1.1/2" Allchin - restoration and completion

[jon38r80]

I have seen 8mm wide clockwork springs on Aliexpress if its any help for the brake band

[springcrocus]

Thanks Jon, I will have a look. However, 8mm is just too wide, the space between the brake lever plates is a bare 5/6". There is no rush, the brake band can be fitted anytime right up to completion.

Regards, Steve

[springcrocus]

Boiler 2

The next job I tackled was getting the firebox square at the base. I used the wrong term before, I meant rhomboidal (if that's a word) rather than trapezoidal and this was achieved suprisingly easy with a large "G" cramp. The copper is much more maleable than I would expected after thirty or so years.



Onto the frontplate and this needed reducing in width. All the materials have been specified as 13 swg (3/32") so far but this, along with the smokebox tubeplate, are made from 1/8" copper and look to be professionally made so were probably purchased from Reeves. This made it an easy task to mill an equal amount off each side without weakening the plate.



Once milled, I scribed a centreline on the frontplate and offered it up to the outer wrapper. The size was as expected, 3.11/16", and the centreline will be used to set the position of the firehole.



I'm going to hold the crown stays to the wrapper using four 4BA countersunk PB screws and I was able to tap the stays around a little bit until I was happy with the position of the firebox. Hole positions were then marked on the top of the boiler and the the parts disassembled. The four clearance holes were drilled first, then the boiler reassembled and the holes spotted though, drilled and tapped 4BA. Even I remember that, occasionally, machine tools are not the ideal tool of choice.



With some temporary steel bolts holding the girders in place and clamps holding the bottom together, it was time to get the frontplate into place. But first, the firehole ring had to be adjusted because it was too high. It should be level with the back of the outer wrapper. The screws held the assembly firm enough that I could use a drift to ease the firebox wall inwards until the firehole ring was level.



The frontplate was offered up so that I could scribe through the firehole, a job that really calls for small hands. It's a bit tight in there.



Then I stitch-drilled a load of 3mm holes around the perimeter.



The waste was cut out with an Abrafile and the hole dressed to size, starting with a rough file and finishing with sanding drums in the dremel.



Coming along nicely.

Steve

[coniston]

Nice job Steve, looks like you've really got the hang of this boiler making malarkey.

Chris D

[jon38r80]

Since I looked at that spring on Aliexpress I got loads more shown to me by Aliexpress, it's the way their website works, with lots of different lengths an widths for toys, drill press return springs etc etc. I expect you will find something of suitable width there or Bangood. I wish that I got more choice for what I was originally looking for which was a flat spring handle. Of course they have them but just not quite the style I was looking for!

I agree with Chris D, the experience you gained making your Loco boiler certainly has stood you in good stead for this one. As usual good neat workmanship. Looking forward to you putting it all together.

[springcrocus]

Boiler 3

More work was needed on the frontplate including holes for the decorative rivets around the firehole, three holes for some blind bushes to carry the firehole door and it's catch, ten holes for the stays and cutting the bottom off to length. Apart from the two on the centreline, the firehole rivets were drilled by eye as I could find no dimensions given anywhere.



The water gauge bush had already been made but I needed to make the three blind bushes and these were made from 5/16" diameter Colphos. It's much nicer to machine than phosphor-bronze and is perfectly OK for this job. The O/D was turned first, then a 1/4" x 40 button die run down and finally parted of with a 1/16" shoulder. Screwed back into a tapped bush, the 7BA thread was drilled and tapped, stopping the drill at 1/4" deep.



The frontplate was fitted to the firehole ring and clamped with a pair of penny washers and an M8 nut and bolt. The vee-block clamp is a convenient way of getting over the firehole rim and ensures that the frontplate stays put while I drill and tap five 4BA holes in the sides and top of the wrapper and frontplate. These will be countersunk screws made from bronze as they are in the water space.



Everything was placed in the pickle, including the copper rivets, and then rinsed off. Correction fluid was painted around the firehole area to stop all the silver solder running away when heated. Flux was painted into the rivet holes, the three blind bush holes and onto the bushes and rivets before assembly. The rivets were snipped to length and gently peened into the countersinks, hopefully leaving adequate room for solder penetration.



Solder was stategically-placed inside the ring and the frontplate set up in a hearth. The plate is raised on blocks so that I can apply bottom heat and the whole thing is enclosed to retain whatever heat I can. A final helping of flux was applied generously around the area and the torch fired up.



