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Copyright John Dunn Engineering

Welcome to the Barclayblog.

No.8 was the last 16″ 0-4-0 saddle tank built by the Kilmarnock firm of Andrew Barclay and Sons Ltd. Works No. 2369 she was delivered new to the Scottish Region of the National Coal Board in 1955, the last brand new steam locomotive they bought.

I am lucky enough to own a 3/4 share in the locomotive and I thought people might be interested to share the highs and the lows, the trials and the tribulations, which go cap in hand with the day to day maintenance and running of a full sized industrial “pug”.

I will post on a fairly ad-hoc basis depending on just what there is to talk about so keep checking back!

If you have any photographs or information about No.8 when she was in service I would be pleased to hear from you.

I hope you find the site interesting.

John.

Fitting the Bearing Brasses – 2.

In the last post I explained how we fitted the bearing brass flanges. Once this had been finished the next job was to fit the outside diameter of the brass to the crown of the axlebox, the aim being to get a reasonable area of contact between the two parts. Although the brasses have been turned accurately there is, inevitably, a certain amount of wear in the crowns due to movement of the brasses (fretting) whilst the locomotive was in service with the NCB and this is not uniform; hand fitting is the way this situation is dealt with.

A reasonable area of contact between brass and ‘box is necessary for two reasons; to stop the brass fretting when the locomotive is working and to prevent the brass distorting under the weight of the locomotive which could lead to problems with oil distribution etc.

The process involves using engineers’ blue in a more conventional manner than in the previous post.

This photograph shows the crown of the axlebox after it has been coated in engineers' blue and before the brass has been tried in place. The studs are there to maintain the sides of the 'box at the correct distance apart, this particular one has a tendency to close in slightly for some reason. (Copyright John Dunn Engineering).

This photograph shows the crown of the axlebox after it has been coated in engineers’ blue and before the brass has been tried in place. The studs are there to maintain the sides of the ‘box at the correct distance apart, this particular one has a tendency to close in slightly for some reason. (Copyright John Dunn Engineering).

The crown of the ‘box is initially coated in blue and the brass lowered into position. The brass is then tapped down with a mallet and a piece of wood to ensure that it is making as much contact as possible before being removed with the aid of a small lever.

This photograph shows the high-spots after the first trial fitting of the brass.(Copyright John Dunn Engineering).

This photograph shows the high-spots after the first trial fitting of the brass.(Copyright John Dunn Engineering).

The pattern of the transferred blue on the outside diameter of the brass indicates the points of contact (high-spots) between the brass and the ‘box. These high-spots are preventing the two parts making any further contact and need to be removed if the area of contact is to be increased. You would normally use a scraper to remove high-spots but I found this an awkward way to do things on the convex surface of the brass. It was much easier to use a brand new smooth or second cut hand file; this ensured a sharp file with a safe edge to protect the sides of the flanges on the brass.

 

Part way through the process and the pattern of the blue is beginning to change, extending over a larger part of the surface. (Copyright John Dunn Engineering).

Part way through the process and the pattern of the blue is beginning to change, extending over a larger part of the surface. (Copyright John Dunn Engineering).

 

Once the high-spots have been filed off, the crown of the ‘box is given another coating of blue and the brass is again tried in place and the high-spots checked. The process is repeated over and over until the necessary fit is achieved. I was aiming for around 70 to 80% contact with the main areas being along the top and upper parts of the brass and some along the bottom edges.

 

 

 

This is time consuming, laborious, back-breaking work. The brasses weigh over 3-1/2 stones each at this stage (23kg) and they have to be lifted off the bench, carried down the ‘shop, dropped into the axlebox which is on the floor, manipulated in position, lifted back out and then returned to the bench. They are then filed and the whole process begins again, and again, and again, ad nauseum. Thankfully this stage of the work is now behind us but it has been something of  marathon.

This shows the work almost completed. There is a reasonable area of blue over the whole of the outside of the brass. A bit more work will see this one completed. (Copyright John Dunn Engineering).

This shows the work almost completed. There is a reasonable area of blue over the whole of the outside of the brass. A bit more work will see the blue spread a liitle more and that will be this one completed. (Copyright John Dunn Engineering).

I must apologise but I have neglected to take a photograph of one of the brasses with the final coating of blue on but I think the pictures give a pretty good idea of how the process evolves.

Fitting the Bearing Brasses – 1.

Even though the bearing brasses have been turned to suit each axlebox individually, they still need to be hand-fitted to ensure a proper relationship between the mating surfaces. The axleboxes are worn where the original brasses have been “fretting” and we would be extremely lucky to get the required fit with brand new brasses straight off the machine.

