Fitting W irons

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Andy W
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Fitting W irons

Postby Andy W » Sat Oct 26, 2013 11:07 am

I've built a fair few locos and coaches in P4 over the years - but I'm scratching my head over some "simple" problems re fitting W irons to Slater vans. I've used Bill's sprung w irons on a number of coaches lately and had planned to use them on these. However, I can't fit the spring tails in behind the buffers. I know I could give the springs a central pivot instead, but I want to keep this build as simple as possible. I've got some P4 stores rocking W irons (MJT are O.O.S.) and plan to use these.

The problem is I've been given contradictory advice and I'm not sure which to take. I would have thought the "best way" to proceed is to use etched W irons on both axles, one rocking and one not - and cut away the plastic kit ones. Then fix these to the upturned floor and then fix the solebars against these.

However some people seem to only remove the plastic W irons for the rocking axles, and retain the plastic W irons at the rigid end - inserting bearings into the plastic axlebox. Although this approach would save work cutting and filing back the plastic W irons, it seems to make fixing the distance between the bearings, and the squareness, more difficult to obtain. I.e. by adjusting the position of the solebars.

I intend only attaching the axle boxes to the rocking W iron and keeping the springs on the solebar (as suggested by Russ), but is it best to leave the plastic spring and axle box details attached to the solebar for the non-rocking axle? Or would I achieve a flusher finish if I stuck them on the W iron?

I'm looking at reliability rather than speed of construction. I'm not sure why this has stopped me in my tracks - but if anyone can point me in the right direction/towards any reference, I'd be most grateful.
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Guy Rixon
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Re: Fitting W irons

Postby Guy Rixon » Sat Oct 26, 2013 11:52 am

Where you have one fixed axle, then you have to be able to get this square to the chassis in two planes and get the ride height correct. In my experience, Slaters kits are not your friend here: the bearing holes in the mouldings I've seen recently are all over the place. This was for PO-wagon parts; the (MR?) van mouldings may be more accurate. I think it would be vastly easier and less error-prone to replace the axleguards at both ends than to drift the holes in the mouldings true.

For the fixed axle, I suggest keeping the spring and box attached to the solebar (principle of minimum mutilation) and gluing the axlebox to the brass axleguard. I've built wagons where the spring and axleboxes were just resting against the axleguards and found that the springs tend to break at the spring hangers when the plastic gets old and brittle. You'd need to open out the bearing holes in the axleboxes to give some clearance for fitting - the electric adze (2mm router bit in minidrill) does this better than a twist drill if the holes are moulded off-centre.

Of course, you could try a different springing system, e.g. Exactoscale where the springs are finer and shorter. Much as I like Bill's system sometimes the alternatives fit better.

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Russ Elliott
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Re: Fitting W irons

Postby Russ Elliott » Sat Oct 26, 2013 5:13 pm

Ealing wrote:I would have thought the "best way" to proceed is to use etched W irons on both axles, one rocking and one not - and cut away the plastic kit ones. Then fix these to the upturned floor and then fix the solebars against these.

Yes.

However some people seem to only remove the plastic W irons for the rocking axles, and retain the plastic W irons at the rigid end - inserting bearings into the plastic axlebox. Although this approach would save work cutting and filing back the plastic W irons, it seems to make fixing the distance between the bearings, and the squareness, more difficult to obtain. I.e. by adjusting the position of the solebars.

It is more difficult to do, for all the reasons Guy gives, and moreover, it is unlikely the etched and plastic W-irons will look the same.

Whether the box is separated from the spring, or the box and spring are separated from the solebar, depends on the shape of the top of the box, and your personal preference. What I would say is to do the same for both axles, for visual consistency.

For the rocking W-iron, you will need a wider recess in the solebar at that point, to enable the rock. That will in turn affect how 'closely' you can fit the box, and it can be a bit of a jiggle to get it right.

