RMweb Premium Michael Edge Posted March 30, 2018 RMweb Premium Share Posted March 30, 2018 I had to bore out the bevel gears on the lathe but they are a good friction fit on the shaft and the axle. A lot of these motors are described as used but I haven't had any faulty ones, they are quoted with wildly varying voltages, I just try them on 12v DC (nominal, usually higher than that anyway) and see if the ammeter moves much. In most cases the current consumption is very low, sometimes almost imperceptible so I don't worry about it. A lot of the well regarded Mashima motors get very hot in continuous use but nobody worries about it. Link to post Share on other sites More sharing options...
micklner Posted March 30, 2018 Share Posted March 30, 2018 I had to bore out the bevel gears on the lathe but they are a good friction fit on the shaft and the axle. A lot of these motors are described as used but I haven't had any faulty ones, they are quoted with wildly varying voltages, I just try them on 12v DC (nominal, usually higher than that anyway) and see if the ammeter moves much. In most cases the current consumption is very low, sometimes almost imperceptible so I don't worry about it. A lot of the well regarded Mashima motors get very hot in continuous use but nobody worries about it. The joys of owning a Lathe !! 1 Link to post Share on other sites More sharing options...
brack Posted March 30, 2018 Share Posted March 30, 2018 The joys of owning a Lathe !! You can buy the bevel gears with 3mm bore, remove the excess collar from the axle gear with a hacksaw or razor saw and bore it out to 1/8" using cutting broaches and sore fingers (I don't have anything so fancy to hold the broaches with). It'll work fine. I did just that a few years ago before I bought my unimat. I'm not saying I wouldn't be using my lathe on another one, but it didn't take too long and it worked. Link to post Share on other sites More sharing options...
brack Posted March 30, 2018 Share Posted March 30, 2018 True, but you don't half miss them on a layout where trains need to stop on a gradient................ John I might go a bit overboard on the gear ratios, but just because there's no worm in the gear head doesn't mean they'll backdrive easily once you're past 100:1 (or at all!). Link to post Share on other sites More sharing options...
RMweb Premium Michael Edge Posted March 30, 2018 RMweb Premium Share Posted March 30, 2018 These definitely won't back drive. Link to post Share on other sites More sharing options...
Robin2 Posted April 9, 2018 Author Share Posted April 9, 2018 After wasting a lot of time I have finally got my new wireless control package working and have been able to do some initial tests with a worm on the motor shaft meshing with one of the gears from the gearbox. Here are some pictures. First, to give an overall impression, this is being designed to fit a Midland 1F body made from card (using my Silhouette portrait). And this is the chassis with the electronics and motor in place. The battery goes in the bunker. This picture shows the gear on the axle. The axle is 3mm brass tube. And the same thing from underneath for a clearer view This picture shows a similar motor with the worm gear. The worm is a piece of M3 brass screw. The black disc with the white spot is used for detecting the speed of the motor. The coin is a 2P piece. The final picture shows the underside of the electronics and the optical detector for motor speed. ...R Link to post Share on other sites More sharing options...
Robin2 Posted April 12, 2018 Author Share Posted April 12, 2018 Good morning. I think the small Slaters FD03 crossed helical 1.3:1 gearbox with 2mm. input and 1/8" output could make an excellent partnership in medium to larger 4mm. steam outline models. Regards. Serron. Rather too expensive for my liking. And not nearly enough reduction. I think I would have 4 motors and gear sets for half the price ...R Link to post Share on other sites More sharing options...
Horsetan Posted April 30, 2018 Share Posted April 30, 2018 (edited) The big plus factor with these motors is getting rid of the worm drive. At last, a proper reversible drivetrain. ......problem I have is that I want to try them in something with 10.5mm wheels and can't find any bevel gears that'll fit ..... How about these? Edited April 30, 2018 by Horsetan Link to post Share on other sites More sharing options...
Robin2 Posted April 30, 2018 Author Share Posted April 30, 2018 At last, a proper reversible drivetrain. Not what Reply #30 says How about these? Looks like an interesting selection of parts. I have bookmarked it ...R Link to post Share on other sites More sharing options...
Horsetan Posted April 30, 2018 Share Posted April 30, 2018 Not what Reply #30 says..... That may be something to do with the number of spur gears in the gearhead mounted on the motor. Link to post Share on other sites More sharing options...
AndyID Posted April 30, 2018 Share Posted April 30, 2018 That may be something to do with the number of spur gears in the gearhead mounted on the motor. Fundamentally it's the ratio. Any large ratio gear-train creates a lot of friction. Worms get a bad rap. They do create a bit more friction than spur gears but it's usually the large ratio that's responsible. I have Tri-ang worm gears that do back-drive but they don't have a large ratio. Link to post Share on other sites More sharing options...
Horsetan Posted April 30, 2018 Share Posted April 30, 2018 (edited) ....I have Tri-ang worm gears that do back-drive but they don't have a large ratio. The Triang worm may have multiple starts as well. If the worm has something like six or eight "starts" or more, and the helical worm wheel has a suitable angle, then you will get a reversible drivetrain (see ABC's gearboxes, and also Slater's crossed helicals) Edited April 30, 2018 by Horsetan Link to post Share on other sites More sharing options...
AndyID Posted April 30, 2018 Share Posted April 30, 2018 The Triang worm may have multiple starts as well. If the worm has something like six or eight "starts" or more, and the helical worm wheel has a suitable angle, then you will get a reversible drivetrain (see ABC's gearboxes, and also Slater's crossed helicals) Yes, it's a two start. Worms are really just helical gears (with extreme prejudice). If they are made with combinations of low-friction materials they will back-drive almost as well as spur gear trains with the same gear ratio. Helical gears do produce more friction than straight-cut spur gears but they have the benefit of being much quieter than straight-cut gears. My main point is to debunk a common misconception that it's impossible to back-drive a worm gear combination. You picks your poison Link to post Share on other sites More sharing options...
