JLRT 45/55xx Build in S7

[jc2001]

I've been a frequent visitor to WT but a very poor contributor as I have for a very long time been focussing on my narrow gauge which has been largely reported through my blog http://pentewan.blogspot.co.uk/ and the O14 group. Now it's one and only exhibition is over I have decided for a compete change to finally build my JLRT 45/55xx which my wife gave me as a present 2 (perhaps 3) years ago. This is my first proper standard gauge loco and I would like to share my experiences and seek advice here if I may.

I have been assessing what I have and planning my first steps. I had acquired at the time the JLRT super detailing kit, an ABC gears motor/gearbox, some milled coupling rods (of now unknown provenance), some Slaters insulated hornblocks, a set of Slaters wheels which have been re profiled to S7 and number and shed plates - it will be no. 5519 as it appeared in the late 1950s.

I definitely want some form of proper, i.e. up/down, springing and would dearly like to try split axle pickup. With this in mind I immediately came up against some issues that need to be resolved as follows:

Coupling rods and crankpins



When I looked at the milled coupling rods they seemed very poorly finished (file marks) and are distinctly fish bellied - unfortunately I don't have photos of the motion of 5519 so don't know if this is correct or not. The etched ones seemed much better looking so I resolved to make these up as best I can before choosing one or the other. Along the way I managed to lose one of the Slaters crankpin bushes and then found (via the web and WT) that many suggest these are far too small and should either be tapped 10Ba or go the whole hog and get Derek Mundy ones. I would welcome some advice on both the rods and crankpins.

Hornblocks and Springing



I had bought the Slaters insulated hornblocks as I wanted to try split axle pickup. I am contemplating using horizontal piano/guitar wire springing bearing directly on the bushes (perhaps as a Continuos Spring Beam) with fulcrum points mounted on double sided PCB. I now understand Slaters do a much more detailed version which look similar to the ones in the super detailed kit which obviously I can't use as they are rigid. Again I would welcome any advice - and please excuse my ignorance, but do the detailed flange/bolts go on the inside or outside of the chassis?



The ABC motor/gearbox has what I assume are PTFE bearings. I can't recall if I tried at the time, but I have found the inner holes have shrunk so it is almost impossible to insert the axle - let alone turn freely. Should this be expected? Is it a simple matter to ream them out or should I contact ABC assuming they are still in business?

I'm sorry for so many questions.

John

 

[Dog Star]

ABC gearboxes in our care have ball bearings for the driven shaft - the Slater's axles are often a mite over size and hence can be a real pain to fit to the gearbox. Try easing one end of an axle with 400 grit wet and dry. If easing an axle helps then polish the axle from end to end... you may forget which way the axle was inserted into the gearbox and hence you could end up driving the axle the wrong way.

 

[Steph Dale]

John,
In the hope it helps, here's how I'd do it:
Use the etched rods, assembled to pivot on the knuckle. For the sake of the extra accuracy and strength I'd replace the screws with 10BA equivalents and tap the bushes.
For the springs and axleboxes note that there are insulated square bearings available from Slaters that are broadly compatible with most standard horn guides. I have built a demo chassis for the Guild Technical Committee that used Finney etched guides, insulated bearings and springy wire (CSB) suspension with split axles. One small advantage with using the insulated bearings is that you won't need to insulate the fulcrum points for the wire.
There are other ways of insulating horn guides from the chassis; thin double-sided copper clad can work as can a layer of tissue and epoxy.
I'm not certain what's going on with your gearbox. I don't think it has PTFE bearings, I've had a couple from Brian with insulated bearings until I found other ways of splitting the axle which made the insulated bearings unnecessary. Just another quick thought is that sometimes the oil on the axle and the tape used to hold it in the package can react and jam an axle in a bearing, I now clean all axles with lighter fluid before using.
Steph

 

[jc2001]

Thanks guys. I must stress I only tried fitting the axle in the gearbox today. I've measured the axle and it doesn't appear to be oversized, however the end had a slight burr. After smoothing it is still a tight fit in the bearings, but an easy fit in the final drive gear and the hornblocks. Thus it is only the bearings that are tight - far too tight to turn freely. I'm at a quandry as to what to do. Perhaps I should try replacing them with the brass bearings from the kit. All further suggestions most welcome.

