Wright writes.....

[St Enodoc]

Nobody has mentioned insurance. Over here, as a result of COVID-19, most if not all insurers have either stopped writing public liability cover for events run by small organisations or raised the premiums to the extent that the events are not viable.

[Tony Wright]

11 hours ago, micklner said:

Tony

        Have you ever tried a High Level Gearbox, the days of Gearboxes protuding in the cab are long gone (or should be).

 

Mick

I have tried High Level gearboxes, and they are excellent. 

 

Only a tiny bit off the bottom of the backhead will need removal to accommodate the worm wheel on the J6. It'll be covered with a dummy 'footplate' eventually, angled to clear it (as suggested by Iain Rice) and when a crew is fitted, it'll be invisible.

 

Regards,

 

Tony. 

[Tony Wright]

10 hours ago, APOLLO said:

Back from local pub, no pies left so fish chips & peas for four quid - just the job with a couple of pints of Wainwright !!  

 

Good to meet  (illegally in Wigan at the moment !!) a couple of mates though. We socially distanced and sanitised, as seemingly did everyone else. Well done Cherry Gardens hotel Wigan.

 

What a world though  - Hmmmm - Staff with plastic masks, tables marked out with yellow tape, no scratching of balls or backsides, hilarious to see football on the super huge TV with no crowds - what a  blimmin joke !!!

 

Some hopper cars to load with real coal and white PVC glue tomorrow, (That's if I survive the night !!)

 

Brit15

 

 

And no Wigan Show this year for us to enjoy another of our chats.

 

Regards,

 

Tony. 

[Tony Wright]

1 hour ago, Barry O said:

Oh dear. Stainless Steel drivers with nickel silver pick ups..hmmm!

Why change to stainless steel. To work properly it needs a decent carbon content and it means it can go rusty so don't get them wet.

Yes high level gearboxes could provide a better solution..of course they are the same gear sets used by DJH apparently ..no single stage worm and gearwheel can be as quiet.

 

Baz

'Stainless Steel drivers with nickel silver pick ups..hmmm!'

 

What's the problem, Baz?

 

So far, as with all my nickel silver pick-ups, the system works perfectly. I have have to say, a lot better than the phosphor-bronze muddle I had to sort out at Glasgow this year! 

 

Regards,

 

Tony. 

[Northmoor]

Stainless steel rusts in saltwater, otherwise it has the name for a reason.  It is the Chromium content that gives the corrosion resistance, not Carbon (which influences the stiffness achievable, amongst other things).

 

[FarrMan]

16 minutes ago, Tony Wright said:

'Stainless Steel drivers with nickel silver pick ups..hmmm!'

 

What's the problem, Baz?

 

So far, as with all my nickel silver pick-ups, the system works perfectly. I have have to say, a lot better than the phosphor-bronze muddle I had to sort out at Glasgow this year! 

I think the problem will be different metals and electrical current causing corrosion.

 

Lloyd

[Atso]

20 hours ago, queensquare said:

 

The C1 looks superb Steve and many thanks for your kind comments. I should point out that whilst I'm reasonably competent at cutting things out and nailing them together my ability with a computer is next to zero so I'm hugely grateful to you and your 3D printing skills. The axle boxes on this L&Y 0-8-0 and the tank on the Midland water tower for Bath are courtesy of you. Half the fun of the hobby is about sharing skills.

 

Jerry

 

 

 

Thank you Jerry, those models look superb and what you have done with the raw materials is exceptional. I agree completely about sharing skills and I do hope that we'll be able to do so again in person once things are a bit safer.

 

4436 is now more or less at the same stage as 4452 and 3286 is well on the way to becoming a runner.

 

 

It's just occurred to me that I am building these models in the reverse order of the prototypes. The fourth C1, 3280 will continue this trend, as will 3279 which is slated to be the next C1 (although probably not the next loco) after that. 3280 has been chosen as it was a Copley Hill locomotive and apparently a frequent choice for hauling the Queen of Scots - I don't have a photo of 3380 without the QoS headboard fitted.

 

Why so many C1s? I have several turns requiring these locomotives and, as I'm working in N gauge, I'm not even contemplating having removable lamps and headboards.