The flanges at each end of the brass need to be a tight fit in order to prevent any end float between the brass and the ‘box. The outside diameter of the brass needs to be in contact with a substantial portion of the crown of the axlebox to prevent any distortion whilst taking the weight of the locomotive and also to prevent any movement. This state of affairs is achieved by using files, scrapers, engineers’ blue, patience and an awful lot of time.

Right driving axlebox with the original brass fitted as a comparison. (Copyright John Dunn Engineering).

Right driving axlebox with the original brass fitted as a comparison. (Copyright John Dunn Engineering).

 

Just by way of a comparison, this photograph shows one of the original brasses in the the right driving ‘box. It’s not the best of photographs but you can see that there is 1/16″ clearance between the flanges and the ‘box and 5/64″ clearance per side (5/32″ in total); there should be no clearance at all in any of these places. There are also areas of wear along the bottom edges of the brass where it has been fretting against the keep.

 

 

The first part of the job involves establishing the correct fit between the flanges on the brass and the flange faces in the axlebox. Once this has been achieved the outside diameter of the brass can be fitted to the crown of the axlebox.

Normal practice is to apply engineers’ blue (Micrometer Blue) to the surface which is being used as a datum, the surface which is to be “fitted” is then offered up to this and points of contact are indicated by the blue being transferred from the datum to the fitted surface. The points of contact (high-spots) are removed from the fitted surface with a scraper or file, the two surfaces are then tried together again and the process is repeated until the desired fit has been obtained. In tackling the flanges we adapted the method slightly as explained below.

The insides of the flanges on the brass were coated in ink from a felt-tip pen, this was allowed to dry and then the brass was lowered into position before being tapped home with a mallet and a piece of wood. The ink coating was damaged wherever there were any points of contact. In theory any areas which were left as solid blue were therefore “high” and needed removing to allow the brass to move further into position; in practice it is not quite as simple as that! Some of the skill in this job is having the ability to read the witness marks and knowing exactly where to remove metal it, is not always as obvious as it might first appear. The aim is to end up with a light tap-fit, the outside diameter of the brass touching the crown of the axlebox and as much contact as possible over the full area of both flanges.

The last photograph shows a flange part way through the fitting process. The damaged areas of ink can be seen.

Witness marks on one of the bearing brass end flanges. (Copyright John Dunn Engineering).

Witness marks on one of the bearing brass end flanges. (Copyright John Dunn Engineering).

Turning the Axlebox Brasses

The outside diameters of the remaining three axlebox brasses have now been turned using the horizontal boring machine. The process is fairly straightforward, hopefully the explanation and photographs will make things clear.

The casting before setting up on the machine. The milled end-face described in the text can be seen as can the rough nature of the casting. (Copyright John Dunn Engineering).

The casting before setting up on the machine. The milled end-face described in the text can be seen as can the rough nature of the casting. (Copyright John Dunn Engineering).

The brasses were previously milled to establish faces on both ends and on the bottom “joint” which butts against the keeps when everything is assembled; these faces are all flat and at 90 degrees to each other. The brass is bolted onto a large box angle plate on the borer using these faces to set-up to. Various parallels, clamps and packing pieces are used to make the set-up as rigid as possible. The facing head is then set up so that it is in the centre of the finished diameter.

The machining process is fairly straightforward and can be broken down into a number of stages. The central portion is roughed out first, this involves using left and right handed tools to remove the material up to the inside faces of the end flanges. Next, the flanges are roughed out.

Rough turning the central portion of the brass. (Copyright John Dunn Engineering).

Rough turning the central portion of the brass. (Copyright John Dunn Engineering).

Finish turning the central portion, the flanges have been rough faced and will also be finished at this setting. (Copyright John Dunn Engineering).

Finish turning the central portion, the flanges have been rough faced and will also be finished at this setting. (Copyright John Dunn Engineering).

 

The central portion is then finished from approximately the centre line back to one flange using a right hand knifing tool, the first flange is then faced to finish using the same tool. The central portion is next turned to finish in the opposite direction using a left hand knifing tool and the second flange faced to finish. The distance between the two flanges is critical as this affects the end float (or lack of it!) on the brass when it is inserted into the ‘box so this dimension was made about 0.003″ small to allow for fitting.

 

Turning the outside diameter of the first (inside) flange. (Copyright John Dunn Engineering).

Turning the outside diameter of the first (inside) flange. (Copyright John Dunn Engineering).