After an hour or so in the pickle, this is the result. The correction fluid has done it's job and contained the solder and, apart from one rivet adjacent to the water gauge bush hole, everything has soldered well. I shall remove the dodgy rivet, clean the hole and start with a fresh one rather than try and resolder this one. The bush will be done at the same time.



After that, the rivets will need to be dressed back to flush so that the firehole ring sits correctly.

Steve

[springcrocus]

Boiler 4

With the front plate drilled it was time to drill the rest of the stay holes in the shell and firebox. The throatplate holes were marked out with a vernier caliper and then centre-popped, no real accuracy here as they are hidden behind a dummy thoatplate. I silver-soldered a 1/8" drill into a length of mild steel to give me an extended drill.



The inner and outer were then reassembled, along with the frontplate, screwed and clamped into position, adjustment being made to get the firebox central within the wrapper. The front and rear stay holes were drilled first, loading temporary steel rivets into the holes as the job progressed. Once these were in place, the assembly was offered up to the hornplates and the side stays spotted through with a hand drill. The pump feed bush and blowdown bush were also marked out. Then all the holes were opened up on the mill.



Due to years of handling, the tubes were all out of position and a couple out of shape as well. I used the drill jig that father had made, opening the holes up an extra 1/64", and worked this down to nearly the bottom of the tube nest. Then the tubeplate was offered up and the tubes teased into position. In the picture, I have the tubeplate upside-down.



The tubes were quite a tight fit and needed to be eased somewhat to aid assembly. First, the tubeplate holes were cleaned up with a sanding drum in the dremel, then the drill jig was brought up near the top for support and the tubes given a clean-up with emery cloth.



After assembling everything together, it became obvious that the smokebox tubeplate was going to give trouble because of it's poor fit and because the barrel is slightly tapered (narrower) at the front. It's impossible to fit the tubeplate from the firebox end so I'm going to solder the plate in first and load the firebox and tube assembly later. In the meantime, I've also decided to fix the longitudinal stays to the frontplate now, rather than try and locate them later. Because I'm hard-soldering all round, I dont need to worry too much about the smokebox end but more on that later.



Steve

[timb]

Hi Steve, Just realised that this thread has been updating the last year!! Doh.

Now following with interest, I have mentioned to you before Ihave an Allchin in similar order but without a boiler waiting under the bench!

Thanks for posting, looking great!!

Tim

[springcrocus]

Mar 7, 2021 13:16:21 GMT timb said:

Hi Steve, Just realised that this thread has been updating the last year!! Doh.

Now following with interest, I have mentioned to you before Ihave an Allchin in similar order but without a boiler waiting under the bench!

Thanks for posting, looking great!!

Tim

Hello Tim,

Taking a break from the Britannia for a while, it's pretty much finished now but I don't like platework and I don't like painting. There's a couple more pictures added to the last post of the diary if you hadn't seen them but I'm not mindful to revive the thread at present. There's a much lower readership down here in the long grass but I'm fine with that, don't need a large audience.

If you start on your boiler, there are some design features that could do with an overhaul. Boiler stay and bushes need redesigning and some of the doubling pads are superfluous.

Regards, Steve

[springcrocus]

Boiler 5

Before joining the two sections of the boiler, there are a few more parts that need fitting first. The pump inlet and blowdown cock bushes were fitted next and I also found a small hole between the barrel and the wrapper that needed filling. A tiny wedge of copper was banged into here and all three things done at the same heating. I've buried as much of the boiler as possible to help keep the heat in.



Some people think that's a waste of time but I find I get up to temperature much more quickly and, therefore, don't exhaust the flux.

I usually leave the workpiece covered for a few minutes rather than risk rapid cooling. This is after fifteen minutes and it's just about cool enough to pick up with bare hands.



While that was in the pickle, I made the mounting pad for the steam manifold from an old, scrap gunmetal casting. This pad is 7/8" square and needs to sit on top of the outer wrapper. After milling all round to get it square, I needed to dish the underside to match the 3.750" diameter of the barrel. The billet was mounted at one end of the vice and a packing piece (a Hoffman roller) at the other end.



Using a boring bar in my boring head and adjusted to the absolute maximum is just a little shy of the required diameter but it will have to do. Four cuts of ten thou on the "X" axis just using the quill completed the operation.



Then the pad was set on parallels, clamped tight and the parallels removed. The four holes for the mounting studs were drilled, followed by a 5/32" hole in the middle and a 1/4" wide slot to clear my frontplate clamping screw. The holes were tapped freehand 8BA: the drawing says 7BA but I think that's a touch too big.



