Remagnetizing loco magnets

[Davjan]

Hi guys

I have some older loco's with weak magnets, how can i remag these at home.

LOco,s are Wrenn,Hornby and Mainline all OO gauge

[LCDR]

 Re-magnetising needs specialist kit. There are dealers that do it, and some clubs have equipment.  Then there are 'Neo-Magnets' you can buy to replace yours.

[choralc]

There is a bloke on on you-tube who sells the kit and shows how to do work it. On the video he gives his contact information

 

https://www.youtube.com/watch

v=yyyPKCHa0gQ

[james_nelmes]

 I have one of the kits mentioned above and it works really well. A bit expensive if you are only doing a few so it might be worth contacting one of the motor refurbishers out there and ask them for a quote to remag your motors.

I use an app on my iphone called MMF-Meter. If I get a reading which exceeds the limit of 1000 micro Tesla the motor is generally ok, if not I remag. You can also (and I have) remag ringfield motors and X03/4. The key is making sure you line up your magnets with the remagnetising field. Also make sure they go back in the right way (X03/4) or the loco runs backwards.

[RDS]

How do you know if your Loco's need remagnetising?

I have a Class 08 Diesel (Blue Box) that just stops every now and again for no apparent reason.  Could that be the cause.

[james_nelmes]

 It's older locomotives that suffer from this mainly of the wren / Triang-Hornby era up to 1975. I have had occaisional problems with ringfield motors which have been fixed with a remag, but these tend to keep their magnetic field quite well. I've not come across a modern motor which suffers from this but it could do.

Symptoms of weak motors are poor pulling performance and the armatures tend to get hot and can burn out. If you run a motor and it smells like it's getting hot, there may be a problem.

As I said above, you can remove the body and use an app to measure the magnetic field. Alternately you can place a small screwdriver on the magnet and you should feel reasonable resistance pulling it off. If there feels to be little resistance, the magnet is probably weak. Some people buy 'super neo' magnets to replacethe originals and they do give a really strong field. I have read posts which say this puts a strain on the motor and damages it in the long term. I bought a remagnetiser off ebay and so remag my motors myself and this does work.

There are lots of reasons why models stop randomly and almost certainly not the magnet. Could be dirt on the pickups, dirt on the track, odd pickups not contacting the wheels or losing contact on bends. If it's happening in the same place on the layout it's a track / pickup thing. If it's random, a service should help (lubrication and pickup cleaning). 

[RDS]

Thanks James.  That was interesting to read.  I am aware of all the pick up problems you describe and they have been checked fully.  I will try the screwdriver test, the next time the body is off.

[81F]

 Why not get a new Neomagnet. There are several available on ebay for different motors. I have heard good reviews abot them.

[Davjan]

Hi Guys 

Thanks for your advice .I will look into your suggestions.

Dave

[96RAF]

 Why not get a new Neomagnet. There are several available on ebay for different motors. I have heard good reviews abot them.

Neos do not suit all motors.

 

I have two 3-pole ringfields with circular magnets that work very well, but one 3-pole with twin arch shaped magnets that will not run properly. It seems the magnets are TOO strong and make the motor very notchy, such that it will only run after a push start and at high revs, but with the old magnets it is dead smooth at all speeds but totally gutless, so its a shed queen at present, until I get a slim CD motor for it.

[Davjan]

An older post in another model railway forum suggests that an old PC's harddrive magnets can be used by placing a loco's magnets on them.

Will this work ? as checking websites that do this service charge as much as the loco is worth.

Ron Dodds makes a remagnetizer but he cannot be contacted .

[The Doc]

How do you know if your Loco's need remagnetising?

I have a Class 08 Diesel (Blue Box) that just stops every now and again for no apparent reason.  Could that be the cause.

RDS,

 

My Blue box class 08 was very similar - on applying current to the wheels I discovered that only one pick-up was working on one side, and two on the other.  This made it very sensitive to dirt on rails, plastic frogs etc.  I cleaned the backs of the wheels and adjusted the pick-ups (very flimsy strips of copper so take care) and it now runs much better.  Incidentally, I've occasionally noticed similar problems with other makes, including Hornby, so it can happen to anyone.

[The son of Triangman]

A warning, neo magnets can pull motor armature shafts out of alignment causing bearings to wear in one place, which causes squealing of bearings in time, remagnetising is the best way to go.

[RDS]

@The Doc

Thanks.  Actually, I had forgotten I had posted a question on this thread and only looked at it by coincidence just now when I noticed new posts.  Since I posted my question in October I have had it apart again and it was the same problem as yours - bad pick ups on one side.

[TCSC47]

Hi everybody. I know this is an old string but with the C-19 isolation and time on my hands, I'm contemplating building a re-magnetiser. Anybody know what magnetic field strength is needed? Easy matter then to calculate turns and wire guage to be used.

[Chrissaf]

The Ronald Dodd magnetiser video gives you a good clue as to what might be involved in building your own. Some time ago I did a search for coils and soft iron slugs that could be used and came up empty handed.

.

.

Going by the demonstration in the video, the magnetic field strength looks extremely high. The current draw from his power supply is in AMPs.

[TCSC47]

Had a look. The supply is 12V 10 A so that will get me started. I can see the volume of the electromagnets so the next step is to figure out what temperature I can let the coil rise to and choose an appropriate resitance to give wire guage and number of turns..

Umm-m I think. Well it is a start anyway.

[Chrissaf]

If you do build a successful project, then please publish the full constructional details. I'm sure there are many on here who would like to know the component list details and methodology, and try building their own.

[Rana Temporia]

Chrissaf

 

when I wanted a soft iron slug for a guitar effect pedal that I saw the schematic for online the suggested thing to buy was a radio tuner (I think, big inductor). I got one from either Maplin or my local Radio spares shop and took the wire off. That pedal never worked and I have no idea what happened to the iron bar. I can't even remember what it was supposed to do to my guitar, just that I had a load of resin coated wire left at the end that I had no use for. 

[Rog RJ]

Post Office (BT) relays are wound on soft iron cores, rather scarce nowadays though.  Ordinary mild steel is a reasonable alternative.

[Australian model rail road]

I use a Russel Dodds machine which I bought from UK great machine test the current draw of your loco if it is high  above 700 Milli amps once recharge the magnets current draw drops a lot and they run much better The neo magnets can coarse problems being to strong and cause a lot of wear on the bearings of the motor

[Chrissaf]

Post Office (BT) relays are wound on soft iron cores, rather scarce nowadays though.

.

Example of said relays....

[gaz1953]

Just got around to getting my 60+ year old OO set out to use. Looks like most of the motor magnets will need re-magnetizing. The Russell Dodds re-magnetizer seems to be the best for the job, but can't find any details on the Internet. Does anyone know where, how much etc??

Also if it comes out as too expensive, are there any dealers, clubs etc that could do the work?

[Going Spare]

For a remagnetising/rewinding service, contact www.scalespeed.co.uk.

[Howbi]

@gaz1953...........his name is Ronald Dodd, easily found on internet and Utube...........HB