Carefully calculated, measured and scribed lines on the outside of the valve block to enable it to be tilted to the correct angle for making the steam passages. One the scribed line was as vertical as I could get it everything was centred up and a 4mm flat milled on the inside edge of the bore followed by a centre drill then a 2mm drill. I had to run the reamer through the valve bore again to get rid of the burrs from drilling.
Measuring the position of point where the holes break through into the valve chamber isn't easy but using the 'wrong end' of my vernier calipers the hole positions seem about right (i.e. 5mm in from each end). A matching flat was milled on the inside lip of the cylinder heads to allow a good flow.
Just realised that I can now unclench my teeth - the fear of wrecking the hours of work that went into the cylinder have passed. Phew!!
Here's the inboard head showing the steam passage - I tried a shot of the other end but it was too dark in there!
Decision time after much pondering how to attach the valve chest to the cylinder; well silver solder obviously but what shape should the mating pieces take?
In the event I couldn't come up with an accurate way to get a 2mm deep 11mm radius curve on the bottom of the chest so I decided to mill a flat on the cylinder rather than use curves. That does mean a change of plan for the steam passages though - rather than straight line drilling and milling they'll have to be drilled at an angle from the cylinder to the chest. Scary stuff!
Here's the state-of-play with a stub of steel in the valve 'ole and the piston poking out the back!
After a break of over a month (frustration at seemingly intractable alignment problems) it's time to get back to work! A little attention to all the suspect bits soon had it winding over reasonably well so I hooked it up to the lathe drenched it with oil and gave it some water to play with :D
Couldn't resist spending another few minutes making the pump piston or ram. Miraculously it slid beautifully into position and screwed straight into the yoke. Too good!
With the slot in the yoke opened, threaded holes made in the crank disc, the follower 'block' and in the base for the standards, assembly starts to make it look decidedly engine-like and, thankfully, all is reasonably 'square'.
Decision time for the valves now and I think the piston variety will cut the mustard and be easier to make. Aside from the usual annoyance of custom made fasteners there's only the valve block, valve and eccentric gubbins to do.
Here's the next couple of operations completed (well almost). Soldered the two parts together then back to the lathe for drilling/reaming the 'bore'. Still not having bought a DTI this would have been tricky to get right... fortunately, and for a change, I thought ahead when it was in the lathe first time round i.e. I made a suitable hole with a centre drill. I could then use a sharp 'live centre' to relocate the part accurately enough second time round. Professionals will probably cringe in horror but it seemed to work for me - needs must when the devil drives.
Once that was done it was time to cut the vertical slot for the follower. I wanted to use a 3mm rod to connect the wheel to the follower but I don't have a 3mm slot drill. Choices were 2.5mm slot drill followed by careful filing or maybe using a 4mm ball nose mill (that I picked up cheap at a show last year :D ) and making the rod thicker in the middle (or allowing 1/2mm slop either side). In the end I went for the slot drill. Didn't have time to attend to the filing today but here's the part as it stands with a piece of rod taking the place of the follower and a couple of bits of studding showing where the threaded rods will go.
Time to make the yoke. A bit different to others I've seen in that the block will be a little cylinder travelling up and down inside another - seems like a sensible design as it'll help to keep everything square (while being round :D ).
So, phase 1, make the upright and cross drill for the horizontal piece. Took longer than anticipated as I couldn't find any 1/2" or near brass stock so had to turn down a length of 1"! No matter. That done, it could be cross-drilled to accept a piece of 1/4" brass rod (threaded through to accept the piston rod and ram connections). Here are those bits assembled (with some screws inserted to check alignment) ready for the next step - more soldering.
Getting everything square for soldering was a right royal pain. I ended up de-soldering twice due to poor alignment which meant a thorough clean up after each attempt - lots of wasted time and silver solder! Third time lucky though - here's the part after the third attempt showing the rod I used to keep alignment along with a couple of clamps.
A quick de-scale, pop in the brass bearings and see if it lines up vertically with the piston rod...looks ok!
Over the last couple of sessions the uprights were chopped to the correct height, the thinner sections milled away and the tops made and drilled. Next operation - thread the holes, fasten together and make the hole to accomodate the brass bearings. Once those holes are done yet another jig can be made to hold the standards parallel while they're soldered to the base. Or I might yet file some curves....
The solution to the knackered thread in the cylinder might be to reduce the outer diameter of the cylinder body and make the holes go straight through the flanges rather than have the studs in blind holes...
While thinking on that and not fancying more CAD/computer work for a while I decided to cut some metal for the standards - here's the 1/4" steel all squared up but the plan is to thin a good part of the uprights to 4mm to mimic the original castings. I might file some curves on the uprights as well to make them look a little less blocky. Brass or bronze crankshaft bearings will be used in the split tops. If I had the skill they'd look like the one on this page ...we can but dream.
Oh yeah, I also fitted the outlet connector to the pump but a photo of that can wait 'til next time.
Soldered up the cylinder flanges, marked out, drilled and tapped the inboard cover and flange. Everything seems ok except I trashed the thread in one hole :( Threading M3 about 2.5mm deep into a blind hole is not the easiest task...it might be a case of soldering in a stud, not ideal but can't think of an alternative.
The piston was next; the moment of truth is seeing if it has a good and equal fit for the length of the cylinder bore and it seems so. Hurrah!
