N20 motors - Railway Modeller April 2018

[Robin2]

I wonder if anyone else has experience with these small motors?
 
By the way N20 refers to the motor only. It is a classification used by Mabuchi though I doubt if the cheap motors are actually made by Mabuchi. 
 
I have been using some N20 motors with cheap plastic gears I bought from Squires. With a worm drive from the motor shaft and an overall reduction of about 45:1 and powered with a pair of AA alkaline cells it is not at all easy to stall the motor. I don't understand what tests the Author of the article (Geoff Helliwell) was doing in which the worm drive gear box was so much worse.
 
I have recently bought a few motors with gearboxes. The 'boxes really are beautifully made - almost silent. The reason I bought them was with a view to taking the 'box apart as a source of small gears. As far as I can see an M3 set screw will make a nice worm for driving the gears.
 
...R

Edited March 10, 2018 by Robin2

[DCB]

I read the article but don't have the mag with me, can someone please post the name of the eBay supplier who supplier the Bevel Gears the guy used as a final drive please.

 

The off putting bit is the D shaped 3mm final drive which the guy in the article turned down in his lathe to 2mm. Sounds like the dark ages when modellers made wheelsets out of buttons and knitting needles on their trusty Unimat 2's, If I tried it would wobble.

 

Probably the most interesting article in RM in the past 20 years, |I have been eyeing those motors up for ages and the transverse idea sounds really good, thinking CD tray motor driving some of those gears.

[Robin2]

I have now taken one of my 'boxes apart. The gear module seems to be 0.15 (hope that is the correct jargon). The bigger gears have 38, 37, 35 and 34 teeth.

 

I plan to try building a gearbox with a worm drive to one of those gears to see if the single stage reduction is adequate. If that works each N20 gearbox could provide the parts for 4 loco gearboxes.

 

...R

[AndyID]

I have now taken one of my 'boxes apart. The gear module seems to be 0.15 (hope that is the correct jargon). The bigger gears have 38, 37, 35 and 34 teeth.

 

I plan to try building a gearbox with a worm drive to one of those gears to see if the single stage reduction is adequate. If that works each N20 gearbox could provide the parts for 4 loco gearboxes.

 

...R

If they are spur gears (straight teeth) they won't interface correctly with a worm, but you might get away with it if there isn't a lot of pressure at the pont of contact.

[Robin2]

If they are spur gears (straight teeth) they won't interface correctly with a worm, but you might get away with it if there isn't a lot of pressure at the pont of contact.

You are quite correct. I will be happy with a working kludge.

 

I plan to mount the worm at slight angle to better align with the gear teeth

 

...R

Edited March 12, 2018 by Robin2

[AndyID]

You are quite correct. I will be happy with a working kludge.

 

I plan to mount the worm at slight angle to better align with the gear teeth

 

...R

That should work.

[DCB]

I used a similar looking motor without the gearbox on an Airfix 14XX and burned it out.  Didn't like the standard gearing. That was on DC. I wonder if on board overload protection would be sensible, 1/4 amp or less polyswitch or similar.  Plenty of Controllers rely on Polyswitches for overload protection as they reset automatically.

Worms at an angle on straight cut gears will probably work for a bit but the tooth profile will almost certainly be wrong and when I tried an Airfix 14XX brass worm on a steel gear wheel of almost the right profile it stripped the teeth off the worm in a very short period of time.  

You may also have gathered I don't have a great deal of luck with Airfix 14XX 

[Robin2]

I used a similar looking motor without the gearbox on an Airfix 14XX and burned it out. 

Were you powering it with 12v?

Was the motor designed for 12v?

 

The N20 motors come with a variety of windings for different voltages. Identifying which voltage a motor is intended for can be difficult.

 

...R

[Nimbus]

Any pictures, or links to sources please?

 

The Nim.

[Robin2]

Any pictures, or links to sources please?

 

 

Pictures of, or links about what?

 

...R

[Nimbus]

... of the 'beautifully silent' gearboxes and motors you bought!

 

The Nim.

[Robin2]

... of the 'beautifully silent' gearboxes and motors you bought!

 

The Nim.

Lovely pictures in the article in Railway Modeller. I got mine from HobbyComponents, but they are widely available on Ebay and elsewhere.

 

...R

[Nimbus]

You realise that you are restricting this thread to RM readers don't you? Maybe explains the lack of posts!

 

The Nim.