To protect the tapped holes, I have screwed 8BA bolts in and put a spot of correction fluid on the underside to stop any solder filling them. Flux has been painted over the rest of the area and on the top of the outer wrapper.



The pad has been held in place with a sacrificial spring clip, a horseshoe of solder place around he outside and more flux added. I have set it at an angle so that I can apply heat from inside the wrapper but still have gravity working in my favour and see what's going on. It was not so easy to get blocks around the boiler this time but, because I'm working near an outer edge, it should still go quickly.



I managed to get the part soldered into place but then ran out of time. After a spell in the pickle, I will see whether or not this has been successful.

Steve

[springcrocus]

Boiler 6

The manifold mounting pad was not as successful as I'd hoped. There was a hollow at the back of the pad and, when I put the airline to the steam hole, water bubbled out from underneath where the arrow points. A clamp was fitted to the front of the pad, the work re-fluxed and another piece of solder set in place. The second attempt was satisfactory and the steam hole can now be drilled.



The manifold had been mostly machined but it's base had been left at casting size and overlapped the pad. Holding on the edges, I first machined a pair of flats on the sides of the outlet pipe. The fitting was then upended in the vice and set on a pair of 1/16" thick packers at the end of the vice. The packers were removed, the work centre found and the edges milled all round to leave a 7/8" square. The four mounting holes were drilled 8BA clear at the corners and I also formed a recess for an "O" ring.



The "O" ring is not featured on the drawing and a gasket would have been used originally. I have used a 9mm diameter by 2mm section ring and made the recess 1.7mm deep. If it turns out that it doesn't seal well enough, a little more can be skimmed off the base. This is the manifold ready to be screwed into place.



This is the manifold screwed into position. I will need to clean up the outside of the casting somewhat but this can wait until a later time.



Steve

[springcrocus]

The smokebox tubeplate was soldered into place next using 40% silver solder and, although it has sealed all round, it has not formed as nice a fillet as I would like. This was followed by joining the two sections together, manipulating the tubes through the holes with a pencil and screwing the crown stays and front foundation ring section into place for accurate spacing. In the next picture, I have placed solder rings around the tube ends and you can see where a bit more solder is needed on the perimeter.



The correction fluid is to prevent solder flooding away to the top of the boiler. The tube at the top right is just flush with the tubeplate and will probably cause the solder to flow down the inside of the tube so an extension piece was made from more copper tube, the inner section being the next size down. It was cut off about 1/2" long overall and cleaned up really well before placing in the short tube.



Extra solder was placed in the perimeter gully, 55% solder this time, and the whole assembly well fluxed.

Learning from our experience with the Britannia boiler, I set everything up as shown in the next picture. The small butane kit clamped in the workmate will supply continuous heating into the firebox and will ensure the tubes get nice and hot. The biggest problem we found before was that the tubeplate got hot and the solder puddled all over it but the tubes didn't get as hot and the solder didn't take very well. We had to revisit the job twice before we had all thirty two tubes soldered to our satisfaction.



The next picture was taken a few minutes after removing the heat and it looks very encouraging. After five minutes cooling, I removed the surrounding insulation and left it until I could hold it in bare hands. This now goes into the pickle for an hour or so before getting a really good rinse.



And this is the result, which I'm very pleased with. The one tube indicated by the black mark will need resoldering but all the others, including the extended tube, have perfect joints. The extra solder around the periphery has also melted well and formed a nice fillet. I'm very encouraged by this.



Now to crack on with the firebox stays.

Steve

[uuu]

So the lesson here is, if you want to get good at boilermaking, a Britannia is a good starter project.

Or, to put it another way: Starting small and working up means you'll always be just beyond your comfort zone. But start big and everything after that is easy.

Wilf

[springcrocus]

Boiler Stays

I decided to fix the throatplate stays first and these are made using 1/8" diameter copper rivets. They were loaded from inside the firebox and solder rings placed on each in the waterspace before the rivet was pushed through to the outer skin and a second ring placed on the outside. Flux was painted onto the rivets both in the firebox and in the waterspace, then the rivets pushed fully home. A dimple was crimped into each to keep them in place when upended. This was how we did the Britannia.



With the assembly resting on the firehole, the rings were pushed down to the surface and loads more flux applied. The it was carried through to the hearth and surrounded with thermal blocks. Heat was applied inside the firebox until the lower rings flashed, then the upper rings followed shortly due to conducted heat.



After an hour in the pickle this is the result. Solder has migrated through to the inside of the firebox and formed a perfect joint around each of the stays.



