Last year I decided to convert a pair of newish Hornby 51xx 's to P4. The option of using a Comet chassis was avoided as the ballast problem is very difficult to handle and I planned to use the original rather elegant casting. The first difficulty is the original axles being 3mm diam and the replacements for P4 being 1/8" diam and 2mm for the pony truck axles. The former were tackled by old fashioned fitting techniques (file and reamer) with slight adjustment to the geartrain location. The pony trucks were fixed by the use of brass tubing for a sleeve. This resulted in a good running chassis without piston rod gear attached.
At this point the problems arrived.The saddle arrangement of the cylinder framing is a good fit and replaces the original plastic ones exactly. The problem lies in the conflicting alignment of the piston rod guide hole and the front axle crank pin -- they are in direct line. The same crank pin also fouls the guide bars and the cross head.
Using the advice of both Comet and Gibson I have filed down the front axle boss as much as I dare and applied the same treatment to the cross head. Despite these efforts the arrangement still demands that the guide bars are inclined outwards towards the rear and the piston rod cranked rather obviously to my entire dis-satisfaction!
The next problem is the length of thread available on the centre crankpin to mount up both conn rod and piston rod. The comet laminated bar are too thick to enable the nuts to meet the crankpinend face and so will not lock. I have thinned down the rod faces in way of this fixing but am moved to ask if I should be considering either thinning the piston rod down to one thickness or dismantling the centre wheelset in order to remove the crankpin screws in order to relieve the hole by 1mm to provide that much more thread projection --- OR a bit of both!
These problems brought back memories of a fiasco with an OO build of a 43XX which uses the same comet Components when I ran into a similar problem by not using finescale at that time.
The big questions are:
1. What should I do now ?
2. Is this a standard problem with Gibson Wheels versus P4 and valve gear ?
Hornby 51xx to P4
-
doggeface
Hornby 51xx to P4
You do not have the required permissions to view the files attached to this post.
-
Russ Elliott
- Posts: 930
- Joined: Thu Jun 02, 2011 6:38 pm
Re: Hornby 51xx to P4
For the middle axle, you should use the longer crankpin bush AG item number 4M45. It looks as though you are using the short bush.
For the front axle, clearance between coupling rod and crosshead is always a bit of a problem. There have been a number of threads/posts here on the matter, so it's worthwhile reading them.
The Comet 2-cylinder redesign of 2003 was based on the following recommendation:
There should be 25.6mm clear between the inside faces of the Comet crossheads. With 21.8mm over wheelfaces, 22.3 over wheelbosses and 22.8 over the front of flange of the crankpin bush, there should be 1.4mm left (each side) for the combined width of rod and its retainer nut. Options include: using only a single etch rod thickness at its front boss; countersinking the front of the front rod at the boss; making the nut as thin as possible. Needless to say, front axle sideplay should be minimum. It does depend critically on how much of the rear of the crosshead the front crankpin impinges onto. I can't remember offhand how much this is on the 61xx.
For the front axle, clearance between coupling rod and crosshead is always a bit of a problem. There have been a number of threads/posts here on the matter, so it's worthwhile reading them.
The Comet 2-cylinder redesign of 2003 was based on the following recommendation:
There should be 25.6mm clear between the inside faces of the Comet crossheads. With 21.8mm over wheelfaces, 22.3 over wheelbosses and 22.8 over the front of flange of the crankpin bush, there should be 1.4mm left (each side) for the combined width of rod and its retainer nut. Options include: using only a single etch rod thickness at its front boss; countersinking the front of the front rod at the boss; making the nut as thin as possible. Needless to say, front axle sideplay should be minimum. It does depend critically on how much of the rear of the crosshead the front crankpin impinges onto. I can't remember offhand how much this is on the 61xx.
You do not have the required permissions to view the files attached to this post.
-
Tim V
- Posts: 2870
- Joined: Tue Jul 29, 2008 4:40 pm
Re: Hornby 51xx to P4
Have a read of MRJ9, or from the archives, MRC for June 1977! Both articles detail conversions of the Airfix prairie. I was interested to see that a 3mm axle is used these days, it was 1/8" on the Airfix model.
Tim V
(Not all railways in Somerset went to Dorset)
(Not all railways in Somerset went to Dorset)
-
doggeface
Re: Hornby 51xx to P4
I did pose the problem to Gibsons but they indicated that this is a new problem without a stock answer. If I succeed then that will be the standard solution.
I have decided to 1) Thin down the conn rod by about half of one lamination
2) Thin down the short crankpin to the thickness of one lamination.
3) Reverse the lock nut.
This leaves only the bolt to be filed off as the web on the nut really cannot afford any reduction.
The Cross head can be thinned on the inside face but the greatest protrusion is the head dome of the pin for the piston crank. I have been used to plated brass dress makers pins in the past which were very user friendly but the modern types are all stainless iron - difficult to file or solder to! The dremel ground off the dome but the comet method of solder retention does not guarantee that the pin is home when the solder decides to cooperate.
The front axle is able to float laterally but is retained by the conn rod (the centre is fixed by the drive sprocket and the rear unit is free to do it's own thing.)