I will persevere with the etched coupling rods and explore CSB

John

 

[Scale7JB]

I'm at a quandry as to what to do. Perhaps I should try replacing them with the brass bearings from the kit.

Noooooo!! Get in touch with Brian Clapperton at ABC gears ( still going strong ) and go from there.. They're very helpful!

JB.

 

[Buckjumper]

It might be deemed heretical to purists, but after the mainframes have been erected on a jig with 3/16" jury axles and everything is checked for squareness, I ream axleboxes and the ABC gearbox bearings 4.8mm which gives a couple of thou working clearance on a 3/16th" axle.

Of course take lots of care and mask off the gears as any swarf trapped in the teeth is going to end in tears.

 

[adrian]

Hi, thanks for posting, it'll be great to see how this progresses.

I hope you don't mind but I dragged one of your photo's over to here. If only to encourage people to check out your blogspot http://pentewan.blogspot.co.uk , I spent a fair amount of time looking through the development.

I hope the exhibition went well, it would have been great to see as it's something a little bit different.



Anyway sorry to hijack your thread, back to the loco build.

 

[jc2001]

No problem Adrian - I'm glad you liked it. There will be an article on the PLR in Narrow Gauge & Industrial Review soon.

I've emailed ABC so will see what transpires.

John

 

[Steph Dale]

John,

I hope some links with more info may be of use to you:
Joining coupling rods on the knuckle; http://www.westernthunder.co.uk/index.php?threads/jointing-coupling-rods-on-the-knuckle.1712/
Tapping Slater's crankpins; http://www.westernthunder.co.uk/ind...ters-crankpin-bushes-for-10ba-crankpins.2899/
Modifying Finney hornguides to Slater's insulated square bearings; http://www.westernthunder.co.uk/index.php?threads/re-stephs-wr-workbench-springside-2251.605/ (note this thread will need me to reinstate the pictures after the last update, which I'll do this week, mutter, mutter)

And I'm not sure what approach you're using for the split axles, here are my approaches:
http://www.euram-online.co.uk/tips/splitaxle/splitaxle1.htm
http://www.euram-online.co.uk/tips/splitaxle/splitaxle2.htm
http://www.euram-online.co.uk/tips/splitaxle/splitaxle3.htm

Steph

 

[jc2001]

A big thank you for these Steph.

John

 

[jc2001]

To help me plan the springing, can anyone advise what sort of finished weight I should be aiming for? Is it just the built kit weight or is it usual to add extra?

John

 

[Steph Dale]

I usually add extra weight. For a start, if using a spring-borne system being able to 'trim' the ride height or attitude of the chassis with ballast is useful.
I tend to be pretty loyal to the NMRA weights for my rolling stock, but doubling the weight for locos. The rule runs something like this for rolling stock:
1oz for the vehicle +
1oz per axle +
1oz per inch length over buffers

Steph

 

[Steph Dale]

John,
I've reinstated the photos in the 2251 thread http://www.westernthunder.co.uk/index.php?threads/re-stephs-wr-workbench-springside-2251.605/ some text miraculously reappeared, so it might be a bit more useful to you now!
Steph

 

[jc2001]

Once again many thanks Steph.

A quick question regarding your 3rd split axle method. Is the GRP rod very rigid or slightly flexible? I ask this because I have some rod of 2mm size which I am certain is GRP salvaged from an old (but good quality) umbrella which is slightly flexible. I'm assuming that once assembled with the Devcon in all the gaps it will be quite rigid.

John

 

[Steph Dale]

John,

It is a bit flexible, true, but if it's assembled the way I do it it's in a relaxed state, so can take up any curve it wants to.
Once it's packed with resin and the cuts filled you're right; the axles are very strong and rigid.

Steph

 

[jc2001]

An update on progress.

I've converted the 3 driving axles to split axles - not perhaps as neat as Steph's but hopefully they will work ok. The wheels have been shorted out using soldered joints on the bush and rim. The first wheel I did developed a slight wobble as I think I clamped it a bit too hard but I think I've managed to correct it. I've tapped the crankpin bushes and wheels 10BA as per advice on this forum.



I had gone too far with the coupling rods to make the knuckle joint functional but I think they will serve ok.



