1.1/2" Allchin - restoration and completion

[suctionhose]

These Allchins are really fiddly work. I have one in the lounge. You are doing a nice job there! They are lovely when finished.

Looks like I'm too late to mention this - apologies for not keeping up with the news - the top of water gauge connected to steam manifold.

The water level shoots up when you turn on the injector and the injector won't work because of the water being carried over with the Steam.

Frankly, such an arrangement is uncertifiable under our codes. That said, it's not a deal breaker because the pump is the main water feed.

Keep up the good work!

[springcrocus]

Thank you for that info, Ross.

Frankly, if I get it past the hydraulic test  (which is debatable to say the least) then I will probably steam it once, then retire it to a glass case.

The only reason I'm trying to finish it is as a mark of respect to my father.

Regards, Steve

[timb]

Mar 24, 2021 1:06:52 GMT suctionhose said:

These Allchins are really fiddly work. I have one in the lounge. You are doing a nice job there! They are lovely when finished.

Looks like I'm too late to mention this - apologies for not keeping up with the news - the top of water gauge connected to steam manifold.

The water level shoots up when you turn on the injector and the injector won't work because of the water being carried over with the Steam.

Frankly, such an arrangement is uncertifiable under our codes. That said, it's not a deal breaker because the pump is the main water feed.

Keep up the good work!

Out of interest Ross, is there a way to solve this issue?

Great work Steve, enjoying the journey very much!

Tim

[suctionhose]

Mar 24, 2021 7:32:40 GMT timb said:

Mar 24, 2021 1:06:52 GMT suctionhose said:

These Allchins are really fiddly work. I have one in the lounge. You are doing a nice job there! They are lovely when finished.

Looks like I'm too late to mention this - apologies for not keeping up with the news - the top of water gauge connected to steam manifold.

The water level shoots up when you turn on the injector and the injector won't work because of the water being carried over with the Steam.

Frankly, such an arrangement is uncertifiable under our codes. That said, it's not a deal breaker because the pump is the main water feed.

Keep up the good work!

Out of interest Ross, is there a way to solve this issue?

Great work Steve, enjoying the journey very much!

Tim

[suctionhose]

Mar 24, 2021 7:32:40 GMT timb said:

Mar 24, 2021 1:06:52 GMT suctionhose said:

These Allchins are really fiddly work. I have one in the lounge. You are doing a nice job there! They are lovely when finished.

Looks like I'm too late to mention this - apologies for not keeping up with the news - the top of water gauge connected to steam manifold.

The water level shoots up when you turn on the injector and the injector won't work because of the water being carried over with the Steam.

Frankly, such an arrangement is uncertifiable under our codes. That said, it's not a deal breaker because the pump is the main water feed.

Keep up the good work!

Out of interest Ross, is there a way to solve this issue?

Great work Steve, enjoying the journey very much!

Tim

You simply attach the top of water gauge to a separate bush on the boiler.

Perhaps of interest is that many full-size engines do indeed have the water gauge connected to the Steam turret. What is less obvious is that there are separate passages within the turret...

[Cro]

Ross,

You may be able to explain why my 3" Burrell did something similar, whenever the boiler had pressure the water would shoot to the top and remain there no matter how much water you had in the boiler. It is a steel boiler and had been sat for a number of years unused after Grandad died and I wondered if it was crud as after a few steamings and blow downs it did eventually just stop.

The boiler needs inspecting and re-tubing as a minimum really so until that happens we don't use it sadly.

Adam

[suctionhose]

Mysterious. Blockage perhaps.

[springcrocus]

Boiler Side Stays continued

I was going to try and do both sides at once but, in the end, I chickened out and did the job in two halves so that, once again, I had gravity in my favour. All the screws were set in place and the boiler laid over to about twenty degrees from the horizontal. Then solder rings were placed on the uppermost side of each one, inside or outside to suit, and well-fluxed.



After cooking, it was pickle, rinse and repeat for the other side. It appears to have been successful but I won't be sure until I can pressure-test the boiler. This side is a little neater than the other side which has a couple of solder puddles. None of this is seen as the firebox sits between the horn plates.