[Barry O]

Have a look at Mike Edge/Judith Edge Kits thread on RMWeb in smaller manufacturers. Mike has been looking at different types of motors and gears for a while.

 

Baz

[Robin2]

You realise that you are restricting this thread to RM readers don't you? Maybe explains the lack of posts!

I am not restricting it in any way. The idea for the Thread was sparked off by the RM Article.

 

If you want to see pics of the motors without buying the mag then there are plenty of variants on the Pololu website

 

 

If you are thinking of using one of the motors I reckon the copy of RM would be an excellent investment.

 

...R

Edited March 27, 2018 by Robin2

[Michael Edge]

I've used two of these motors so far, both with bevel gear drive to the axle but this is the first one of the other configuration I've tried. This has the output shaft underneath the motor, still in the same plane.

 

 

This is an LBSC D1 0-4-2T being built from an Albion kit in 00 gauge, the motor is entirely in the firebox of this quite small loco.

 

 

View of the bevel drive from below, I leave a small gap between the gearbox and the bevel gear so that it can be slid back along the shaft (levered with a screwdriver) to disengage the drive. I wouldn't normally fit pickups at this stage but I wanted to make sure the loco's speed range was acceptable (it is). The motor's gearbox is soldered to a plate across the ashpan, coupling rods temporarily held on with slices of wire insulation.

 

 

Another view from the top showing the gears more clearly. The plastic bevels are bored out with a 3mm drill for the gearbox shaft and 1/8" drill for the Gibson axle.

[Robin2]

Lovely pics.

 

I have been making progress with using a gear from from one of the boxes with an M3 screw as a worm. It will be a few more day before I have pictures to post as I am building another "Arduino" controller so I can do a back-to-back comparison with my earlier setup using the plastic gears from Squires. Assuming it all works the motor/drive will be very much smaller - smaller even than the standard N20 + 'box.

 

...R

Edited March 29, 2018 by Robin2

[Michael Edge]

The big plus factor with these motors is getting rid of the worm drive.

[Downendian]

Thanks for the excellent description and photos Michael.

Where did you source the bevel gears? I intend playing with these motors soon.

I shall follow this thread with interest, especially following the excellent RM article.

Neil

[Robin2]

The big plus factor with these motors is getting rid of the worm drive.

I remain to be convinced.

 

With either of my worm drives I can't stop the driven axle with my finger without the risk of breaking something - and that's with 3v power (or a bit less - my test AA cells are past their prime)

 

...R

[Red Devil]

One variant that I came across recently was this one with an extended but 2mm shaft. All the others I'd seen had the 3mm version.

 

https://www.ebay.co.uk/itm/DC-3V-6V-5V-1600RPM-N20-Micro-Full-Metal-Gearbox-Gear-Motor-DIY-Robot-Smart-Car/253286079809?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

[Michael Edge]

I've not come across that one, there don't seem to be as many gears in there - is it a higher gear ratio?

Bevel gears come from Ebay, I think they were £1.98 for 20 (post free from China).

Worm gears are very inefficient and well worth getting rid of but the model railway wold is firmly wedded to them.

[Red Devil]

I've not come across that one, there don't seem to be as many gears in there - is it a higher gear ratio?

Bevel gears come from Ebay, I think they were £1.98 for 20 (post free from China).

Worm gears are very inefficient and well worth getting rid of but the model railway wold is firmly wedded to them.

 

Not sure, I think so, I've got some on order to play with, 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 so was going to try these with a worm gear added....as to if it'll work no idea but at the prices it's worth playing about with them.

[Dunsignalling]

I've not come across that one, there don't seem to be as many gears in there - is it a higher gear ratio?

Bevel gears come from Ebay, I think they were £1.98 for 20 (post free from China).

 

Worm gears are very inefficient and well worth getting rid of but the model railway wold is firmly wedded to them.

True, but you don't half miss them on a layout where trains need to stop on a gradient................

 

John

[micklner]

Nice setup by Mike.

 

The obvious problems are ensuring the mounting hole are parallel when drilling if needed, and how do you ensure the gears do not turn on the axles/shaft. If glue is used, it looks almost impossible to remove the gear set without a lot of problems/damage top the surrounding running gear as well in the future ?

 

The last motor shown above,  is quite long for 4mm use and the 2mm part of the shaft has a large slot on the one side. Not helped by the fact they are listed as secondhand motors with unstated amount of previous use, or on what kind of machine they were fitted too.

Edited March 30, 2018 by micklner