[Tony Wright]

12 hours ago, cctransuk said:

 

I think that Tony is something of a Luddite when it comes to recent developments in model loco propulsion. Not many of us are still blessed(?) with a blind eye, that cannot see motors protruding under boilers, or worms poking out of firebox doors.

 

I know that Tony will say that he uses old practices because they work for him - but, in his own words, if you don't try you don't know what you can achieve.

 

There does seem to be something anomalous about worrying about the wrong bogie wheels, the absence of loco lamps and crew, etc.; when there are very obvious portions of an electro-mechanical propulsion system poking out of the 'steam' loco infrastructure.

 

I know - each to our own!

 

Regards,

John Isherwood.

I think we can all suffer from 'selective blindness' from time to time in our model-making, John.

 

I do, of course, admit to being a Luddite, and visible bits of motors/gearboxes are obtrusive. But, as I've mentioned to Micklner, by the time the J6 is complete, I'd defy anyone to see anything 'amiss'. Unless they pick the model up, detach the tender and look at extremely close quarters into the cab. No photograph taken of the loco at work on the layout will show any obtrusive gear wheel. 

 

However, were it missing lamps, or had no crew in operation, those omissions would be immediately apparent.

 

Some pictures to show what I mean...................

 

 

 

 

Seen some months ago, this was one of my 'lockdown locos', a Crownline J17 (please, forget about the firebox!). 

 

I used a DJH AM10 motor/gearbox, driving off the rear axle; I didn't want to see the 'box underneath the boiler. Yes, the gearbox frames impinge on the cab interior. 

 

That said, once completed and painted......................

 

 

Obviously no visible drive from this angle, but no lamp would be a serious omission. 

 

 

 

And, with a crew fitted, even from these 'looking into the cab' shots, can you (or anyone else) see the gearbox? Actually, if you look between the fireman's legs in the first shot, there's a glimpse of the brass worm! Painting the gearbox frames matt black helps as well.

 

Not only is having a running loco crewed imperative, they help to hide any drive. 

 

The J17 will be expertly-weathered (by Tom Foster) by the time its picture is taken again. 

 

I will concede that driving on the middle axle of a high-boilered 0-6-0 means disguising the drive is more difficult. 

 

 

That's why I'm driving off the rear axle of the latest J6, even though it's (slightly) less mechanically advantageous.

 

Regards,

 

Tony. 

Edited August 20, 2020 by Tony Wright
to add something

[Tony Wright]

49 minutes ago, FarrMan said:

I think the problem will be different metals and electrical current causing corrosion.

 

Lloyd

Thanks Lloyd,

 

It'll be given a through test at the weekend. I'll report accordingly.

 

Regards,

 

Tony. 

[chris p bacon]

19 minutes ago, Tony Wright said:

I will concede that driving on the middle axle of a high-boilered 0-6-0 means disguising the drive is more difficult. 

 

 

That's why I'm driving off the rear axle of the latest J6, even though it's (slightly) less mechanically advantageous.

 

Regards,

 

Tony. 

 

That is the beauty of High level boxes, with a drive stretcher the motor and main part of the gearbox is in the boiler and firebox, and drive is to the middle axle.

 

 

[Barclay]

3 hours ago, Barry O said:

Oh dear. Stainless Steel drivers with nickel silver pick ups..hmmm!

Why change to stainless steel. To work properly it needs a decent carbon content and it means it can go rusty so don't get them wet.

Yes high level gearboxes could provide a better solution..of course they are the same gear sets used by DJH apparently ..no single stage worm and gearwheel can be as quiet.

 

Baz

I've been using some of these drivers on a loco recently. I've had some issues with it so they have been on and off dozens of times, gripped between my sweaty fingers, and they are still clean and shiny. The appearance is noticeably better than the old Nickel Tyres too so I say full marks to Mark for making the switch!

[FarrMan]

28 minutes ago, Tony Wright said:

It'll be given a through test at the weekend. I'll report accordingly.

Tony

 

A little knowledge is a dangerous thing. I have just looked up the following chart

 

https://www.zygology.com/cms/upload_area/pdf/Zyg-Anodic-Index.pdf

 

and see that nickel silver and stainless steel are close together or adjacent to each other, indicating little risk of corrosion, hence my previous post was rubbish. My apologies for any unnecessary worry caused.

 

Lloyd

[micklner]

2 hours ago, Tony Wright said:

I have tried High Level gearboxes, and they are excellent. 