Then it was on to making the rest of the foundation ring pieces, starting with the back and then the two sides. These are made from 1/4" square copper bar. In addition, a pair of packing pieces were made for each side for fixing with screws through to the foundation ring, doing two jobs at once. The extra screw holes in the two side sections are for withdrawal screws, used during the sizing process when they have to be in and out all the time: file a little, test, file a little more, test etc. Two further packing pieces, to the right of the picture, were made which get fixed adjacent to the frontplate.



After a really good clean-up, the foundation ring pieces were assembled into place and the boiler set up on the hearth with plenty of surrounding material to keep the heat in. Some tiny wedges were made from beaten copper wire to plug the small holes at each corner and hammered into place.



I ran out of time today but, although the soldering seemed to have gone well, one of the wedges must have popped out because there is a hole at one of the corners. Tomorrow, I shall make a closer inspection and do whatever repairs are needed. Then it will be time to do the final job which is solder the longitudinal stays at the smokebox end. I collected the test kit from the club this morning so I should be able to finish the boiler in the next couple of days.

Steve

[springcrocus]

Boiler - final stages

After a really good soak in the pickle to get right into any tiny crevices, I had another go at the foundation ring and, this time, all seems to be well.



Then it was the turn of the longitudinal stays on the smokebox tubeplate along with more solder to the one tube that leaked from the first session. As before, I set the boiler up with the butane torch providing secondary heat to the inside of the firebox. This also helps to protect the tube joints from cracking due to differential expansion. After cooling and pickling, it looks like I've had a good melt.



This was the first time I've been able to perform any sort of test on the shell and a couple of things immediately came to light. First problem was this joint between the boiler shell and the outer wrapper. There is a collar underneath here but it leaked profusely so some copper wire was beaten flat, almost to foil, and set in the three visible sections. I've just filled the centre section in this picture. However, the other side was fine and required no extra work.



The other place that leaked was around the doubling plate used under the cylinder. This doesn't need to be steam-tight in use because, obviously, the hole get drilled through and provides steam to the engine. Sticking my thumb over it was enough to find the previous problem but not much good for the shell test. So, for now, I have made a cover plate and gasket that is held in place with a large jubilee clip. The gasket didn't seal but a couple of "O" rings did the trick, instead.



I also discovered that one of my side stays had a pinhole leak so the area was cleaned up and repaired also. After that, I was able to lightly pressurise the boiler with the airline and a potentially fatal problem reared it's head. There were a few bubbles coming out of the joints between the firebox inner wrapper and the two end plates. it's not much but it could be a killer. I will discuss this with the boiler inspector and see what he suggests.



This is one of the disadvantages of working with something that was soldered up about thirty years ago. There was no way to test these joints beforehand, nor is there any record of what solder and flux was used. Probably cadmium-bearing, which I don't have a problem with, but it probably also had a lower melting temperature that what we use today. So it could have been poor joints to start with or I may have disturbed the joints with my subsequent soldering operations. It may also be that a flood of comsol on the crown will allow the boiler to be used but I don't know.

And one further piece of information for those who didn't know, myself included.

Those flat, red, fibre washers that plumbers use for sealing taps and other spigoted fitting do not withstand silver-soldering temperatures! It was only after the last heat-up that I realised I'd left one of the blanking plugs in place and, when I looked, the washer had completely disintegrated and the threaded plug was loose in the bush. It's a good thing I have loads of those washers, although I may not need them if the boiler fails.

Steve

[coniston]

I hope that your boiler inspector can suggest a suitable remedial action to take on the wrapper to plate joints after all the effort you've put into finishing the boiler.

It's been an interesting thread to follow and will help I am sure in my upcoming boiler building exercise.

Cheers for the insights

Chris D

[John Baguley]

Hope you manage to sort it Steve. It would be a great shame to scrap it after all that work. Personally, if the boiler is structurally sound I would just use Comsol to seal the pinholes. Frowned upon by some no doubt but I consider it perfectly acceptable.

My first boiler was the Allchin about 1973 and I really struggled with getting it hot enough. I only had a small propane bottle and it kept icing up and losing pressure. I never finished it and it still has several pinhole leaks in various joints on the wrapper and firebox that I never sorted out. One day maybe!

