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This seemed quite straightforward at the start - My friend Roy, who's building up a fleet of GE loco's for a future layout, had obtained a J17, built from the old Bec kit, and it looks pretty decent too, except that it's old Hornby chassis couldn't cope with the finer modern trackwork. I found myself offering to build a new chassis for it. A simple enough job, until I actually compared the loco to some drawings. The story so far....

 

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It soon became apparent that Bec had severely compromised the body to allow it to use that Hornby chassis. At this point I could have simply built a chassis that matched the Hornby one and we'd be laughing, but unfortunately I am quite incapable of doing anything the easy way, and instead decided to build a scale chassis and modify the body to fit it.

 

This has involved removing the centre splashers as they are at least a foot too far forward, and re-modelling the splashers on the cab front as they are far too big and completely the wrong shape. At this point the boiler, with the bottom third missing, and very coarse boiler bands started to seem more trouble than it was worth, so off it came too. A new boiler has been rolled from 10 thou brass, and the correct shape splashers made up from brass and let into the cab front/firebox area. Middle splashers will wait until the chassis is ready, so that clearances can be checked.

 

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Time to leave that sorry lump of white metal and start on the chassis. Frames have been sawn out of 15 thou brass:

 

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At this point and before the spacers were seam soldered in it was time to check the chassis on some serious curves - this is a long wheelbase loco and Roy's layout has some very tight curves in the storage sidings. With squealing flanges I think it will make it. Hornblocks were only temporarily fitted at this stage. I must say these latest Romford/Markits wheels look very good, with reasonably fine flanges, and tyres that seem somehow less yellow and more like steel, although I presume they are still Nickel.

 

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More to follow....

Edited by Barclay
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The coupling rods have been made up using the Gibson 'Universal' set, which, with some head-scratching, works very well. The prototype rods were in one piece despite their length so the rods have been built up to hopefully look like that although these are jointed at the centre crankpin to facilitate flexibility. To ensure all 4 rods are exactly the same a simple jig was built from small drill bits stuck in a piece of wood - all very model engineering on my workbench!

 

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The rods were used with London Road Models hornblock alignment jig axles to set up the hornblocks, and a beam and pivot installed between the leading and middle axle with the pivot about 2/3 of the way between the 2 axles to bias the load towards the front axle at the expense of the middle one. This I hope will help the front wheels to track better on tight curves.

 

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A trial fit of the body shows that everything fits although I've had to trim the front corners of the firebox to clear the 00 wheels. Splashers will hide this. At this stage I should be going round to Roy's for a thorough test, pushing the loco round the layout with fingers crossed. That can't happen now of course so I'll be pushing on with the body next.

 

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In due course there will be a High Level Roadrunner (40:1) and a Mitsumi mounted vertically in the firebox. I hope that's powerful enough, but nothing bigger will fit into that slim firebox. we'll just have to give it a good thrashing at some stage and if it can't cope it'll be back to the drawing board to try to find something else.

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  • 2 months later...

Some progress at last. The middle splashers have been made from brass and fitted to the running plate. It was at this point I discovered that I had 6 live wheels, and since we're not going down the split frame route they had to be exchanged. Gearbox is a High Level Road Runner, 45:1, and the motor is the Mitsumi M15N that seems to have become my default choice at the moment, with another batch of 5 arriving from China last week. The postage has gone up - they cost me just over a pound each - shocking !!  Running well on the leads, so pickups next. 

 

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  • 1 month later...

Pickups were fitted, followed by brakes from a Mainly Trains etch produced by Wizard. Then the loco was extensively tested on the 18" radius oval of track I have set up on the floor of my railway room. With a little extra weight at the front the loco behaved itself well and was run for an hour and a half continuously (about half a mile). With the relaxation of the lockdown rules it was time for a test on Roy's Grimsby layout, and this was very successful. The loco handled the tight curves in the fiddle yard going in both directions and happily hauled a 20 wagon train for some time without the motor self-destructing. 

 

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Curiously whilst at Roy's the loco developed a judder going forwards only. I suspected a possible slight short which seemed as if it must be the case when I got it home and it ran fine with the body off. However this has now become the strangest fault I have ever encountered. Everything has been tested, I even temporarily installed a different drivetrain, and yesterday stripped the chassis down and rebuilt it, taking extra care with the hornblock alignment. Still it does it. I think there may be some movement in the hornblocks, perhaps I was sloppy when I bedded them in and they aren't true enough any more. New hornblocks have been ordered from MJT and the chassis will be rebuilt from the ground up. I have built 20 or so loco's over the years, most of them compensated, and never had such an issue. I'm thinking of calling it "Christine". Signing off for now, somewhat depressed and fed up.....   

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  • 1 month later...

