There are quite a few parts that need to be made and brought together to make the boiler water level gauges or 3-cock gauges as they are sometimes known. The drawing suggests making the main bodies as two parts and brazing together but I've chosen to make them in one piece.
After having my ear chewed by Adam, I thought I had better make these from bronze. This material was kindly donated by Wilf (uuu).
Making two back-to-back from the same billet gave me a bigger section to hold on for the first operation. Here, I've turned and threaded the part that screws into the boiler and also drilled a blind hole for the water passage, being careful to get the depth spot-on. The hand-ground form tool for the globe section is also on view. Rather than the shoulder that's drawn, I will be using thin locknuts instead.
After both were machined, the billets were sawn in half and then held in soft jaws to machine the back to the finished size of 3/8". I've made this as close to size as I can to help a future operation.
Moving to the mill, the were machined down to 3/8" wide by 25/32" long. I deliberately left a shoulder after the globe part so that I could hold it in a collet. This is a square-sided ER25 collet block with ground faces all round.
Once again, I made sure that the 3/8" dimension was accurate so that I could hold the work in a self-centering 4-jaw chuck. The witness left near the collet is about five thou thick.
After filing away the flash, this is what I was left with.
Back to the lathe and with the S/C 4-jaw chuck mounted, the reason for getting those 3/8" dimensions accurate is clear. Holding on one section, the O/D was turned first and the 1/4" x 40 tpi hole drilled and tapped. This was extended with a 1/8" drill until it broke into the cross-hole at the half-way point.
The parts were then reversed in the chuck and the external thread for the gauge glass nut made.
As can be seen on the drawing, the only difference between the top and bottom fittings is the through-hole, the upper one allowing the glass to be inserted from the top and rested in the lower fitting. The holes were drilled to suit, two of each.
Before I go further with these, I shall make the valve spindles and a special reamer for cutting the 12 deg hole.
Steve
Last Edit: May 15, 2020 10:01:56 GMT by springcrocus
The spindles for the 3-cock gauges were made from surplus M8 stainless steel bolts and I wish I hadn't bothered - tough as old boots! Another time, I will treat myself to some free-cutting material.
After sawing off the bolt heads and the threaded section, they were held in a collet and the front-end section turned. The compound slide was set round at 6 deg. for this so the tapered section was also machined at this visit.
I didn't go any further with these yet as I wanted to make the reamer while the compound slide was still set. This was made from some 5/16" silver steel, hardened and tempered.
Next I drilled and reamed the tapered bores in the valve bodies to match the taper on the spindles. It's not so easy to control the depth when working with tapers and, since I don't have a quill stop, I worked very precisely to the digital depth gauge. I screwed them into a threaded bush to protect the ends from crushing.
Then it was back to the spindles and get the squares milled on.
To turn the opposite end, I made a small carrier from brass with a matching taper and a hollow back for a locknut. Twelve degrees inclusive is way above the self-locking taper amount, usually taken to be about five or six degrees, depending on surface finish.
The rest of the turning was done in one visit using the compound slide to index along for each shoulder. Not a very good picture, unfortunately, the morning sun was shining strongly through the window.
These are the finished valve spindles with a modification that I've chosen to make. They are about 1/8" longer and have an 8BA thread on the opposite end for a handle retaining nut. I've also increased the size of the thread on the front end.
I didn't bother to take pictures of making the gauge glass nuts, locknuts or handles and I still have to finish the blowdown valve at the bottom of each assembly but here is a picture of them at the end of play today.
A question and I hope you don't mind me asking it here. The idea of machining the taper on the reamer whilst machining the spindles is a perfect way to do it but how would you go about making the setup repeatable if you were to do the valves again to get the taper the same? I know we can set to 6degrees again but will it be the same 6 as before? Any thoughts as its something that has prevented me from designing taper spindles into my own scale water gauge castings there are sat here waiting for a cunning plan.
If this detracts from the build log I'll move it elsewhere but you are a master at machining set ups so I had hoped you wouldn't mind me asking.
Adam
Trying to Finish 5" 9f Producing Scale fittings using 3D wax printing and lost wax casting - www.crofittings.co.uk/ Renovating house stopping all of the above!
