Comet Chassis Saga

[hayfield]

David

 

This is the problem of working on something you have not built, however I have been in your shoes trying to assist a friend who was having issues with a Southeastern Finecast chassis, nothing wrong with the chassis, just badly built. I took it apart and started again, thankfully all is well

 

One of the things I have learnt from advice on here is to check the build as you go and never move to the next step until you are 100% happy with each step. I am building two chassis at the moment, one has an issue with the pickups and it seems all I can think of is one set had a masking fluid on it which may now be causing issues as all the parts are much the same and work as good as each other except for when pickups are fitted. Annoying but a learning curve

 

As for motors, I try to keep to can motors. I do have some locos with K's motors and I do eben have some D11's, I do find the latter much better, but I guess you can have bad examples in all makes, it may have been that the stiff chassis burnt out the D11 or badly affected it. Could it be the motor mount and gears that are the issue? or if the chassis still stiff when these are removed?

[Enterprisingwestern]

 

Although not directly modelling related, if, when I was a plumber, I was asked to sort out problem created by a previous "workman", my first corse of events was to rip all the rubbish work out and start again from scratch.

Personally, although obviously with an honours degree in hindsight, I think that's where you went wrong, it would probably have been quicker, and definitely less frustrating, to have started from first principles.

 

Mike.

[DCB]

I got the K's Mk2 (?) motor fitted, the motor mounting has more holes than the average colander now, and the out rigger bearing to keep the worm tight against the worm wheel and stop the motor mount flexing troubles, I even have an oil felt as I nicked the bearing from a dead X04.  All I have to do is re attach a loose pickup, connect the motor, fit the body and test it. Which is why I am posting now as I may feel like chucking it in the bin again if it still doesn't work.   Which genius designed the K's motor to have approx two of 6Ba thread as its only fixing. and to glue it together.  Anyway enjoy the pics, No apology for the soldering I was not in the mood to make it neat.   Also included  in the pics the original motor for size comparison. The 28XX had a K's motor and chassis originally and easily pulled 25 H/D wagons, it was a good piece of kit but for some reason he wanted a modern chassis which went round corners and had all wheels flanged, the old one had Hamblings, no flanges on two axles and had a bit of an issue with curves.   The old motor should be Ideal for an Airfix railbus or L&Y 0-4-0T if I can get it going again but not for hauling 25 Hornby Dublo mineral wagons

[micklner]

You obviously dont read what other people post for advice. Bin it !!

[hayfield]

9 minutes ago, micklner said:

You obviously dont read what other people post for advice. Bin it !!

 

Mick

 

I bought a badly constructed SEF E1 chassis, I took it apart, cleaned it up. Rebuilt it (to a new gauge) in my chassis jig and it works fine. I have also done similar where a friend had issues in building a new chassis, again took it apart and rebuilt it for him to the same gauge.

 

I do agree with your sentiments though, sometimes its better to rebuild something than take over others work.

 

In hind sight I would have taken it back to a rolling chassis, which I think David has now done. A brave decision to fit an old K's motor (and I love K's kits).  My Achilles heal is motor mounts !!! I rarely get them right.

 

I find High Level gearboxes suite my own skill set. They are easy to build and work exceptionally well with modern can/coreless motors. I have also had success with modern Comet and Branchlines gear boxes 

[Denbridge]

Why keep focusing on the motor and gears when it seems you haven't ensured the chassis is correct? You need to ensure it rolls freely and doesn't bind before even fitting a motor. Also ensure it sits properly with all wheels touching on a level surface.

Only then, once you know the chassis is good do you move on to fitting a mechanism.

[cctransuk]

39 minutes ago, Denbridge said:

Why keep focusing on the motor and gears when it seems you haven't ensured the chassis is correct? You need to ensure it rolls freely and doesn't bind before even fitting a motor. Also ensure it sits properly with all wheels touching on a level surface.

Only then, once you know the chassis is good do you move on to fitting a mechanism.

 

I couldn't agree more - it's almost as if David is enjoying all this tinkering, motor swapping etc.

 

Let it be said - once again and finally - unless the wheeled frames, fitted with coupling rods but no motor, gears or pick-ups, will roll down a slight incline under gravity, no amount of advice here or reports by David of further tinkering will ever result in satisfactory running.