After all this the head of the fwd crankpin is still able to touch the crosshead if the guide bars remain parallel - but only just . To hold the bars out I am going to try fitting a piece of 0.8 brass rod to the guide support frame and let it into a blind hole on the main frame. To answer the range of interference possible -- the crank pin is behind the inner crosshead for almost 25% of one rev. It is a significant dwell and so demands a "real" solution.
The centre crank lock nut problem is resolved. The photo does show the long pin but I have removed it in favour of a short one, this acts for the conn rod and the crank is the supported by a reversed locking nut. This arrangement provided thread for all of the nut length.
I seem to remember that my Uncle (GWR loco fitter) had told me that the prototype had only 1/8" clearance in that region for all of the 2 cyl types.
I shall pursue the trials until I achieve a more elegant solution and then replace the whole arrangement with a set of new etches.
Peter
I have decided to 1) Thin down the conn rod by about half of one lamination
2) Thin down the short crankpin to the thickness of one lamination.
3) Reverse the lock nut.
This leaves only the bolt to be filed off as the web on the nut really cannot afford any reduction.
The Cross head can be thinned on the inside face but the greatest protrusion is the head dome of the pin for the piston crank. I have been used to plated brass dress makers pins in the past which were very user friendly but the modern types are all stainless iron - difficult to file or solder to! The dremel ground off the dome but the comet method of solder retention does not guarantee that the pin is home when the solder decides to cooperate.
The front axle is able to float laterally but is retained by the conn rod (the centre is fixed by the drive sprocket and the rear unit is free to do it's own thing.)
After all this the head of the fwd crankpin is still able to touch the crosshead if the guide bars remain parallel - but only just . To hold the bars out I am going to try fitting a piece of 0.8 brass rod to the guide support frame and let it into a blind hole on the main frame. To answer the range of interference possible -- the crank pin is behind the inner crosshead for almost 25% of one rev. It is a significant dwell and so demands a "real" solution.
The centre crank lock nut problem is resolved. The photo does show the long pin but I have removed it in favour of a short one, this acts for the conn rod and the crank is the supported by a reversed locking nut. This arrangement provided thread for all of the nut length.
I seem to remember that my Uncle (GWR loco fitter) had told me that the prototype had only 1/8" clearance in that region for all of the 2 cyl types.
I shall pursue the trials until I achieve a more elegant solution and then replace the whole arrangement with a set of new etches.
Peter
Last edited by doggeface on Mon Jan 23, 2012 5:37 am, edited 2 times in total.
-
doggeface
Re: Hornby 51xx to P4
As threatened I have pursued the problem of clearance. On measuring everything very carefully with my trusty caliper gauge (what would I do without them?) has resulted in a minus 1.08mm clearance if the units were assembled as per design.
As Comet suggest the forward connecting rod was thinned to single section and the piston to driven crank will need the same treatment. The Gibson crank pins for the forward axle were then filed down to almost zero depth to make a shouldered washer. The reversed locking nut then sat happily in the conn rod. During these many excursions of nuts on the 1mm bolts it became evident that three tightenings is sufficient to ruin the thread of the bolts - so they were replaced.
There is nothing to be gained from the crosshead as the rod is already recessed.
This exercise led to the idea that it may be worthwhile to contact Colin Seymour and suggest that they is a market for both a 1mm shouldered washer and a long bolt (same length as the long crank pin). This would not only negate the need to thin the piston rod but would use all of the thread to do it's job.
The other advance is to have removed the wheels and reset the clearances such that the front axle has less than 0.5mm free movement laterally and the centre uses the same size shims to keep the lateral load off of the driven sprocket. The after axle is shimmed to 0.5 mm less than the other two. This arrangement works well over B6 pointwork.
Filing down these small components caused some head scratching but eventually solved with the use of a vice mounted brass rod over which the crank pins were dropped. The wire(0.8) was then filed down with the pins being very careful to not lift the file at the end of the stroke!
Equally the assembly of these little pesky screw units (for those like me having worn out eyesight) was proving to be expensive on lost (dropped) bits and screamingly irritating when co-operation was not forthcoming. Suddenly inspiration arrived! I have two telescopic mounted magnets. The smaller has a head diam of 6mm and the other 14mm. Now all components are put in place with smaller magnet - it is quite capable of starting the thread on the nuts. Of course a piece of brass wire helps to retain them in place whilst the magnet is removed. Things still get dropped but a quick floor search with the bigger magnet now unfailingly retrieves the lost item.
The chassis is once again running reasonably smoothly without piston assembly to the point where any trip ups prove to be further faults on my dreaded C16 cross over unlike the user friendly B6 & B8 pair!
With any luck the mini era of 2 steps ahead and 3 astern has now reversed and progress can be made.
Peter.
Click to read.
As Comet suggest the forward connecting rod was thinned to single section and the piston to driven crank will need the same treatment. The Gibson crank pins for the forward axle were then filed down to almost zero depth to make a shouldered washer. The reversed locking nut then sat happily in the conn rod. During these many excursions of nuts on the 1mm bolts it became evident that three tightenings is sufficient to ruin the thread of the bolts - so they were replaced.
There is nothing to be gained from the crosshead as the rod is already recessed.
