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page 4


buffalo

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Buffalo WorkBench

 

by buffalo

 

original page on Old RMweb

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This is the fourth page of the Buffalo build copied from the old RMweb.

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??? posted on Mon Jul 27, 2009 5:39 pm

 

Ah, the dangers of introducing new topics in the middle of a thread...everything gets interleaved icon_wink.gif

 

Stephen and Andy, thanks for starting a vigorous discussion of the CLAG CSB approach and its antecedents icon_smile.gif As I understand it, the CLAG people favour having no constraints on the movement of the ends of the spring beam. However, the pictures at http://www.clag.org.uk/class2p.html show what I believe is a typical example of their approach where one beam end is bent to form a small tag, presumably just to aid retention. It appears that, under some conditions, this will constrain linear movement of the spring. Under these conditions, the effect would be identical to that of the fixed end Varney and Lindsay approach with the screw and end spring at the fully slack position.

 

The benefit of this latter approach, as described by Stephen, would appear to be that one can start with a slightly too light spring beam and then increase the spring rate until the desired ride height is achieved. This does seem rather easier than hoping you have the fulcrum positions correct and experimenting with different wire thicknesses. Provided that there is no restriction on the linear movement of the spring beam at the intermediate and spring end fulcrums (fulcra?) and over the movable hornblocks, then the two systems should be equivalent.

 

I accept that in practice there will always be some restriction here, but this would be small as would any differences in restriction between the two approaches. Where the approaches differ appears to be in the location of the fulcrums. The instructions in the spreadsheet make it clear that spring rate on the central axle of an 0-6-0 should be reduced to enable a softer spring and hence greater deflection for the same input. If I understand it correctly, this is intended to improve pitch stability. In contrast, Stephen suggests making all spring sections the same length so, I assume, having a constant spring rate on all axles.

 

Of course, I may not understand all this as well as I thought... icon_wink.gif

 

Nick

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Comment posted by Bertiedog on Mon Jul 27, 2009 8:15 pm

 

Apologies for hijack to springing, it is to entertain you whilst musing about the Buffalo and CSB..........

 

I do tend to try on a straight forward equal spaced 060 to space the fulcrums equally, but I do shift them if it's say a GWR Castle chassis, making the middle run longer for more movement, and a shorter run over the front axle to stiffen. The taut wire does the rest. I have never worked out the formulas...life is too short on models..... I did work out such details for test equipment, we made instruments to BS National test standards, no tolerance test gear..but models?

 

The drawing was only a quick sketch and in practice the wire is near straight at the correct tension, a very small deflection occurs as it settles on the track....AND IT IS ALL ADJUSTABLE, a vital de-luxe addition, rather than trying to design a one fits all solution. It does take a bit of thought to find the right springs of course, again it may not suit running straight from the box....but we are building locos and that's what makes it a bit of fun............

 

The max., rise is about 20 to 25 thou (.5 mm is 19.6thou), very small, and makes theoretical calculations of beam angles only an academic exercise........ The inner end is formed in a loop, around a stud, and has no restraint up and down, and the other end is sprung via the shackle.

 

Originally two springs were used by Lindsay, according to my friend who was an NMRA expert, and supplied the details of the Varney long before I saw any. I too am too young to have seen the original at the time.

 

He had several, and I still have one of these, along with a Kemtron Wabash mogul, modified to full springing with duel coil sprung wires.

 

The locos could manage a test track we built with a roller coaster surface to the rails to test the track holding ability. At the time, about 1972, most Japanese brass locomotives also had full springing, but with individual coils on each axle. There were no UK locos with any form of springing, except hand built.

 

The locos worked fine on ordinary track or "rough track", but failed on the roller coaster, which the Varney strolled along, albeit leaning a bit as the bumps were 4 to 8 mm high and random length!!. The main purpose was to test the RP25 wheel profile and how small it could go, and develop fine scale HO standards like the then new P4.

 

The test standard loco was a Tenshodo Niagara, fitted with new rate adjusted springs, and 2mm possible movement.