A question and I hope you don't mind me asking it here. The idea of machining the taper on the reamer whilst machining the spindles is a perfect way to do it but how would you go about making the setup repeatable if you were to do the valves again to get the taper the same? I know we can set to 6degrees again but will it be the same 6 as before? Any thoughts as its something that has prevented me from designing taper spindles into my own scale water gauge castings there are sat here waiting for a cunning plan.
If this detracts from the build log I'll move it elsewhere but you are a master at machining set ups so I had hoped you wouldn't mind me asking.
Adam
Adam, while the compound is set, make a master gauge of a larger diameter, say 20mm, and 50mm long, or whatever your compound slide can travel. When it's time to set the compound again, put the master in the chuck, clock in a toolpost holder and shoot for zero.
To make a repeating-size reamer I would put a shoulder on it at the max required diameter.
To get the spindles to a similar size, I would make a ring gauge with the taper in it and machine half of one face away, maybe ten thou, to leave a Go/NoGo at the minor diameter.
Thanks Steve, I knew it wouldn’t be too difficult I just couldn’t think of a sensible way to do it but never thought about making up a setting gauge like that.
Thank. Adam
Trying to Finish 5" 9f Producing Scale fittings using 3D wax printing and lost wax casting - www.crofittings.co.uk/ Renovating house stopping all of the above!
Today I have been getting the pipework from the filter boxes to the front beam of the tender. The filter boxes were supplied by Adam but he hasn't seen them painted and in place on my tender yet.
I have also finished the blackwork of the tender, leaving the tank to paint.
Another job done today was to mount the gauge glass valves to get them square and measure for the linkages. I also cut the glass tube to length and have loaded them into place.
I took a short video of this for people who are wary about cutting the glass. The glass was loaded to the lathe chuck, held lightly, and the lathe started at it's slowest speed. A diamond disc in the dremel was rested lightly against the glass and it cut cleanly through in very short order.
As you can see, quite straightforward.
Steve
Last Edit: May 20, 2020 21:10:05 GMT by springcrocus
Filter boxes look awesome! I’m fairly confident in saying they are the first set to be finished and on a tender, congrats.
Great work, Adam
Trying to Finish 5" 9f Producing Scale fittings using 3D wax printing and lost wax casting - www.crofittings.co.uk/ Renovating house stopping all of the above!
The water level gauges are now finished and it's suprising just how much work is needed to make these. To make the top and bottom fittings to work in concert a linking arm was made to operate both cocks simultaneously. Considering the size of my machines, these are seriously small. Very little machining, the slots being hacksawed and filed in the rod eyes.
The handles for the cocks were made from 1/4" x 1/8" brass and 1/16" brass rivets used as hinge pins. The tail of an M3 tap made the square holes.
They were assembled on the loco to ensure they had ninety degrees operational movement and the slots in the forks filed out a little more where needed.
Next I made the glass protector covers which were made from 26 swg brass sheet. To start, I bent them around a 12mm former.
This made it easy to set them over a piece of 12mm MDF to drill the fixing holes and mill out the 3/16" wide viewing slot.
Then they were tidied up with files and sanding drums in the dremel. I also cut a couple of pieces of thin polycarbonate sheet to act as windows behind the viewing slots.
Now it was time to do the final machining on the bodies, the most important job being the drilling through of the valve spindles. First, the valves were set in the open position and each of the retaining nuts pulled up tight. Then the assemblies were completely dismantled, except for the spindles, and each valve body loaded to the machine vice. Because the spindles are tapered, there was a chance that a drill could deflect sideways slightly so I used an end mill to create a flat area prior to drilling. The end mill was also used to align the valve upright.
The reason for using a vice in a vice was to allow me to move over to the drilling machine and drill the through-hole without disturbing the mill. Then the valves were dismantled and the drilled holes cleaned up. It is important that the spindles are not turned before this as there is a risk of scoring the inside of the valve body. The spindles should be drawn straight out and the edges of the holes deburred. I used a slip stone for this as there is less risk of damaging the polished surface.
So here are the parts needed to make up a single three-cock gauge and blowdown valve, thirty eight on view but missing the "O" rings to fit around the glass.
And here are the final assemblies mounted on the boiler. Obviously, they have to come off again to fit the false backhead and I will also replace the four 10BA screws holding the covers in place with brass screws as these penetrate through to the water space. The glasses will also need marking somehow but that's for later.
I'm also hoping that Adam might have a look in his "O" ring box and see if he has any 5 x 1 (5mm bore, 1mm section) rings he might like to part with.
