1904 Whitehead Vertical Gas Engine

I toyed with the idea of making a pattern for the cylinder head but in the end took the cheaper option of cutting it from a slice of 65mm dia cast iron bar and letting the CNC cut the iron rather than wood.

The first job was to machine the underside of the head including a spigot to locate in the cylinder liner. I then moved over to the mill and tapped what will eventually be the clearance holes for the head studs so that I could screw the head to a holding plate to give easy access all round for machining. I also ctr drilled the position of the valves at the same setting.



Back on the lathe the valve guide holes were clocked in, drilled and reamed, the cavity behind the valve heads opened up and the seats cut at 45deg using the top slide which keeps everything concentric. I actually only needed to angle the exhaust valve seat but got carried away and did both!



Then onto the CNC, this image shows the contoured effect that the initial adaptive cuts leave.



Then various other paths were run to shape the "cast" surfaces with their draft angles and leave the "machined" faces flat and true



With the head still attached to the holding plate it was easy to hold on the manual mill for the last few operations which were mainly the inlet and exhaust passages and the tapped holes around those for flanges.



This engine has an atmospheric inlet valve where the vacuum caused by the descending piston opens the valve, this can also be used to act as a demand valve for the Propane gas that will fuel the engine by having the flat valve also cover a small 0.7mm gas passage.



The original would have had a water jacket cast in around the cylinder with the water space being formed by a sand core. For our models it is easier to have a separate liner that as well as forming the cylinder also closes off the waterspace. Here the OD has been machined and a steady is in use while the cast iron bar is bored to size. I leave a bit of solid material at the end so that the chuck will not distort the thin liner, this can be cut off afterwards and the liner faced to length.



The cylinder does protrude below the bottom of the entablature and as the liner would have been too thin I turned up a sleeve to add the additional thickness. It also allowed me to silver solder on a bush for a drip feed oiler. Liner, Cylinder jacket and sleeve were all a push fit and assembled with 648 Loctite.

Amazing - the CNC'd component looks incredible, how long does it take to program something as complex as the cylinder head. Also how do you know its going to work before it starts machining?

As you know, I'm I have no idea about CNC hence the question 

Quite a complex part, came out great! 

I probably did the CAM programming in about 10mins and then the same again tweaking it to reduce time etc.

You have to hope that what the computer shows you one screen will be what it actual does. F360 is quite good, It shows the path that the cutter will take for each operation. I don't have the head saved in F360 anymore but attached are the adaptive, horizontal and finishing paths for a pair of bearing caps. It will also do an on screen simulation where I can watch the cutters moving round and deducing the block to the final item. It will show crashes if I say the cutter tries to plunge straight down into the work or if the collet chuck hits something.

Also a video of what a mor ecomplex part looks like in the simulation

https://youtu.be/_WLXVA2JzBM?si=_Bjpw3HjU7YcYqw3

Am I missing something here, are you able to do the CAM programming so quickly as the CAD files exist and you use them as the basis for CAM programming??

I think I'll go back to hammer and chisel ................. you'd never think I'd spent nigh on 40 years in the IT/software industry! 

The actual CAD modeling does take longer eg drawing the actual part, that would be the second image in the first post. Getting the initial shape does not take too long but as the parts are assembled there is a fair bit of going back and forth editing so that things will fit and work together as well as refining the look.

It does depend on the subject and what info I have to go on, a small steam engine I could do in an evening this one was probably spread over several weeks though the  basic "working" design took a lot less.

Some 40 years ago I used to teach cnc and write programmes from a 2d drawing done on a drawing board, but cad/cam completely baffles me now.
So I'll just sit back and admire the work of others in this field and carry on with my hammer and chisel. 
Andy

Thanks Jason/Andy

I'm happy where I am atm (with my hammer & chisel!), but I do like to know how these things are done as maybe one day I'll bite the bullet and dive in. Given the closure of places making castings and their expense, there's almost an inevitability that I'll need to learn

For now, I'll work my way through my stash of castings and knackered old engines!

Hi Sanjay, I would certainly agree with your comments on learning new skills, unfortunately at almost 80 it takes a lot longer to get the information to sink in.
On a more positive note, the Steam Hammer is looking good.
Andy

Cool engine, I like the implementation of the CNC and castings on this build

The two crankshaft webs were drilled and reamed on the manual mill and then the holes used in conjunction with some top hat bushes to hold the material on the CNC mill to profile the  counterbalanced shape. The shaft and pin were from 12mm PGMS and all silver soldered together



After sawing out the unwanted bit of the shaft and filing the ends flush slots for the gib head keys were milled in each end. Don't panic; I did not mill the overhanging left-hand one like that. The small vice ensures that the crank remains in the same orientation when swapped end for end in the main vice which should hopefully mean the keyways and therefore the spokes in both flywheels line up on final assembly.