John

[springcrocus]

Boiler Test

Thank you for the encouragement, gentlemen, but I wouldn't have been too disappointed if it became an ornament only.

Well, it appears that the original soldering was not very good at all as I have spent the last couple of days chasing down weeping tubes and flange joints but, finally, I appear to have reached a satisfactory position. I have needed to resort to comsol because there was no way I could get a high enough heat into the firebox with the equipment at my disposal. Well, without disturbing the rest of the boiler joints, that is.

This is where I'm at now, with two tiny weeps from the barrel to outer wrapper joints and I can't yet hold 10% for ten minutes but it proves that the shell is sound. The firebox is perfectly dry so all those repairs have been effective.



I will try to repair the two weeping joints and, if successful, then I can have the official shell test done. This is all very encouraging considering that I thought I probably had a scrapper a couple of days ago.

Steve

[coniston]

That's excellent news so far, perseverance has paid off yet again, well done and good luck for a successful test.

Chris D

[springcrocus]

I've chased down a few more weeps and am now ready to present the boiler to the inspector for it's shell test. There are a couple of places where water escapes but these will seal on their own, or with the help of a little ground white pepper. The test kit also needs a little TLC as it leaks back past both the lock-off valve and the pump.

The next stage of the job was milling the heads of the stays and the packing to get a snug fit between the hornplates. The boiler was set up on packing to get it as even as possible, then the first side was skimmed down using a home-made flycutter. I took about thirty thou off this side. A single clamp in the firebox was enough to hold it in place.



The boiler was flipped over and the other side milled to bring the width to 3.812". Then it was offered up to the hornplates and this was a very time-consuming job. Hughes designed this boiler to have hollow side stays so that a rivet could pass right through and fix the boiler without disturbing the integrity of the shell. Therefore, positioning was all-important to ensure that the boiler went back to exactly the same place as it was when the side stays were spotted through. I drilled one hole on each side. loaded a steel rivet and manipulated the opposite side until I could see my witness mark, then drilled the second hole.



A flat piece of MDF was laid on the mill table and the 3/32" dia holes drilled through freehand, dropping a steel rivet into each hole as they were done to control any movement. Drilling the other side meant resting on the rivet heads but this presented no problems.



I was able to get some 3/32" copper rivets that were 1" long from "Just the Ticket" and, rather than rivet the hornplates to the shell, I have chosen to thread the ends 7BA and put nuts on the inside. This allows for future disassembly. A split brass collar was made to hold the rivets for threading in the lathe.



As each rivet was converted, the short steel rivets were withdrawn and the hole redrilled with a pistol drill. Getting a hand into the depths of the firebox to fit the nut was a bit tight and the rows nearest the crown were done first. With all the rivets in place, this is the current state of play. The ends need trimming to length but there are a few more holes to drill before disassembly.

I have also decided to omit the lower row of rivets that go through the foundation ring on each side. I will fit blind rivets to the hornplates, instead.

Steve

[springcrocus]

Smokebox ring

With the boiler mounted between the hornplates, attention was turned to the smokebox end. This required a spacer to be made for fitting between the smokebox and the barrel and was fabricated from a strip of copper, bent round a former and silver-soldered at the join. A line was scribed around the outside with the height gauge set at 3/8" and the ring pressed into the smokebox until level with the line. The 1/16" dia rivet holes were then transferred through.



The cutaway in the ring is to clear the one of the chimney mounting screws.

Once they were all drilled, the job was transferred to the lathe and the front of the ring turned away until flush with the smokebox. I'm holding the work on the inside of the smokebox door ring for this. I took small cuts along the diameter rather than plunge the face because of the risk of digging in; it's all too easy to for the tool to drag itself into the job when using the racking handle.



The bore needed opening up to fit on the barrel but there was also some distortion to contend with so the hide mallet helped in getting a snug all-round fit. I had to change over to the other jaws for boring as the door ring wasn't running true enough.

With the two parts married together, the cutaways for the various screws were transferred to the rim of the barrel and these were filed to suit.