 

 

The next stage involves machining the outside diameter of the flange nearest to the facing head. The centreline of this is pitched 5/8″ higher than the centreline of the central portion so the borer is adjusted accordingly. The flange is then roughed and finished to diameter.

 

 

 

The brass has now been set up to allow the second flange to be turned. (Copyright John Dunn Engineering).

The brass has now been set up to allow the second flange to be turned. (Copyright John Dunn Engineering).

 

The casting is now taken off the machine and de-burred before being mounted back onto the box angle plate, this time it is turned through 180 degrees to allow the second flange to be turned. The facing head is set on centre, raised by 5/8″ to achieve the off-set, and the second flange machined in exactly the same way as the first, a series of roughing and finishing cuts.

 

 

 

One awkward bit of this job was deciding on a method of determining the radius of the crown of the axlebox on the face which mates with the brass; because it is a semi-circle there is nothing to use as a surface to measure from if an inside micrometer is used. We took a machinist’s ground parallel of known length and thickness and placed it across the crown of the ‘box. Using a depth micrometer, measurements were taken from the top of the parallel to the top of the radius at the outside, centre and inside of the axlebox. With some maths and a formula it was possible to work out the radius using the measurements we were in possession of. It was then a simple case of deciding the best radius to machine the brass to in order to achieve the correct fit between brass and ‘box.

All turning finished and ready for trying in the axlebox. (Copyright John Dunn Engineering).

All turning finished , the brass is ready for trying in the axlebox. (Copyright John Dunn Engineering).

Axlebox Brass – Fitting.

Over the winter we will concentrate on the axleboxes and the brasses, work that can be done in the workshop where we will not be affected by the vagaries of the british climate.

The brass "as turned" and before fitting. The flanges can clearly be seen. (Copyright John Dunn Engineering).

The brass “as turned” and before fitting. The flanges can clearly be seen. (Copyright John Dunn Engineering).

 

I previously started machining the brass which will be fitted into the left leading axlebox and it has progressed to the stage where the outside has been turned on the horizontal borer; the photographs of this are not brilliant so I will post some better ones when a start is made on the remaining brasses. I wanted to check the fit of this brass within the ‘box before I did any work on the other three, mainly to ascertain whether there were any snags which might be avoided at an earlier stage.

 

 

Not a good picture but you can just see the marks on the gunmetal where the keeps were rubbing. These were removed by filing and scraping. (Copyright John Dunn Engineering).

Not a good picture but you can just see the marks on the gunmetal where the keeps were rubbing. These were removed by filing and scraping. (Copyright John Dunn Engineering).

To start with the fit of the keep within the ‘box was assessed. It is important to make sure this is correct because the keep can force the sides of the ‘box out wider than they should be which might affect the fit of the brass within the ‘box as well as the clearances between the ‘box and the horns. The fit of the keeps had been checked at an earlier stage but the new thrust faces have been attached since then; as it happened the gunmetal on the thrust faces needed a bit of attention with files and a scraper to achieve a decent fit.

 

 

 

I made a series of measurements to check whether the sides of the axlebox were closing in when the keep was removed, again, this may have an effect on the fit of the brass. The sides were moving in slightly, by about 0.004″, so we used a couple of pieces of stud-iron to jack the sides into their proper position, these will be left in place throughout the fitting process.

The start of the fitting process. The sides of the box are held apart by some stud-iron and the brass has been placed into position. There is still a large gap at the crown and this will close up as the job progresses. (Copyright John Dunn Engineering).

The start of the fitting process. The sides of the box are held apart by some stud-iron and the brass has been placed into position. There is still a large gap at the crown and this will close up as the job progresses. (Copyright John Dunn Engineering).

Satisfied with all the above, we moved onto the actual fitting operation. The outside diameter of the brass had been machined to a series of dimensions which had been obtained from the axlebox ( I will explain how I did these in a later post); the distance between the flanges on the brass was made a couple of thou smaller than the distance between the mating faces on the axlebox to allow final fitting. It is important that the brass has no end float and these flanges are the way this is prevented.

The excess material on the flanges was gradually removed using a scraper until we had a decent fit. The brass needs a light tap with a soft mallet to bed it into position but is not that tight that you can’t get it out again! Once down it was checked with engineer’s blue to make sure that it was making contact over the majority of the crown of the ‘box, this is to ensure that there will be no distortion once the ‘box is supporting the weight of the locomotive.

The left leading box with the brass and keep fitted. Requires the joint between keep and brass milling back to size and then boring. (Copyright John Dunn Engineering).

