Hornby Dublo “Ringfield” Motor Rewind

[Hacksworth_Sidings]

Evening RMWebbers,

 

So I bought a Dublo 8F shortly before Christmas in 2023, arrived with a totally fried motor, today I finally attempted to rewind the motor with some 0.2mm enamelled copper wire, but I’m still having issues as the motor is shorting out. This being my first attempt it certainly won’t be to 1950s Meccano standards, let alone modern standards, so any advice or assistance would be greatly appreciated.

 

It’ll rotate if given a nudge, but it still shorts out my controller, I’m using a Dublo A3 to test this motor since that one has the buzzer and lamp to signify a short circuit, unfortunately I don’t have a multimeter on hand to test with but I do have access to them at college.

 

It initially had a short to earth on one of the poles, but that was down to my poor soldering, I thought my bodgy solder job may have been another issue (the joints clipping the insides of the frame), so I filed those back to prevent that from happening. I’ve scraped out between the plates numerous times to ensure there’s nothing between them, but still nothing, any assistance?

 

Before rewind

 

During rewind

[jimwal]

Back in the seventies me and a mate rewound a lot of H/D motors of all types many for local model shops. The main failure with these is the plastic moulded insulation on the armature which was melted, as yours appears to be.

 

It looks as if you have painted it for insulation. This is unlikely to be robust enough. 

A thin heat resistant insulation tape may be the best way now, it wasn't available years ago.

Watever you use, make sure the winding surfaces are properly covered. 

 

Just to add, if you are not aware, the motor will need remagnetizing after reassembly.

If you use a rare-earth or 'neo' magnet the motor will be powerful but slow running is impossible!

 

 

 

 

Edited February 2 by jimwal
Add content.

[kevinlms]

A multimeter would certainly help identify where the issue is. A very cheap one would be more than capable for this task.

[Wolseley]

I had a similar problem with one once and, although it could well be something different in your case, for what it's worth, my problem was caused by one turn of wire sticking out a fraction more than it should have, with the result that the wire would occasionally touch the magnet.

[cypherman]

Hi all,

Out of idle curiosity how many times should you wrap the wire round each pole and what diameter would be best to use. I have quite a few Hornby Dublo and Wrenn locos. So this info wcould be useful  in the future.

[jimwal]

Regarding size and quantity of wire. We reasoned that as it was going to be hand tensioned and wound, the amount may vary if we just counted number of turns. So we stripped a few duff armatures of all three diameters.

We carefully measured the length of wire and its diameter and arrived at the figures of:

   14 feet of 38 gauge enamelled copper wire for each pole.

 

Every rewind we done was successful and with the 350hp diesel-electric shunter actually seemed to improve them.

We didn't often rewind the 'half inch' motors, they didn't lose magnetic strength like the bigger motors.