It's been quite a juggling act to get everything working in concert and they are quite fiddly to make but I'm pleased with the end result. I can see why the commercial one are so pricey.
Trying to Finish 5" 9f Producing Scale fittings using 3D wax printing and lost wax casting - www.crofittings.co.uk/ Renovating house stopping all of the above!
Hi Steve, They came out great! One comment on the glasses them selves, did you fire polish the ends? If you leave them as cut, the edges will be razor sharp & can or will damage your orings. Fire polishing is easy, just fire up your heating torch, best that it’s held in your vice, & use a nice pencil flame, glass is interesting in that it doesn’t heat transfer ....short lengths of tube it still pays to use gloves....just heat the end until it just starts to glow, remove from the flame & let cool......word of warning, just cause it’s not glowing doesn’t means it not bloody hot! Repeat on the other ends. They should now have a nice rounded corner.
No, the ends of the glass are not sharp and don't need the flame treatment. I wouldn't bother, anyway, because Aluminium Oxide is just a little harder than Boron Silicate. They can be linished on a fine belt perfectly well, most people are just to frightened to try. I've successfully "sandpapered" the edge of both domestic glass and laboratory glass for years without issue.
I've looked around for a casting for the exhaust injector but there only seems to be one on offer, a white-metal casting for about £38 but it looks a bit squashed to me. So I've started to sculpt one out of some old brass offcuts.
The first part to make was the main body and for this I used a lump of brass that my father cast in sand nearly fifty years ago. There were loads of inclusions and it was no good for anything else.
The middle section of the injector was turned first, finishing at about half-inch diameter, using a radius form tool to help mimic the actual casting. The big hole is one of the sand inclusions and will be filled with stopper before painting.
Then it was turned round in the chuck, the major diameter turned to just over 1.1/8" and a 3/4" dia spigot turned that will be the pipe flange.
Next, it was over to the mill and reduce the sides to about 9/16", leaving the flange 3/32" wide.
Top and bottom were also milled to their respective sizes. None of this is measured beyond rule-accuracy, just machined until it looked about right.
The basic shape is starting to appear. The photo I am using throughout is a grey-scale version of one from the Nigel Fraser Ker site, which Nigel has kindly given me permission to use.
A 3/16" end mill was used to clear the underneath area behind the flange.
Then the first of the angles was machined on the top, just aligned by eye.
The photo shows a small flat area before the slope of the other angle, so this was machined next.
This front slope appears to be a bit steeper.
There is also some sort of pad on the top so this was machined next.
The three square pipe flanges were made next. The drawing shows them as all the same size but the one on the right is smaller so I've made two from 1/2" square brass and one from 3/8" square. There is a small locating spigot on each to assist assembly.
Because all these parts are cosmetic only, the flanges were faced to twice the thickness to simulate both top and bottom flanges at once. Then the were drilled for the dummy 10BA nuts and bolts.
The next part made was the thinner barrel-section at the front, a piece of 7/16" diameter brass faced flat at the joining point and with a 6BA tapped hole at the front. Into both this and the main body, spot-faced holes were machined to locate the pipe flanges.
A few other drilled and tapped holes were made in the body where bits stick out or are bolted on, the six bolt holes in the main flange drilled and the area behind this flange hacksawed and filed out to allow nuts to fit the space. Then the front barrel was silver-soldered to the main body. The flanges have been attacked with a junior hacksaw to simulate the join.
The square flanges in the picture are not yet fixed, just rested in place, and also on view is a lump of 3/16" brass plate shaped to suit the overflow valve at the front. Once I was happy with the shape, I drilled and tapped a pair of 10BA holes and one 6BA hole for the piston and lever parts.
One intricate little part made was the fork in the centre, made from 1/8" square brass, turned and threaded 10BA, then cross-drilled with a 0.8mm drill to take a 1/32" rivet as a hinge pin. For the size of my kit, these are seriously small parts. Drilling a No.68 hole freehand needs a delicate touch.
This is the little valve completed. The tiny stirrup on the left is a piece of ten thou shim screwed onto a 10BA stud. The lever is 20 swg brass filed to shape.
The last couple of pictures show the valve fitted to the barrel with a 6BA screw. There is a blind tapped hole in the back of the body and a hole through the barrel. Two of the three flanges have also been soft-soldered to the body.
There are some more bits to make to fit the underside and back, along with the bracket to fit it all to.