This exercise led to the idea that it may be worthwhile to contact Colin Seymour and suggest that they is a market for both a 1mm shouldered washer and a long bolt (same length as the long crank pin). This would not only negate the need to thin the piston rod but would use all of the thread to do it's job.
The other advance is to have removed the wheels and reset the clearances such that the front axle has less than 0.5mm free movement laterally and the centre uses the same size shims to keep the lateral load off of the driven sprocket. The after axle is shimmed to 0.5 mm less than the other two. This arrangement works well over B6 pointwork.
Filing down these small components caused some head scratching but eventually solved with the use of a vice mounted brass rod over which the crank pins were dropped. The wire(0.8) was then filed down with the pins being very careful to not lift the file at the end of the stroke!
Equally the assembly of these little pesky screw units (for those like me having worn out eyesight) was proving to be expensive on lost (dropped) bits and screamingly irritating when co-operation was not forthcoming. Suddenly inspiration arrived! I have two telescopic mounted magnets. The smaller has a head diam of 6mm and the other 14mm. Now all components are put in place with smaller magnet - it is quite capable of starting the thread on the nuts. Of course a piece of brass wire helps to retain them in place whilst the magnet is removed. Things still get dropped but a quick floor search with the bigger magnet now unfailingly retrieves the lost item.
The chassis is once again running reasonably smoothly without piston assembly to the point where any trip ups prove to be further faults on my dreaded C16 cross over unlike the user friendly B6 & B8 pair!
With any luck the mini era of 2 steps ahead and 3 astern has now reversed and progress can be made.
Peter.
Click to read.
You do not have the required permissions to view the files attached to this post.
-
doggeface
Re: Hornby 51xx to P4
Well in between making up pointwork and debugging my dreaded C16 curved crossover I have been continuing the attempts to fit piston guides and rods in a parallel arrangement to the 51XX. The motion rods have thinned as recommended and the crankpins reversed and all but disappeared, the cross head taken down to a tissue on the inboard face. The only concession for track holding is to leave the lateral play on the axle at 0.5mm. This has proved to be too much for the small clearance available and I find that the offsetting of the piston rod and opening of the guides to form a vee is just as bad (to my eye) as the state before all this effort.
If I reduce the lateral clearances to zero on the leading axle I am not sure that the chassis will corner. The centre axle is fixed laterally by design which leaves only the rear capable of movement. I am not convinced that this is enough to allow the wheel set to self align. Perhaps one of you has solved this problem on a GW 2 cyl arrangement?
The other alternative is to use the spare rear cover for the comet cylinders and shift the guide rod fixing holes outboard by 1.25mm.
Of course I have no idea if the pristine models which I have admired from afar, actually run or if they do run are they modified? The other nagging doubt is whether there are components available which can do a better job. I have spent hours scouring the trade ads without success and yet seem to read articles which mention Kits by people I have not heard of nor can I find them via the internet.
During one of my (many) fits of pique when my RTR monster defied all reason and cajoling and I am glaring at the many examples of P4 locos and
it came to me that the vast majority of those locos are examples of inside cylinder models. I leafed through several issues of the news and found that the latest (176) to be typical in having 15 steam locos on view of these only one the RSH 0-4-0ST had valve gear. Being a 4 wheeler it obviously can operate on the curve with a laterally rigid wheel set.
Like some of the contributors (of recent times) who have made the point that those of us trying to construct a working system which is not a highly detailed localised scenario joining two fiddle yards cannot afford to be rivet counters. I find myself wondering if the references to accepting compromises were not in fact pointing out that perfection can only be achieved at the expense of immobility!
If I reduce the lateral clearances to zero on the leading axle I am not sure that the chassis will corner. The centre axle is fixed laterally by design which leaves only the rear capable of movement. I am not convinced that this is enough to allow the wheel set to self align. Perhaps one of you has solved this problem on a GW 2 cyl arrangement?
The other alternative is to use the spare rear cover for the comet cylinders and shift the guide rod fixing holes outboard by 1.25mm.
Of course I have no idea if the pristine models which I have admired from afar, actually run or if they do run are they modified? The other nagging doubt is whether there are components available which can do a better job. I have spent hours scouring the trade ads without success and yet seem to read articles which mention Kits by people I have not heard of nor can I find them via the internet.
During one of my (many) fits of pique when my RTR monster defied all reason and cajoling and I am glaring at the many examples of P4 locos and
it came to me that the vast majority of those locos are examples of inside cylinder models. I leafed through several issues of the news and found that the latest (176) to be typical in having 15 steam locos on view of these only one the RSH 0-4-0ST had valve gear. Being a 4 wheeler it obviously can operate on the curve with a laterally rigid wheel set.
Like some of the contributors (of recent times) who have made the point that those of us trying to construct a working system which is not a highly detailed localised scenario joining two fiddle yards cannot afford to be rivet counters. I find myself wondering if the references to accepting compromises were not in fact pointing out that perfection can only be achieved at the expense of immobility!
You do not have the required permissions to view the files attached to this post.