For the non-rocking end, I take the view that if you are keeping the spring attached to the solebar (both will need recessing of course as per the rocking end, but maybe not quite so much), it will be easier to nudge the spring up against the W-iron for a flusher fit. The counter-argument applies, however, namely that for an initial setting of the solebar in a (reasonably confident) position, there is a danger of a less flush fit. I don't think one way is intrinsically better than the other. It does depend a bit on sequence, and how consistently you have filed off the remains of the W-iron bits from the backs of boxes.

Remember, for the sake of nudging one end of a solebar say 0.5mm one way or another, no one will be able to tell if your solebars are not parallel. <cheat mode off!>

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Will L
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Re: Fitting W irons

Postby Will L » Sat Oct 26, 2013 5:54 pm

Ealing wrote:I've built a fair few locos and coaches in P4 over the years - but I'm scratching my head over some "simple" problems re fitting W irons to Slater vans. I've used Bill's sprung w irons on a number of coaches lately and had planned to use them on these. However, I can't fit the spring tails in behind the buffers.


Masokits do a some different style wagon springing unit that use a stainless steal leaf spring which is no wider than the w iron unlike the Bill Bedford guitar spring type. These will happily go in where the Bill Bedford ones wont. In use there is little to chose between them performance wise but I think the guitar wire system is cheaper and easier to produce so even Masokits have gone over to that system for their later items but the older stainless steel spring type are still available as far as I know. Not in a wide variety of W iron shapes but there is a RCH standard which is the one your most likely to need. See page 4 of the Masokits price list, and get in quick before he produces a new list with higher prices!

Will

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Andy W
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Re: Fitting W irons

Postby Andy W » Sat Oct 26, 2013 9:14 pm

Thanks for al the advice chaps, much appreciated.
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billbedford
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Re: Fitting W irons

Postby billbedford » Sun Oct 27, 2013 8:24 am

Ealing wrote:I've built a fair few locos and coaches in P4 over the years - but I'm scratching my head over some "simple" problems re fitting W irons to Slater vans. I've used Bill's sprung w irons on a number of coaches lately and had planned to use them on these. However, I can't fit the spring tails in behind the buffers. I know I could give the springs a central pivot instead, but I want to keep this build as simple as possible. I've got some P4 stores rocking W irons (MJT are O.O.S.) and plan to use these.


Which w-irons are you using? BWF001 were designed to fit on Slaters 15' wagons so should also fitting on their small vans.
Bill Bedford
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Andy W
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Re: Fitting W irons

Postby Andy W » Sun Oct 27, 2013 9:03 am

I think I must have 03s - thanks Bill I'll try some 01s.
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Andy W
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Re: Fitting W irons

Postby Andy W » Tue Nov 05, 2013 2:40 pm

Yes, they work.
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Julian Gascoyne
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Re: Fitting W irons

Postby Julian Gascoyne » Tue Nov 05, 2013 4:16 pm

billbedford wrote:Which w-irons are you using? BWF001 were designed to fit on Slaters 15' wagons so should also fitting on their small vans.

I've been using BWF001 for the Slaters 10T and 8T vans, and they work a treat! :D

But I'm about to do a 10T fruit van which has 3'7 wheels. So 3'7 vs. 3'1 wheels means 2mm extra diameter so the van buffer height will be raised by 1mm. I was thinking the best approach to this would be to dispense with the little tabs underneath the W iron, either by removing them or not folding the sides over. The tabs are about 1mm thus moving the buffers back to where they should be.

Is this a good idea? OR is there a different W iron I should be using?

Thanks
Julian

allanferguson
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Re: Fitting W irons

Postby allanferguson » Tue Nov 05, 2013 7:01 pm

You may find that the tops of the wheels foul the top of the W-iron. Better to get some of the W-irons that are designed for bigger wheels, e.g. BWF 003 NPCS

Allan F

Julian Gascoyne
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Re: Fitting W irons

Postby Julian Gascoyne » Tue Nov 05, 2013 11:25 pm

allanferguson wrote: Better to get some of the W-irons that are designed for bigger wheels, e.g. BWF 003 NPCS

Allan F

Many thanks for the suggestion Allan - an order for Auntie Eileen is winging its way as we speak........

