that it's best to keep an individual overseas order under £15 if possible. Above that there's a risk it might get caught for VAT and Royal Mail's legalised theft of a "handling fee" With free postage, you can still get plenty of motors for fifteen quid. We do seem to have rather a heyday for small motors at the moment which leaves me thinking how long it will last. I also came across these can motors, 19mm by 15mm by 12mm with a 1.5mm shaft http://www.ebay.co.uk/itm/311577682012?var=610546601325 which I have in mind for repowering some early Farish diesel mechs, brass geared thankfully. Mark Link to post Share on other sites More sharing options...
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