 

The Varney Pacific has movement of about 3mm, much more, and it weighed about 4 pounds due to a lead boiler. The wires are about 25 thou.

 

I added a compensated bogie pivot, with side and weight transfer from the main frame, and also modified the trailing bogie to springing, without compensation. The trucks were Central Valley fully sprung 6 wheeled.

 

It was very difficult to find track bad enough to stop the loco......the test run was made from old Wrenn 16.5..the fibre base, so had warps in it already!

 

I also built a roller coaster test track in P4, to see how far you can go with rough track, and the Varney system was again the best, allowing 4mm bumps and dips of random lengths. By it's very natural P4 is more difficult, most UK locos are more difficult to arrange the springing due to the variety of wheel bases. The test loco was a P4 Castle, and a Tri-ang Lord of the Isles converted to P4, with springing by coils.

 

As some as the bugs were worked on UK outlines, I stuck with the sprung wire as the preferred method making locos professionally. Believe it or not many UK customers ordered locos without springing at all, they disliked any form of springing.....I hope their track was perfect............

 

Stephen.

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Comment posted by Bertiedog on Mon Jul 27, 2009 9:01 pm

 

I accept that in practice there will always be some restriction here, but this would be small as would any differences in restriction between the two approaches. Where the approaches differ appears to be in the location of the fulcrums. The instructions in the spreadsheet make it clear that spring rate on the central axle of an 0-6-0 should be reduced to enable a softer spring and hence greater deflection for the same input. If I understand it correctly, this is intended to improve pitch stability. In contrast, Stephen suggests making all spring sections the same length so, I assume, having a constant spring rate on all axles.

Before it gets taken as gospel that I said the fulcrums should be equally spaced, it only applies to reasonably symmetrical chassis, after all the real thing has no fulcrums, wires or beams, and may not be compensated at all. you have to use a bit of judgement, and adjust things to allow more or less movement as needed.

 

I should state firmly that I really prefer to fit full compensation beam suspension, and I have built 5 inch gauge passenger haulers with "real" suspension several times.....the whole wire system for HO and OO is only a workaround to get good working results, not related to the real arrangements of full sized locos.

 

Stephen.

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Comment posted by intelegence on Mon Jul 27, 2009 9:24 pm

 

Bertiedog wrote:

"intelegence"

 

Firstly, I don't believe the the CLAG team has laid any claim to being the original inventors of CSB's. Many of their comments on various lists have humbly referred to merely building on the work on others.

I did not say that CLAG originated it..........

You said they re-invented it.

 

But having replied to the assumptions posted, I would like to say that, as a past manufacturing industry professional, the thought of an "adjust on test" requirement on a design intended to be reproduced by others as simply as possible , seem to me to be a major retrograde step.

.

 

So.... all spring designs should work without adjustment, and each loco would need individual diameters to suit the weight?

Yes. the loco weight isn't going to change after it's commissioning icon_wink.gif And all locos of the same design should be able to work with the same diameter wire. I haven't yet bought an automobile that subsequently required any adjustments to it's spring rates either icon_wink.gif

 

.The only adjustment possible* on the beam is the diameter...

That simplification is CLAG's major point and claimed advantage.

 

unless other springs are added. Adding the coil spring eases matters all round.

*without adjusting the fulcrum points, and consequent spring length

 

I think that you may be over estimating the effect of the spring, it is the wire beam that takes the weight, not the coil spring, which is there to exert extra assistance to the springing.

No. by your own logic, you just said it compensates sufficiently, for not having different wire diameters. That's a big effect.

 

May I add I too have long experience in engineering and instrument design, and also have built large quantities of chassis with this springing, all worked. When I suggest a method, I know from practical experience that it works, and make the suggestion a simple as possible to aid newcomers.

I realize that the net effect has been shown to be very good, either as the CLAG implementation or Varney's/yours. And I wonder whether, as seems likely, the CLAG and your implementation, with the extra spring, are or are not actually functionally identical, although superficially they may seem so.

 

My only interest and concern is knowing HOW it works. Only then can you make any meaningful adjustments to alter the characteristics, and in the right direction.