Turned down a shoulder at each end of the cylinder to accomodate the flanges and made the latter from a piece of 35mm dia brass about 9mm thick. As each flange needed to be 3mm thick and I couldn't fit the part in my 'inside' chuck jaws to part it off I had to saw it carefully, mount it in the outside jaws and face down to 3mm. For a change everything went to plan!
Here's the two flanges in place ready for soldering but before that I need to figure out exactly what type of valve to use and where the steam passages need to go. CAD time again.
I decided the first cylinder cover wasn't as good as it could be - the threaded portion was fractionally misaligned when screwed into the frame but otherwise alright, so I chopped off the threaded bit made a domed piece with a little peg to fit the hole and soldered it together to become the cover for the other end.
Next I made the basic cylinder tube and re-made the front cover (better this time). Here's the bits sort of assembled; the cylinder needs some flanges making for each end yet.
Oh yeah, I lost one of the studs somewhere so had to make another one of those as well.
Not a great deal to show for the last two short workshop sessions, just the cylinder cover shown here screwed in place. It just needs the holes for bolting down to the cylinder.
As I don't have a 3mm reamer (my nearest being a very odd 3.3mm) I made a new D-bit to ensure a nice accurate hole... there's something very satisfying about making these simple tools and getting a good final hole just as there is when grinding HSS tools for the lathe and getting a good finish. Or maybe it's just me! I took care to get the hardening and tempering right on this D-bit too, some of my previous attempts have got a little chewed up after 3 or 4 uses so obviously weren't properly hardened.
As the first picture is pretty boring, here's another version spiced up with some fine ales to look at instead :D
Got to make those studs sometime so might as well get the tiresome task out of the way now. I suppose I should harden or at least normalise them then conjure up the enthusiasm to make some nuts instead of these ugly stock jobbies.
Amazing how good 'macro' is on even average digital cameras these days... I never even noticed the pips on the end of these until I looked at the photos! Must set the facing tool a gnat's higher :)
Having cut a slot in the threaded portion of the top section..
...and made a threaded hole for the outlet it was time to solder up the pump body to the cylinder.
I tried threading wires through the various holes to hold it together then using a couple of clamps to hold the parts together but neither was ideal, the wired version because it might all move around and the clamped version because it would probably mark the brass when heated.
In the end I went for a simple widget made from scrap brass sheet, a bit of annealing/bending and a couple of bits of studding seemed to make it all firm enough bit still allowed a bit of fiddling to get it all straight - a screw in the outlet hole helped to ensure 'vertical' alignment. Soldering went like a dream, taking care not to get too much heat onto the widgety bit!
First moment of truth; would it all be square when assembled?
Yay!
Second moment of truth: would it actually pump water?
Yay #2!
With a vigourous pump it'll squirt the water a few feet. Considering there's no stuffing or other leak-proof stuff in place I'm well pleased with that.
After the pump cylinder comes the tricky bits - the valve chamber, on the right and the air chamber on the left.
The valve chamber went pretty much to plan although I might need to make an elbow connector for the bottom rather than this straight one as space is pretty limited.
The air chamber was a different kettle of fish: I made the body from a solid piece of brass, turning the lip then doing the top using a file by eye (in the lathe) all nice and easy. The threaded piece of hex to be silver soldered in the bottom wouldn't play ball though, I made it twice and had to solder/desolder three times to get it properly lined up but it came out right in the end. The original drawing shows a threaded cap for this part and no means to properly tighten it into the valve chamber which is why I went for solid+hex. The bottom of the 'can' is slightly chamfered towards this 'nut', I decided this would look better than using a larger piece of hex (i.e. wider than the can) which I didn't have in brass anyway :)
All that remains it to cut a notch in the bottom of the threaded bit then solder the vlave chamber to the cylinder... think I might test the pumping action somehow before I commit to that though :D
Here's a blurry shot of the two parts screwed together resting on the cylinder.
Cleaned up the steel bits and started the pump body, shown here in position but not fully inserted as it needs to be a driving fit. An ersatz pump piston in the form of a stub of 8mm silver steel was used to test the bore and it gives a fair bit of suction in either direction. Nice!
The rod sticking out the back end (sounds painful) is where the hex-headed blanking cap will fit.
To ensure alignment when silver soldering I made a threaded gizmo with a bush to fit the pump end and added nuts to keep it all in place. I used some wire (actually a stretched out spring!) threaded through the base holes and around the gizmo to avoid any side-to-side rocking. Tippex was used as a solder resist around each end - last thing I wanted was to solder the gizmo in place!
Here's the assembly immediately after soldering...
When it had cooled the bar was removed and the whole thing dropped in some fresh citric acid 'pickle'...
There's a fair bit of excess solder that needs removing by file/emery but overall it looks ok - clean up time!
Four posts (well studs) it is then. The gland was marked out in the lathe using my home-made indexer and looked pretty accurate.
As the drilling required was pretty lightweight I decided to super-glue the gland and steel carrier together to drill/spot the holes. Big mistake. Although it all seemed to go smoothly, when I separated the two parts the holes in the steel part were completely out of position - it seems that being fractionally different sizes (less than a couple of thou') the vice had held only the upper part, the glue had failed to hold and as a result the steel bit had turned at some point. Bugger.
So goes another hour...turn mild steel to 18mm OD, face both ends, drill then thread central hole, ream one end for gland, cut slot for mating to upright. Second time around I used a nut and bolt to hold the parts together and all went to plan.
Here we are with the remade steel part and brass gland in situ. It's getting close to burn time again.
