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.
Having made the basic part for the the cylinder gland another dilemma presents itself - due to the 'tongue and groove' construction there isn't room to fit studs above and below the piston rod as per the original drawing so the choices are two studs placed horizontally, or three or four equally spaced on 12mm PCD. Time to look at some other pumps and engines and see what would look right.
It took a lot of careful filing to get the gland to shape but I'm happy enough with the outcome. Next will be the simpler, circular gland for the cylinder end then I can assemble all these bits and get on to some interesting parts...
I had a close look at the steel boss and the brass gland I'd made for the pump side of things and decided they weren't good enough - I'd used the gland as a template to drill the holes into the boss and one of them was slightly out of place. As there's no going back once the boss is soldered in place I decided to remake both parts and they came out much better second time around. Here they are with the filing buttons I also made for the next step...
I can't fix the buttons in place at the same time as there's overlap between the big 'un and the little 'uns so it's a case of marking out the circle round the big one and scribing a line to the outside of the little ones; this pic shows the general idea, the finished shape will be a 'rounded elongated diamond'. If I'm lucky :D
Here's a progress assembly with the bits loosely piled up together. The threaded rod at left will be where the cylinder screws in, the plain rod in front of that is where the cylinder gland will fit. The plain rod at t'other end is where the pump piston will go.
Once the two brass glands are finished it should be possible to fix it all together rigidly and solder the carriers at each end in place.
Well that's the first mistake but fortunately it can be rectified easily - the 8mm hole in the last part should be an 11mm hole (8mm is the pump piston diameter, doh!). So, set it back up on the lathe drill to 10mm (my nearest drill) then some nice boring to size. When boring goes well it's great!
The circle about halfway 'twixt hole and edge is where I marked out for the fixing holes.
Once that was finished it was time to start on the gland. The first attempt was ok but the spigot was a rather loose fit in the hole so I turned the piece around and did it again. Second attempt came out much better, here it is with the two diameters turned to size then mated with the steel part.
The part was reversed and the 8mm hole reamed (yeah, the right size in this part :P). Just needs some facing down the the right thickness but I didn't have time to complete that so it's still in the chuck and no picture to show.
"Once that's done the basic frame on which to hang all the other bits will be pretty much finished" he said. Ah, forgot one major task; filing this new part so the flange is a 'rounded diamond' shape. Thinking about it it'll probable be easier to make the matching gland at the same time i.e. before solding to the frame, as the pair can be fixed together and filed/drilled as one. Need to make another widget though as they have different bores...
This is the flanged part that will carry the pump cylinder and it'll eventually be soldered in place on the right-hand end. Even a simple part like this eats up time...
Find and cut suitable piece of steel bar (in this case inch and a quarter diameter)
Face end then turn down to size
Progressively drill then ream central hole to 8mm
Manually form a nice curved end
Turn it round, finish flange to diameter and face off
Mark off for gland holes
What with sharpening lathe tools that's pretty much two hours down the chute (and it still ain't finished..need to drill and thread those two holes then cut the groove to fit it to the frame). Never mind, getting all dimensions to within a couple of thou' (or 0.05mm) makes it worth the time. Possibly!
Next up, cut the slot in this part and drill and thread the holes for each of the glands. Once that's done the basic frame on which to hang all the other bits will be pretty much finished.
Lots more filing and basic milling finally brought the upright to shape. The top bits are going to be another 'tongue and groove' arrangement when it comes to mounting the cylinder and liquid end hence the tongues ;P
I don't have the equipment, skill or knowledge to mill the curves so they're the result of careful marking out and filing. The stub of 3/4" diameter rusty steel at left will form the ring into which the cylinder is screwed. As the simplest part so far this part this bit caused me no end of trouble...
My HSS lathe tools needed sharpening to cut it (must have been some work hardening, it's certainly been parted off from something in the past
A hex wrench slipped out of the toolpost bolt while being tightened and I cut my finger on the top-slide casting - hideously painful
I broke a centre drill while starting the hole
No matter, I turned the slug around and worked from the other end instead - damned if I'm throwing away a penny's worth of steel :) Once that bit was made I decided to solder up the base/upright. Assembled with two clamps this total mass of metal was just about at my limit for silver soldering (using a hand held propane torch). I'm not sure that solder penetrated all the way along the joint but it's solid enough.
I like the appearance of metals after soldering, it gives them a proper industrial look so here's a picture with the cylinder holder thingy perched in place... The aforementioned part is threaded ready to accept the cylinder top cover but it needs a couple more threaded holes to hold the gland bush. Once the corresponding part is made for the opposite side they'll both need to be soldered to the upright as well...might need to upgrade the gear or build a better 'nest' of firebrick to achieve that!
I really should have mentioned at the outset that the current project is a steam pump with double acting engine. It's a direct acting pump i.e. the piston rod is attached to the pump piston (ram, plunger call it what you will). The engine was designed by Australian O B Bolton around the 1940's and has been available as a set of castings at some point.
As the design is pretty straightforward my fabricated version shouldn't look too different to the one made from castings.
Other engines by Bolton can be found here and here
Cut out the basic cuboid for the upright frame and milled a 2 x 2mm tongue on the bottom edge. The fit in the slot has to be slack enough to leave room for the silver solder so it's possible to wobble the upright a degree or two either side of vertical - easy to take care of by careful clamping and some square supports when soldering up. Hopefully ;)
...think I'll keep that slot at 2mm wide and cut two shoulders on the upright instead. The bottom edge of the upright will be 'T' shaped in cross section which will help it to stay perpendicular to the base when soldering. The threaded holes for the standards can wait, they'll be better if spotted from the holes in the standards themselves to ensure alignment.
I own a micro milling machine with just a couple of end mills and slot drills and a basic machine vice. When it comes to making a part with curves that can't be done on the lathe, the mill isn't a lot of use other than for making a nice 'square' initial block from which to cut the part.
One the base 'block' was ready it was a case of marking out then resorting to hacksaw and file. On a 1/4" thick piece of steel you need to allow a fair bit of time...getting to this stage took about three hours. Once the basic shape was filed I put it back on the mill and cut a lengthways slot; the upright will also be 1/4" (well 6mm) thick so I'll need to make this slot three times as wide (note to self: buy a bigger slot drill, a rotary table and a tilting vice when finances permit :D).
Apart from widening the slot I also need to make a couple of threaded holes to fasten down the standards (where the blue bit is in the photo). Anyways, it's pretty cool to have a nice shiny, shapely part made from a bit of rusty old angle.
It always looks so easy on a drawing; a 3mm curve here, a 4.5mm curve there. I always find marking out such small radius curves really tricky, especially on harder metals. Anyway, here's the base being roughed out and major excess metal sawn off. Time to make some filing buttons then lots of filing to follow. Great :(
Started on the base for the latest project. The only bit of steel I could find of the right size was a peice of rusty 1/4" thick angle..here it is having one end milled after sawing off a side.