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Russ Elliott
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Re: Fitting W irons

Postby Russ Elliott » Tue Nov 05, 2013 11:29 pm

Julian Gascoyne wrote:I was thinking the best approach to this would be to dispense with the little tabs underneath the W iron, either by removing them or not folding the sides over.

I fold the sides over and then nibble off those projecting tabs. I don't remember having a problem with clearances on 3'7" wheels, but I haven't got current access to the BB W-iron type I was using. (It was one of the longer ones.) Any clearance problem will be a matter of a little bit of filing.

The tabs are about 1mm thus moving the buffers back to where they should be.

I don't understand - 'moving the buffers back' ?

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Re: Fitting W irons

Postby Julian Gascoyne » Tue Nov 05, 2013 11:44 pm

Russ Elliott wrote:I don't understand - 'moving the buffers back' ?

Sorry, that should have been 'moving the buffers down by 1mm'

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Russ Elliott
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Re: Fitting W irons

Postby Russ Elliott » Wed Nov 06, 2013 12:02 am

Julian - your buffer height should be your datum. All BB W-irons vary, so it is impossible to generalise the relationship of their tops to the buffer height datum, so fix the W-irons as the last step, not as an initial step.

billbedford
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Re: Fitting W irons

Postby billbedford » Wed Nov 06, 2013 9:12 am

I wish some people would stop putting out false information about these etches.

The geometry of the w-iron is constant, mainly because they were drawn by copying the centre section between drawing and fitting newly drawn axleguards. What varies is the amount of space for the w-irons to go into. Partly this has to do with the wagon modelled, Solebars could vary between 9" and 12" deep, and partly this has to do with the construction of the model. Not all models have the bottom of the floor at the top of the solebars, this is especially true of RTR models.

So in general modellers will have to think about the relationship between the w-iron and the ride height.
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Russ Elliott
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Re: Fitting W irons

Postby Russ Elliott » Wed Nov 06, 2013 10:31 am

Bill - I accept that floor heights vary (which was my main point), but if the geometry of the W-irons is constant, what is the following dimension for a 13.8mm buffer height?

w-iron-to-buffer.png
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Re: Fitting W irons

Postby billbedford » Thu Nov 07, 2013 10:29 am

Russ Elliott wrote:Bill - I accept that floor heights vary (which was my main point), but if the geometry of the W-irons is constant, what is the following dimension for a 13.8mm buffer height?


I don't see the relevance of this. The buffer height depends as much on the deflection of the springs as the dimensions of the w-iron etch.

And where did measuring the buffer height to the nearest 0.1mm come from? It sounds to me like real ivory tower thinking.
Bill Bedford
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Natalie Graham

Re: Fitting W irons

Postby Natalie Graham » Thu Nov 07, 2013 11:15 am

billbedford wrote:
Russ Elliott wrote:Bill - I accept that floor heights vary (which was my main point), but if the geometry of the W-irons is constant, what is the following dimension for a 13.8mm buffer height?

I don't see the relevance of this. The buffer height depends as much on the deflection of the springs as the dimensions of the w-iron etch.


billbedford wrote:So in general modellers will have to think about the relationship between the w-iron and the ride height.


Surely that dimension is what determines the relationship between the w-iron and the ride height.

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jjnewitt
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Re: Fitting W irons

Postby jjnewitt » Thu Nov 07, 2013 3:09 pm

billbedford wrote:
Russ Elliott wrote:Bill - I accept that floor heights vary (which was my main point), but if the geometry of the W-irons is constant, what is the following dimension for a 13.8mm buffer height?