The left leading box with the brass and keep fitted. Requires the joint between keep and brass milling back to size and then boring. (Copyright John Dunn Engineering).

 

The final photograph shows the brass fitted into the axlebox with the keep replaced. We still need to machine away some of the joint face on the brass to allow the keep to enter fully into the box but this will be done at a later stage. For now I am happy with the method and we can concentrate on the final fitting of the remaining three keeps and the turning of the rest of the brasses.

Horn Flange Faces- 2.

Having got to the point where we had manufactured the new flange faces for the horns the rather obvious next step is to fix them into position onto the locomotive. They have all been individually made to achieve the correct side-to-side clearances between the axleboxes and the horns; each face had been stamped to identify where it was meant to go.

One of the new flange faces after fitting. (Copyright John Dunn Engineering).

One of the new flange faces after fitting. (Copyright John Dunn Engineering).

 

The process was relatively straightforward but time consuming. The plates were held in position and an assessment made; inevitably they required some attention with a file to allow them to sit snugly. Once this had been achieved they were screwed into place and another check made. If everything was correct then the screws were removed one at a time, the screw and the female thread in the horn were thoroughly de-greased and then the screw replaced with the addition of some thread locking compound.

 

 

The finished flange face after blending the join with the horn cheek. (Copyright John Dunn Engineering).

The finished flange face after blending the join with the horn cheek. (Copyright John Dunn Engineering).

 

 

The new flange faces had intentionally been made slightly wider than needed to allow them to be dressed back to achieve a neat join with the horn cheeks. This involves the use of an angle grinder to rough the edge down followed up by files and emery to achieve a decent joint. I have managed to get the left driving horns finished but unfortunately the weather has beaten us for this year so the others will have to wait until the Spring now.

Horn Flange Faces.

The last couple of months or so have seen a slight change in emphasis. Way back in February 2013 I posted some details about the process of grinding the flange faces of the horns; these require completing before we can replace the axleboxes and this involves the fitting of some “sacrificial” flange faces. I gave quite a lot of thought to the best material for these faces, in the end I settled on phosphor bronze, PB102; it will be interesting to see how this holds up in service. It seemed appropriate to attempt to get these fixed into place whilst we still have reasonable weather during the summer and autumn months; we can finish machining the axlebox brasses during the winter when it is more difficult to do any work in the open air.

The bronze plates with the holes initially drilled and tapped M6. (Copyright John Dunn Engineering).

The bronze plates with the holes initially drilled and tapped M6. (Copyright John Dunn Engineering).

I had expected the bronze plate would be flat but it had been fettled before being delivered and the surfaces were very slightly bowed across the width. This presented a problem because I wanted to be certain the back face would make a firm and full contact with the ground flange face, partly to prevent any distortion but also to make certain that the chances of water ingress were minimised. I knew that one face of each bronze plate would need machining in order to achieve the thicknesses required to establish the correct clearances but did not expect to have to do both sides. This is a bit of a nuisance and involves more work but it’s not the end of the world!

One of the bronze plates clamped to the fixture to allow the initial light skim over the rear face. (Copyright John Dunn Engineering).

One of the bronze plates clamped to the fixture to allow the initial light skim over the rear face. (Copyright John Dunn Engineering).

To start with I made a basic fixture which would allow the plates to be clamped down flat using the eight holes which will be used to screw the plates into place on the locomotive. Initially these holes were drilled clearance for an M6 screw and counterbored to take the head of a cap screw. The flange plates were then drilled and tapped M6 at the same hole centres. The plates were screwed to the fixture and a very light skim taken on the milling machine to establish a flat face.

The fixture is now bolted to the machine table to allow the plate to be milled to the finished thickness. (Copyright John Dunn Engineering).

The fixture is now bolted to the machine table to allow the plate to be milled to the finished thickness. (Copyright John Dunn Engineering).

The fixture was now modified by enlarging the eight holes and tapping them M8. The holes in the flange plates were drilled out to 5/16″ clear and then countersunk to take a 5/16″ Whitworth countersunk Allen screw. The plates were fastened to the fixture using M8 countersunk screws and then milled to thickness.

 

 

I realise that there is a mixture of metric and imperial going on here; the plates will be fastened onto the locomotive with 5/16″ Whit screws but these are expensive when compared with metric screws so it makes economic sense to use metric on any jigs and fixtures.

The finished plates ready for fitting onto No.8. (Copyright John Dunn Engineering.

The finished plates ready for fitting onto No.8. (Copyright John Dunn Engineering.

Facebook.