 

A question which I still have, which perhaps you can shed some light on, is as follows. The beam rigidity aspects of either system apparently tend to partially transfer an up motion of one wheel, through the intermediate fulcrum, into a lesser down motion of an adjacent wheel. So if this is good for an x-6-x wheel arrangement, why is it also then similarly good for an x-8-x arrangement? Clearly the up and down motion pressure of adjacent wheels would match the shape of a single track distortion for the 6 coupled passing over the distortion, but not then in the case of the 8 coupled chassis. And then the same issue arises if the 8 coupled chassis is compared with a 10 coupled one.

 

Your thoughts?

 

Andy

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Comment posted by Bertiedog on Mon Jul 27, 2009 10:06 pm

 

Springs on cars are adjusted and changed all the time, only a bog production car would have no changes. each set up does a different job, my father and I built many rally and hill climb cars, each had multiple set ups for each special use, even having air dampers with variable pressure.

 

All springs relate to the job, and require adjustment to get the right results, that's why leaf springs are adjustable by removal or addition of leaves, various thickness's, and sets of various shackles. My own classic Austin has a custom set designed by myself.

 

On 0-8-0 or 0-10-0, I simply would not fit the wires method but use compensation beams split into two units and in the case of an 0-10-0 spring the centre separately on an OO model. I built GER Decapod in P4 with springing, and that had all coils, with two compensation units.

 

I know from long experience with live steam 5 inch gauge that springing has to be adjustable, springs settle for a start!.. and needs fine tuning to get the best ride. Even with the minute movement on OO, the wire will sag with age, and must require re-setting, which with the shackle spring can be done in seconds.

 

The CLAG outline works well, and the suggested positions for fulcrums work, but it is all non adjustable, if it is wrong, you would have to start again, moving the fulcrums, but with adjustment you would cure it in seconds.

 

I design simple solutions I know work, with adjustments where practical. It's great that CLAG have published the details, it suits them I am sure, but some solutions mentioned are complex, and the average modeller is not Mike Sharman, or capable of applying his methods.

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Comment posted by Bertiedog on Mon Jul 27, 2009 10:28 pm

 

Actually I have a suitable Loco coming for conversion to proper springing, coming on to the workbench soon, after the Taff Vale, an early 1950's brass Japanese NYC Niagara, un-marked with maker, but believed to be an early Tenshodo that was made before the days of springing such models. It was bought from the States from a closed shop clear out, un-used, and stored away for 40 odd years.

 

It runs fine, but baulks at poor track, due to the rigid design, so is worth a re- build to add full springing following the Varney springing layout. By the way the Super Pacific product was about the only item from Varney that did work well, a lot of the range was poor in design, somewhat crude, and cheaply made.

 

The brass Niagara is well detailed , with stamped parts rather than etched , but to a very fine standard. The only let down is the lack of any springing at all, bar a coil spring on the lead bogie, which frankly does little to keep the thing on the track.

 

A saving grace is that it has near RP25 profile wheels, albeit with sharper flange shape, years before the NMRA standards were mooted.

 

I will start a new thread when the work is under way.

 

Stephen,

 

BACK TO THE BUFFALO!!

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Comment posted by Miss Prism on Tue Jul 28, 2009 12:24 am

 

Bertiedog wrote:

The spring wire is still loose over the axle boxes and is not attached in any way to them, or to the fulcrums,

I'm trying to understand the first diagram you posted, Stephen. Is the spring at the left-hand outer fulcrum point constrained in the longitudinal axis or not?

 

In the second diagram, what was the ballpark dimension achieved for the length between the beam/coil attachment point and the head of the adjuster bolt?

 

Btw, I hope Buffalo will say if he feels his thread is being 'overly diverted' - I'm sure the Mods could move the recent CSB postings to a separate thread if he wished, and it might be good forum order to do so. ('The CSB thread'?)

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Comment posted by LNWRmodeller on Tue Jul 28, 2009 9:25 am

 

London Road Models produce an etch of CSB "adaptors" to fit onto their hornblock bearings (and anybody else's with a 4.0mm OD lip). The etch includes chassis mountings, fixed single hole, fixed mutiple hole and screw adjustable types.