This is the smokebox with the ring in situ and both the chimney and saddle bolted on. These are needed to ensure that the smokebox is orientated correctly to the barrel and that the chimney is truly vertical in both planes.



This is the first time I've been able to bring the front end and the main body together. It looks a little nose-high but I'm not sure if this is how it should look in full-scale. I will double-check all the dimensions but I expect this is how it should be.



I can't do any more on the boiler until the shell test has been done because fitting the cylinder means drilling the barrel for the fixings. There will now be a pause in this build while I get on and finish the Britannia.

Steve

[Cro]

Looks great Steve, nice work!

Adam

[springcrocus]

Blowdown Cock

Another item that I made between boiler sessions was the blowdown cock that sits on the lower right-hand side if the firebox (from the driver's point of view). I started making this from phosphor-bronze but part-way through the first operation I broke a 1/16" dia drill up the hole, scrapping the part. I swear, I'm never going to make anything from phosphor bronze again unless it's absolutely neccessary; bloody awful stuff.

Starting again with a different, unknown grade of bronze I polished the stock diameter first, then turned the 3/8" diameter shoulder and the 3/16" diameter for the thread. A small undercut was made at the back, a button die run down using the tailstock die-holder and the 1/16" diameter hole drilled for a depth of 7/8". There was no problem with drilling this material although I still brushed on lots of suds.



A threaded bush was made from a piece of 3/8" dia material next and the blowdown cock screwed into it.



Then the 5BA hole was drilled and tapped to depth, followed by turning the outer form of the cock.



1/8" dia stainless steel stock was used for the spindle, simply running a 5BA button die down to length and turning a 80 thou spigot on the front along with a 45 degree point. After parting to length, the spindle was held in a collet block and the square head milled. The collet was just nipped up tight enough to hold without damaging the thread.



The blowdown cock was offered up to the boiler bush before marking where the outlet needed to be. The outlet was turned from some 3/16" diameter brass tube and silver-soldered to the body. I haven't made my mind up yet whether I will bother with the dummy studs and nuts.



Steve

[springcrocus]

Pump feed clack

I made the pump feed clack from an offcut of bronze plate so that I could make the main body as a single piece, rather than silver-soldering a three-part assembly together. It ended up as three pieces, though.



The billet was held in a four-jaw chuck and the front faced off to set a datum.



Then the upright section of the clack was turned to 3/8" O/D, the bore drilled 7/32" dia. by 3/8" deep to the point for a 1/4" x 40 thread and followed with a 3/32" drill right through. A 7/32" slot drill was used to flat-bottom the hole before tapping 1/4" deep. Finally, the neck of the clack was turned to 5/16" dia using a tool that leaves a 45 degree angle at the back.



The chuck was then swapped for a collet and the work held on the turned diameter to allow facing to overall length. I screwed a threaded plug into the body first to protect the thread from being squashed down.



This is how it looked after the first two operations. The 7BA thread has been tapped in the bottom for the dummy test cock.



Back with the four-jaw and the other leg of the clack was machined next. The three faces that are in contact with the chuck jaws all have further machining to be done, thus no jaw packing, but the bung protecting the thread is clearly visible. After facing to length the 5/16" dia was turned to depth, just short of the other leg. A 1/4" dia by 1/8" long spigot was turned on the front and a 3/32" diameter hole drilled until it broke into the other leg.



The job then moved to the mill where the sides were milled down to just over 5/16" thick.



The cross-hole for the branch was drilled next, followed by a tiny recess to locate the branch pipe and flange. A 1/4" diameter slot drill was used for this. After machining, the elbow-shape was formed with files and the linisher.



The branch and flange were made next, just straightforward turning on the lathe. Hughes shows the flange bolted to the boiler bush but my bush is threaded 1/4" x 40 so I made my fitting to suit. It's easier to do the plain end first.



This is the second operation with the work held in a collet, turned and threaded to 1/4" x 40 and drilled through.