DCB Posted April 30, 2018 Share Posted April 30, 2018 Yes, it's a two start. Worms are really just helical gears (with extreme prejudice). If they are made with combinations of low-friction materials they will back-drive almost as well as spur gear trains with the same gear ratio. Helical gears do produce more friction than straight-cut spur gears but they have the benefit of being much quieter than straight-cut gears. My main point is to debunk a common misconception that it's impossible to back-drive a worm gear combination. You picks your poison You can back drive Hornby Dublo/Wrenn worm drive Ringfield and vertical motor locos with fairly coarse worms but when you get to 00 scale and a Romford 30:1 gear set its not going to back drive, however I have some motor driven pump gearboxes donated by a friendly plumber with spur gears about 100:1 which back drive no problem. The gears are really useful for everything from scenery. wagon loads, crane gears etc to actual spur gearing for locos. Link to post Share on other sites More sharing options...
Horsetan Posted April 30, 2018 Share Posted April 30, 2018 ....point is to debunk a common misconception that it's impossible to back-drive a worm gear combination.... Why aren't they available more widely? Link to post Share on other sites More sharing options...
AndyID Posted April 30, 2018 Share Posted April 30, 2018 Why aren't they available more widely? Good question. I bought nylon worm-gears for my Tri-ang DMU a very long time ago. The brass/nylon combination works really well. The trick is to minimize the lateral sliding velocity between the worm and the worm-wheel, and use material combinations that tend to minimize friction. To achieve that the worm should have the smallest possible diameter to make the angle of attack as large as possible. It's not rocket science. I learned most of it from my physics teacher about fifty years ago. (He was great BTW - RIP Bilko.) Link to post Share on other sites More sharing options...
Robin2 Posted April 30, 2018 Author Share Posted April 30, 2018 (edited) Why aren't they available more widely? Reversible worm drives are a very specialized taste - the unit cost would be very high for the tiny quantities that would be required by modellers. Even with an expensive reversible drive I don't think an 00 gauge model would have enough kinetic energy to freewheel convincingly. I suspect it would not do so even if you could take it out of gear completely. ...R Edited April 30, 2018 by Robin2 Link to post Share on other sites More sharing options...
AndyID Posted April 30, 2018 Share Posted April 30, 2018 Reversible worm drives are a very specialized taste - Not really. Minimizing losses due to friction is always a good idea, in either direction. Link to post Share on other sites More sharing options...
Robin2 Posted May 1, 2018 Author Share Posted May 1, 2018 Reversible worm drives are a very specialized taste - Not really. Minimizing losses due to friction is always a good idea, in either direction. That is not the context of my comment. I just meant that very few people use them. ...R Link to post Share on other sites More sharing options...
Sam Moss Posted June 20, 2018 Share Posted June 20, 2018 One of the variants fitted into a Hornby tender drive black 5. Yet to be tested under power as the araldite has been setting. Using bevel gears would probably have been the better option space wise as I had to do a lot of carving with a rotary burr. Won't get chance to fit pick ups until next week so will have to wait and see how it performs. 1 Link to post Share on other sites More sharing options...
Robin2 Posted June 21, 2018 Author Share Posted June 21, 2018 Looks good. However I can't see what motor/gearbox you are using - are there additional reduction gears? ...R Link to post Share on other sites More sharing options...
Dazzler Fan Posted July 15, 2018 Share Posted July 15, 2018 (edited) Hi ! On eBay.co.uk there are Shapeways 3D HP-Nylon bevel gears bespoke for these N20 motors sold as 2 pairs. Axle Gear is a force fit on a 1/8" axle and has glue lines; the motor gear fits the flat of the motor shaft. Edited July 15, 2018 by Dazzler Fan 2 Link to post Share on other sites More sharing options...
Robin2 Posted July 15, 2018 Author Share Posted July 15, 2018 the motor gear fits the flat of the motor shaft. I have never seen an N20 motor with a flat on the motor shaft. It is only a 1mm diam shaft. Do you have a link to the Shapeways item? ...R Link to post Share on other sites More sharing options...
RMweb Gold Huw Griffiths Posted July 15, 2018 RMweb Gold Share Posted July 15, 2018 (edited) Hi ! On eBay.co.uk there are Shapeways 3D HP-Nylon bevel gears bespoke for these N20 motors sold as 2 pairs. Axle Gear is a force fit on a 1/8" axle and has glue lines; the motor gear fits the flat of the motor shaft.[/url] I have never seen an N20 motor with a flat on the motor shaft. It is only a 1mm diam shaft. Do you have a link to the Shapeways item? Not the motor, perhaps - but a lot of them are supplied fitted with metal gearboxes, whose output shafts are about 3mm diameter, with a flat on one side of this shaft. Some suppliers have started supplying them with pairs of plastic bevel gears with round holes slightly too large for this shaft and too small for a 1/8 inch axle - with small split pins - and suggested that people drill holes in the shafts to take the split pins. I suspect these 3D printed gears might be a reaction to this. Huw. Edited July 15, 2018 by Huw Griffiths Link to post Share on other sites More sharing options...
Nicktoix Posted July 15, 2018 Share Posted July 15, 2018 Hi ! On eBay.co.uk there are Shapeways 3D HP-Nylon bevel gears bespoke for these N20 motors sold as 2 pairs. Axle Gear is a force fit on a 1/8" axle and has glue lines; the motor gear fits the flat of the motor shaft. gears.jpg Do you have a link? Nick Link to post Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now