 

A scan of the etch and a pdf file of the instructions can be found in the price list section of LRM's website (hosted by the Scalefour Society) at http://www.londonroadmodels.co.uk.

 

The CLAG website provides a downloadable Excel file which is a great aid in calculating the locating points for the CSB chassis mountings, wire diameter, wire type, etc. I would strongly recommend that anyone considering CSB's look at the CLAG site and the LRM items before drawing any final conclusions from the postings on this topic.

 

Jol Wilkinson

 

(with apologies for the continued hijacking of this topic, but it's only about GWR locos anyway icon_smile.gif

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Comment posted by Bertiedog on Tue Jul 28, 2009 9:41 am

 

Miss Prism wrote:

Bertiedog wrote:

The spring wire is still loose over the axle boxes and is not attached in any way to them, or to the fulcrums,

I'm trying to understand the first diagram you posted, Stephen. Is the spring at the left-hand outer fulcrum point constrained in the longitudinal axis or not?

 

In the second diagram, what was the ballpark dimension achieved for the length between the beam/coil attachment point and the head of the adjuster bolt?

 

Btw, I hope Buffalo will say if he feels his thread is being 'overly diverted' - I'm sure the Mods could move the recent CSB postings to a separate thread if he wished, and it might be good forum order to do so. ('The CSB thread'?)
.

 

The wire is looped around a pin or bolt, and soldered or crimped to itself, loosely mounted, in other words and allows the wire to move in arc restrained by the loop.

 

This movement is very small indeed, a matter of a couple of degrees at extremes of movement. The adjusting bolt is usually about an inch of 8 or 10 BA, what ever is to hand. I set the spring to just tension with the nut at the farther end and simply tighten till the ride height is correct for the weight, and then test run.Most of the locos weight is taken as per the CLAG CSB calculations.

 

From that point it behaves the same as any spring wire beam suspension, although I am sure a mathematical analysis will indeed reveal differences, friction, effective fulcrum positions moved,etc., etc., if I had the time and inclination, I would work it out in mathematical terms, but that's not what I was after, I want a simple system that works, as this method does, as does the full CLAG method

 

I am not stopping anybody from using the CLAG figures or buying in full commercial implementions of it, just pointing to another alternative. I take no credit for the way I do them, and I do not sell any item whatsoever in connection with it.

Stephen.

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Comment posted by Bertiedog on Tue Jul 28, 2009 9:47 am

 

To get out of Buffalo's thread I will post on CSB separately this morning,

As I said.......... Back to the Buffalo.....

Stephen.

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??? posted on Tue Jul 28, 2009 10:37 am

 

Miss Prism wrote:

Btw, I hope Buffalo will say if he feels his thread is being 'overly diverted' - I'm sure the Mods could move the recent CSB postings to a separate thread if he wished, and it might be good forum order to do so. ('The CSB thread'?)

Bertiedog wrote:

To get out of Buffalo's thread I will post on CSB separately this morning,

As I said.......... Back to the Buffalo.....

Feel free to hijack icon_smile.gif . I've found it very instructive and, together with the CLAG and LRM material, it has helped me clarify my understanding of the CSB approach. Of course, it probably does warrant a new thread, but it would be simple enough to put in a link back to the start of this CSB discussion. It may be a bit of a fiddle for the mods to move a whole load of posts. I've put a link in the 'index' in the first post of this thread.

 

I'll get back to the Buffalo as soon as I have something to show, perhaps even a springy chassis icon_wink.gif

 

LNWRmodeller wrote:

London Road Models produce an etch of CSB "adaptors" to fit onto their hornblock bearings (and anybody else's with a 4.0mm OD lip). The etch includes chassis mountings, fixed single hole, fixed mutiple hole and screw adjustable types.

Thanks, Jol. Yes. I have been looking at these and found the instructions very useful, but I think I will probably use a simple arrangement based on handrail knobs or similar.

 

Nick

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??? posted on Tue Jul 28, 2009 12:38 pm

 

Stephen's new CSB thread is at http://www.rmweb.co....t=48546&start=0. I'll continue to follow it with interest.

