C2 Project News
It's been a while since our last website update - sorry! But a lack of news on the website means we've been far too busy working on the loco, and there's loads to report. Over the summer we've been holding two working parties each month, and many of these have been 3-4 days rather than the normal 2 days. With extra hands available around Boston Lodge, progress has been good.
This update covers the first four summer working parties, bringing us up to Mid August. As I write this, we've had two more working parties since then, so we'll get another update published soon! So, onto what we've been working on....
Late June working party report
To assist in with the grinding of the horn wedges and wedge faceplates, Dave 1 made a second part to the wedge jig. Because this has exactly the same slope angle as the first part of the jig, it can be fitted to a sloped face and clocked with a dial test indicator to ensure that the slope is at the correct angle.
With the brass sheets for the axlebox sides cut into appropriate sizes, it was time to machine them more precisely. Andrew and Dave 1 both worked on milling machines to straighten and square up the edges to their nominal dimensions.
We want the brass plates to fit onto the axleboxes really well, so we are making final adjustments to the size of the plates by hand filing them. It is hard work, so Chris, James and Dave 1 took turns at it. Chris stamped each brass plate with an identification number, so we know which side of which axlebox it will be fitted to.
The fixing screw holes in the axlebox sides were machined in China, so we're not assuming that they are all exactly aligned! This means we needed a method for marking the hole centres on the brass plates, using the axleboxes themselves as templates. Dave 2 and James devised a method for doing this.
Dave 2 machined the heads of a number of bolts into a point, and hardened them. By screwing the bolts into the fixing holes, resting the relevant brass sheet on the points on the bolt heads, and tapping the brass with a hammer, the brass is marked with the hole centres. The method works very well.
With the hole centres marked, Chris and Dave 2 took turns to start drilling holes in the brass sheets. There are a lot of them!
Early July working party report
With both milling machines in operation, Dave 1, Dave 2 and Andrew took turns at machining the edges of the remaining brass plates, and finished the task.
Dave 1 and Dave 2 took turns at fettling the edges of the brass plates to get them to fit perfectly into their allocated positions on the axlebox sides.
Dave 2 made a special tool to fit through the oil ports in the sides of the axleboxes. Again, it has a point on and is hardened, so can be used to mark the centres of the required holes in the brass plates. Dave 1 finished marking out the hole centres for the fixing screws on the brass plates, while Dave 2 continued drilling the holes.
Using the measurements taken during the late May working party, Paul and Dave 1 sat down for a few hours, fed all the numbers into a spreadsheet, and devised a grinding plan for the next iteration of grinding of the horn wedges. Paul then set to on the surface grinder, and ground the sides and sloped faces of the horn wedges.
Late July working party report
A very important task which takes a long time is the manufacture of stepped keys to locate the faceplates and horn wedges onto the frames. There are 16 of them to manufacture; each one unique. Andrew continued this work.
Dave 2 continued the work of hand fitting the brass plates to the sides of the axleboxes, and Dave 1 continued drilling the fixing holes in the brass plates. The brass plates are fixed to the sides of the axleboxes with countersunk screws, and so the fixing holes in the plates need countersinking. Using the scrap plates removed from the locomotive when we disassembled it, Chris devised a method of countersinking the holes to a consistent depth.
An unexpected problem was that the countersink tool wanted to pull itself into the brass, and the morse taper shank could not prevent it from doing so. Fortunately the countersink tool has a small flat on its end, so by positioning a steel stop at a fixed position below the hole, the countersink tool could not go too deep. Dave 1 continued the countersinking work the following day.
With the second iteration of grinding of the horn wedges completed by Paul at the previous working party, Dave 1 and Geoff fitted them, along with the fixed horn faceplates to use as a datum, to the frames. It takes several hours to fit 16 plates, considering that the bolts are not the easiest to access.
A set of measurements of the position and alignment of the horn wedges was then taken. The numbers will need to be processed in a spreadsheet as before, but at a glance it can be seen that the alignment is getting considerably better.
To make a change from working on axleboxes and horn guides, Geoff took a look at the crash beams. These have seen some action and are rather distorted, so we will replace them. The beams incorporate steps to access the front of the locomotive. A particularly nice feature is that instead of using off the shelf chequer plate, the Chinese have made grips on the surface of the steps by welding Chinese characters onto the surface. We are told that it says "Tread carefully".
Geoff has therefore started to remove the steps from the crash beams so that we can keep these features.
Mid August working party report
Andrew and Dave 1 found themselves in Wales again in mid August, and took the opportunity to fit in another weekend of C2 work. Dave 2 once again joined us; he's becoming one of the most dedicated workers on the project!
Andrew continued the manufacture of the faceplate keys. It is good to know that he is over half way through them now.
Dave 2 suggested that a better fit could be obtained between the axlebox sides and the brass plates if the axlebox sides were skimmed flat with a mill. We don't want to remove more material than necessary, but after discussion it was decided to give it a go. The first axlebox side looked good after skimming, and the brass plate fitted very much better, so it was decided to skim all the axlebox sides. Dave 2 then spent the next three days on the milling machine carrying out the task, and has very nearly finished all nine axleboxes.
Dave 1 finished drilling the fixing holes in the brass plates. He then marked out the holes for the oil pots using the special tool made by Dave 2 a few weeks previously, and drilled those holes too. With all the fixing holes drilled, the countersinking of them was also completed by Dave 1.
With the brass plates drilled and countersunk, and the axlebox sides being skimmed by Dave 2, Dave 1 started what is hoped to be the final fitting of the plates to the axleboxes. By the end of the weekend, five axleboxes had their brass plates fitted and screwed on, and more are in hand.
We're now getting very close to handing over the axleboxes to the staff at Boston Lodge Works for the final precision machining of the bearings and brass plates!
Working party reports for late August and September to follow soon, with some photos if you're very lucky!