 

Only a tiny bit off the bottom of the backhead will need removal to accommodate the worm wheel on the J6. It'll be covered with a dummy 'footplate' eventually, angled to clear it (as suggested by Iain Rice) and when a crew is fitted, it'll be invisible.

 

Regards,

 

Tony. 

I look forward to a pictures , personally its not my idea of how models should still be made, when there are much better options now available.

[t-b-g]

Any sort of middle axle drive on a J6 would be visible. The boiler clearance and the relatively small splashers leave the middle axle easy to see.

 

It would even be a good candidate for a little representative dummy inside valve gear (leaving the working stiff for watchmakers!). Just a few scraps of etch soldered into a basic shape looks so much better than being able to see through to the track.

 

I have done something like that on Valour as there was a hole that you could see through that shouldn't be there.

 

 

The NuCast J6 I did many years ago has a similar motor arrangement to Tony's and as he says, the tiny mount of gear wheel visible in the cab is well covered by a crew or a dummy slightly raised footplate. Mind you, I was about 16 years old and the ECM can motor superglued to the whitemetal chassis block may not be how I would do it now! It still runs sweetly, 44 years later.

 

I much prefer that to seeing a brass gear wheel on the middle axle. I find a small amount of gear showing in the cab less of a problem than I do cut away boilers and gearbox sides showing between boiler and footplate.

 

Edit to add that my preferred method now would be a motor mounted vertically in the firebox driving on the back axle or to use a High Level box with the extended drive. Either would give a totally hidden drive.

Edited August 20, 2020 by t-b-g
To add content

[Headstock]

2 hours ago, Clem said:

Good morning Andrew. Sorry to hear that you've had experience of this awful virus. I know very little first hand apart from my uncle who died from it in a nursing home. But from the writings of others who have had it and recovered, it seems it is not like flu. They describe it as much worse and far more persistent with the effects lasting weeks and even months after. I wonder if this fits  with your experience? From my point of view, Chris, my other half, suffers from RA and as such has impaired immunity due to her drugs, so I cannot afford to take risks with it for her sake, never mind my own.  (in the same boat, I'm sure, as many on here). 

 

Anyway,  I entirely agree with your sentiments here. Apart from anything else, there's no evidence that having been through C19, you can't catch it again. Also, the latest estimates are that about 4-5% of the population have had it. Herd immunity, even if it did work,  requires at least 60% and that translates to many thousands more deaths. A vaccine, or vaccines, is/are our best hope and at least there seems to be some optimism on that from the developers. Please don't give up on making stock etc. for LCSG. Your superb models of carriages shown on here are a massive inspiration to me and others. I'm very much looking forward to seeing LCSG again when it's safe. If you're not fully through it yet, I hope you get through quickly.

 

Clem

 

Morning Clem,

 

You wouldn't mistake it for the flu. I would say it took a good month to shift all the symptoms. However, there being no available antibody test, I'm still not one hundred percent sure that it was C19!  I continue to behave towards others as if I haven't had it, or could still potentially carry it.

 

The more we learn about C19 the more it seems to fit with my experience. The most unsettling thing for me, was not its severity, more that there was a definite sense of progression in the illness, it was almost as if it was trying to attack in different ways. For the first week it was so mild, that under normal circumstances I would have continued about my usual routine. If I had not voluntarily locked down, I could have infected people right left and centre without me evening knowing. 

 

I don't have any intention of stopping modeling, though I have had time out recently, partly due to the heat but enjoying nature in the garden when I can. I hope LSGC will run again, even if it is for one last time. I don't see why model railway exhibitions shouldn't return to normal eventually but I think that some are jumping the gun on this. My own thoughts, bearing in mind that a year's worth of planning is often required, give it that year, maybe two, perhaps longer, certainly not less.

 

P.S. I will post something in a couple of days when I have finished painting it.

Edited August 20, 2020 by Headstock
add P.S.

[Chuffer Davies]

2 hours ago, Tony Wright said:

I

That's why I'm driving off the rear axle of the latest J6, even though it's (slightly) less mechanically advantageous.

 

Regards,

 

Tony. 

Hi Tony,

We've been here before and I really am sorry to do this but I worry that a comment from you  (which is  technically invalid) will then mislead other modellers into thinking the same thing. 

