Wright writes.....

[Chuffer Davies]

42 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.

 

 

Hi Tony (G),

 

I'm delighted you wrote the above paragraph because in doing so you reminded me of something that will potentially blow peoples minds:  in mechanics nothing pulls!  Therefore your statement that the driving forces are pulling on one wheel and pushing on the other is wrong.  Everything is actually pushing everything else.  It is not the front of the coupling rod hole pulling the crank it is the back of the hole pushing the crankpin.  Since the coupling rod is a solid piece of metal the position of one wheel relative to another is irrelevant.  The only truth is that the crank pin on the driven axle is pushing the coupling rod and the coupling rod is then pushing the crank pin of the other wheel(s).  

 

If you can understand this then you will realise that what I have been saying all along is technically correct, If you can't then my reputation will continue to be mud because I'm contradicting Sir and apparently because of the empirical evidence I'm talking out of my a**e.....

 

I will now go and beat myself with a birch twig!!!!!

 

Regards to all,

 

Frank   

[richard i]

I think that there is merit in both approaches. The theoretical  and the practical. In theory it should make no difference but in reality everything is not perfectly aligned so some fudge is needed to make it work in our miniature world. With my hand tools I can only get down to 0.5mm ish of accuracy. Not enough for perfect theory to work. I remember Tony Showing me a Bulleid pacific with huge amounts of slop in the valve gear. In the full size loco it would have been fatal but in the model it ran like a sewing machine. 
I try for perfection but accept that I will fall short due to my abilities.
Richard

[Chuffer Davies]

1 minute ago, richard i said:

I think that there is merit in both approaches. The theoretical  and the practical. In theory it should make no difference but in reality everything is not perfectly aligned so some fudge is needed to make it work in our miniature world. With my hand tools I can only get down to 0.5mm ish of accuracy. Not enough for perfect theory to work. I remember Tony Showing me a Bulleid pacific with huge amounts of slop in the valve gear. In the full size loco it would have been fatal but in the model it ran like a sewing machine. 
I try for perfection but accept that I will fall short due to my abilities.
Richard

Here here,

I just want to make sure that people are making decisions based on accurate information including the differing experiences and sometimes contradicting evidence of others.

 

I too struggle sometimes.  I’ve always said that I consider myself a competent modeller not because I get everything right first time, but because I have the patience to undo and retry again and again until I get it right.  That’s why it takes me 100+ hours to build a loco when Sir can do it in 30+.  
Happy modelling.

Frank

[micklner]

1 hour ago, Tony Wright said:

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. 

Tony

No idea what r.t.r has got to with my response to a cab half full of gearbox . Can you imagine the fuss if Hornby et al were still making Locos with a XO4 or similar in the cab !! I have plenty of my kit builts with no motor or anything else on show !!

 

e.g my latest build a Nucast G6  fitted with a High Level box and a N Drive motor sitting  vertical in the firebox. As for pulling she will will pull Eight Hornby Pullmans without slipping , not that she needs too,  as they were only normally used on a couple of Push pull coaches in the real world !!.

 

regards

Mick

 

 

 

Edited August 20, 2020 by micklner

[Tony Wright]

1 hour ago, Chuffer Davies said:

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   

Agree to disagree I think Frank,

 

Whenever someone cites the 'laws of mechanics', I respectfully retreat. That to me sounds like a lot like hard sums; that being the case (and only ever having taught maths to O level, and not even full-time) I'll concede your 'evidence', even though I don't understand it. 

 

However, I'm puzzled as to your reference to a 'tight spot'. When I initially arranged the chassis to be driven off the centre axle, after opening out the coupling rod holes to give a 'working' clearance, there was absolutely no tight spot, so there was none to remove. The only tight spots occurred when the drive was on the rear axle. Empirical evidence, or what, though not substantiated by the 'laws of mechanics', of which, I remain, happily ignorant.

 

Regards,

 

Tony.   