And on the outside, the solder has left a nice fillet around each of the stems. I can see that solder has flowed through to the waterspace but the camera is unable to capture the detail.



This method appears to give good results every time and, hopefully, the rest of the soldering will go as well as this. However, the smaller size plays an important part; I don't think I would like to tackle one as large as the Britannia without assistance.

Wilf, you can get some more practice in next year, if you want, as I will be looking at the next build once the Britannia is out of the workshop.
A 5" Adams "O2", W24 "Calbourne" as she is today on the IWSR.

Steve

[uuu]

That sounds like a good plan - although 7 1/4" might be better?

Wilf

[springcrocus]

Mar 14, 2021 14:23:20 GMT uuu said:

That sounds like a good plan - although 7 1/4" might be better?

Wilf

Not too sure about that. At 7.1/4" gauge the loco wil be (1.45 x 1.45 x 1.45 = 3.05) times heavier and 3.05 times more expensive also. Stretching both my machinery and my budget, I'm afraid.

Regards, Steve

[springcrocus]

Valve Gland

In between soldering the boiler, I've been making some of the smaller missing parts and fitting things together. Another problem arose when I came to load the slide valve into position. Because I had reworked the motion bracket, the valve gland was now out of line and it was far enough adrift that I had to plug the existing hole in the steam chest and remachine the gland housing. The first job was to machine away the raised part of the housing using a lathe boring bar in the mill.



The housing needed moving about 1/32" outwards and 1/64" downwards so a 7/16" end mill was sufficient to clear away the lower tapped hole but not the top one. Bigger would have broken out of the back of the steam chest. A 7BA brass bolt was screwed into the upper one and cut off flush. Over on the lathe, a top-hat plug was made from 3/4" diameter Colphos and parted off. This was then silver-soldered into the steam chest. A transfer punch was made from some 7/32" dia steel and used to spot the top of the new plug through the motion bracket valve guide.



Back on the mill, the steam chest was loaded to the vice and the DRO centred on the punch mark. The 1/4" diameter housing was drilled and reamed along with the 1/8" through-hole. I used 3.2mm for that to give a touch of clearance. The two fixing screw holes were drilled and tapped and I decided to go down to 8BA for these because 7BA looks a bit chunky.



Putting it all together, the valve had only a hint of stiffness in the movement which can be eased by polishing the spindle. The packing in the gland will compensate for any looseness.



And then it all went pear-shaped. I needed to bring the rim of the top hat to the same shape as the gland and started to nibble away at the raised section with a small end mill. In a moment of inattention I had a dig-in which not only damaged the remaining section of the seat but wrecked the gland as well. Resisting the urge to throw the whole damn lot out of the window, I completely milled away the seat, made a new gland and also a separate packing piece from 1/16" brass sheet.



The packing piece was bolted to the steam chest and soft-soldered into place. It has no functional purpose so silver-bearing soft solder is fine for this. After cleaning up, the steam chest was built up once more and this time it looked more as it should. Because the mill was still centred on the hole, the assembly was loaded back to the stop, the reamer taken down to depth again and the 3.2mm hole redrilled. With the steam chest back on the cylinder, all is now well.



As with the boiler, I'm finding that every time I change something to bring it in line with the drawing or make it fit correctly, something else goes out of kilter. I've come to the conclusion that doing up unfinished models is not for me. I would rather bin the whole lot and start again. You've only got yourself to blame if it goes wrong after that.

Back to the boiler tomorrow, let's hope it's not going to be another lousy day.

Steve

[springcrocus]

Boiler continued

Soldering up the girder stays was next and, as with the Britannia, were a pain in the rear, needing three visits before I was happy. The advantage of using bronze screws to hold them in place means you can test the screws afterwards. If any unscrew then there is not enough solder and another heat-up is required.



Then I hit a problem, one of my own making. All that fiddling with the girders had distorted the wrapper by a small amount and needed to be teased back to the shape of the frontplate. However, I had already soldered in the longitudinal stays and this made the job many times longer because I had to keep loading the stays through the smokebox tubeplate, which was a fiddle. I used this method for locating them, bits of plastic tube of varying length fitted over the ends.



This method works for the Allchin boiler because there are threaded stay bushes at the tubeplate so the holes are a lot bigger.



This made it fairly easy to assemble but didn't help much with easing the wrapper as the frontplate had to be removed completely each time to tap the copper from the inside. However, I managed to get a decent fit in the end and then set up for soldering. To help keep the solder in place, I filed a chamfer around the inside perimeter of the wrapper to create a tiny gulley, and the same again around the firehole. Setup was as previous so I took no photos of that but this is the outcome.