Ding-Ding, round 2....

 

Dart Castings supplied new MJT hornblocks and these were carefully made up and bedded in with Brasso until nice and smooth, but wobble free. They have now been soldered into the chassis using the coupling rods to set their spacing and the chassis awaits re-wheeling. Since I don't really know what caused this loco's problems I have some anxieties about this, but it has to be done. I was reading a thread by Captain Kernow on Romford/Markits wheels and whether the quartering is always perfect, and as a result, I have eased what was a rather tight fit of the wheels onto the axles. Ready to try again.

 

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I would rather suspect the Mitsumi used might be the issue. I have a few sourced from different vendors and the performance and the level of end float varies considerably between different ones. It sounds like the one used had developed quite a bit of end float and this can produce the problem you have in any motor with it in one direction when intermittent loading is encountered for a variety of reasons. Sometimes it can be down to the internal thrust washers at either end. Adding more if possible to reduce any end float can often help or just using a different motor altogether if you have the option.

 

Izzy

 

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Short update - it's back in one piece and actually works !

Foolishly I have ignored the most basic piece of advice when problem solving, which is to only alter one variable at a time. Thus it has new hornblocks, but I also oiled the motor bearings, which might have provided a temporary cure for the motor end float issue which remains very possible I think. Much testing to follow, but for now it feels like a weight has been lifted, and I've even started finishing the body.

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I do feel for you, it's a very lonely place when things don't run the way they should.  It's so easy to imagine all sorts of things. It would be so nice to have someone with knowledge looking over your shoulder and with a few words of encouragement.  Still if it was easy ........ and there's a good feeling when you do crack it.  Some people never have that sense of achievement.

Looking forward to the next installment.

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  • 1 month later...

Progress - A simple brake rig has been made up with the help of a very useful etch of LNER brake shoes by Wizard. Meanwhile a few extra details for the body including a basic cab interior with Belpaire back plate and the large box-shaped splashers. A first coat of primer show some areas that need a rub down but it's starting to look like a J17 I think:

 

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With the chassis entirely reconstructed it will need another test on Roy's layout, but unfortunately we've just moved onto Tier 2 restrictions so that's a no-go at the moment. I can at least get on with the body though. 

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  • 2 weeks later...

A spray of Halfords' satin black and the cab roof, running plate, and smokebox brush painted matt black, let down with some tan and pale grey.

Then lettering with HMRS Pressfix transfers. She will be Colchester's 65564, as depicted in this lovely photo from the GE society. They have thousands of images you can pay 25p each to download. That would be a brave weathering job though. Still a few bits to do - I have smokebox number and shed plates from Narrow Planet, and real coal for the tender. Plus I have to attempt the smokebox handrail, which I always find particularly difficult to do in a nice curve. Any tips?

 

Full completion including chassis paint can only happen after a test run on Roy's layout so I think a short hiatus is in prospect.... Meanwhile I can drive it up and down this test track on my desk whenever work becomes stressful !

 

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G'Day Folks

 

Just thought up a way to bend handrails, so haven't tried it yet. Bend handrail around a pipe, about boiler size, add handrail knob, to curved bit, lay flat on bench, put a piece of steel ( or something like that, eg a steel ruler) across the two legs of the handrail, where you need to bend the curved bit, slide a heavy duty scrapper razor blade under the curved bit of handrail, and bend the handrail up to 90 degree's or until your happy with it.

 

manna

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  • Barclay changed the title to Great Eastern Blues - Bec J17 rebuild

Using some tube as a former is key I think, but I'm going to anneal the wire first because otherwise it doesn't take the curve and then you end up fighting it! 

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The Ghost in the machine.......

 

No sooner had I posted that last update than I gave the loco a run on the yard of track that sits in front of my monitor. The judder is back. Not the once in a revolution stickiness that suggests there's a tight spot but a proper stammer. Now I can't say I'm pleased about this but it's re-assuring in a perverse kind of way. I am determined to look at this logically:

 

As with last time it ran fine initially.

As with last time it runs beautifully in reverse.

 

If I had thought about this before I would have realised that there simply can't be anything wrong with the chassis, so I've wasted my time re-building it, but no matter.

I think the answer must lie with Izzy's suggestion about excessive motor end float. The only thing that niggles at my mind is that I was building another loco in the summer and I tried the complete motor/gearbox from it in this loco, to no avail. But... that was also a Mitsumi motor. But... that loco is now complete and runs fine.

 

Who knows? Motor fiddling/replacement coming up soon!

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Your before and after pictures are very telling in respect of the BEC kit's defects.

 

Would I be right in thinking that you've lengthened the boiler (and so the running plate), as well as alter the splashers? Or is the apparent increase in length simply an illusion as the rear axle is now set a lot further back?