[Tony Wright]

7 minutes ago, micklner said:

Tony

No idea what r.t.r has got to with my response to a cab half full of gearbox . Can you imagine the fuss if Hornby et al were still making Locos with a XO4 or similar in the cab !! I have plenty of my kit builts with no motor or anything else on show !!

 

e.g my latest build a Nucast G6  fitted with a High Level box and a N Drive motor sitting  vertical in the firebox. As for pulling she will will pull Eight Hornby Pullmans without slipping , not that she needs too,  as they were only normally used on a couple of Push pull coaches in the real world !!.

 

regards

Mick

 

 

 

A nice build, Mick,

 

Thanks for showing us.

 

However, either the loco rides far too high up or the carriage to the right much too low down. On any track undulations, the buffers will overlap!

 

From this angle, it looks like the loco body isn't level, being up at the front. 

 

Regards,

 

Tony. 

[Tony Wright]

1 hour ago, Chuffer Davies said:

Hi Tony (G),

 

I'm delighted you wrote the above paragraph because in doing so you reminded me of something that will potentially blow peoples minds:  in mechanics nothing pulls!  Therefore your statement that the driving forces are pulling on one wheel and pushing on the other is wrong.  Everything is actually pushing everything else.  It is not the front of the coupling rod hole pulling the crank it is the back of the hole pushing the crankpin.  Since the coupling rod is a solid piece of metal the position of one wheel relative to another is irrelevant.  The only truth is that the crank pin on the driven axle is pushing the coupling rod and the coupling rod is then pushing the crank pin of the other wheel(s).  

 

If you can understand this then you will realise that what I have been saying all along is technically correct, If you can't then my reputation will continue to be mud because I'm contradicting Sir and apparently because of the empirical evidence I'm talking out of my a**e.....

 

I will now go and beat myself with a birch twig!!!!!

 

Regards to all,

 

Frank   

I can do nothing more that haul up the white flag, Frank,

 

'I'm delighted you wrote the above paragraph because in doing so you reminded me of something that will potentially blow peoples minds:  in mechanics nothing pulls!'

 

 My mind is completely blown (and not just by the omission - by a man of your many talents - of the possessive apostrophe from 'peoples'!), but for as long as I can remember, I always thought a locomotive (which, I assume, is a mechanical piece of apparatus?) usually PULLS its train. If not, what does it do? Impel it? Attract it? 

 

My brain hurts!

 

More regards,

 

Tony. 

 

 

[Clem]

15 minutes ago, Tony Wright said:

 My mind is completely blown (and not just by the omission - by a man of your many talents - of the possessive apostrophe from 'peoples'!), but for as long as I can remember, I always thought a locomotive (which, I assume, is a mechanical piece of apparatus?) usually PULLS its train. If not, what does it do? Impel it? Attract it? 

 

My brain hurts!

Lol (as they say). We talk about the locomotive pulling a train because in the direction of travel, the force for forward propulsion - the locomotive -  is ahead of the train. But technically, Frank's argument applied to this case is correct as the inside of the loco's rear screw coupling is *pushing* the inside of the leading vehicle's 3-link or screw coupling and it becomes a train of many push points. But in an every day non-technical terms we look at the location of the energy source providing the force for movement,  to decide whether something is pulled or pushed. I declare it  a draw!! But the discussion does illustrate the difference in the approaches of the rigid chassis and compensated/sprung chassis modellers. I keep saying it, at the end of the day we all make our choices and do what works for us.

[LNER4479]

I wade into this whole area of coupling rods / chassis, empirical vs theory with some trepidation ...

 

One obvious effect not hitherto mentioned is that, when placed on the rails, all wheels will have a tendency to turn when propelled along even without coupling rods affixed. For a 0-4-0 this is guaranteed; for a 0-6-0 there may be the occasionally slipping of one if the chassis encounters any high or low spots. So the rotation of whichever of the driving axles are not directly driven by the gearbox is not solely reliant on the coupling rods when the loco is running on a layout.