 

I will state again that if your coupling rods are rigid (which I know you personally prefer)  then there is absolutely no difference to the system of driven axle, crankpins and coupling rods,  which ever axle you decide to drive off.  I am 100% certain of this fact. 

 

You have also stated in the past that when using a coupling rod that is articulated on the centre crankpin, that sorting out tight spots is much easier if you drive off the centre axle.  I don't actually share your opinion on this because this is not my  personal experience, but I can't come up with a convincing argument as to why your statement is incorrect so I have to let that ride, for now at least.  Perhaps someone else on this thread can come up with an argument one way or another. 

 

With 0-6-0 loco's such as these (i.e. with tenders),  I have yet to build a model where I haven't been able to drive off the rear axle and at the same time completely hide the motor in the firebox and boiler.  That having been said I know that this is not something that bothers you and you have a preference to use out of the box motor and gearbox combinations to both save time and to eliminate risk, and why not. 

 

But please don't continue to convince yourself (and others) that there is a benefit in driving off the centre axle when there isn't.

 

Respectfully,

 

Frank  

Edited August 20, 2020 by Chuffer Davies
missing word

[davidw]

18 hours ago, Headstock said:

 

Unfortunately, LSGC will not be attending. I've been building stuff all year for this exhibition, it will now not be seen. However, that is unimportant, to defeat this virus we need to thinking about others and not judging the risk to ourselves.

 

November is far to soon in my opinion. Due to underlying health issues, this C19 has already taken one of our team. Others, such as Frank 'chuffer' Davies of this forum, may not be able to fight of this virus if inadvertently infected by the herd immunity gang, better to keep him and others safe. Herd immunity is a a nonsense with this virus, certainly by November. It would require community spread again and that can not be controlled without recourse to a second lockdown, that would bankrupt the country. I am younger and fitter than most who post on Wright Writes, I've had C19, though comparatively mild, it wasn't pleasant.

 

Sorry to hear of that of the LSGC team. Thoughts, prayers and condolences

[Woodcock29]

I have to say that from my experience I would agree with Tony, even with rigid coupling rods, its still preferable to drive off the centre axle of a 6-coupled loco. I can't really explain it properly but when driving on say the rear axle of a 6-coupled loco that axle becomes the leading axle in terms of movement and the front axle actually lags behind by a fraction because the coupling rods have a small amount of slop (obviously not as much as in some RTR locos- which actually amaze me that some even run given the amount of slop).

Andrew

[Tony Wright]

1 hour ago, Chuffer Davies said:

Hi Tony,

We've been here before and I really am sorry to do this but I worry that a comment from you  (which is  technically invalid) will then mislead other modellers into thinking the same thing. 

 

I will state again that if your coupling rods are rigid (which I know you personally prefer)  then there is absolutely no difference to the system of driven axle, crankpins and coupling rods,  which ever axle you decide drive off.  I am 100% certain of this fact. 

 

You have also stated in the past that when using a coupling rod that is articulated on the centre crankpin, that sorting out tight spots is much easier if you drive off the centre axle.  I don't actually share your opinion on this because this is not my  personal experience, but I can't come up with a convincing argument as to why your statement is incorrect so I have to let that ride, for now at least.  Perhaps someone else on this thread can come up with an argument one way or another. 

 

With 0-6-0 loco's such as these (i.e. with tenders),  I have yet to build a model where I haven't been able to drive off the rear axle and at the same time completely hide the motor in the firebox and boiler.  That having been said I know that this is not something that bothers you and you have a preference to use out of the box motor and gearbox combinations to both save time and to eliminate risk, and why not. 

 

But please don't continue to convince yourself (and others) that there is a benefit in driving off the centre axle when there isn't.

 

Respectfully,

 

Frank  

I can only speak from my own experience, Frank,

 

Though I didn't mention this, initially I arranged the J6 to drive off the middle axle. Having opened up the crankpin holes in the 'rods to give a 'working' clearance, I tested it and it worked fine. 

 

However, as mentioned, I could see the obtrusive gearwheel beneath the boiler. So, I switched the drive around to the rear axle. Immediately, the coupling rods were binding, to the extent that I had to broach the holes out further. No other elements had changed (other that the motor running the opposite way, which, in this case is irrelevant). Though I've still got a beautifully-running chassis, it's now got considerably more 'wear' in its coupling rods that previously. If you think what I've just said is 'misleading' to modellers, then so be it. 