-
Paul Willis
- Forum Team
- Posts: 3048
- Joined: Sun Jul 20, 2008 6:00 pm
Re: Hornby 51xx to P4
doggeface wrote:Of course I have no idea if the pristine models which I have admired from afar, actually run or if they do run are they modified? The other nagging doubt is whether there are components available which can do a better job. I have spent hours scouring the trade ads without success and yet seem to read articles which mention Kits by people I have not heard of nor can I find them via the internet.
During one of my (many) fits of pique when my RTR monster defied all reason and cajoling and I am glaring at the many examples of P4 locos and
it came to me that the vast majority of those locos are examples of inside cylinder models. I leafed through several issues of the news and found that the latest (176) to be typical in having 15 steam locos on view of these only one the RSH 0-4-0ST had valve gear. Being a 4 wheeler it obviously can operate on the curve with a laterally rigid wheel set.
Like some of the contributors (of recent times) who have made the point that those of us trying to construct a working system which is not a highly detailed localised scenario joining two fiddle yards cannot afford to be rivet counters. I find myself wondering if the references to accepting compromises were not in fact pointing out that perfection can only be achieved at the expense of immobility!
From a personal point of view, I don't think so... A lot of what you have seen is to do with people's choice of prototype to model.
Modelling the Great Eastern Railway, almost everything between 1880 and the end of its life was built with inside cylinders. There were a few exceptions, but not the mainstay of the fleet. Ditto, the late Victorian/early 20th century archetypal locomotive was an inside cylindered 0-6-0 in either tank or tender form.
After the last CHEAG workshop, I posted the picture of Richard Dunning's S&D 2-8-0. Not only is that a locomotive with lots of wheels, but outside valvegear as well. If I remember, I'll post a picture of it when I'm back in the country.
Just think - it can be done!
Cheers
Flymo
Beware of Trains - occasional modelling in progress!
www.5522models.co.uk
www.5522models.co.uk
-
essdee
- Posts: 554
- Joined: Sat Nov 29, 2008 4:47 pm
Re: Hornby 51xx to P4
Peter,
I can empathise! As a confirmed (just-)pre-Group modeller, I have always regarded outside valve gear much as a rabbit faces a stoat. I am currently in the midst of my second set of Walschaerts, however, for my second SDJR 2-8-0 (coincidentally, in view of Paul's last posting), in this case largely scratchbuilt.
Looking at your latest pic, I think you are not so far away from success however, so do not despair.
If you could washer-up that leading wheelset so that it has minimal sideplay, whilst free to spin unhindered, you will actually have an excess of clearance between the crankpin and the rear of the crosshead, which is forcing the slidebars - and hence the piston rod, out at that alarming angle. I would have thought that, even with the leading two axles of a 61XX having constrained sideplay, a generous sideplay on the rear axle should work - what is your tightest radius?
Assuming you tighten up that leading sideplay allowance, and even without the measures below, I think you ought to derive immediate benefit from straightening the connecting rods, and bringing the outer ends of the slide bars inwards - that does seem to be an excessive clearance for the leading crankpin/crosshead?
My own 2-8-0s use a three-laminate coupling rod assembly, giving a width over rods of 25.13mm. The distance between the inner slidebar faces is 26.71mm, allowing plenty of room for the 8 thou nickel silver inner crosshead faces, with countersunk screws for the connecting rod pin. After soldering these screws in place I file the head as near to flush as I dare. I think you could shave quite a bit more off your own crosshead fixing screw?
My three-layer rods allow me to countersink the leading crankpin fully within the rod thickness (I use a dental burr to widen the hole in the outermost laminate, and thin the crankpin as well as rounding off its corners). SInce you only have a single layer rod, this is not an option, but with a thin rod you should not need such a measure anyway. However, you have the option of slightly thinning the rod towards the boss, and also ensuring that your inverted crankpin has just enough clearance for free rod rotation, but no excess. Again, I think you still have room to gain a bit more clearance here, if need be.
I would suggest: 1) take up nearly all sideplay at the front axle, 2) straighten the connecting rods/slide bars, 3) next reduce the projection at the rear of the crosshead and, if you still get fouling, look at reducing the front crankpins projection/rod thickness.
Once you have this critical leading axle area working OK, you can look at washering-up the third axle for appropriate sideplay for your curves.
I hope the above gives you a strategy to pursue -once more into the breach etc. Good luck and ultimate success!
Best wishes
Steve
I can empathise! As a confirmed (just-)pre-Group modeller, I have always regarded outside valve gear much as a rabbit faces a stoat. I am currently in the midst of my second set of Walschaerts, however, for my second SDJR 2-8-0 (coincidentally, in view of Paul's last posting), in this case largely scratchbuilt.
Looking at your latest pic, I think you are not so far away from success however, so do not despair.
If you could washer-up that leading wheelset so that it has minimal sideplay, whilst free to spin unhindered, you will actually have an excess of clearance between the crankpin and the rear of the crosshead, which is forcing the slidebars - and hence the piston rod, out at that alarming angle. I would have thought that, even with the leading two axles of a 61XX having constrained sideplay, a generous sideplay on the rear axle should work - what is your tightest radius?
Assuming you tighten up that leading sideplay allowance, and even without the measures below, I think you ought to derive immediate benefit from straightening the connecting rods, and bringing the outer ends of the slide bars inwards - that does seem to be an excessive clearance for the leading crankpin/crosshead?