I don't see the relevance of this. The buffer height depends as much on the deflection of the springs as the dimensions of the w-iron etch.
And where did measuring the buffer height to the nearest 0.1mm come from? It sounds to me like real ivory tower thinking.


The point Russ made is very relevant. If you wish to have a consistent buffer height then how can you arrange things to arrive at this? I don't see at all how measuring buffere centres to one decimal place is ivory tower thinking. Perhaps we shouldn't bother measuring track gauge to 2 decimal places... I am very aware that buffer centres varied on the real thing but Russ has made some very good points in the past as to why having a consistent buffer centre is a good thing and even if you aren't bothered about it there is a range within which it should prototypically fall.

Buffer height depends on many things. Spring deflection, length of spring carriers, wheel diameter. Just because it depends on many things doesn't mean that a kit designer shouldn't know how things will relate to each other under the ideal conditions with which it would have been drawn up. If people wish to deviate from the idea situation then that's up to them. My chassis are designed very carefully to provide a 13.8mm buffer centre when using Exactoscale wheels with a total weight on the springs of 25g per axle. If people want to change any of the elements that produce this result then that's up to them but they know where they're starting from.

In a similar vein I relly don't see why the society can't specify a standard for buffer centres to at least give the impression that it is important. Russ has argued that people will be complaining that their company had a different buffer centre of whatever but that doesn't entirely stand up. People can and do model gauges other than standard in P4, that doesn't mean the distance between their rails is 18.83mm... Anyway since when has having standards stopped people from deviating from them. Of course none of this matters if you're not bothered what your buffer centres are or don't think it's important.

Justin

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Re: Fitting W irons

Postby billbedford » Fri Nov 08, 2013 11:05 am

jjnewitt wrote:The point Russ made is very relevant. If you wish to have a consistent buffer height then how can you arrange things to arrive at this? I don't see at all how measuring buffere centres to one decimal place is ivory tower thinking. Perhaps we shouldn't bother measuring track gauge to 2 decimal places... I am very aware that buffer centres varied on the real thing but Russ has made some very good points in the past as to why having a consistent buffer centre is a good thing and even if you aren't bothered about it there is a range within which it should prototypically fall.


The prototype buffer height dimension was nominal only. There was a 3 inch (1mm in 4mm scale) allowance for loads, weak springs etc. In addition, while the buffer height is marked on many drawings, we don't know the convention behind the drawing. Does the figure on the drawing represent the unloaded or loaded height or something in between? It is tempting to assume that it is the unloaded height, because that would be the easiest dimension to measure in the works, but I have never seen this expressed in any contemporary document.

It seems to me that trying to express a model dimension to an order magnitude tighter than the prototype is the mark of a theoretician rather than a practical model maker -- and Russ has form for that.
Bill Bedford
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LesGros
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Re: Fitting W irons

Postby LesGros » Fri Nov 08, 2013 1:50 pm

billbedford wrote:
...The prototype buffer height dimension was nominal only. There was a 3 inch (1mm in 4mm scale) allowance for loads, weak springs etc. In addition, while the buffer height is marked on many drawings, we don't know the convention behind the drawing. Does the figure on the drawing represent the unloaded or loaded height or something in between? It is tempting to assume that it is the unloaded height, because that would be the easiest dimension to measure in the works, but I have never seen this expressed in any contemporary document...
Bill,
Obviously, when you designed your W iron etches you will have examined the available drawings and will have made some assumptions about the relationships between your etch design and the prototype. Presumably, you will have considered how the etches would be used under an existing model frame. What is so difficult about answering Russ's enquiry about the dimension, and sharing your assumptions with the rest of us?
LesG

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Paul Willis
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Re: Fitting W irons

Postby Paul Willis » Fri Nov 08, 2013 2:12 pm

LesGros wrote:Bill,
Obviously, when you designed your W iron etches you will have examined the available drawings and will have made some assumptions about the relationships between your etch design and the prototype. Presumably, you will have considered how the etches would be used under an existing model frame. What is so difficult about answering Russ's enquiry about the dimension, and sharing your assumptions with the rest of us?