 

From my own experience (repeated getting on for 600 loco constructions now), if one can, then driving off the middle axle (or an inner axle) is mechanically-beneficial. 

 

I was once tasked with building a GWR 47XX 2-8-0 (from a Cotswold or Sutherland kit; I forget). The chassis was milled from solid brass, with a hefty great slot in it to take an XO4-style motor, driving off the rear axle. Could I get it to go sweetly? Not until the leading holes in the coupling rods resembled 'dustbins'! Then, I had the opposite of a tight spot - just lots of slop; far too much slop for good running. The cure? Scratch-build a new set of frames and new rods, this time driving off the third axle. 

 

Again, I state this is from my experience. It's not theory, it's what I've encountered. It seems to me that the 'further' one gets from the actual drive, clearances have to be increased. 

 

Thus, with that in mind, I'll continue to convince others that (where possible) it's best to drive on the centre (or inner) axle (why do I need to convince myself?). 

 

Perhaps the scores of owners of the locomotives I've made might like to comment. And comment on how well they run. Or the scores of folk I've helped in their loco constructions...........

 

It also 'worries' me when folk don't seem to be able to accept empirical evidence - 'collected' over near five decades.  

 

Regards,

 

Tony. 

Edited August 20, 2020 by Tony Wright

[Tony Wright]

2 hours ago, micklner said:

I look forward to a pictures , personally its not my idea of how models should still be made, when there are much better options now available.

Thanks Mick,

 

We all have different ideas about how we go about making locos, and using RTR motive power (however much-altered) is personally not one of mine. 

 

Regards,

 

Tony. 

[Chuffer Davies]

4 minutes ago, Woodcock29 said:

I have to say that from my experience I would agree with Tony, even with rigid coupling rods, its still preferable to drive off the centre axle of a 6-coupled loco. I can't really explain it properly but when driving on say the rear axle of a 6-coupled loco that axle becomes the leading axle in terms of movement and the front axle actually lags behind by a fraction because the coupling rods have a small amount of slop (obviously not as much as in some RTR locos- which actually amaze me that some even run given the amount of slop).

Andrew

Hi Andrew,

Again I can't agree.  The amount of slop is determined by the tolerances in the driving  crank pin and the driven crank pin.  If the coupling rod is solid then it matters not whether there is another crank pin in the system (the centre in your scenario) because the distance between the driving and driven crank pin is irrelevant.   Introducing articulation in the rod at the centre crank pin will introduce additional slop but this effectively mechanically creates two  interconnected  0-4-0's.   This will mean that the front crank pin will (as you say) lag behind the centre crank pin so visually if you have a lot of slop.  Whilst it may look wrong there will be no difference in terms of mechanical efficiencies.

Regards,

Frank         

[t-b-g]

55 minutes ago, Chuffer Davies said:

Hi Tony,

We've been here before and I really am sorry to do this but I worry that a comment from you  (which is  technically invalid) will then mislead other modellers into thinking the same thing. 

 

I will state again that if your coupling rods are rigid (which I know you personally prefer)  then there is absolutely no difference to the system of driven axle, crankpins and coupling rods,  which ever axle you decide to drive off.  I am 100% certain of this fact. 

 

You have also stated in the past that when using a coupling rod that is articulated on the centre crankpin, that sorting out tight spots is much easier if you drive off the centre axle.  I don't actually share your opinion on this because this is not my  personal experience, but I can't come up with a convincing argument as to why your statement is incorrect so I have to let that ride, for now at least.  Perhaps someone else on this thread can come up with an argument one way or another. 

 

With 0-6-0 loco's such as these (i.e. with tenders),  I have yet to build a model where I haven't been able to drive off the rear axle and at the same time completely hide the motor in the firebox and boiler.  That having been said I know that this is not something that bothers you and you have a preference to use out of the box motor and gearbox combinations to both save time and to eliminate risk, and why not. 

 

But please don't continue to convince yourself (and others) that there is a benefit in driving off the centre axle when there isn't.