My own 2-8-0s use a three-laminate coupling rod assembly, giving a width over rods of 25.13mm. The distance between the inner slidebar faces is 26.71mm, allowing plenty of room for the 8 thou nickel silver inner crosshead faces, with countersunk screws for the connecting rod pin. After soldering these screws in place I file the head as near to flush as I dare. I think you could shave quite a bit more off your own crosshead fixing screw?
My three-layer rods allow me to countersink the leading crankpin fully within the rod thickness (I use a dental burr to widen the hole in the outermost laminate, and thin the crankpin as well as rounding off its corners). SInce you only have a single layer rod, this is not an option, but with a thin rod you should not need such a measure anyway. However, you have the option of slightly thinning the rod towards the boss, and also ensuring that your inverted crankpin has just enough clearance for free rod rotation, but no excess. Again, I think you still have room to gain a bit more clearance here, if need be.
I would suggest: 1) take up nearly all sideplay at the front axle, 2) straighten the connecting rods/slide bars, 3) next reduce the projection at the rear of the crosshead and, if you still get fouling, look at reducing the front crankpins projection/rod thickness.
Once you have this critical leading axle area working OK, you can look at washering-up the third axle for appropriate sideplay for your curves.
I hope the above gives you a strategy to pursue -once more into the breach etc. Good luck and ultimate success!
Best wishes
Steve
You do not have the required permissions to view the files attached to this post.
-
Will L
- Posts: 2529
- Joined: Sun Jul 20, 2008 3:54 pm
Re: Hornby 51xx to P4
Are the delights of a creative hobby, I do like to watch others suffer too. I suspect most of the pleasure comes looking back on the battle once its over. Please take what follows as moral support. I'm sure that if you keep at it you will get there in the end.
Personally I think this whole saga points up the problem with taking the easy way out and "just re-wheel an RTR", your not in control of your own destiny. Given there is never going to be more than b****r all clearance behind the cross head and you meck demands the centre axle has no side play, you have little choice other than put all the movement on the 3rd axle and see how you get on. I suspect this will give you less trouble than trying to maintain some movement in the front axle, and you probably wont need as much movement on the 3rd as fear suggests. It ought to be OK so long as your wary of buffer lock when pushing stock bunker first. The GW did nice big oval buffers as I rememberer it, perhaps there is a hint there.
You are of course absolutely right that the great Victorian inside cylinder loco is a god send to some modellers, but the popularity of Gods Wonderful must imply there are solutions.
Will
Personally I think this whole saga points up the problem with taking the easy way out and "just re-wheel an RTR", your not in control of your own destiny. Given there is never going to be more than b****r all clearance behind the cross head and you meck demands the centre axle has no side play, you have little choice other than put all the movement on the 3rd axle and see how you get on. I suspect this will give you less trouble than trying to maintain some movement in the front axle, and you probably wont need as much movement on the 3rd as fear suggests. It ought to be OK so long as your wary of buffer lock when pushing stock bunker first. The GW did nice big oval buffers as I rememberer it, perhaps there is a hint there.
You are of course absolutely right that the great Victorian inside cylinder loco is a god send to some modellers, but the popularity of Gods Wonderful must imply there are solutions.
Will
-
essdee
- Posts: 554
- Joined: Sat Nov 29, 2008 4:47 pm
Re: Hornby 51xx to P4
Peter,
Whoops - bad proof reading by me. I hope it is obvious in my earlier posting that when I referred to 'thinning and rounding corners of crankpin', I meant 'crankpin nut', and also later reference to 'inverted crankpin', also meant 'crankpin nut'. Apologies for any confusion.
Hope you get past this hurdle soon, anyway. (Last night I tackled a critical assembly of slidebars and motion bracket that has worried me for last couple of weeks; in the event it took ten minutes, with a further five for final adjustment - phew! So on to the next hurdle....)
Best wishes
Steve
Whoops - bad proof reading by me. I hope it is obvious in my earlier posting that when I referred to 'thinning and rounding corners of crankpin', I meant 'crankpin nut', and also later reference to 'inverted crankpin', also meant 'crankpin nut'. Apologies for any confusion.
Hope you get past this hurdle soon, anyway. (Last night I tackled a critical assembly of slidebars and motion bracket that has worried me for last couple of weeks; in the event it took ten minutes, with a further five for final adjustment - phew! So on to the next hurdle....)
Best wishes
Steve
-
doggeface
Re: Hornby 51xx to P4
Thanks for the moral support chaps. I confess to avoiding the issue for a while and throwing myself into track assembly and electrics. The 51XX is matched only with my long curved cross over for sheer cussidness but that seems to have given up the struggle with the lungeing rein!
I have made the decision to remove all play from the forward axle and to thin the crosshead end of the crank rod. I am using the standard comet idea of a dress makers pin for the x-head fixing , the rod does not seem to have enough meat to stand drilling out to 1mm+ needed for my smallest c/s bolts (Gibson crank pin bolts). The procurement of small metric fasteners is another nightmare and the simple answer is to use BA. I gave away all my BA gear together with a near hundred weight of BSF & BSW spanners on being driven out of business by the Thatcher regime in 1992! I must say that I have never regretted retiring at that point and suppose that I should be grateful to her!
