K's motor stiction?

[Virgil]

Any thoughts on this, I have one of the original type K's motors (Mk 2?) with the pole pieces/brush holders glued to the magnets and the motor shaft passing through both magnets, this ones a 5 pole and hardly used from new..
The darn thing acts like there is considerable stiction as it will only start with a burst of revs, the controller can be turned down and it will run reasonably slowly but always shows an unwillingness to start.
I'm using an old H&M Duette and interestingly the motor will start at slower revs on half wave but runs more slowly at full power due to the setting.
I've seen this problem before on similar K's motors and never really got to grips with it.
Has anyone ever got over this problem wit these motors?

[Miss Prism]

I had one of those (a Mk I). The behaviour seemed to be caused by a fractional misalignment of the magnet bores. I cured the problem by throwing it in the bin.

 

[Virgil]

Sounds like a good solution to me!
However I have been running the motor using T Cut as a lubricating fluid at both bearing ends of the motor shaft - so far with no improvement but I'll keep trying for now.

[Pebbles]

T Cut is a mild abrasive not a lubricant, you will degrade the bearings. K's motors suffer from many problems, perhaps the main ones being their glued construction and narrow pole pieces. It is possible to break the glue bond, carefully realign, reglue then remagnetise. The narrow pole pieces can be widened by gluing shaped pieces of iron/steel to the pole pieces. However, one other possible issue is a misalignment of the commutator and armature. Despite their shortcomings, the late Mike Sharman used some heavily modified K's motors in many of his weird locos, that said at that time there was no alternative!

[John Isherwood]

11 minutes ago, Pebbles said:

T Cut is a mild abrasive not a lubricant, you will degrade the bearings.

 

Sort of true - but if the problem is misalignment of the bearings, and dismantling is a step too far, some slight abrading of the bearings and shaft MIGHT free things up a little.

 

CJI.

[kevinlms]

On 13/11/2022 at 09:49, Miss Prism said:

I had one of those (a Mk I). The behaviour seemed to be caused by a fractional misalignment of the magnet bores. I cured the problem by throwing it in the bin.

 

Sounds like the problem was taken away!

Sometimes it's not worth the effort to fix.

[DCB]

On 12/11/2022 at 22:49, Miss Prism said:

I had one of those (a Mk I). The behaviour seemed to be caused by a fractional misalignment of the magnet bores. I cured the problem by throwing it in the bin.

 

Good plan, These motors are ok when working but when the glue gets tired and pole pieces separate it's endsville.   The armature's sometimes rub the pol pieces when the lacquer starts to fail.  They are gutless and don't like resistance controllers much.  Older H&M had a boost button to unstick these motors and the Safety Minor had a minimum of 5 volts off load which is about what these things need to unstick.  The Mk1 is not too bad as you can undo the pole piece screws but the MK2 is past it.   Best solution scrap theMk2 but recover parts, save the brushes, springs and brush holders, (sought after sell on eBay) save the armature (with the shafts shortened it fits X04 and H/D 1/2" motors) save the magnets they are always useful and just bin the pole pieces.    That's what I dd with mine, except my brushes were worn out.   K's Armature in the H/D Wrenn R1 motor makes a lovely smooth if slightly gutless motor.

Edited November 16, 2022 by DCB

[Virgil]

Sound advice I think, the problem for me is that the loco which it powers is very tight on space and the narrowness of the Mk 2 allows it to partly fit between the frames (the lower pole piece) and the body.
I as yet haven't found a suitable replacement motor type.

[John Isherwood]

1 hour ago, Virgil said:

Sound advice I think, the problem for me is that the loco which it powers is very tight on space and the narrowness of the Mk 2 allows it to partly fit between the frames (the lower pole piece) and the body.
I as yet haven't found a suitable replacement motor type.

 

Google 'N20 motor'.

 

CJI.

[DCB]

2 hours ago, Virgil said:

Sound advice I think, the problem for me is that the loco which it powers is very tight on space and the narrowness of the Mk 2 allows it to partly fit between the frames (the lower pole piece) and the body.
I as yet haven't found a suitable replacement motor type.

That is a problem.   The Mk2's big advantage over just about everything else is it fits between 00 gauge frames.  