 

Respectfully,

 

Frank  

 

Somebody could probably prove that driving on the centre axle creates a more balanced movement, in that the drive forces are pushing one wheel and pulling the other, rather than pushing two the pulling two. In our scale, with the sizes and masses of parts involved, I am not convinced that there is enough to cause any problem, at least with rigid coupling rods. If you took the middle wheels out, a six coupled loco would run just like a 4 coupled one. so the middle wheels only need to be quartered correctly to go along for the ride.

 

The only time I had any problem driving on a rear axle was on an 0-8-0 with jointed rods and the multiple amounts of play by the time the drive reached the front gave me lots of grief. I soldered the rods up solid and the loco works as smoothly as anybody would wish now.

 

On a loco like Valour, where you could put any motor you like on any axle, I would choose the centre one but I have enough locos (and have seen enough built by others, including yours) to know that a rear axle drive can give perfectly good results.

 

I prefer solid rods anyway as I have seen models where you can clearly see the driven axle move first and then watch as the rods take up the slack in the other axles, rather like an uncoupled coal train starting up. It is like "loose coupled" passenger trains, it just looks wrong.

 

If you have a loco that does what Tony W has just described, works when driven on the centre axle but binds when driven on the rear axle, it means that the coupling rod centres were not spot on but the drive on the centre axle just allowed it to get away with it because of the way the rear crankpin would not be pulled or pushed right up against the edge of the hole in the rod until it was driven by a motor.

 

When I build a 6 coupled loco, I always test it by spinning each pair of wheels by finger power, with the rods on, in both directions. I have had several where spinning one pair of wheels is fine and spinning another shows a tight spot. Even just running the whole thing along a track freely is no guarantee that driving one or other axle won't cause a problem. Making it go from friction from 6 wheels on the rails is not the same as driving it on one axle. There has always been a fault, either quartering or rod length, that has caused the binding.   

[Tony Wright]

3 minutes ago, t-b-g said:

 

Somebody could probably prove that driving on the centre axle creates a more balanced movement, in that the drive forces are pushing one wheel and pulling the other, rather than pushing two the pulling two. In our scale, with the sizes and masses of parts involved, I am not convinced that there is enough to cause any problem, at least with rigid coupling rods. If you took the middle wheels out, a six coupled loco would run just like a 4 coupled one. so the middle wheels only need to be quartered correctly to go along for the ride.

 

The only time I had any problem driving on a rear axle was on an 0-8-0 with jointed rods and the multiple amounts of play by the time the drive reached the front gave me lots of grief. I soldered the rods up solid and the loco works as smoothly as anybody would wish now.

 

On a loco like Valour, where you could put any motor you like on any axle, I would choose the centre one but I have enough locos (and have seen enough built by others, including yours) to know that a rear axle drive can give perfectly good results.

 

I prefer solid rods anyway as I have seen models where you can clearly see the driven axle move first and then watch as the rods take up the slack in the other axles, rather like an uncoupled coal train starting up. It is like "loose coupled" passenger trains, it just looks wrong.

 

If you have a loco that does what Tony W has just described, works when driven on the centre axle but binds when driven on the rear axle, it means that the coupling rod centres were not spot on but the drive on the centre axle just allowed it to get away with it because of the way the rear crankpin would not be pulled or pushed right up against the edge of the hole in the rod until it was driven by a motor.

 

When I build a 6 coupled loco, I always test it by spinning each pair of wheels by finger power, with the rods on, in both directions. I have had several where spinning one pair of wheels is fine and spinning another shows a tight spot. Even just running the whole thing along a track freely is no guarantee that driving one or other axle won't cause a problem. Making it go from friction from 6 wheels on the rails is not the same as driving it on one axle. There has always been a fault, either quartering or rod length, that has caused the binding.   

Thanks Tony,

 

'If you have a loco that does what Tony W has just described, works when driven on the centre axle but binds when driven on the rear axle, it means that the coupling rod centres were not spot on but the drive on the centre axle just allowed it to get away with it because of the way the rear crankpin would not be pulled or pushed right up against the edge of the hole in the rod until it was driven by a motor.'

 

Isn't this a ringing endorsement for driving off the centre axle? I say this because I've lost count of the number of loco kits I've built where the rods don't exactly match the bearings in the frames - Nu-Cast springs to mind, and a certain K2. 

 

I agree, this should not be the case, but how many others have found this out to their cost? 

 

I offer no scientific proof why driving off the middle axle is better, it's just that it's my personal experience. 