 

Nick

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??? posted on Wed Jul 29, 2009 9:33 pm

 

Well, I think I have worked out my fulcrum positions, now I just need the courage to drill the holes where the sums tell me they should be -- there really should be a 'grossly over-confident' smiley here but I can't find anything suitable icon_wink.gif

 

In the meantime attention has turned to fitting the main parts of the body and then some of the detail castings. The first problem to arise was that the cab floor is about 1.5mm too long. It was not possible to fit the tanks and bunker in their correct positions with the cab and floor in place. After a while I realised that this floor is intended for both the open and closed cab variants, the closed cab being appropriate for the pannier conversions. The kit contains an etched cab back for the closed cab and a w-m bunker front for use with the open cab. The cast bunker front is, of course thicker than the etched brass and the floor must be trimmed to allow for the difference*. I also found the floor needed some work to get it to fit correctly over the rear splashers but, once this had been done, the cab and floor fitted properly between tank and bunker.

 

* Edit: WARNING, if you are following this, don't cut the cab floor until you are happy with the cab position and alignment of handrails (see below). I did, and my cab floor is now too short icon_redface.gif See later post

 

This led to the next problem:

 

blogentry-6746-12561498314228.jpg

 

The tanks, cab and bunker are now placed in their intended positions, nothing is fixed yet, and the width of the 'doorway' is reasonably close to that in both of the drawings in Russell. However, it appears that the cutout in the footplate at the top of the steps is a bit too big. I also suspect that on the prototype it was less rounded with squarer corners. In the photo above, it looks as though the bunker actually overlaps the cutout, but it's not that bad. There is a small amount of movement in the bunker and it can be fixed to avoid the overlap. The real problem is that there is not enough room to drill a hole for the lower end of the hand rail.

 

I'm not sure of the best solution yet, although comparison with photos suggests that the cab front is perhaps an inch or so too far back and there is some variation in the position of the tank/boiler front relative to the buffer beam. Perhaps it will be possible to take a little off the back or the tanks and/or the locating surfaces under the smokebox saddle, to enable the cab to move forward by just a small amount.

 

Next installment when I've solved this one or made progress on the springy bits.

 

Nick

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Comment posted by Bertiedog on Wed Jul 29, 2009 11:11 pm

 

I have been discussing today very, very, extensively the CSB and the CLAG website details with my friend David, who started my using the wire system in the 1970's. and can I suggest one point to help ease the fitting of the whole CSB system as outlined by CLAG , and that is to have adjustable fulcrum points.

 

My friend had not previously seen the CLAG calculations, but suggests, (as I did), after reading through them that they are followed exactly as to the position on the top of the fulcrum points, but to drill the holes slightly lower down and fit the screw mounted fulcrums I suggested on the other posting.

 

They would be say 8/10 BA bolts, screwed in to the side frames, with a "Blade" soldered in to the screw slot. This would be the thickness of the slot, about 25/30 thou, and about double the width of the head. The area that touches the head could be recessed to get the end of the blade wider, to make the actual fulcrum point in contact with the wire. The top edge could also be chamfered to a knife edge to minimise friction.

 

Once screwed in, but not tight, it will be possible to move the fulcrum pivot point backwards and forwards by about 4mm or so, albeit with slight,(forget it!) up and down movement as well. If the figures from CLAG are correct then the blade will be vertical, and any adjustment very small.

 

He suggests that the screws could then be sealed with a drop of loctite, or with a thicker frame, a grub screw could be inserted in to the outside of the same hole to lock it. With the double framed Buffalo, a full nut could be used on the inner frames outside without showing.

 

I notice that for simplicity, the CLAG group suggest the use of handrails knobs and these make the use of a keeper for the hornblock un-necessary. If the adjustable bolts are used the keeper plates will be needed( or a keeper wire etc., or small wires across each hornblock to retain the wheel sets from dropping out..

 

The fulcrum positions and the suggested wire sizes would remain exactly the same as the CLAG calculations, no change whatsoever, and no coil spring added to the ends, and therefore no experimentation at all, but there will be a method of adjustment should it need it.