I have a couple of K's kits, Dukedog and 28XX which had Anchoridge  DS 11, I think, motors fitted.  Both used direct worm drive not 2 stage and both failed and a replacement also failed.  They ran beautifully initially, but overheated pulling trains. getting more and more sluggish as they warmed up, until they failed completely.    They may have been fine on a 8 X 2 plus FY BLT, but the typical run in the shed is 50ft (1 lap) and loadings 20 heavy wagons.   The Hornby 1/2" motor also does the same thing in Castles etc where the metal body is a tight fit, yet the same motor on the same train is fine with a Plastic body.

My only slightly helpful suggestion is to see if you can get the motor re magnetised without dismantling it.  And check the chassis is not binding. You can't usually change the gears on K's chassis without changing the wheels, but the K's gears are a bit naff and the motors like to rev.  A 2 stage High level or similar gearbox 60:1 or more might be the answer to get a motor above the frames, and the slop and reduced end thrust on the motor would help any motor even a K's Mk2 start.  A gearbox with bevel gears and without a worm gear would be even better.
 

Edited November 16, 2022 by DCB

[DCB]

44 minutes ago, cctransuk said:

 

Google 'N20 motor'.

 

CJI.

It will certainly fit between the frames, but I was amazed how tiny they are in real life, far too small IMHO for anything but the tiniest 00 loco.  I can't see the gears on the gearbox fitted ones   lasting long.    but the speed isn't bad at circa 400 rpm if you use 1 to 1 bevel final drive.  A typical industrial tank loco does  400 revs per mile, Mixed traffic circa 300, express 260?

But the power isn't there and fluff will soon ruin the gearbox.

[Virgil]

CJL
I did indeed try an N20 motor driving a KMT gearbox ( not sure of the reduction ratio but true to my experience of these motors it ran excessively hot, it's a K's Ci Atlantic by the way so probably asking too much of it.
Mind you the K's Mk2 is currently running hot on my rollers!
DCB
Thanks for the informative answers to the thread, sounds like quite a layout you have there!
I do have the original K's motor which came with the loco, it has longer armature pole pieces and is physically longer too. It has neither brushes, springs brush holders or the insulating brush spring top hat bushes unfortunately. I'd like to try using the assemblies from the Mk2 but I'm wary of trying to remove the insulating bushes from it as they are easily damaged.
Any suggestions from anyone please? Edited November 16, 2022 by Virgil

[John Isherwood]

2 hours ago, DCB said:

It will certainly fit between the frames, but I was amazed how tiny they are in real life, far too small IMHO for anything but the tiniest 00 loco.  I can't see the gears on the gearbox fitted ones   lasting long.    but the speed isn't bad at circa 400 rpm if you use 1 to 1 bevel final drive.  A typical industrial tank loco does  400 revs per mile, Mixed traffic circa 300, express 260?

But the power isn't there and fluff will soon ruin the gearbox.

 

Not in mine, and and a lot of well-respected modellers' experience.

 

The N20 is extremely powerful and smooth-running, and can be had with or without a huge range of gearboxes.

 

Their performance is exemplary, and the gears show no sign of wear after significant running, and I have had no problem with fluff - your layout conditions may vary!

 

The days when we had to cram in the largest motor that would fit are long gone; small precision motors will do all that the old, open-frame motors did, and much, much more.

 

Try one before dismissing them - you may be amazed.

 

Alternatively, I can supply : -

 

https://www.cctrans.org.uk/MITSUMI M15N-3 DATA SHEET.pdf

 

Only £8.50 each including UK P&P, and as good as, if not better than, the old Mashima motors; see https://www.cctrans.org.uk/products.htm

 

John Isherwood.

[Virgil]

John, as I cannot guarantee that the N20 I tried is to the same specification as the ones that you supply as I got mine direct from China I am interested, but do you supply sans worm?
Doug

[John Isherwood]

1 hour ago, Virgil said:

John, as I cannot guarantee that the N20 I tried is to the same specification as the ones that you supply as I got mine direct from China I am interested, but do you supply sans worm?
Doug

 

Doug,

 

I supply Mitsumi motors as per my link, they are not N20 motors.

 

They are supplied without a worm, but complete with fixing screws.

 

John Isherwood.