 

I say this because, when on the workbench (eg with croc clips attached) you do NOT have the benefit of this effect. I sometimes find that a chassis binds on the workbench but is perfectly OK on the track, (particularly with some weight added); sometimes it's vice-versa! My suspicion is that this is relevant in the rear-versus-middle driving axle debate.

 

My other comment is that I only open out coupling rod holes further as a last resort. I check each has a sufficient running clearance individually and no more. If the thing won't push freely along the track as an assembled chassis (rods on but no motor fitted) then something else is wrong - put it back in the Poppy's jig and check for fit. In that respect, I'm with Frank in wanting to get to the root cause of the mechanical problem.

 

On the other hand, I'm reminded of the tale of the aerodynamics engineers who studied the 'engineering' of the bumble bee and concluded that there was no way the damn thing could ever possibly fly. Fortunately, no-one told the bumble bee...

 

[Barry O]

7 hours 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! 

 

Regards,

 

Tony. 

Stainless steel and nickel. Dissimilar metals and as we keep trying to get you to understand Tony nickel silver pick ups are a thing of the ancient past. They squek...and, looking at some I had to sort out recently..you can make just as bad a job with nickelsilver wire as you can with phosphour bronze...

 

As for stainless steel tyred wheels...why???

Baz

[t-b-g]

1 hour ago, Chuffer Davies said:

Hi Tony (G),

 

I'm delighted you wrote the above paragraph because in doing so you reminded me of something that will potentially blow peoples minds:  in mechanics nothing pulls!  Therefore your statement that the driving forces are pulling on one wheel and pushing on the other is wrong.  Everything is actually pushing everything else.  It is not the front of the coupling rod hole pulling the crank it is the back of the hole pushing the crankpin.  Since the coupling rod is a solid piece of metal the position of one wheel relative to another is irrelevant.  The only truth is that the crank pin on the driven axle is pushing the coupling rod and the coupling rod is then pushing the crank pin of the other wheel(s).  

 

If you can understand this then you will realise that what I have been saying all along is technically correct, If you can't then my reputation will continue to be mud because I'm contradicting Sir and apparently because of the empirical evidence I'm talking out of my a**e.....

 

I will now go and beat myself with a birch twig!!!!!

 

Regards to all,

 

Frank   

 

Mind not blown at all Frank. I was actually trying to agree with you. Perhaps instead of push and pull I should have said that the rods are under tension or compression. With a drive at one end, you get two lots of compression or tension, instead of one of each. It alters the position of the crankpins within the holes in the rod from one side of the hole to the other. If your rods are the right length, it makes no difference. If your rod lengths are out it can cause binding.

 

The difference, for what we do, is not worth worrying about.

 

All you need to do is to get the basics right.

 

If I have a coupling rod that doesn't match the wheel centres, my answer isn't "find an axle to drive where it doesn't show". It is to fix the problem with altering the rod length. I don't ever use a single thickness etch rod, so altering the length slightly on a double layer is quite easy. You don't need to enlarge the holes, just shift them slightly.

 

I think it all comes down to the individual approach and aims of the modeller. There are those who can take a kit and build it in a short time, possibly accepting things like slightly wrong valve gear. There are those who accept that their output will be a smaller number of completed locos but like to pull out all the stops to "do a proper job".

 

The difference between a showcase model and a "layout loco". I am sure that Tony W has the ability to build a showcase loco if he set his mind to it but if he built things your way, he would still have a huge number that needed building. Likewise, I am sure you could have built more than 60 if you had adopted Tony's "layout loco" philosophy.

 

I am more in your camp than Tony 's when it comes to such things. To me, how long it takes to build a loco doesn't matter as long as when it is finished, I know I couldn't have done it any better no matter how much longer I spent. I would rather build another 4 or 5 locos to the best of my ability than another 50 with compromises that I would have accepted when I was a novice but which I wouldn't let go now.

 

 

[Northmoor]

6 minutes ago, LNER4479 said:

On the other hand, I'm reminded of the tale of the aerodynamics engineers who studied the 'engineering' of the bumble bee and concluded that there was no way the damn thing could ever possibly fly. Fortunately, no-one told the bumble bee...

