LRM K2/2 61775 Loch Treig

[Rannoch Moor]

New rods fitted (extremely carefully!) - these were made up by measuring using screw dividers set against the tips of London Road tapered axle jigs (seen below) which I then used to trim each individual half section.  These were then clamped using aluminium dinky clips and deftly (!) matched up to the axle jigs set in their holes. 

 

These were then tack soldered together, offered up as a double check (on both sides and treble checking there are no tiny gaps between the holes and ends of the jig-axles, particularly fore and aft!).  In retrospect, I think that as well as the over-sizing the rear axle-bearing, I had probably over done the clearances on the bearing holes on the rods themselves. A check of the originals against both the LRM and Jamieson rods rather suggested that this was the case - do beware!  The photos below show the new rods before fettling and tidying up.

 

Edited April 6, 2013 by Rannoch Moor

[Rannoch Moor]

Testing continues...   Chassis rolling well but possibly a bit tight as the extension piece on the High Level extended gearbox keeps stretching and the motor seem to be running a bit hot - even after refining the quartering.  May ease the rear axle holes a tiny bit although it all rolls reasonably freely without the gear tightened on the axle - I'm now certain 3 point compensation is so much easier!

 

Gus

[Rannoch Moor]

Nearly there I think.  Despite everything, and the chassis running smoothly as a powered 0-4-0 as shown here (ignore the jerky start - too much welly caused by poor multi-tasking - it runs equally well ahead as in reverse really):

 

http://youtu.be/PVIHNRdujyA

 

BUT!  As an 0-6-0  there remains a very slight tight spot that causes the motor to rise once a revolution of each wheel when running forward (but not reverse...!).  If I hold the motor it is actually virtually un-noticeable and I have tweaked the quartering ad nauseam.  Loosening the rear axle gear wheel allows it to run very smoothly as a push along or by rotating the rear wheelset - the tightspot is undetectable like this.  Here is the symptom under power - any thoughts -shuld I leave it until it has a bit more weight:

 

http://youtu.be/5yegTpHL7y4

[Jol Wilkinson]

Gus,

 

I couldn't get either link to work.

 

However, I have sometimes found that the build up of tolerances between the crankpin bush and crankpin screw can sometimes upset what seems like an otherwise accurate set up. If you push the chassis along, then the rod/bush/pin relationship seems to work itself out. When you start putting effort through the rods then the build up in tolerance imposes a tight spot.

 

If alright as four coupled, but not six, then try loosening and then retightening the crankpins nuts at the tight spot position on the third axle. You may have to try the middle axle as well, although that could upset the four coupled running.

 

It's a bit more trial and error, but it may help.

 

Jol

[Rannoch Moor]

Jol,

 

Many thanks - will try loosening and re-tightening the nuts on the middle axle crankpins as well.  If I can't nail it (the nuts at least aren't self loosening!) then I may leave it and get back to the body. 

 

An alternate startegy may be to investigate mounting the motor on the middle axle - this may be possible and may also actually help if the loading on the rods can be spread out (although equally it may also be grasping at straws...!)

 

Gus

[Rannoch Moor]

Ho Hum...     Set up the chassis on the rolling road for a session of diagnostics and correction, after taping the wires connecting the pick-ups' busbars to the motors' connecting tabs to the body of the motor, and...

 

... a smoothly running 0-6-0 chassis.  Fate gratefully accepted - no investigation into why or how intended (other than I suspect that stabilising the motor's movement helped...!)

Edited April 9, 2013 by Rannoch Moor

[benachie]

Not very fond of rolling roads myself, Gus.

On the track, there are two forces linking the wheels - the coupling rods and the rails.   Jerkiness can sometimes be due to inconsistencies between these.

Alan

[Rannoch Moor]

Cheers Alan - I'm content with it for now.  I tend to agree that rolling roads are only part of the story (mainly useful for proving pick-up connectivity I think) but I also always feel that you need to have the body reasonably complete and mounted on the chassis (correctly weighted) and the tender attached before you can be fully confident.  I will now progress to that point and road test through my layout as a simple 2-6-0 before mounting the valve gear.

 

Given the location of the motor on the rear wheel, I think I will also now set up the tender as a floating type, weighted forward and bearing down onto the rear loco drawbar.  So much to do, so little leave left!  (Domestics, Special Hobby Sea Balliol to build too, layout to ballast!)