I had thought about having the gears 3D printed in steel but Graham Corry of Alyn Foundry kindly donated a pair of equal diameter 2:1 timing gears that had been maturing and developing his usual patina in a damp Welsh workshop for some time. I'm sure he gave them to me in thehope of less steam engine forum content



After a bit of a cleanup and suitable modification of the holes I could put the crankshaft into the bearings with its gear in place and then holding the other gear on an arbor in the spindle set the mesh of the gears and zero the DRO.



The lower gear support bracket could then be drilled and reamed at this position.



Without disturbing the setup the columns, cylinder and head were assembled to the base and the roughed-out top camshaft bracket screwed into place so that too could be drilled and reamed for it's bearing at the same DRO setting ensuring the shaft was true and vertical.



Five spoke flywheels are always a bit of a pain to hold. Usually I like to use a 3 or 4 jaw chuck to grip the ferttled casting by the inside of the rim but the spokes and jaws always clash on a 5 spoke layout. So the faceplate was used with a piece of 6mm MDF between it and the flywheel so I could machine the whole outer face, one side of the rim and hub and also bore the central hole to a firm push fit onto the crankshaft.



The castings were woth the cost with nice to machine grade 250 iron and no hidden holes or hard spots thought I will be painting the rims so not quite as critical as a bare finish requires.

Those flywheels came out beautifully, you must be pleased with the way they turned out - almost a shame to paint them, but if that's what the original had ...............

The crank and the parts including the rusty bits fantastic .......I do like a reused rusty parts! 

Rounding up the last build photos the Piston was done using the common at the time separate gudgeon pin holder, here the pin hole has been drilled and reamed and then the collet block stood upright to mill the slot and add a tapped hole for a grub screw to keep the pin in place.



Not sure what I did with the original image but this is the piston and pin holder. It also illustrates how with the addition of shims or discs the early engines could have their compression ratio adjusted to best suit the local gas supply. Just a single groove for a Viton O ring.



The conrod and it's cap were cut and turned from some hot rolled flat bar and bronze bearings fitted.



The photo of the surviving engine shows a round air filter strainer which I replicated by first turning the outside profile



It was then held by the smaller diameter to bore out the inside. I cut a shallow rebate around the edge to leave just 0.5mm thickness. Half the depth of the rebate was milled away just leaving three short sections full length. These were then bent over to retain the drilled brass screen.



Valves were fairly straightforward turning jobs from 303 Stainless, this is the flat one that also closes off the gas supply hole which I showed earlier.



Here they are in place complete with spring retainers and pins.



And a better look at the inlet screen in place.



I am able to buy quite nice looking 1/8" BSP threaded brass elbows which can be retapped to M10 x 0.75 but the image of the engine shows two 135deg bends that I could not find good looking fitting for. So I drew one up and had some 3D printed in aluminium along with some smaller ones to suit M6 fine threads for the water cooling plumbing.



A simple split plate with some holes in it and a vice stop made it easy to change fittings so they could be tapped, unlike the cast "trees" that PM Research do mine were printed ready bored with a nice flowing curve and counterbored to just have the thread cut.



As you can see the two fittings match quite well and once painted it will be hard to tell the different sources.



I could not go to all that trouble with the pipe fittings and use an old tin can as the exhaust pot so fabricate done with what was to hand.

The water tank started life as a length of 40 x 80 hollow box section. I reduced the thickness of the walls so that I could get a smaller external corner radius and then silver soldered on the top & bottom plates



The hot tube chimney was turned from stainless steel as was the angled burner holder. This is actually threaded internally to allow a small Sievert burner to be screwed in once it's chrome end has been removed which gives a fairly compact arrangement that does not look too out of scale.



The engine stood like this for a few months while I got distracted with steam engines and also I did not fancy cranking over an engine in the hot weather we have had. I got back to it a couple of weeks ago and did the last few minor items which were cutting the face cam, making the rocker arm and plumbing in the gas supplies. It was then ready for a test run.

It was poping but as soon as it did the hot tube burner went out, I soon traced that to me having just done the hot tube up finger tight when it was made. The application of a copper washer and spanner soon had that sorted. After another few minites of the odd pop I realised when I had timed the exhaust valve for some reason I set it as though it was the inlet valve. With that corrected compression was much better and the engine fired into life if a bit on the fast side. Sorry it is jumping about but I made the stand just to assemble the engine on and the screws soon pulled loose with starting loads.

https://youtu.be/Q7Wx1L71lpY?si=--UFLvb5wznDI7Jr

With the engine now known to run it wa stime to make all the studs, nuts and scale fixings, a wooden base and apply some paint.

The stand was made from Oak and the mortice and tennon joints cut on the mill.





Next post should see it with some paint on.

Fabulous, everything looks so precisely manufactured and fits together beautifully. That is the best sound, it sounds like one of those old fashioned rubber horns being squashed very fast. Looks like its definitlely going to require clamping down to the bench before being on full power