I'm particularly pleased with this effort. The five fixing screws have passed the test and there is a nice fillet all round the perimeter and around the firehole, all in a single session.

One new lesson in the art of boilermaking has been learnt, though. Don't solder things together until they are needed. Soldering the long stays to the frontplate before doing the crown stays was a mistake as I would have been able to reshape the wrapper much more easily if those stays weren't there to get in the way. Just before joining the frontplate to the wrapper would have been the right time.

Steve

[springcrocus]

Governor pulleys

Other parts I have needed to make included the governor and countershaft pulleys. These were made from mild steel because I didn't fancy plunging the radius shape into stainless steel. The larger countershaft pulley was first and I decided to make it in two parts because of the internal protruding boss that is shown. A piece of 7/8" diameter EN1A was skimmed to 13/16", faced off and then drilled and reamed 3/8" diameter. After that, the front of the pulley was opened out to 7/16" diameter by 5/32" deep with a small boring bar.



A grooving tool was used to finish the 9/16" diameter of the smaller part behind this. I'm doing it this way round so that I can complete the wheel in a single operation. In addition to a frontstop for the tool, I am using a bedway clamp to act as a backstop so that I can just wind back and forth until I get to depth.



The form tool for turning the radius was made next, using 1/4" square high speed steel. This was freehand ground with the sides relieved and front ground square, finishing with a Heath Robinson set-up on my drilling machine as this has the fastest spindle speed. The wedge is one of a pair of ball-joint splitters I made nearly fifty years ago.



The next picture shows the form quite clearly, plunged in at about 200 rpm and a firm cut applied.



However, it is very easy to break the clamping lug on these small Myford-size toolposts if a dig-in occurs and I use additional clamping when doing work like this to protect the toolpost.



With the work parted off, attention turned to the core piece. This was made from 10mm diameter bar, skimmed to 3/8" diameter and a 1/8" diameter hole drilled through. The front had a little nose turned onto it 1/4" diameter by 1/32" deep using a 0.8mm tip to leave the radius, although it can't really be seen in the picture.



The two parts were then silver-soldered together, although an adhesive would have done the job just as well. The drawing is not very clear due to age-fade but the small boss detail can be seen to the left.



The smaller governor pulley was made in a similar fashion although I used an 8mm slot drill as a boring bar to create the recess. The grooving tool again created the rear boss prior to stepping along and parting off. The material here is a redundant copper-plated earth rod as I couldn't find any 1/2" diameter mild steel anywhere in the workshop.



This is finished apart from the cross-pin hole which I shall drill when I have made the spindle. At 3/32" dia, the slightest misalignment would be difficult to correct so I will drill both together.



Steve

[springcrocus]

Boiler continued

The stays to the front plate have now been soldered, duplicating the work done on the throatplate. As before, solder has migrated through the holes to form fillets either side.



Attention then turned to the side stays. These are bronze screws with a 1/4" x 40tpi thread on them, thirty two in total. They are threaded through both the inner and outer skins and are designed to be nutted on the inside and soldered with comsol. However, if silver solder is used the nuts can be omitted. Hughes recommends making a special tap for this job and one was duly made using 1/4" dia silver steel, turned to 7/32" dia at the front for 7/16" and threaded with a button die. On the mill, a collet block was used to index round and cut the flutes.



The turned section is to enable the tap to be perfectly aligned with the inner hole before cutting the outer hole. The cutter was then moved up and over to further relieve the flutes but the photo of this is too blurred to use. After hardening, then tempering to light straw, this is the finished article. The cutting lead was freehand-ground after the picure was taken.



My tap was a little undersize so, after each hole was tapped, a manufacturers tap was run through for sizing and the screws set into position. This ensures that the relative positions of the inner and outer skins stays exactly in place. A couple of the bronze screws that Jack made can be seen resting on the foundation ring.



However, after assembling the whole lot together, I felt that it was not possible to use my previous method for soldering the stays. The waterspace is too narrow and too far down to control solder rings on the lowest row each side. I decided to turn the heads to 1/4" diameter and put a small screwdriver slot in the ends for assembly purposes. With the foundation ring uppermost, two solder rings can be placed on each stay and, hopefully, will flow inwards to seal. I will find out if it works tomorrow!



Meanwhile, I have cut off the stays on the frontplate and dressed them with the dremel to look like rivets. They don't need to be too precise, they are practically out of sight under the footplate.



Steve