 

Both David and I feel that the chances of designing a wire and position to work by pre calculation first time is a long shot, he is a qualified engineer, as I am, and find the idea of designing the springs as a working system first time out very intriguing.......

 

For a start you would need accurate scales, and scales able to read individual down pressures on each wheel..... but in the real world you will have to measure the total weight reasonably accurately, and the near symmetrical layout of the Buffalo comes to the rescue.....estimates will do.

 

If you are into reading each wheel pressure to the track, try to buy old Post Office phone relay contact setting scales, they are like probes and can measure from 0 to 5 grammes, or 0 to 10 grammes. For the total loco weight kitchen scales should do.

 

In practice I would do the whole design a bit light by a few grammes, and give myself the leeway to add the final bit of ballast to get the suspension to ride level.

 

Hope this helps, I would still add the coils, but...............

 

Stephen.

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??? posted on Thu Jul 30, 2009 7:37 pm

 

Thanks for the additional thoughts on adjustable fulcrums, Stephen. The main reason I haven't drilled the holes yet has been the different positions depending on whether these or handrail knobs are used. I'll make a decision by the weekend. As to retaining the hornblocks, that's not a problem as the High Level ones already have holes for a retaining wire.

 

Both David and I feel that the chances of designing a wire and position to work by pre calculation first time is a long shot, he is a qualified engineer, as I am, and find the idea of designing the springs as a working system first time out very intriguing.......

Agreed, it's all very hypothetical until the complete model has been built. I can make a reasonable estimate of the total weight and it should be possible to get an even weight distribution over the three axles, but I can't be certain until it is built. As you say, the compact and symmetrical layout of the Buffalo should help.

 

Nick

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Comment posted by Bertiedog on Thu Jul 30, 2009 8:11 pm

 

The pigs to spring are Atlantics*, they pitch fore and aft, and have to have the bogies "in the loop",...... and the easiest are Decapods, big easy footprint!.....another awkward one is the Brighton 042 Gladstone, very difficult to get right.

 

Big overhangs at the front and back spell difficulties, and Cramptons are best left to Mike Sharman.

 

With Gladstone, I used coil sprung wires over the drivers, and separate wires over the trailing wheels with a single extra spring in the middle, pulling on an equalising beam.....That meant three adjustable screws on the drag beam, and the loco (00) ran like a dream.

 

*I should also add any 2-2-2-2 LNWR Webb design, like Teutonic

 

By the way, the idea of wires strung along the axleboxes is older than Varney, I have a 2-8-0 chassis, with 6 volt motor, rumoured to have been built by, or inspired by, one J Ahern, which has spring wire along each side, running on tubes over the axles. Believed to date to the late 1920's or very early thirties.

 

Agreed, it's all very hypothetical until the complete model has been built. I can make a reasonable estimate of the total weight and it should be possible to get an even weight distribution over the three axles, but I can't be certain until it is built. As you say, the compact and symmetrical layout of the Buffalo should help.

Keep a little ballast weight back, design to get it about right, and then load the weight till correct............

Stephen.

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??? posted on Thu Jul 30, 2009 8:53 pm

 

I'm leaving further thought about the chassis to the weekend. This evening I've been resolving the problem with the cab position so that there is enough room to fit the handrails. This has been achieved by filing a small amount away from:

  • the inside of the rear of the smokebox saddle where it fits over the front locating plate on top of the footplate
  • the rear of the tank where it meets the cab
  • the inside of the front of the bunker where it fits over the rear locating plate on top of the footplate

Together, these have given just enough room for the handrails whilst keeping the boiler front and bunker rear in acceptable positions.

 

Now, this reveals the mistake I made earlier icon_redface.gif The cab floor is now too short and will need some re-shaping and filling of gaps to get it to fit properly. I'll post more pictures once this has been resolved and the cab attached.