After a lot of head scratching and experimentation I think I have got the CSB worked out. I estimate after weighing all the etchings and castings the finished weight will be about 1300 grams. Using the CLAG spreadsheet I have worked out that with a slight shift of position of the middle spacer I can use the spacers as fulcrum points - giving slightly more weight on the outer two axles. I am planning to use 0.7mm piano wire (as I have some in hand) which the spreadsheet says will give a 0.4mm deflection. I want to try using the spring itself as the power pickup so am planning to use a bit of tube with paper/epoxy to provide insulated holes. I have soldered some small bars onto the Slaters axle bushes to both bear down onto the bearings and collect the power.




I haven't cut out all the slots for the Slaters hornblocks yet as I want to use the middle hole with a plain bush in it to set the correct distance of the end hornblock using the connecting rods and then work towards the other end.

I've also not soldered all the spacers in yet as I want to be sure it will work before committing myself. I then want to fit the wheels and load it up with temporary weights and see the spring and deflection seems right etc. before progressing to adding cylinders and detail etc.

And finally I had a response from Brian Clapperton who advised me that the insulated bearings can shrink if left with no axle in them. I followed his advise to carefully ream the bearings out which eased it considerably. I've temporarily fitted one of the pony truck axles and a dab of oil (also as advised) so they hopefully wont shrink any more.

All comments and advise very welcome.

John

 

[Steph Dale]

John,

It all seems sound to me!

Your wobbly wheel is the reason I don't solder wires in to the brass insert any more. I've had a few shift and that's what got me thinking about other ways to solve the problem.

I wonder if the deflection on the CSB wire might be a bit low. Not because you'll need the deflection to cope with rough track, I suspect you've got enough for that, but more to even out the load across the axles under all conditions. On 0-gauge I've found that around 1mm normal deflection works fine. I suspect you're just about okay providing your track is good, you're not expecting the loco to pull the side of a house and you don't want it to do 80mph across a double slip on a garden railway!

Steph

 

[jc2001]

Thanks for the comments Steph. Playing about with the CLAG spreadsheet it looks like I can get more deflection either with a bit more weight or going to a slightly thinner wire, either of which should be easy to achieve.

John

 

[jc2001]

Finally some progress (after a nasty cough curtailed both modelling and festive consumption over the Xmas period).

I miscalculated the insulated gap positions so had to make a second split axle for the middle wheel. The frames are very narrow despite using the S7 spacers (I definitely did use the right ones) and the ABC gearbox would only fit once I shaved a little off the insulated bearings.

The CSB seems to work ok although I might substitute a lighter wire in due course. I've been exploring how to provide some springing and centering on the pony trucks. Initial attempts were done with a U shaped spring soldered to the spacer with arms acting on the insides of the pony truck frame. Two sizes of wire were tried (the thicker shown below) but it didn't seem that positive - pushing it by hand though a rough bit of pointwork (which needs to be rebuilt) the wheels seemed to derail a bit too often. I've now switched to a spring wire acting on the bottom frame of the pony truck in a small brass tube. I know this may spoil the look a bit but it seems more reliable, although I need to get some slightly stiffer wire.

All comments and suggestions very welcome.
John

 

[jc2001]

The last couple of weeks have been a case of one step forwards and two five steps backwards. Firstly I realised there was no way the front rod and crankpin were going to fit behind the slidebars and crosshead. After a lot of (but patently not quite enough) thought I decided to move the cylinders and slidebars out a bit. I then realised that the support brackets needed to be flush with the side valences. I assembled the main footplate so I could test it would all line up and then realised the wheels were far too high, and the front wheels would touch the footplate especially with the thinner wire I'm now using. There was no way to remove that bit of footplate without it being very obvious. I then realised that part of the clearance problem was that I had made the connecting rods inside out, with thick bosses on the outside which the real thing does not have (the instructions are a bit vague on much of this). All a bit of a disaster. The only thing for it was to strip it down and start again.

With remade bearings (1.75mm extra height) and rods (sans the thick bosses) it went together reasonably well. With lots of thinning of the crankpin bushes, rod ends (on the inside), crankpin nuts and crosshead it did eventually fit – but it is VERY close. I have made sure there is no sideplay on the front axle. A bit of manual pushing backwards and forwards it all seems to run fairly freely and without the crankpin hitting.

There is now a bit of clearance above front wheels but I feel it could potentially touch (see red marks in photo). If it does I will either go back to a stronger spring wire or potentially remove a little bit of the footplate.

So quite a milestone for me. Hopefully the worst is now behind me and the chassis detailing and bodywork will go to plan.

John