I don't know what research Bill did in devising his sprung w-iron system.

However, in connection with something that I'm designing for 5522, I've been poring over a number of detailed LNWR wagon diagrams. These seem to be consistent in showing:

Buffer height 3' 5 1/2" or 13.83 mm in 4mm scale

Underneath of wagon/van floor 3' 10 1/2" or or 15.50 mm in 4mm scale

Therefore I'm working on the observation that the dimension "x" under discussion is near as damn it 1.7 mm.

All of Bill's points about the factors that *can* vary buffer height are perfectly valid. No doubt someone can produce lots of examples of LNWR vehicles with slightly different floor heights. I've taken the view that I have to draw a line somewhere!

HTH
Flymo
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Guy Rixon
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Re: Fitting W irons

Postby Guy Rixon » Fri Nov 08, 2013 2:50 pm

Flymo748 wrote:[
However, in connection with something that I'm designing for 5522, I've been poring over a number of detailed LNWR wagon diagrams. These seem to be consistent in showing:

Buffer height 3' 5 1/2" or 13.83 mm in 4mm scale

Underneath of wagon/van floor 3' 10 1/2" or or 15.50 mm in 4mm scale

Therefore I'm working on the observation that the dimension "x" under discussion is near as damn it 1.7 mm.


I thought that Russ asked for the height difference between buffer centre height and the top of the tabs on the BB axleguards when the wagon is set up correctly (presumably for some nominal wheel size and axle-weight, as per Justin's post). That might be 1.7 mm too but we don't know yet. Bill implied that the axleguards accommodate low floors in RTR vehicles, so maybe x < 1.7 mm.

BTW, I never bend up the sides of the BB axleguards, preferring to pack from the flat base of the unit rather than the upstanding tabs. Am I doing it wrong?

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Tim V
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Re: Fitting W irons

Postby Tim V » Fri Nov 08, 2013 3:14 pm

billbedford wrote:The prototype buffer height dimension was nominal only. There was a 3 inch (1mm in 4mm scale) allowance for loads, weak springs etc. In addition, while the buffer height is marked on many drawings, we don't know the convention behind the drawing. Does the figure on the drawing represent the unloaded or loaded height or something in between? It is tempting to assume that it is the unloaded height, because that would be the easiest dimension to measure in the works, but I have never seen this expressed in any contemporary document.

It seems to me that trying to express a model dimension to an order magnitude tighter than the prototype is the mark of a theoretician rather than a practical model maker -- and Russ has form for that.

Sorry Bill, but to get reliable propelling (through the buffers), a consistent buffer height is essential.

We are back to my comment about publishing a set of standards for 4mm models(in another thread). Buffer height/distance apart is specified on the real thing so why cannot manufacturers get it right? Anyone got any ABS wagons? Checked the buffer centres recently?

Is it any wonder beginners are put off?
Tim V
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billbedford
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Re: Fitting W irons

Postby billbedford » Fri Nov 08, 2013 3:30 pm

LesGros wrote:Obviously, when you designed your W iron etches you will have examined the available drawings and will have made some assumptions about the relationships between your etch design and the prototype. Presumably, you will have considered how the etches would be used under an existing model frame. What is so difficult about answering Russ's enquiry about the dimension, and sharing your assumptions with the rest of us?

Because:
    Measuring the height of the buffer centre above the floor is really quite difficult on a built wagon.
    Until the wagon is built you have no idea where the axles will be in the w-iron, because of the springs.
So it seems to me that building the wagon, resting it on the assembled w-irons, and checking the height of the buffers against a know marker, e.g. a buffer height gauge, is a lot more practical than trying to work out a lot of arcane dimensions.
Bill Bedford
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