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Welcome

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.

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).

 

 

 

Fixing the Thrust Faces – ‘Boxes & Keeps

The 1/2" B.S.W. countersunk screws made to hold the thrust faces onto the front of the 'boxes. (Copyright John Dunn Engineering).

The 1/2″ B.S.W. countersunk screws made to hold the thrust faces onto the front of the ‘boxes. (Copyright John Dunn Engineering).

As I mentioned in a previous post the drawing I found in the Barclay Archive at Glasgow University specified that the thrust faces should be held on with nine 1/2″ Whitworth high-tensile brass countersunk socket screws. I was unable to find any countersunk brass screws of this size so our only option was to make some. The material chosen was CZ114, a high tensile brass.

The keeps needed new faces on the outside because these were also badly worn and I had obtained some suitable castings. These had been machined up in a similar manner to that described for the thrust faces and would also need some means of attachment. It seemed logical to use a similar style of screw to that specified for the thrust faces but, for practical reasons, these were reduced in size to 3/8″ Whit. I decided to use four to a keep plus a couple of “off the shelf” 3/16″ Whit. brass countersunk screws on each side at the top of the radius for a bit of added support in what might be a fairly “flimsy” area – the photographs should make this clear I hope.

The screws were turned to the standard Whitworth countersunk specifications but the heads were left extremely long, the idea being that they would be tightened down with a pair of Stilsons and then the heads milled off flush with the surface. Hopefully this should provide a neat finish and maintain the integrity of the bearing surface.

Countersunk holes being drilled in the thrust-faces on the borer. (Copyright John Dunn Engineering).

Countersunk holes being drilled in the thrust-faces on the borer. (Copyright John Dunn Engineering).

The axleboxes were set up on the borer and, once a datum had been established, the various holes were drilled and tapped. The keeps were smaller and easier to manage. In this case the holes were drilled into the plates on the milling machine and these were spotted through onto the actual keeps on the drill; they were then drilled and tapped to size.

 

 

Attaching the various plates was a simple matter of tightening the various screws down evenly. All of the holes were thoroughly cleaned first and a thread locking compound was used.

The thrust faces bolted in position on the front of the left leading 'box and keep. The screws on the keep have been machined back to make them level with the face, there is still some machining work to do on the 'box. (Copyright John Dunn Engineering).

The thrust faces bolted in position on the front of the left leading ‘box and keep. The screws on the keep have been machined back to make them level with the face, there is still some machining work to do on the ‘box. (Copyright John Dunn Engineering).

Thrust Faces – Diameter.

Having got the rear face of the thrust faces flat, it was now necessary to machine the outside to the correct diameter to allow the face to enter the recess on the axlebox.

There are several ways this job could have been done but I chose to use a rotary table on the milling machine. I felt this made for the easiest and quickest “set-up”.

The thrust faces were milled down to a diameter that was a snug fit in the recess. There is not a great deal more that can be said about this operation and the picture is pretty much self-explanatory I think.

Milling a thrust face to diameter on the rotary table. (Copyright John Dunn Engineering).

Milling a thrust face to diameter on the rotary table. (Copyright John Dunn Engineering).