 

Gus

[Rannoch Moor]

Continued progress this weekend past with the boiler shaped and made ready for mounting on the footplate once the smokebox saddle is constructed (next weekend's job in between ballasting sessions on Kilbrannan Ferry).

 

First job was to solder up the seam on the pre-rolled boiler barrel which was successfully achieved even using my 25W Antex (with lots of Carrs Green label flux) and then roll the smokebox wrapper.  The latter was done using my X-Acto knife handle (blade removed!) against my thigh.  I first annealed the wrapper using a blow-torch (blasted till cherry red then left to cool naturally - NOT quenched in water!) which made the process easy.  I did avoid rolling the centre section with the the holes flor the chimney and snifter valve and instead formed this using my thumbs against the boiler in order to avoid distortion.  This worked pretty well and I then positioned it accurately against the boiler (did not pre-tin with solder to allow it to remain flexible and lie flat) using a couple of broaches through the handrail holes and by securing it by wrapping wire round and twisting as shown below... 

 

 

Again using penty of flux, solder was run into the joins at front and rear, making sure the wrapper had a tiny overlap ahead of the boiler to permit the smokebox front to sit correctly half in, half out as shown below (I hope!)

 

 

You will note that I first secured the smokebox wrapper by securing the seam at the bottom before continuing the seams at the front and rear...

 

 

The key to securing the smokebox front accurately I think will be to align the hand rail holes so they are matched on each side - my plan is to use a wire running through the 2 steam pipe holes (or handrail holes on the boiler side and mount 2 stantions in the holes on the smokebox front with a single wire through them and then tack the front in place ensuring the wires are parallel:

 

 

I also formed the firebox flare (more easily than expected) using long nose pliers

 

 

Final jobs were to fit the washout plugs and mudhole/inspection covers.  After a bit of indecision, I also fitted the supplied boiler bands as they refined the join between the smokebox and boiler and sanded them down once they were on - don't think they look too bad even given the originals were quite refined.  Pics next week!

 

 

 

[Rannoch Moor]

And, so getting back to the bench after a week in Navy Command HQ, I ran out of excuses not to get on with one of the scariest bits of the build - construction of the smokebox saddle and then, mounting the boiler.  I was slightly nervous as Tony Wright had been a bit dismissive of the etched approach to the former - especially the sides which he found to thick to form.  The pieces are seen arranged here after forming...

The base and side pieces were annealed (heated to red hot and allowed to cool naturally) before rolling.  The base plate (upon which the smokebox rests) was formed by rolling using my X-Acto knife handle against my thigh and the sides (which were reasonably easy as it turned out...) by placing in a V Block and by pressing a needle file handle against them to form the curve.  I then soldered the front and rear to the base...

before attaching the side plates between them using the half etched area as a guide - a bit fiddly but not excessively so.  There was then a bit of fettling to allow the ends to snugly drop between the frames and, using round nose pliers, to ensure that the edges of the base plate were flush against the curve of the smokebox.  Dry fitting ensured success and I was impressed with how well the boiler settled into place - a tribute to the kit's design I hasten to add...

Accuracy of attachment in the instructions as described in the instructions involves marking the cab and boiler top centres and aligning - I wasn't sure if I could crack this accurately enough so instead I fitted some wire through the rear hand-rail knob holes and, by eye, aligned both sides to the handrail holes in the cab front sheet.  Using my trusty scorched peg to hold the rear of the boiler snugly into the half-etched guide in the front of the front cab sheet (thumb pressing the boiler front), and after ensuring interior scrupulous cleanliness, I tacked the top of the boiler to the cab from the inside.  I left it an hour, came back, stared at it from all angles, and happy, seamed all round with no drama.  Having first tinned the inside of the baseplate, the smokebox was soldered to the saddle and all was complete - reasonably simples!  Having finished and removed the jig now that the shebang was very rigid - I decided it was time to quit whilst ahead after also making good progress on ballasting and my Sea Balliol!.  The photos below will also hopefully show that the boiler bands are reasonably refined.

[dajt]

Good job on the smokebox saddle, that looks like a tricky part to make with those small side curves requiring forming! Seeing that might come in handy later.

[Scale7JB]

Looking very nice gus.. I think you might have missed a couple of bits of etch on the saddle though...