 

Many thanks,

 

John.

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22 hours ago, Barclay said:

The Ghost in the machine.......

 

No sooner had I posted that last update than I gave the loco a run on the yard of track that sits in front of my monitor. The judder is back. Not the once in a revolution stickiness that suggests there's a tight spot but a proper stammer. Now I can't say I'm pleased about this but it's re-assuring in a perverse kind of way. I am determined to look at this logically:

 

As with last time it ran fine initially.

As with last time it runs beautifully in reverse.

 

If I had thought about this before I would have realised that there simply can't be anything wrong with the chassis, so I've wasted my time re-building it, but no matter.

I think the answer must lie with Izzy's suggestion about excessive motor end float. The only thing that niggles at my mind is that I was building another loco in the summer and I tried the complete motor/gearbox from it in this loco, to no avail. But... that was also a Mitsumi motor. But... that loco is now complete and runs fine.

 

Who knows? Motor fiddling/replacement coming up soon!


Having been here/done this a few times in the past you have my sympathies because often what can occur seems to defie logical conclusions. The ‘runs fine one way’ does seem to indicate some kind of on/off loading/resistance but of course there can be quite a few culprits and tracking it down can sometimes drive you around the proverbial bend.....

 

Once a revolution is of course indicative of quartering problems usually but more often seems to rule this out. The motor thrust washer might be the issue, it would be handy if you had a different size/type motor you could just try in there to see. Other thoughts are the gears/gearbox used - in 4mm I don’t think I would bother with anything else than the latest version High-level’s with their screw fixing of the final drive gear these days. Or it might just be current collection, a bit ‘off the wall’ but if they are back or rim scrapers they could be causing variable pressure, and more noticeable one way than the other. 
 

Actually - it would be very handy if you could stuff the drive in the opposite way around, again as a temporary measure. It might give a different result and thus food for thought.... because quite often it’s not one single thing, but several in a particular combination. As I said, been here, done........

 

Be interesting to hear if you manage to cure it. Best of luck!
 

Izzy

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1 hour ago, John Tomlinson said:

Your before and after pictures are very telling in respect of the BEC kit's defects.

 

Would I be right in thinking that you've lengthened the boiler (and so the running plate), as well as alter the splashers? Or is the apparent increase in length simply an illusion as the rear axle is now set a lot further back?

 

Many thanks,

 

John.

Hi John - the overall length is the same. It is, as you say, the much longer wheelbase that makes it look so different. It is more or less correct against the Isinglass drawing, but not perfect, that would be one of those "If you want to go there, don't start from here" moments !

 

33 minutes ago, Izzy said:


Having been here/done this a few times in the past you have my sympathies because often what can occur seems to defie logical conclusions. The ‘runs fine one way’ does seem to indicate some kind of on/off loading/resistance but of course there can be quite a few culprits and tracking it down can sometimes drive you around the proverbial bend.....

 

Once a revolution is of course indicative of quartering problems usually but more often seems to rule this out. The motor thrust washer might be the issue, it would be handy if you had a different size/type motor you could just try in there to see. Other thoughts are the gears/gearbox used - in 4mm I don’t think I would bother with anything else than the latest version High-level’s with their screw fixing of the final drive gear these days. Or it might just be current collection, a bit ‘off the wall’ but if they are back or rim scrapers they could be causing variable pressure, and more noticeable one way than the other. 
 

Actually - it would be very handy if you could stuff the drive in the opposite way around, again as a temporary measure. It might give a different result and thus food for thought.... because quite often it’s not one single thing, but several in a particular combination. As I said, been here, done........

 

Be interesting to hear if you manage to cure it. Best of luck!
 

Izzy

Thank you - yes, it's been a right bundle of laughs this one. First step is to simply swap out the motor, and see what happens. I'm slightly limited here because there is very little room in that firebox/boiler. I have lots of motors at the moment but the only ones that fit are the same as this. Nonetheless I do have loco's that run fine with these motors so it would be a proof of concept if it suddenly worked. If that's the case I will probably obtain one of the new High Level motors for peace of mind. Gearbox is a modern High Level so with that and Markits wheels I can at least pull it to bits as often as I need to. To be honest if it's not that I am completely out of ideas, and that has never happened before.  

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  • 3 weeks later...

Another interesting thread which I missed.

 

A great rebuild, thought you might have been going to use an etched Triang replacement chassis and leave the body alone. But really liked the full blown treatment,  I must say an enjoyable read and I am curious on what the fault is.

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If end float could be the cause, firstly establish in which direction the motor shaft is being pushed when the the model is moving forward - this on the basis that it works OK in reverse. Any end float can be reduced/contained by using a piece of tube and suitable washer externally rather than dismantling the motor.

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