 

Nick

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??? posted on Fri Jul 31, 2009 11:59 pm

 

The cab front has now been fitted and the handrails added. I noticed from the prototype photos in Russell that these handrails are attached to the footplate by a small ferrule (right word?) at the base. Conveniently, this helps to overcome the problem of the recess in the footplate being a bit too wide and too rounded. Soldering a short piece of 1/32" brass tube over the handrail wire to represent the ferrule added a bit of strength to the join and avoided the need to drill holes that would have been too close to the edge of the footplate.

 

blogentry-6746-12561498666545.jpg

 

Now, dealing with my self-inflicted cab floor problem has opened a new can of worms. The kit provides a floor visible in this earlier post. The floor is raised about 3mm with spacers provided on the etch. At a quick glance, this raised floor seems to correspond with the Maskelyne drawing and several of the photos in Russell. However, after some more study of the photos, I have come to doubt the existence of a raised floor icon_eek.gif

 

Firstly, I noticed that several of the pannier conversions did not have a raised floor. A fascinating article entitled "Working on 'Tankies'" by Bob Crump in GWRJ 66 mentions that the older Dean designs "...had very cramped footplates with sandboxes just inside the entrance on either side." There are further details about their operation that are well worth reading even though it does not refer specifically to Buffalos. Returning to Russell, these sandboxes are visible in fig 247 and, once you know what you are looking for, it is clear that many of the other photos, including that of 1176 with saddle tanks (fig 231) also show these sandboxes. Often, posed photos of engine and crew show the fireman standing on the sandbox so that he is visible behind the driver. The clearest photo of all is a high angle shot of an 850 class in fig 301 where the sandbox can be seen in the bottom left of the picture. Incidentally, the cab height of the 850s is the same as the Buffalo, which might be taken to suggest they had similar floor heights..

 

All this leads me to believe that there never was a raised cab floor. Perhaps the answer will be to fix the floor piece with its etched wood pattern directly to the floor and to add the extra sandboxes. Incidentally, the rod linking the two sandbox levers represented on the bunker front casting appears to be a rarity. So far, I have only found one example in fig 237 in Russell which shows 1600 in early pannier form. The Bob Crump article also refers to the need to operate both handles together.

 

Another problem with the bunker front can be seen in the above photo. The coal hole is represented with the side rails and door finishing at the raised floor height. Perhaps the answer here would be to extend the rails and carve out a hole below so that it is modelled in the open position.

 

Nick

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Comment posted by Miss Prism on Sat Aug 01, 2009 12:31 pm

 

Nick - I suspect we'll never get to the bottom of the 'floor business', if you'll excuse the pun. Certainly the sandboxes do feature prominently in the side views. My feeling is that the floor, whatever it was, was not at the top of sandbox level, because I think that would be too high to get to the firebox door. Having said that, and comparing views and drawings of the contemporary Metro tanks, I'm inclined to think there was some sort of rudimentary planking floor. Such a rudimentary floor might be say, 2" or 2.5" thick???

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Comment posted by Bertiedog on Sat Aug 01, 2009 2:17 pm

 

The floor may depend on where it was serviced, Wolverhampton, or Swindon, etc, who delighted in perverse alterations to each others work. Most was replaced on a regular basis by local fitters, and the wood used was usually oak or ash, although I do not have evidence of exact GWR practice to hand.

Usually, by which I mean other companies, wood was about 3 inches thick, with cross battens underneath to raise the floor from any water gathering, the battens were loose to pattern needed, with boards coach bolted on.

 

Stephen.

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??? posted on Sun Aug 02, 2009 11:48 am

 

Miss Prism wrote:

Nick - I suspect we'll never get to the bottom of the 'floor business', if you'll excuse the pun. Certainly the sandboxes do feature prominently in the side views. My feeling is that the floor, whatever it was, was not at the top of sandbox level, because I think that would be too high to get to the firebox door. Having said that, and comparing views and drawings of the contemporary Metro tanks, I'm inclined to think there was some sort of rudimentary planking floor. Such a rudimentary floor might be say, 2" or 2.5" thick???

Thanks for this. Yes, I agree, a simple planked floor, perhaps fitting around and between the sandboxes seems the most likely.