 

Regards,

 

Tony. 

[Chuffer Davies]

9 minutes ago, Tony Wright said:

I can only speak from my own experience, Frank,

 

Though I didn't mention this, initially I arranged the J6 to drive off the middle axle. Having opened up the crankpin holes in the 'rods to give a 'working' clearance, I tested it and it worked fine. 

 

However, as mentioned, I could see the obtrusive gearwheel beneath the boiler. So, I switched the drive around to the rear axle. Immediately, the coupling rods were binding, to the extent that I had to broach the holes out further. No other elements had changed (other that the motor running the opposite way, which, in this case is irrelevant). Though I've still got a beautifully-running chassis, it's now got considerably more 'wear' in its coupling rods that previously. If you think what I've just said is 'misleading' to modellers, then so be it. 

 

From my own experience (repeated getting on for 600 loco constructions now), if one can, then driving off the middle axle (or an inner axle) is mechanically-beneficial. 

 

I was once tasked with building a GWR 47XX 2-8-0 (from a Cotswold or Sutherland kit; I forget). The chassis was milled from solid brass, with a hefty great slot in it to take an XO4-style motor, driving off the rear axle. Could I get it to go sweetly? Not until the leading holes in the coupling rods resembled 'dustbins'! Then, I had the opposite of a tight spot - just lots of slop; far too much slop for good running. The cure? Scratch-build a new set of frames and new rods, this time driving off the third axle. 

 

Again, I state this is from my experience. It's not theory, it's what I've encountered. It seems to me that the 'further' one gets from the actual drive, clearances have to be increased. 

 

Thus, with that in mind, I'll continue to convince others that (where possible) it's best to drive on the centre (or inner) axle (why do I need to convince myself?). 

 

Perhaps the scores of owners of the locomotives I've made might like to comment. And comment on how well they run. Or the scores of folk I've helped in their loco constructions...........

 

It also 'worries' me when folk don't seem to be able to accept empirical evidence - 'collected' over near five decades.  

 

Regards,

 

Tony. 

Hi Tony,

I know how many loco's you have built, and you are without doubt a more experienced builder (by volume) than I.   I can't compete when it comes to the quality of the superstructures and would not dare to challenge you on that topic.  Your wiggly pipes are to die for.

 

BUT......

 

I have probably only built 60 or so working chassis in my time but the difference between you and I is that I invest a lot more time and effort building each individual chassis.  All are compensated, and if they are tank engines then they are split frame. I believe I have possibly invested as much time in constructing my 60 or so chassis as you have building your 600.  I too have taken on the role of loco doctor from time to time sorting out problems with compensated chassis but rather than solder the whole lot up solid, I have taken the time to analyse the root cause of the problems and have successfully got the compensated chassis working properly.   

 

Solid coupling rods  are a specific case which eliminate the middle axle, rear axle argument.  Your reference to moving the drive from the centre axle to the rear being proof that my theories are wrong is I regret flawed - you will have changed the way the chassis was set up when you moved the drive.  Had you at the outset started with the drive at the back you would have had no more problem than you had initially driving off the centre axle, but having compromised the rods to remove the original tight spot,  it does not  then follow that moving the drive to the rear axle will then have no consequence, hence the new tight spot.  In fact you cannot know that had you driven off the rear axle in the first place you would have had any tight spots. 

 

I am more than ready to accept empirical evidence when there are no other arguments to contradict that evidence.  I could equally argue that it worries me when people are using empirical evidence to contradict the laws of mechanics.  

 

All I can do is try to encourage people on this thread to believe that with rigid coupling rods the laws of mechanics indicate that it is irrelevant as to which axle is chosen as the driven axle.   I know this contradicts your empirical evidence but we will have to agree (or disagree) to differ on this.

 

Still respectfully,

 

Frank   

[CF MRC]

I think it all comes down to developing a ‘feel’ for how the chassis / wheels are performing, when making adjustments (but I’ve probably only made a dozen engines...). One rule I always adhere to is never to open out the driving axle crank pins holes and to try out each end of an 0-6-0 independently when checking for binds.  Driving rear or middle? I would normally go for the middle, but it depends on the appearance.  Jointed rods? By the time a loco has done a 100 miles on CF any jointed rods would have been completely worn out and floppy!

 

Tim