A few other simple parts were made which I didn't bother to photograph. A bronze washer was made to act as the flange on the inlet side of the clack and I also made the injector-feed clack at the same time but that was a very simple item. Both clacks needed a top plug and these were made from 7/16" diameter bronze. After turning, they were screwed into a hexagonal block and the spanner flats milled. Doing it this way, the work is always being tightened into the block.



After silver-soldering the various components together, I decided to add the dummy nuts and bolts to the two flanges. Holes were drilled and tapped 10BA on a 7/16" dia PCD and long screws inserted from the back. Nuts were tightened onto the fronts and the rest of the screw cut away at the back. This way, I get to use the screws on another job.



Another flange was made for soldering to the 1/8" dia delivery pipe, 1/8" dia silicon nitride balls were pressed into the seats of each valve and the caps fitted using plumbers washers to seal. These are the two completed valves, ready to fit to the engine.



Steve

[springcrocus]

Winding Drum Guard

The drawing suggests making the winding drum guard from brass but I have made mine from 1.1mm (45 thou) mild steel sheet as there is a ready supply of this material in the skip of a local tinbashing firm. However, first I needed to make a former from some 20mm MDF. This was cut from a redundant kitchen end panel.



The outline of the guard was traced from the drawing, then transferred to the steel sheet, although the centres of the two circles were accurately marked and centre-popped. There is no hole for the third motion shaft but I need to mount a former behind here so will drill a 4mm hole and fill it later. The large inner ring will be cut away later.



The rim of the guard was cut from another piece of the material, 20mm wide by about 500mm long. Meanwhile, the former had a boss screwed to the back and was then turned to 6.660" diameter, allowing two lots of 45 thou for the material thickness. The body of the guard was roughly cut out with about 1/8" extra to get the basic shape, then screwed to the former.



The outside of the guard has approximately forty dummy rivets set around the perimeter and holes for these were drilled next, missing out the five positions that cross the 3rd motion shaft, seen as felt-tip marks on the plate.. Hughes suggests 1/32" dia rivets but I have opted to use 3/64" rivets instead as these seem closer to the prototype. These were drilled at 9 degree intervals on a 6.562" dia PCD with a 1.2mm PCB drill.



The strip was formed freehand around various formers - the lathe screwcutting gears came in handy here because of the wide range of diameters - and the ends trimmed to meet as a butt join at the bottom. The clamps were used to keep the top section in place whilst shaping.



At this point, I removed the plate from the two MDF formers and placed both metal parts in the pickle to remove all the galvanising. Once these were clean, a joining piece was rivetted to the rim with four 1/16" steel rivets. The rim was then placed on the plate, aligned with the holes for the dummy rivets and clamped in place with four engineers clamps, ready for silver-soldering.



However, all did not go to plan! I didn't use enough clamps and I probably got the assembly a bit too hot. The outer plate lifted at the two sides and the whole thing distorted in just about every direction. I was able to get one section soldered by extra heating and using mole grips to close the gap but the other side didn't want to play. I left it all to cool and this is the dismal result.



Luckily, I was able to get the centre pressed somewhere near flat by leaving it under the hydraulic press for an hour and I was able to close the gap on the side by using a hacksaw blade to saw away some of the silver solder, then pressing the gap closed in the vice. This was then patched up with silver-bearing soft solder.

Next job was to remove the waste from the centre and, for this, the formers were once more screwed to the assembly. This was then loaded onto the rotary table and a 1/8" dia slot drill used to cut a channel at the correct PCD.



The rest of the work was cleaning up the perimeter on the linisher and with sanding drums, drilling the dummy rivet holes around the third motion shaft cover, plus redrilling all the other holes, then setting the 3/64" diameter rivets into place. I've been very lucky in being able to recover this. You'd think that, by now, I would be able to solder two bits of tin can together without making such stupid errors but such is life.



I will get the brackets made next, plug the small hole and then the guard can be primed and put away.

Steve

[Cro]

Steve,

A good trick I found years ago for doing jobs like this is to get a thick piece of steel plate, 10mm or so and pop it in the oven at max temp. Then place the hot plate on a camping gas stove on max to keep the plate as hot as possible with offending item on top and that allows you to work around it without overheating in places.

Looking good, how's the Brit?

Adam