bertiedog Posted April 3, 2016 Share Posted April 3, 2016 Being away from modelling for a while , I researched what was around in very small DC motors on ebay, and several interesting items have surfaced that would suit scratch building in 2mm scale. The motors and gearboxes come from cameras, the autofocus drive or aperture control. There is a design change in the cameras over to linear stepper motors and it has rendered the DC motors redundant. There are several models, the motors are rated at about 5 Volts but will take more, and are really tiny. The motors are either coreless or 3 pole types, most sellers do not specify. The bonus is the gearbox which can be used in 00 , but the internal gears can individually used to power 2mm locos, with usually a 2 start worm drive then several spur gears. The moulded gears are top quality. Best of all is the price, you can get 4 or 5 for about £3.00. I doubt if these will be around long , it looks like a sell off situation by the suppliers. The one illustrated has a large output gear which is 1:1 to the gear train and can be removed and sawn off, or the internals used in a new gearbox or frames. The motor fits between 2mm frames. Stephen Link to post Share on other sites More sharing options...
Robin2 Posted April 3, 2016 Share Posted April 3, 2016 Have you a link to the Ebay site, or the search terms needed to find them? ...R Link to post Share on other sites More sharing options...
bertiedog Posted April 3, 2016 Author Share Posted April 3, 2016 Have you a link to the Ebay site, or the search terms needed to find them? ...R The search tern sub miniature dc motors should bring them up. But check or change the term and look in the similar items suggested in case other seller miss name them. Also micro motor brings up good selection on other tiny motors Link to post Share on other sites More sharing options...
bertiedog Posted April 3, 2016 Author Share Posted April 3, 2016 http://www.ebay.co.uk/itm/5x-DC-3v-5v-micro-Gear-Motor-Variable-Speed-Gearmotor-reduction-gear-box-for-DSC-/171927012175?hash=item2807a6034f:g:wF4AAOSwEetV8TYu Ref for one type I bought, picture shows the gears inside There is a worm, then spur gears, that can be used as needed. They are standard metric pitches. Link to post Share on other sites More sharing options...
bertiedog Posted April 3, 2016 Author Share Posted April 3, 2016 http://www.ebay.co.uk/itm/5pcs-DC-3v-6v-Gear-Motor-Variable-Speed-Gearmotor-micro-reduction-gear-box/181793207307?_trksid=p2055119.c100022.m2048&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20140122153843%26meid%3D8357c77fcc3740f18b1b0dac49259f84%26pid%3D100022%26rk%3D1%26rkt%3D4%26sd%3D171927012175 Another type with a smaller motor, with good selection of gears inside. The gears could be left in place on the frame, the last gear being the axle, or driving from the final coarser spur gear. Stephen Link to post Share on other sites More sharing options...
RMweb Premium DavidLong Posted April 3, 2016 RMweb Premium Share Posted April 3, 2016 Being away from modelling for a while , I researched what was around in very small DC motors on ebay, and several interesting items have surfaced that would suit scratch building in 2mm scale. The motors and gearboxes come from cameras, the autofocus drive or aperture control. There is a design change in the cameras over to linear stepper motors and it has rendered the DC motors redundant. There are several models, the motors are rated at about 5 Volts but will take more, and are really tiny. The motors are either coreless or 3 pole types, most sellers do not specify. micro motor.jpg The bonus is the gearbox which can be used in 00 , but the internal gears can individually used to power 2mm locos, with usually a 2 start worm drive then several spur gears. The moulded gears are top quality. Best of all is the price, you can get 4 or 5 for about £3.00. I doubt if these will be around long , it looks like a sell off situation by the suppliers. The one illustrated has a large output gear which is 1:1 to the gear train and can be removed and sawn off, or the internals used in a new gearbox or frames. The motor fits between 2mm frames. Stephen Stephen, Do you have any dimensions for the motor? David Link to post Share on other sites More sharing options...
Robin2 Posted April 4, 2016 Share Posted April 4, 2016 Much appreciated. Thanks. ...R Link to post Share on other sites More sharing options...
nigelb Posted April 5, 2016 Share Posted April 5, 2016 what sort of shaft RPM should we be thinking about for a general 2 MM loco Link to post Share on other sites More sharing options...
bertiedog Posted April 5, 2016 Author Share Posted April 5, 2016 Do not pick motors by the RPM, they quote figures sometimes for max rated voltage, but Chinese suppliers over estimate the speed. Any small DC motor will reach a couple of thousand revs easily, but it is not needed for normal running on a model. With say 30:1 gears at about 4 volts a small motor running at 1000 is 1000/30 final drive, or 33.3 RPM Some sellers of the small coreless motors for aircraft models claim very high Revs. so high the figures are unbelievable. A small motor should start turning at about 2 volts no load, and rev to it's max at 12volts, it the dynamic range that determines suitability. You can do a load load graph against voltage and speed, then a loaded graph, and compare and find a good average figure that keeps the ampage within what the windings can stand. But it is easier to that a guess and fit as high a ratio as possible, dependent on whether the loco is a shunter or a main line loco. Link to post Share on other sites More sharing options...
bertiedog Posted April 5, 2016 Author Share Posted April 5, 2016 On the dimensions they vary on the various camera lens units, some are really small 1cm x 6mm, others are 6/7 mm wide and 15mm to 20 mm long, These motors are not 12 volts but abut 5 volts, this makes little difference except to the degree of rotation of the speed controller. To get the speed range to match the controller, diodes or resistors can be used in series for DC, with DCC it can be adjusted via CV values. Link to post Share on other sites More sharing options...
pointstaken Posted April 5, 2016 Share Posted April 5, 2016 Suggests that suitable especially for small steam locos - Southern P class. Anyway, great to see you back on the forum. Dennis Link to post Share on other sites More sharing options...
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