 

An amusing old tale but long overtaken by events.  A bit like how people looked for several hundred years at Leonardo Da Vinci's drawings of a helicopter and concluded it couldn't fly, but no-one seems to have told Sikorski.

It wasn't that the laws of physics were wrong, it was that they weren't being applied correctly to the application.

[Michael Edge]

1 hour ago, Barry O said:

 

 

As for stainless steel tyred wheels...why???

Baz

It's cheaper and easier to source, I haven't tried them yet so I don't know how well thye will work.

[Tony Wright]

3 hours ago, Barry O said:

Stainless steel and nickel. Dissimilar metals and as we keep trying to get you to understand Tony nickel silver pick ups are a thing of the ancient past. They squek...and, looking at some I had to sort out recently..you can make just as bad a job with nickelsilver wire as you can with phosphour bronze...

 

As for stainless steel tyred wheels...why???

Baz

Since I don't use phosphor bronze (what's phosphour bronze?) for pick-ups Baz, how can I make 'just as bad a job'? 

 

As for squeaking, Tony Geary used phosphor bronze for pick-ups on all his OO locos. Please ask all those who've ever operated Stoke Summit and Charwelton about the 'Geary squeak'. Those locos I've 'inherited' from Tony now longer squeak. Why not? Because, in most cases I've replaced the pick-ups with nickel silver wire. The result - no squeaking, just as with all my locos...........

 

And returning to Glasgow, and the operation of Shap, ask Graham Nicholas about the loco fitted with phosphor bronze pick-ups which hardly picked-up at all. Until I fixed it, with nickel silver in the main! 

 

The ancient past? Great, I rejoice in being an inhabitant of it. 

 

Regards,

 

Tony. 

[Tony Wright]

3 hours ago, t-b-g said:

 

Mind not blown at all Frank. I was actually trying to agree with you. Perhaps instead of push and pull I should have said that the rods are under tension or compression. With a drive at one end, you get two lots of compression or tension, instead of one of each. It alters the position of the crankpins within the holes in the rod from one side of the hole to the other. If your rods are the right length, it makes no difference. If your rod lengths are out it can cause binding.

 

The difference, for what we do, is not worth worrying about.

 

All you need to do is to get the basics right.

 

If I have a coupling rod that doesn't match the wheel centres, my answer isn't "find an axle to drive where it doesn't show". It is to fix the problem with altering the rod length. I don't ever use a single thickness etch rod, so altering the length slightly on a double layer is quite easy. You don't need to enlarge the holes, just shift them slightly.

 

I think it all comes down to the individual approach and aims of the modeller. There are those who can take a kit and build it in a short time, possibly accepting things like slightly wrong valve gear. There are those who accept that their output will be a smaller number of completed locos but like to pull out all the stops to "do a proper job".

 

The difference between a showcase model and a "layout loco". I am sure that Tony W has the ability to build a showcase loco if he set his mind to it but if he built things your way, he would still have a huge number that needed building. Likewise, I am sure you could have built more than 60 if you had adopted Tony's "layout loco" philosophy.

 

I am more in your camp than Tony 's when it comes to such things. To me, how long it takes to build a loco doesn't matter as long as when it is finished, I know I couldn't have done it any better no matter how much longer I spent. I would rather build another 4 or 5 locos to the best of my ability than another 50 with compromises that I would have accepted when I was a novice but which I wouldn't let go now.

 

 

Thanks Tony,

 

Though I don't think I could ever build a 'showcase' loco. No matter how long I spent on it.

 

I suppose this is the nearest, at least in 4mm Scale...........................

 

 

I built this P2 for Mark Allatt. It's a much-modified ACE kit, and what 'makes' it is Ian Rathbone's breathtaking painting. 

 

In a way, it is a 'showcase' model, because that's where Mark keeps it. Though it has run on Grantham (for which I actually built it; it being a 'layout loco'), Mark never lets it out now. A pity, because it'll go like stink! 

