hayfield Posted February 24, 2022 Share Posted February 24, 2022 On 07/02/2022 at 01:42, Rod Hutchinson said: Is you process something like the following: 1. Remove shaft from housing, 2. Press off drive gear, 3. Replace shaft with one of desired diameter, 4. Add a bush to support original drive gear, 5. Stick it all back together? On 08/02/2022 at 15:28, tomparryharry said: Hi Rod. Yes, that's basically it. I used a 1/8" Romford axle to replace the final gear axle, and re-assembled. If you're careful enough, there is a possibility to retain the 2 hollow rivets which pass through the gearbox. If this is the case, it 'should' provide ability to accurately retain the motor on station. Like Tomparryharry I am also new to this motor Not shown on my photos is the screw and rivets on both sides of the gearbox but I am being a bit thick. Firstly to change the axle do I have to take the the gearbox side off and or the other side of the gearbox. Or can one simply push it out of the gear and gear sides You then talk about bushing the axle, I assume you bush the gearbox sides I am working to EM gauge so I have plenty of side play as the gearbox is 10mm wide, I assume though as the axle is glued to the final gear I would have to make it removable from the chassis using hornblocks ? Would the 3mm axles fit Gibson wheels? Link to comment Share on other sites More sharing options...
RMweb Gold ianLMS Posted November 16, 2022 RMweb Gold Share Posted November 16, 2022 (edited) I have just succesfully replaced the axle on one of these lovely N20's with a Markits Alan Gibson 1/8" axle. In the end, i reamed out the hole to take the new axle and added bearings as spacers, the soldered these to the axle and gear. So far so good. I managed to retain the rivets holding the geabox together. Will test it in one of my next loco builds using hornblocks so its removable. Pics later. If i can do it......... Ian Edited November 17, 2022 by ianLMS 6 Link to comment Share on other sites More sharing options...
RMweb Gold ianLMS Posted November 18, 2022 RMweb Gold Share Posted November 18, 2022 (edited) To expand a little on how i did it...... First, choose the right motor. This is a 12v dc dual shaft D model, 16000 rpm from ebay. About £7.80 plus postage i think. Leave motor on gearbox. Undo only one of the side screw on the gear box (1st pic above). Using a large drill bit, gently ream out enough of the rivet tops so u can ease the side off. Take it slowly as the other shafts are pushed into the side holes and you dont want to displace these. Remove main drive shaft and gear. Leave all other gears and shafts in place. Tap out the drive shaft gently, supporting just the gear. I used a hollow socket and tapped the shaft out with a pin hammer. The middle of the shaft is ribbed so the gear slots in and doesn't rotate, but the shaft will come out without issue. Ream out the gear slightly to remove the tip of the ribs so its a tight fit on your chosen axle. 1/8" in my case. Slide on gear onto new axle. Slide on brass bearing with thin end facing the gear. Add other bearing on the other side of the gear and make sure the drive gear lines up with the other gears and it fits with only the slightest side play before soldering the bearings to the gear and shaft. You may need to ream out the axle hole in side of gearbox to take new axle. A little at a time and test for a nice loose, but not sloppy fit. Relocate axle and gear into gearbox making sure everything lines up. Add side back on, lining up the other shafts in the holes. Tap side over rivets and fit back the screw. If you removed too much rivet, a little solder or superglue with fix it. Test and make sure all works. Either build chassis around gearbox, or use hornblocks. Hope this explains it. Ian Edited November 18, 2022 by ianLMS 3 2 Link to comment Share on other sites More sharing options...