 

End of story!

 

John Isherwood.

[DCB]

Yes I'm determined to make this work and hopefully someone else will read it and realise that fitting a tiny twenty year old motor to a draggy 8 wheel pick up chassis was not a bright idea.  I still haven't tested it. A pick up came loose again.  They are so low they can catch in points, but fingers crossed for later. The out rigger bearing could be the key to making this work, the motor mount is too flexible to maintain gear mesh, I had to shorten the armature shaft at the back but instead of chopping it I chose to push the armature shaft forward which made the outrigger do able. I also have the worm securing screw at the outer end engaging a flat on the shaft to try to keep it concentric. 

To re cap, to quote my original post   of 14th Feb.    "It runs well fast, it runs well at a crawl, but it is absolutely gutless and needs full power to get a reasonable train rolling and then rockets away at the first sign of a downhill run. "

and " Tonight it packed up completely. Haven't had a chance to see what's wrong."

Edited July 12, 2020 by DavidCBroad

[Enterprisingwestern]

 

Well, if nothing else, I admire your perseverance and fortitude. I'd have slung it long ago!

 

Mike.

[DCB]

3 minutes ago, Enterprisingwestern said:

 

Well, if nothing else, I admire your perseverance and fortitude. I'd have slung it long ago!

 

Mike.

I would have too but It's not mine to sling out  (and there's no budget for a High level gearbox)  

[DCB]

K's motor is light years ahead of the anchoridge motors power wise , its running the same gearing, 60:1 I believe . Its running nicely now but the gears keep coming out of mesh under load despite the outrigger bearing, or maybe because of it.  No wonder people like motor gearboxes.

[hayfield]

David

 

From memory I think I used to epoxy the motors into position to get a firm support holding the motor in position

 

I understand you have no budget for a new motor and gearbox, but even with the older style motor and motor mount combinations they worked because motors were firmly held in position, in some cases they still required tweaking to get the meshing correct

 

It has also been said on other threads the issues of older gear sets and their poor meshing charsets, a claim was made that fewer than 1 in 4 worked well. worm gears are inefficient making the worm gear smaller seemingly eases the issue

 

Having said this there are plenty of older locos running perfectly well using older style gearsets, look at the Hornby X03 and their gears they have been running for years without issue. 

[Izzy]

If the gears are as I suspect 60-1 Romford then I am not surprised constant mesh is not achievable. The tooth form is just too small -100dp IIRC - to use with the large OD (relative) worm and the thin dished wormwheel if not used in an enclosed gearbox. It’s a great shame, and of course makes your life so much harder, not being able to fit a HL box. I would think that whatever motor you had used, with a decent ratio of say 60-1, all the issues would have faded away. 
 

Crude though they were/are, the K’s ‘slab’ motor, like X03/4’s, Bulldogs, MW5 poles, are at least fairly powerful and slow running, if liable to be capable of transmitting a fair level of noise through a chassis. The later HPM2(?) was quite weak by comparison...   If you could replace the gears with a Romford 40-1 set (they all have the same meshing distance centres) you might find it actually runs better. No de-meshing and the motor could cope being slower running.

 

Izzy

[DCB]

On 15/07/2020 at 08:24, Izzy said:

If the gears are as I suspect 60-1 Romford then I am not surprised constant mesh is not achievable. The tooth form is just too small -100dp IIRC - to use with the large OD (relative) worm and the thin dished wormwheel if not used in an enclosed gearbox. It’s a great shame, and of course makes your life so much harder, not being able to fit a HL box. I would think that whatever motor you had used, with a decent ratio of say 60-1, all the issues would have faded away. 
 

Crude though they were/are, the K’s ‘slab’ motor, like X03/4’s, Bulldogs, MW5 poles, are at least fairly powerful and slow running, if liable to be capable of transmitting a fair level of noise through a chassis. The later HPM2(?) was quite weak by comparison...   If you could replace the gears with a Romford 40-1 set (they all have the same meshing distance centres) you might find it actually runs better. No de-meshing and the motor could cope being slower running.