I take the point about RTR conversions but it is not always due to ease & convenience! Prior to my decision to come into this wonderful world of P4 I had an extensive 00 DCC system with some 45 locos. These were the ones which I did not wish to abandon after dismantelling the previous even bigger system with some 75 locos! Having looked at the RTR conversion kits on offer it was clear that only the simplest were catered for and I would need to either build new P4 chassis or find ways of doing the deed with the existing chassis. Both the 14XX and the 51XX(I use this as a generic) have elegant chassis born ballast whereas the normal chassis kit is not easily ballasted and thus passes the problem of fitting it to the body moulding. The only other solution being the cast body kits. My research on that front found that not only are the kit makers few in number but their range is limited and the cost very high. This always rings a little hollow as a Martin Finney on completion would clearly top £200 I have to balance that against the asking price of a HO SNCF pacific in the Dijon model shop shown as a bargain at only €498 !
It is a non argument in any case as no one is rushing to give me any more money in my retirement and every politician in the UK & Yerp is training their sights on my remaining dosh. So onwards with making the most of what we have!
Another cost which is allied to my hobby is (yesterday) having to buy my dear wife a new motorbike to replace her ageing Honda!
The 51XX is on the bench awaiting the butchers attention.
As a complete irrelevance , as a lad I really enjoyed the 12 mile ride over the hill to Green Park, Bath to goof at those S&D 2-8-0's rubbing shoulders with 3 or 4 West Countries (of both configurations) and those gangling 7' 4-4-0 2P's.
I have made the decision to remove all play from the forward axle and to thin the crosshead end of the crank rod. I am using the standard comet idea of a dress makers pin for the x-head fixing , the rod does not seem to have enough meat to stand drilling out to 1mm+ needed for my smallest c/s bolts (Gibson crank pin bolts). The procurement of small metric fasteners is another nightmare and the simple answer is to use BA. I gave away all my BA gear together with a near hundred weight of BSF & BSW spanners on being driven out of business by the Thatcher regime in 1992! I must say that I have never regretted retiring at that point and suppose that I should be grateful to her!
I take the point about RTR conversions but it is not always due to ease & convenience! Prior to my decision to come into this wonderful world of P4 I had an extensive 00 DCC system with some 45 locos. These were the ones which I did not wish to abandon after dismantelling the previous even bigger system with some 75 locos! Having looked at the RTR conversion kits on offer it was clear that only the simplest were catered for and I would need to either build new P4 chassis or find ways of doing the deed with the existing chassis. Both the 14XX and the 51XX(I use this as a generic) have elegant chassis born ballast whereas the normal chassis kit is not easily ballasted and thus passes the problem of fitting it to the body moulding. The only other solution being the cast body kits. My research on that front found that not only are the kit makers few in number but their range is limited and the cost very high. This always rings a little hollow as a Martin Finney on completion would clearly top £200 I have to balance that against the asking price of a HO SNCF pacific in the Dijon model shop shown as a bargain at only €498 !
It is a non argument in any case as no one is rushing to give me any more money in my retirement and every politician in the UK & Yerp is training their sights on my remaining dosh. So onwards with making the most of what we have!
Another cost which is allied to my hobby is (yesterday) having to buy my dear wife a new motorbike to replace her ageing Honda!
The 51XX is on the bench awaiting the butchers attention.
As a complete irrelevance , as a lad I really enjoyed the 12 mile ride over the hill to Green Park, Bath to goof at those S&D 2-8-0's rubbing shoulders with 3 or 4 West Countries (of both configurations) and those gangling 7' 4-4-0 2P's.
-
Horsetan
- Posts: 1385
- Joined: Tue Jul 29, 2008 9:24 am
Re: Hornby 51xx to P4
doggeface wrote:...... The 51XX is matched only with my long curved cross over for sheer cussidness but that seems to have given up the struggle with the lungeing rein!....
Some horses are more difficult to train than others.
That would be an ecumenical matter.
-
Tim V
- Posts: 2870
- Joined: Tue Jul 29, 2008 4:40 pm
Re: Hornby 51xx to P4
My Airfix 51xx has been found, here is a picture. Quite difficult to show both sides in one picture, but there is sufficient room as you can see.
You do not have the required permissions to view the files attached to this post.
Tim V
(Not all railways in Somerset went to Dorset)
(Not all railways in Somerset went to Dorset)
-
doggeface
Re: Hornby 51xx to P4
Well, after what seems several months (actually some 5 weeks) I put my mind onto the problem. Tim had shown the space on his original Airfix example but I have struggled to make it the same using Gibson wheelsets. I can recognise the cyls as Comet but the wheels are other than Gibson (Exacto perhaps?).
