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Giles

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Giles last won the day on November 15 2013

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    http://gilesfavell.com/By%20Giles.htm

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    Middlesex

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  1. Your micro engineering is unequalled is this field! I've have the 8mm gearboxes in pieces - but the 4mm ones!!!! As always - superb!
  2. That is indeed the gear motor.... they were available at around £3.80, but sadly the supply appears to have dried up! If you do me across any actually stock, I suggest you buy them! It's very possible it was behaving as you suggest - it was certainly very far from ideal, and I won't be repeating it!
  3. The K20s were 151.1 : 1 according to their data, extrapolating the motor speed of 18,132rpm at 5v.
  4. Also, if you were designing an RC loco from scratch, you would likely use lower voltage motors and avoid the complexity of higher voltage battery requirements.
  5. I do applaud your productivity and use of these techniques (not to mention the results!)..... Pantograph milling has been something of a game-changer it would seem?
  6. Andy rightly makes a good and important point. He says that worm gears 'can' be just as efficient as other gear arrangements.... They can be surprisingly efficient - some manufacturers quote just over 90% which is remarkable - however those are very good bits of kit, and worm efficiency varies dramatically. The ones I get to shove in my models certainly aren't anything like that good, sadly. Having said that, I'm in no way anti worm, having fitted and used countless of them on countless models. In theatre, we use a variety of hoists for lifting and flying. The simpler ones are motor/worm/gear arrangements, and one of the very important safety features is that they do NOT feed back (some early manual hand winches did, and it would on occasion end up very nasty!) . The worm and gears are of course specifically specified and designed not to feed back for this application. In the interests of collective experience, the reason I made comment about the poor efficiency of worms was one particularly 'dramatic' empirical example I had when building one chassis- which may be of interest as it concerns the N20s. I build a chassis for a 7mm narrow gauge Bagnall (for radio control) with a white metal body- so relatively a heavy beast..... because I had used many N20s on vehicles and been do impressed with them, I thought I would use one on this as well - but because I needed to off-set it to hide it in the Firebox, I decided to use a 5:1 ratio N20 in conjunction with a 20:1 worm. This proved to be very weak and easy to stall, giving poor slow speed control and overall disappointing performance. I removed that installation, and replaced it with the very much smaller K20, driving through a modified 0.3M brass bevel gear. This was superb, giving the same track speed but much 'stronger' at the wheels, and thereby giving much better, smoother control. Both installations delivered the same nominal RPM at the axle, both were properly meshed. Control etc. remained the same and un-altered. The N20 was a 6v motor (12 x 10 x 20) and the K20 a 5v motor (8 x 6 x 16) with a planetary box.. My experience would suggest that N20s are most effectively utilised with a 1:1 final drive if possible, and avoid a high ratio final drive (like wot I tried..) 5:1 N20 with 20:1 worm and gear 03B65D83-16E9-46C2-88CB-7D1F63F78992_zpsgmmk0e2a by giles favell, on Flickr K20 with bevel gears 2019-02-08_07-14-46 by giles favell, on Flickr
  7. I too use graphite on DCC (Denton Brook, and The End of The Line before that...). It greatly improved reliability. Denton Brook has a 1:10 gradient, and the use of graphite reduces the adhesion performance to something like scale capabilities. The Garrett will cope with anything that fits, whilst the little Fowler can only cope with two wagons. All in all, it works very well!
  8. I use 5 minute epoxy or Loctite 601. If gluing, apply the glue to the bore of the gear - NOT the shaft - that way you'll avoid getting glue in the gearbox. Michael E is absolutely right about the benefit of not using worms. They're only something like 25% efficient if you're lucky, whereas a bevel gear approaches 90%. I've been using some extremely small motors with planetary gearboxes, and they also prove immensely powerful, relatively. A motor 6 x 8 x 16 handling a white metal loco quite happily.....
  9. Having completed the FG, I thought I'd tidy up the work bench and finish off the second 4mm scale Bedford TK conversion. Now duly done..... a matching pair (one in use - one on charge). They both perform very nicely, manuoevring very well, with very nice slow speed work, which can often lack at this small size. They are built in exactly the same wy as the 7mm vehicles, and so share the same characteristics. 2 off 4mm scale radio controlled Bedford TKs by giles favell, on Flickr
  10. Having finally got various jobs out of the way, I've completed the second 4mm Bedford TK, which has been lying in bits without a receiver for a couple of months.... All complete now, electrics done, battery fitted, mirrors made and fitted, so I now have a matching pair (one in use - one on charge) 2 off 4mm scale radio controlled Bedford TKs by giles favell, on Flickr
  11. Steering axles part 1 Steering axles part 2
  12. A couple of my vehicles have these for charging, and yes, as already stated, reduce the size of the latch with a scalpel and secure solidly with epoxy or similar. Works fine......
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