 

Bertiedog wrote:

The floor may depend on where it was serviced, Wolverhampton, or Swindon, etc, who delighted in perverse alterations to each others work...

There certainly was variation within and between similar classes. The sandboxex themselves seem to vary in size and position.

 

Nick

 

ps. see also discussion here on the Q&A pages

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??? posted on Mon Aug 10, 2009 11:44 pm

 

Over a week since the last update! During that time, the chassis has come together quite well and the CSB appears to be working. I've had endless fun just prodding the chassis and watching how it all works icon_biggrin.gif The outer spring mountings are Gibson medium handrail knobs with the longer knobs used on each hornblock. For the fulcrums between the wheels I adopted Stephen's adjustable idea and again it seems to have been a success (thanks Stephen icon_thumbsup2.gif ). The adjustable fulcrums were easily made from 12BA cheesehead screws with a blade of brass soldered into the slot. The resulting chassis is well balanced with a level footplate and rolls along quite freely icon_biggrin.gif It will probably require a heavier wire spring once the full weight is on it.

 

The chassis spacers supplied in the kit left the frames closer together than I liked and would have required almost 2mm of spacers on each axle as well as leaving little room for the springs and gearbox inside. So, I filed a little off the P4 spacers and used these instead. I chose a High Level Road Road Runner 54:1 gearbox which sits between the frames and leaves plenty of room for the springs to work. With this gearbox the 1220 motor can be mounted vertically and so the cutout in the base of the boiler can now be filled in as the motor is completely within the firebox area icon_smile.gif .

 

blogentry-6746-12561498931712.jpg

 

So all was going well and I was hoping that this post would include pictures with the rods attached and quartered and running in on the rolling road. I had reached the stage where the quartering was probably as good as it was going to get and all that was needed would be a slight tweak with the broach to remove any remaining tightness in the crankpin holes.

 

The cranks supplied in the kit are the usual Gibson plastic variety. The pins were fitted with a drop of Loctite 243 and the cranks fitted to the axles with a little Loctite 603 and then left overnight to harden. The next day, I was surprised to find that the cranks were still loose icon_surprised.gif Now maybe I was not thinking too logically and considering all possibilities, because I immediately assumed that the Loctite had failed, perhaps because of some surface contamination from stray oil after the initial gearbox testing. So, I lightly knurled the outer part of each axle, cleaned everything with IPA and, when dry, reassembled one side with more Loctite. The next morning I was even more surprised to find the cranks were still loose icon_eek.gif icon_frustrated.gif

 

It was only when setting up the photos for this post that I noticed the real problem. All six cranks had cracked in the same place, and most of them have signs of the crack extending beyond the axle hole towards, but not yet reaching, the pin. The cracks can be seen in the next photo:

 

blogentry-6746-12561499167574.jpg

 

So, time for a rethink icon_sad.gif Suggestions on where to go from here will be very welcome.

 

Nick

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Comment posted by LNWRmodeller on Tue Aug 11, 2009 7:55 am

 

Nick,

 

I've no doubt you'll get a variety of advice, including machining new ones from rare metals. icon_smile.gif

 

You could start by asking Colin Seymour of AG to supply some more. Then, carefully ream out the axle holes slightly with a 1/8" parallel reamer, so that they are an easy push fit onto the axle. Fit them using a suitable retainer adhesive - I don't know if Loctite 243 is correct for plastics. According to their website, Ultrascale supply 603. I suggest you check the Loctite website.

 

Jol

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Comment posted by Miss Prism on Tue Aug 11, 2009 8:32 am

 

Nick

 

Not sure about machining new cranks from, err, 'rare metals', and I agree with Jol about trying again with another AG set - failing that, you could investigate Martin Finney's outside crank etch, which is a 3-layer-laminate, but I think that crank etch might be for turned down 2.5mm axle ends, so would require quite a bit of careful jigging, drilling and reaming etc to get them all the same. I think Martin's cranks will at least be a better overall size and shape.

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Comment posted by Bertiedog on Tue Aug 11, 2009 8:05 pm

 

I have dropped you a PM about the cranks

Stephen

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