RMweb Gold tomparryharry Posted December 13, 2023 RMweb Gold Share Posted December 13, 2023 On 18/11/2022 at 17:12, ianLMS said: To expand a little on how i did it...... First, choose the right motor. This is a 12v dc dual shaft D model, 16000 rpm from ebay. About £7.80 plus postage i think. Leave motor on gearbox. Undo only one of the side screw on the gear box (1st pic above). Using a large drill bit, gently ream out enough of the rivet tops so u can ease the side off. Take it slowly as the other shafts are pushed into the side holes and you dont want to displace these. Remove main drive shaft and gear. Leave all other gears and shafts in place. Tap out the drive shaft gently, supporting just the gear. I used a hollow socket and tapped the shaft out with a pin hammer. The middle of the shaft is ribbed so the gear slots in and doesn't rotate, but the shaft will come out without issue. Ream out the gear slightly to remove the tip of the ribs so its a tight fit on your chosen axle. 1/8" in my case. Slide on gear onto new axle. Slide on brass bearing with thin end facing the gear. Add other bearing on the other side of the gear and make sure the drive gear lines up with the other gears and it fits with only the slightest side play before soldering the bearings to the gear and shaft. You may need to ream out the axle hole in side of gearbox to take new axle. A little at a time and test for a nice loose, but not sloppy fit. Relocate axle and gear into gearbox making sure everything lines up. Add side back on, lining up the other shafts in the holes. Tap side over rivets and fit back the screw. If you removed too much rivet, a little solder or superglue with fix it. Test and make sure all works. Either build chassis around gearbox, or use hornblocks. Hope this explains it. Ian Hello Folks, Sorry I've been away... Ian LMS: Yes, spot on. The rivet holes accept a small set-screw which can pass through the frame, from one side to the other. If you use a countersunk setscrew, you can tap the one side to keep the motors on station, and you don't need a torsion bar, as those 2 screws takes care of it. I'd suggest going for 'size' at least as axle diameter. Measure the axle first. If it's 3mm, use a reamer that size, or 1/8", if it's imperial. If you've got doubts, try the hole with a ground HSS drill bit, but not a Chinese version. Pay the slight extra cost, and get it right. That Micrometer is just there.... I'm very interested in how everyone has got on thus far. I've had to box up everything, and my memory is a bit dim. I do remember I've got an Aberdare or two somewhere, and if these work, there's a couple of 1701 panniers in the distance. Many thanks, Ian. Link to comment Share on other sites More sharing options...
apl31 Posted May 7 Share Posted May 7 After reading the above posts I plucked up courage to convert a dual shaft N20 motor. I have now converted 2 motors, one with a 3mm and one 1/8th “ axle, surprisingly I got both back together and both work. Thanks to the Ians for their advice. The only thing I would add is to take photos before dismantling incase gears fall out. I misread about taping other side gearbox plate and using a through bolt, I actually tapped spacer M1.6. The thread holds for working but I’d be worried stripping the thread giving it a final tightening up, and intend gluing into place. I made a gear puller as in photo. Probably a bit over the top as final gear only needs to move off the short spline beneath. One drawback of these motors and conversions is the axle is fixed, which is ok if using hornblocks but if you want to use bearing it would need a removable axle. I know nothing about gears other than this one appears to have 21 teeth (Ive possibly miscounted that). Does anyone know what that final gear is, how would you specify it? I was wondering if it was a standard size which could be replaced with a gear with a boss/grub screw fixing. I notice there are lots potentially on line. 2 Link to comment Share on other sites More sharing options...
apl31 Posted May 8 Share Posted May 8 As I said I knew nothing about gears, but I did a little further investigation. Spur gears seem to be defined by module. The module is calculated by: Mod = (OD in mm) /(2+T) where T no of teeth I measured OD as 6.8mm it has 21 teeth giving a module = 0.295. The module is probably 0.3 which makes OD actually 6.9mm. I looked online at 0.3 module gears but couldnt find a 21 tooth gear, closest is 20 tooth which I assume wouldn't mesh. 1 Link to comment Share on other sites More sharing options...
Atchison Posted May 16 Share Posted May 16 Don't worry, there are some links: https://en.wikipedia.org/wiki/Spur_gear https://en.wikipedia.org/wiki/Gear#Standard_pitches_and_the_module_system Here a link https://kkpmo.com to a gear manufacturer in Poland. This people manufacture single gears to your specification. They often had saved my day with exotic gears. Lutz 1 Link to comment Share on other sites More sharing options...
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