 

Izzy

Good point.   The gears are Romford 60:1    I think I have a 40:1 gear set.   I was going to re engineer the outrigger bearing this evening. Maybe I will change the gear set instead.

[hayfield]

David

 

From experience a 30-1 set may be even better as they mesh easier, or if your friend can stretch to it a more modern set of Romford's with the smaller worm, I understand these are far more efficient'

[DCB]

It runs!   It has the K's Motor with chunky Romford 40:1 gears instead of the 60:1, and an outrigger bearing holding the front of the armature shaft.

Last evening after a brief 5 month break I sorted the Pick ups which turned out to be a lack of continuity from brush holder to the chassis and it was actually going well last evening, in a straight line. plenty of power and enough speed for the occasional excursion passenger turn.

Next issue the nominal 2ft radius curves it was specified for in reality are 2" straights connected by dog legs and it can't get round smoothly now I have shimmed the drive gear to keep it in mesh it can't manage 3rd radius, I'll have to change the drive axle tyres to flange less.

Next problem the Dukedog....

Edited December 14, 2020 by DavidCBroad
Typo

[russell price]

Read through this, I think I would be stripping it right down , reaming out all the axle bushes and reassembling checking every wheel set runs free. I always test the motor in the chassis with all valve gear etc fitted off leads direct to the brushes before messing fitting pick ups!!  If it doesn’t run right at this stage it’s never going to on the track!!  As regards the motor I think the Anchorage is not man  enough for a 2800. Can and gearbox is way to go. KS mk1 and II were a bit hit and miss! HP2M forget!!!  

[DCB]

The 28XX is still running, still banned from the terminus due to 3rd radius curves which it does not have enough side play on the driving axle to get round but its working OK, the outrigger bearing seems to have done the trick.   The Dukedog is now in bits having its little D10 (?) motor removed (forcibly) and the wheels dropped out to change from leading to trailing axle drive so I can use a K's motor as originally intended.  I put my spare D13, a dead D10 and some odd bit on eBay.  The Anchoridge problem seems to be the brush springs are just to small to take the current when they are working hard.   One day I will expreiment with additional external brush springs but for now I'll stick with K's, Wrenn and Triang motors.

[hayfield]

7 hours ago, DavidCBroad said:

The 28XX is still running, still banned from the terminus due to 3rd radius curves which it does not have enough side play on the driving axle to get round but its working OK, the outrigger bearing seems to have done the trick.   The Dukedog is now in bits having its little D10 (?) motor removed (forcibly) and the wheels dropped out to change from leading to trailing axle drive so I can use a K's motor as originally intended.  I put my spare D13, a dead D10 and some odd bit on eBay.  The Anchoridge problem seems to be the brush springs are just to small to take the current when they are working hard.   One day I will expreiment with additional external brush springs but for now I'll stick with K's, Wrenn and Triang motors.

 

Daved

 

I don't think these kits were ever designed for sharp radii. Will it run up and down the track was seemingly the design criteria. Even 30+ years ago many saw the need to re-chassis this make of kits.

 

These kits work fine providing the chassis are built free running and square. 

Next up is, obtaining a motor mount or gearbox which meshes nicely and is free running

Once these objectives are achieved you can use one of the modern superior motors for better performance

 

D11 & D13's will work fine, but they need a free running chassis and a decent drive chain. ( I have a D11 in a DJH gearbox, whilst on the large size, it works well)

I think it was reported 1 in 4 Romford gear sets meshed correctly, I have also seen it written that 30-1 and 40-1 Romford gears work far better than their higher gear ratios. K's gears are not that good a quality

Modern gearsets have smaller worm wheels for better efficiency

[DCB]

 Just under 3 years  after I started trying to get this chassis to run I have now decided to stick it on eBay. Father in Law had the chassis built for his K's 28XX which was a lovely loco very powerful with Hamblings wheels.  The replacement would have been fine on a 10ft long BLT but couldn't live with the 22 Hornby Dublo wagon coal trains our 2-8-0and 4-6-0s are rostered to haul.

Sadly he passed away recently, and It's never going to meet my performance target. There's at least £20 worth of bits but I have decided to cut my losses and build a new chassis with the emphasis on haulage power and reliability, Should  be on eBay Sunday.