Any of you who follow this blog and are active on Facebook might be interested to know that I have started a group for No.8. The group title is “NCB No.8 – Andrew Barclay2369/1955”. It is a closed group but new members are more than welcome.

This will run in conjunction with this blog but will probably not contain quite as much detail.

Making a Start on the Bearing Brasses.

Milling the bottom faces of one brass. This is the face which mates with the axlebox keep.

Milling the bottom faces of one brass. This is the face which mates with the axlebox keep.

The original brasses were worn but three out of the four were thick enough to stand re-boring, the fourth was too thin and needed replacing.

The problem with the all of the original brasses was the amount of wear on the ends where the thrust faces on the backs of the wheels had worn them away; this needed rectifying if we wanted to ensure a full bearing contact. There was also some wear on the bottom faces which butt against the tops of the keeps. Both of these issues needed attention and there appeared to be several options open to us; in the end, after a great deal of headscratching, it was decided that, whilst we were having one new brass cast, we might as well have four. The amount of work involved in machining a new brass is not that much different to that involved in trying to “sole and heal” the old ones and it would make a better job all round if they were replaced as a set.

Having got the castings we needed to establish a method for machining them. As with many engineering problems, there is more than one answer but, in this case, we are going to use the horizontal borer.

Milling one of the end faces. This will be at 90 degrees to the faces we established in the previous photograph above.

Milling one of the end faces. This will be at 90 degrees to the faces we established in the previous photograph above.

The first job involves establishing some datums which can be used for holding the brasses square. These are not finished faces but are machined in order to provide some flat, square surfaces which can be used to clamp the brasses onto. The photographs show these faces being milled on the borer. The brass will then be clamped onto an angle plate or box cube to allow the outside diameters to be turned, again on the borer.

 

Milling the second end. When finished we will have two parallel ends which are both at 90 degrees to the faces which mate with the keeps.

Milling the second end. When finished we will have two parallel ends which are both at 90 degrees to the faces which mate with the keeps.

 

Boring Snout.

I haven’t posted for quite a while now. This is partly due to being extremely busy at work and partly due to the need to make the tooling which is the subject of this post.

The two parts; the boring bar and the socket which is bolted to the facing slide.

The two parts; the boring bar and the socket which is bolted to the facing slide.

Believe it or not, the title is not an archaic form of insult; a boring snout, or snout boring bar, is an attachment which is used on the horizontal boring machine. Unfortunately the one which came with our borer was fairly small and would not have been rigid enough to cope with the work required in turning, boring and facing the brasses for the axleboxes. These things are not readily available off the shelf, at least for our borer, and so I had to set to and make one.

The finished and assembled snout boring bar. There is a key on the rear of the flange to locate it onto the facing slide.

The finished and assembled snout boring bar. There is a key on the rear of the flange to locate it onto the facing slide.

There is a lot of work involved here, particularly when it is being fitted in at weekends and during evenings around regular “paying” work. The next stage of the axleboxes, the actual bearing brasses, could not proceed without it, hence the large gap between posts.

I think the pictures are fairly self-explanatory so will leave them to speak for themselves.

As an aside; we now have a Facebook page

www.facebook.com/johndunnengineering/

so please feel free to have a browse….you do not have to be a member of Facebook to visit the page.

Finishing the Thrust Faces to Size.

Once the thrust face castings had all been fastened into position they needed to be machined away at the sides in order to tidy them up and also to ensure that the various parts (keeps, ‘boxes and bearing brasses) would fit together properly. The heads of the countersunk screws were also milled flush with the front faces in order to reduce the chances of them snagging on hands or clothing.

The actual thrust faces will not be machined back to finished thickness until the bearing brasses are bored, this will ensure that the axis of the bearing is exactly at 90 degrees to the thrust face.

The keeps were attended to first on the milling machine. The sides and bottom were milled back and the screwheads reduced as described. They required a bit of judicious filing to ensure a proper fit into the axlebox.

Boring the crown of the thrust face to match the counterbore in the axlebox. (Copyright John Dunn Engineering).

Boring the crown of the thrust face to match the counterbore in the axlebox. (Copyright John Dunn Engineering).

The axlebox faces were slightly more complicated, not only did the outsides and top need attention but the inside edges needed boring to fit the radius in the crown of the ‘box and the straight portions needed milling level with the inside of the aperture which receives the keep. These also had the screwheads reduced in length.

The left leading axlebox after completion of the work described here. (Copyright John Dunn Engineering).

The left leading axlebox after completion of the work described here. (Copyright John Dunn Engineering).