Anyway the first move was to measure the wheel set characteristics again. Taking the driven axle as the reference (it cannot move laterally) it seemed to be centred up correctly. I now applied a straight edge along the inside of the flanges to align the wheel set before measuring the leading axle's spacer lenths (this was allowed to move too much and I am aiming for zero movement). This gave 2.7mm one side and 2.2mm on the opposite side. Try as I may , the 0.5mm difference could not be found on the centre axle. The driving sprocket had been positioned such that it ran central to it's limited running space and left each wheel the same distance from the chassis side face. The after axle is left with a great deal of freedom (1mm each side). The situation was accepted. The Crank nut faces were by now wafer thin (and of course reversed) and the piston rodpin also taken down to the minimum (recessed away from the slide bar surfaces). The result was now that both sides were sitting with a similar gap between Crank Nut and slide crank pin -- that is to say Zero mm! This has been remedied by easing the slide bars outwards. It is now clear and runs but the clearance is smaller than my thinnest feeler gauge!
I very quickly fitted a DCC chip to the loco ( it has to be the easiest of non fitted models) and away it went. It really made my far from perfect track look good by cheerfully traversing the 5 point sets which give my rolling stock so much trouble.
I suppose that I should smile gratefully and take up my 14XX where I abandoned it and try for a similar result!
Anyway the first move was to measure the wheel set characteristics again. Taking the driven axle as the reference (it cannot move laterally) it seemed to be centred up correctly. I now applied a straight edge along the inside of the flanges to align the wheel set before measuring the leading axle's spacer lenths (this was allowed to move too much and I am aiming for zero movement). This gave 2.7mm one side and 2.2mm on the opposite side. Try as I may , the 0.5mm difference could not be found on the centre axle. The driving sprocket had been positioned such that it ran central to it's limited running space and left each wheel the same distance from the chassis side face. The after axle is left with a great deal of freedom (1mm each side). The situation was accepted. The Crank nut faces were by now wafer thin (and of course reversed) and the piston rodpin also taken down to the minimum (recessed away from the slide bar surfaces). The result was now that both sides were sitting with a similar gap between Crank Nut and slide crank pin -- that is to say Zero mm! This has been remedied by easing the slide bars outwards. It is now clear and runs but the clearance is smaller than my thinnest feeler gauge!
I very quickly fitted a DCC chip to the loco ( it has to be the easiest of non fitted models) and away it went. It really made my far from perfect track look good by cheerfully traversing the 5 point sets which give my rolling stock so much trouble.
I suppose that I should smile gratefully and take up my 14XX where I abandoned it and try for a similar result!
Last edited by doggeface on Tue May 08, 2012 4:01 pm, edited 1 time in total.
-
Tim V
- Posts: 2870
- Joined: Tue Jul 29, 2008 4:40 pm
Re: Hornby 51xx to P4
Those are the original unmodified Airfix cylinders and Ultrascale wheels.
Tim V
(Not all railways in Somerset went to Dorset)
(Not all railways in Somerset went to Dorset)
-
doggeface
Re: Hornby 51xx to P4
Well I am impressed that the cyls have shown up so well. There is obviously a difference in the piston centre position between the comet and the airfix.
During my earlier exchanges with both Comet and Gibsons it become clear that my difficulty is not new and that the end result is the best possible.
My earliest thought was that fixing the front axle laterally together with the centre (which is fixed unlike the Airfix which is front axle drive as shown) would give me problems on relatively easy curves. As it transpires the rigid 0-4-0 +0-2-0 arrangement does work. I had already improved the bogie road holding and lead-in ability by using coil springs on the swivel posts (they give a positive declination without forcing the drivers up and provide some tortional friction).
Once I have more than 5.5M run to play with the truth will out!
As I have a second unit to convert I am minded to modify the comet cyl assembly by cutting it and giving it about 2mm extra width. This will solve all of the clearance problems and reduce the production time by several months.
During my earlier exchanges with both Comet and Gibsons it become clear that my difficulty is not new and that the end result is the best possible.
My earliest thought was that fixing the front axle laterally together with the centre (which is fixed unlike the Airfix which is front axle drive as shown) would give me problems on relatively easy curves. As it transpires the rigid 0-4-0 +0-2-0 arrangement does work. I had already improved the bogie road holding and lead-in ability by using coil springs on the swivel posts (they give a positive declination without forcing the drivers up and provide some tortional friction).
Once I have more than 5.5M run to play with the truth will out!
As I have a second unit to convert I am minded to modify the comet cyl assembly by cutting it and giving it about 2mm extra width. This will solve all of the clearance problems and reduce the production time by several months.
-
Tim V
- Posts: 2870
- Joined: Tue Jul 29, 2008 4:40 pm
Re: Hornby 51xx to P4
Between the inside faces of the crosshead 26.44mm
Cylinder Centres 30.04mm
Across outside of the front crankpins 24.15
Across outside of cylinders 38.36mm
Hence a gap of just over 2mm behind the crossheads - more than enough. It is important to make sure there is minimal sideplay in the front axle, all sideplay should be on the middle axle.
Cylinder Centres 30.04mm
Across outside of the front crankpins 24.15
Across outside of cylinders 38.36mm
Hence a gap of just over 2mm behind the crossheads - more than enough. It is important to make sure there is minimal sideplay in the front axle, all sideplay should be on the middle axle.