 

The cutouts in the ends of the saddle take some strengthening plates... Not to worry though, as they can't really be seen unless you really look for them, especially in 4mm...

 

JB.

[Rannoch Moor]

JB,

 

Good spot - I actually could only find 2 of the stays on the etch - no doubt they will leap out at me when I get home next week!  I will probably add the  other 2 (2 were included but cant be seen in my IPhone photos) from scrap.  As you correctly state though, they are hardly visible even on the prototype so I may not bother.  Having said that - you are my conscience!  (For which I genuinely thank you!)

 

Gus

[Rannoch Moor]

For various reasons (work, the layout, Sea Balliol, trips to the mountains etc!) progress has been a bit slow although have fitted the footplate and reversing lever as well as the piston tail rod covers.  The latter have been mounted to the footplate so that their rears butt up against the front of the cylinders when they are slid in from below when mounted on the chassis.  I think doing it any other way would prevent the cylinders being fitted accurately or necessitate fitting them semi-permanently to the body, which would probably make the valve gear impossible!

 

The cylinder frame was completed earlier and the slide bar castings fettled and mounted (see above) but on mounting them and the motion bracket to the frames showed trouble ahead, even after filing down the front wheelset's crankpins...

I have skimmed off some of the rear face of the slidebars but am slightly reluctant to do more in case I introduce too much slop into the crosshead/slidebar system.  I think I may have to ease out the piston/slidebar centres but the motion bracket (which also fouls the front wheels) is another challenge.  Thinking cap on....!  

 

 

[Portchullin Tatty]

I have skimmed off some of the rear face of the slidebars but am slightly reluctant to do more in case I introduce too much slop into the crosshead/slidebar system.  I think I may have to ease out the piston/slidebar centres but the motion bracket (which also fouls the front wheels) is another challenge.  Thinking cap on....!  

 

This happens to me a fair bit too!! Actually, it is not normally worse in P4 as whilst there is a further .63mm of gauge to find, P4 wheels are often narrower.

 

Take a look at options for alternative wheels, as the tread thickness can be different.  Failing that, I think you will be stuck with easing with at lease the slide bars out further (I have not always also moved the cylinders as you can not really see if the piston rod hits the centre of the cylinder exactly).

[Colin parks]

Hi Gus,

 

Just had a read through your entertaining loco topic. Inspiring work.

 

It struck me that the prototype bears more than a passing resemblance to the LB&SCR K class, having seen the picture of 61775 in post #84.

 

All the best,

 

Colin

[Rannoch Moor]

Take a look at options for alternative wheels, as the tread thickness can be different.  Failing that, I think you will be stuck with easing with at lease the slide bars out further (I have not always also moved the cylinders as you can not really see if the piston rod hits the centre of the cylinder exactly).

 Thanks Mark - I think easing out the cylinder centres and slidebars (which are all one NS casting so that helps) on the rear cylinder face plate is the way ahead.  I may get away with leaving the motion bracket as it is but if the worst comes to the worst I may be able to split the spacer and make anew one - that will depend on not (obviously anyway) compromising the relationship between the outer edge of the motion bracket and the footplate.  (But things have to work - I DO so love a challenge!) 

[Rannoch Moor]

Did some more work on easing the slidebar clearances yesterday afternoon.  Managed to skim a little more off the front crankpins (but that really is it now...!) and a little more from the rear of the bars.  I also (after removing the bars from the cylinders) filed gently the mounting holes outwards - I initiallly found that this was putting pressure onto the soldered joints holding the cylinder section together so after annealing the wrappers, these were fitted too to increase structural strength.  This collectively has helped and the cylinders do fit but I think easing a little more will be required.  We will see next weekend...1

 

Intention is to get the cylinders and motion bracket sorted out and then look at running quality with the body and tender fitted.  That should help me decide on weighting the loco and whether or not to have a "floating tender" bearing down on the loco drawbar in order to spread weight around the rear driven axle.

 

Gus

[t-b-g]

I know that prototype clearances are often tiny but it would be interesting to investigate why the model has problems there when the real one didn't. Either the crankpins stick out too far or the slide bars are too close together. You would need a good plan view, such as a GA to check the slidebar dimensions but checking the crankpins can be a bit more visual!

 

Looking at photos of the real thing (most of which don't show the leading crankpin very clearly) it appears that the leading crankpin on the locos may have been recessed into the coupling rod as it doesn't look as if it protrudes beyond the outer face of the rod.