 

And, thanks for pointing the fact out; even assuming that I could build to Frank's standard (which I can't), how old would I be before I'd completed over 200 locos for Little Bytham, even if some have wrong valve gear?  

 

Regards,

 

Tony. 

 

 

 

 

 

[Theakerr]

I would if someone with a better memory than mine could provide me with the pages where the previous J6 build was discussed.  I have completed a search but get nothing.  I am in the process of ordering a J6 for my winter project.

[Tony Wright]

Back to the EM Gauge J6................

 

 

I've now married the 'master's' work with mine, though there's a lot of cleaning-up, filing and filling still to do, as well as completing the loco and building a tender for it. I'd hope Roy Jackson would approve, though I doubt it! 

 

No visible drive at all, though I'll have to make a representation of the inside motion. There shouldn't be that much empty space. 

 

 

And, though there are 'better ways' of doing this (just as there are 'better ways' of making locos than modifying RTR), by the time I've soldered a dummy footplate in place to hide this, fixed in the (slightly-snipped) backhead, painted it all black and installed a crew, who'll be able to see?

 

 

[Tony Wright]

3 minutes ago, Theakerr said:

I would if someone with a better memory than mine could provide me with the pages where the previous J6 build was discussed.  I have completed a search but get nothing.  I am in the process of ordering a J6 for my winter project.

I'll look through my pictures of the build tomorrow for you...............

 

Regards,

 

Tony. 

[jwealleans]

19 minutes ago, Theakerr said:

I would if someone with a better memory than mine could provide me with the pages where the previous J6 build was discussed.

 

It was my build and it starts on my workbench on May 5th.  I discussed it with Tony in the couple of days prior to that, I believe.  Edit - The option to link directly to a post seems to have gone, but they're on page 1788 of this thread, starting half way down.

 

It's also in the BRM Annual for 2011.

Edited August 20, 2020 by jwealleans

[Compound2632]

9 minutes ago, jwealleans said:

 

Edit - The option to link directly to a post seems to have gone, but they're on page 1788 of this thread, starting half way down.

 

Works for me. This post?

 

[jwealleans]

Yes, that one.  I only have the option to 'report' a post, not share it.

[Compound2632]

8 minutes ago, jwealleans said:

Yes, that one.  I only have the option to 'report' a post, not share it.

You've lost the little triangulary thingy icon?

[Buhar]

5 hours ago, micklner said:

fitted with a High Level box and a N Drive motor sitting  vertical in the firebox.

Hi Mick, 

How did you do that, then? I thought the N-Drive had a huge shaft with a D-shape.

Alan 

[cctransuk]

1 hour ago, Tony Wright said:

Since I don't use phosphor bronze (what's phosphour bronze?) for pick-ups Baz, how can I make 'just as bad a job'? 

 

As for squeaking, Tony Geary used phosphor bronze for pick-ups on all his OO locos. Please ask all those who've ever operated Stoke Summit and Charwelton about the 'Geary squeak'. Those locos I've 'inherited' from Tony now longer squeak. Why not? Because, in most cases I've replaced the pick-ups with nickel silver wire. The result - no squeaking, just as with all my locos...........

 

And returning to Glasgow, and the operation of Shap, ask Graham Nicholas about the loco fitted with phosphor bronze pick-ups which hardly picked-up at all. Until I fixed it, with nickel silver in the main! 

 

The ancient past? Great, I rejoice in being an inhabitant of it. 

 

Regards,

 

Tony. 

 

It must be a factor of different pick-up adjustment / pressure.

 

I recently went over to nickel-silver from phospor-bronze; (largely in imitation of your practice); and there is definitely a tendency towards pick-ups squeaking that I didn't experience before.

 

John Isherwood.

[cctransuk]

4 minutes ago, Buhar said:

Hi Mick, 

How did you do that, then? I thought the N-Drive had a huge shaft with a D-shape.

Alan 

 

Isn't the "huge shaft with a D-shape" the output from the normally-attached multi-stage gearbox?

 

I'm assuming that Mick married just the motor to the High Level gearbox.

 

John Isherwood.