Tim V
(Not all railways in Somerset went to Dorset)
(Not all railways in Somerset went to Dorset)
-
Tim V
- Posts: 2870
- Joined: Tue Jul 29, 2008 4:40 pm
Re: Hornby 51xx to P4
I just looked at your first photo again - you've used a standard crank pin. You need to reduce the thickness there, the prototype used a recessed pin.
Tim V
(Not all railways in Somerset went to Dorset)
(Not all railways in Somerset went to Dorset)
-
doggeface
Re: Hornby 51xx to P4
Yes, the photo showing the original state of play was the subject of Gibsons proposing the reversal of the crank pin nut. This involved reducing the inner bush bearing stub thickness and reversing the outer fixing nut so that it's stub became the conn rod bearing. The nut was then reduced in thickness until it no longer looked to have any mechanical strength! The Comet suggestions involved the mounting of the crank pin from the inside and filing off the dome - this after having thinned down the web of the crosshead. It was at this point that the clearance = zero! When I buy in the next set of cyls from comet I intend to spend a while looking at more elegant ways of moving the slide gear outboard a tad.
Peter
Peter
-
Mike Garwood
- Posts: 618
- Joined: Sun Aug 03, 2008 4:51 pm
Re: Hornby 51xx to P4
I think you'll find that the Comet etches for cylinders have this done already. There was a fair bit of discussion some years back which resulted in Jeff Ayres - I think - redesigning the cylinder etches to allow for more room behind the xheads. I have to admit to slicing these etches and pulling them a further 0.5 - 1mm apart to get clearance before now.
If your etches are from brass these are the older not moved out type, if etched in NS these are the newer moved out centres.
Mike
If your etches are from brass these are the older not moved out type, if etched in NS these are the newer moved out centres.
Mike
-
Horsetan
- Posts: 1385
- Joined: Tue Jul 29, 2008 9:24 am
Re: Hornby 51xx to P4
Mike Garwood wrote:.....I have to admit to slicing these etches and pulling them a further 0.5 - 1mm apart to get clearance before now. ....
Same here. Where possible, I've been swapping them for the new n/s etches.
That would be an ecumenical matter.
-
doggeface
Re: Hornby 51xx to P4
The loco has been running for about a week albeit in a 99/ clonck type of propulsion. I believe that it is referred to as "running in!"I did widen the guide bars a little to gain the clearance.
The successful running was marred when the loco tripped the DCC o/l on a particular B6R turnout. The flash of sparking made it clear that the Starboard front bogie was in contact with the cylinder inner front edge momentarily. It looks like a visit from the Dremel is called for.
The same work carried out on a 14XX has been successful and that runs like a dream and thinks that all of my points are wonderful ( as does the 51XX)
Work on the other 14XX went so well that it was bound to be a disaster - and it was! The premade conn rods did not do much of a job so I have reverted to reforming the originals using the Gibson ~2mm bushes made for that job. I reckon that the other 51XX will keep it's valve gear and have only it's wheel set changed - that will be good exercise and also make sense to employ as much of the original as possible. We will see!
The successful running was marred when the loco tripped the DCC o/l on a particular B6R turnout. The flash of sparking made it clear that the Starboard front bogie was in contact with the cylinder inner front edge momentarily. It looks like a visit from the Dremel is called for.
The same work carried out on a 14XX has been successful and that runs like a dream and thinks that all of my points are wonderful ( as does the 51XX)
Work on the other 14XX went so well that it was bound to be a disaster - and it was! The premade conn rods did not do much of a job so I have reverted to reforming the originals using the Gibson ~2mm bushes made for that job. I reckon that the other 51XX will keep it's valve gear and have only it's wheel set changed - that will be good exercise and also make sense to employ as much of the original as possible. We will see!
-
martin goodall
- Posts: 1427
- Joined: Fri Oct 02, 2009 6:20 pm
Re: Hornby 51xx to P4
"Gibson 2mm bushes made for that job"?
I have not heard of these before. Are they available separately? I think I may have a use for bushes of this size to fit adapted coupling rods/con rods on an RTR conversion.
Any information (posted here) would be gratefully received.
I have not heard of these before. Are they available separately? I think I may have a use for bushes of this size to fit adapted coupling rods/con rods on an RTR conversion.
Any information (posted here) would be gratefully received.
-
grovenor-2685
- Forum Team
- Posts: 3923
- Joined: Sun Jun 29, 2008 8:02 pm
Re: Hornby 51xx to P4
AG has bushes intended to fill the holes in RTR rods so that they fit on AG crankpins. I bought some last week, as yet unused.
Code Item Price Price
4800 Crankpin Washers for Conversion £2.00 £2.40
Regards
Keith
Code Item Price Price
4800 Crankpin Washers for Conversion £2.00 £2.40
Regards
Keith
-
Philip Hall
- Posts: 1957
- Joined: Mon Aug 10, 2009 7:49 pm
Re: Hornby 51xx to P4
AG has bushes intended to fill the holes in RTR rods so that they fit on AG crankpins
These bushes are indeed very useful, but beware of locos like the Bachmann 76XX BR 2-6-0 where the holes in the rods are 2.7mm rather than the usual 2.5mm. In these cases I've had to resort to turning my own...
Philip
Who is online
Users browsing this forum: ClaudeBot and 9 guests