 

It is possible to do something similar on the model by countersinking the outside face of the rod and reversing the coupling rod retainer so that the "top hat" part goes into the rod rather than sticking further outwards. It might buy you a few "thous" here and there. 

 

Best wishes with sorting it out!

 

Tony

Edited May 28, 2013 by t-b-g

[Portchullin Tatty]

It is possible to do something similar on the model by countersinking the outside face of the rod and reversing the coupling rod retainer so that the "top hat" part goes into the rod rather than sticking further outwards. It might buy you a few "thous" here and there. 

 

 

That is certainly a technique that I adopt; as of you don't there is so little on the crankpin nut it will not secure to the crankpin thread.

 

I assume you have washered out the drivers too so they do not move from side to side?

Edited May 28, 2013 by Portchullin Tatty

[Rannoch Moor]

Tony and Mark,

 

Many thanks, should have thought of that (reversed crankpins)!  I've done it before and that will also help with the clearances behind the motion bracket.  I did, however, remember to ensure there is no sideplay on the leading drivers, but thanks for the reminder Mark! 

 

Colin,

 

Being a secret  admirer of Billington and Marsh (as I work in Hampshire!) I was a little unsure of your observation until I checked and saw this.  Like non identical twins who have slightly different figures but very similar faces (if you see what I mean!) 

 

 

 

Cheers,

 

Gus

[Rannoch Moor]

Having a (well deserved!!) day off got home yesterday and in between gardening and other chores, managed to countersink the front coupling rod holes, file down the chankpin bushes so they only extend half way through the bearing on the rod and reversed the previously shaved securing nuts as suggested by Mark - mechanically fine!

 

 

Chassis runs smoothly, slidebars are now clear but there is still the very occasional clip of the rod against the inside of the crosshead (despite filing it down).  There is a little sideplay by the crossheads on the bars - I have put a skim of solder on the bars to try and reduce it but I may try to reduce it further by putting a shim inside the bearing surface to stop any slop .  I have also eased the slidebar centres out.  Nearly there....!

[t-b-g]

Looking good!

 

The "brim" of the retaining bush looks to be ever so slightly proud of the front of the rods.

 

You could gain a few extra thou by thinning the outside face of the front bush of the coupling rod until the outside face of the reversed retaining bush is flush with the outside face of the main part of the rod.

 

I have done it in 4mm and it really doesn't show and looking at more K2 photos it is probably more realistic to have it totally flush.

 

Best wishes,

 

Tony

[Rannoch Moor]

The "brim" of the retaining bush looks to be ever so slightly proud of the front of the rods.

 

You could gain a few extra thou by thinning the outside face of the front bush of the coupling rod until the outside face of the reversed retaining bush is flush with the outside face of the main part of the rod.

 

......... and looking at more K2 photos it is probably more realistic to have it totally flush.

 

Thanks Tony.  Worth a try - I had left that part intact to allow a bit of purchase to tighten the nuts but I guess I can replace them at worst - certainly easier than trying to add a few thou by shimming out the slidebar bearing surface...!

Edited June 1, 2013 by Rannoch Moor

[jrg1]

Nearly there I think.  Despite everything, and the chassis running smoothly as a powered 0-4-0 as shown here (ignore the jerky start - too much welly caused by poor multi-tasking - it runs equally well ahead as in reverse really):

 

http://youtu.be/PVIHNRdujyA

 

BUT!  As an 0-6-0  there remains a very slight tight spot that causes the motor to rise once a revolution of each wheel when running forward (but not reverse...!).  If I hold the motor it is actually virtually un-noticeable and I have tweaked the quartering ad nauseam.  Loosening the rear axle gear wheel allows it to run very smoothly as a push along or by rotating the rear wheelset - the tightspot is undetectable like this.  Here is the symptom under power - any thoughts -shuld I leave it until it has a bit more weight:

 

http://youtu.be/5yegTpHL7y4

I believe that the dummy axles you are using could be part of the problem.  Any engineering locating arrangement similar to that should have tapered diameters for the connecting rods.  This takes up any slack in the rods, and ensures they are central to the axles.  I believe there was a version of this produced possibly by Rod Neep some years ago.  Also, the rod centres and frames centres should be calibrated before assembly-DJH were sometimes out, leading to erratic running and binding.