Economy Model

[b.lindsey]

Yes that fixed it Martin...thanks!

Bill

[Dave Otto]

Enjoying your progress on the Economy Martin,

It's amazing how the errors and lack of material allowance on some of these engines never get fixed! Kind of maddening actually.


Dave

[jadge]

Martin: This is as far as I got with my Economy, mechanically mostly there apart from the carburettor:



I also sketched out a design for my own side electrode spark plug, using a TIG electrode as the central spark plug element. Along side the spark plug was a design for an ignition system using a coil with a turns ratio of 10 between primary and secondary, rather than the more common 50 to 100 ratio. Last time I played with it I was getting about 3-4kV on the secondary, which is probably a little on the low side. The next move would be make a small jig with an adjustable spark gap to see how it behaves at atmospheric pressure. Paschens Law can then be used to extrapolate to the pressures in the cylinder just prior to ignition.

Andrew

[mhirst121]

Well with one thing and another progress has been slower than I would like on this project, but hey, its only a hobby and nobody is desperate for it to be finished.
So I thought I would fetch the project up to date with where I am at the moment.

The crankshaft
I decided to go with a built up crank for this one due to the physical size of it. Some plates were machined to size but left thicker than required to finish off later, holes were machined with the boring head to take the shafts.



After sizing up some 20mm bar it was then assembled. I set it all up and taper pinned it then silver soldered it all to give a good strong crank, the flywheels are pretty heavy after all. The side plates were then machined to the correct dimensions to fit between the bearings and the shaft on one end reduced in diameter.



The centre section was machined out and then a couple of bearings turned up for the mains, remembering to make them longer to make up for the shortfall in the casting!!!



And hey presto, it all fits. I will profile the webs at a later date and the keyways are still to cut.



The spacers for the various parts on the crankshaft have been made from stainless steel.



The cylinder liner was machined from the piece of cast iron that was included in the kit. Once completed the piston was turned up from a piece of aluminium.



Well thats us up to date, next up the connecting rod

Cheers,
MartinH

[mhirst121]

The connecting rod next. This started out as a piece of hot rolled plate 20mm thick.
The sides were milled to size and the top skimmed flat.



Once the bar was to size the holes were machined for the little end and holes also put in for the radii of the various transitions on the rod.



The radius was then machined for the step from the big end to the rod.



This side was then milled to the correct thickness.



The material was then turned over, milled to thickness, radius for the step done then machined to the correct thickness.



The shape was then marked out and the excess material cut away on the bandsaw. The edges were then milled to the lines.



As I do not have any large horizontal cutters, I decided to use a small 4mm ball end cutter to profile the pocket in each side of the rod. The rod was set up square on the mill and a back plate bolted down to use as a datum to cut all four sides. The remainder was cut away with a small cutter to give the correct size pocket.





A piece of the spare plate was machined to size to make the cap and drilled for mounting bolts



The end of the rod was machined to size and square and then drilled and tapped M6.



The end cap was assembled to the rod and the big end drilled and machined with the boring head to the correct size.



The little end was then finished off in the rotary table.



And there we have it, a connecting rod



Cheers till next time,
MartinH

[1dbweldor]

Great build log. I'm impressed. Keep up the good work.

[b.lindsey]

Nice looking crankshaft and conrod too Martin!  Thanks for the update.

Bill

[Dave Otto]

You have been busy Martin.

Great progress and nice looking parts.

Dave

[Roger B]

Coming along well    I like the con rod 

[Bertie_Bassett]

looking great !

[mhirst121]

Well I managed to get a few more bits done over the last few weeks. First up were the flywheels. These were as big as I would like to go on my Warco, they just fit on the faceplate.
They are cast iron castings and all appeared to be ok till I started machining them. There were alot of hard parts in them, but I managed to get under them with a nice sharp carbide tool and a couple of biggish cuts at high feed rate, this seemed to stop the tool burnishing on the hard spots. They were faced off on one side and then turned round on the faceplate, this gave me a flat surface to bolt up against. The other side was then taken to size, this size on the drawing is dimensioned as `skim this face flat`, little bit vague to say the least so I measured up and took the dimensions that I ended up with and noted them for the others. The boss was then cleaned up and the bore machined. The flywheel was then turned round and the first side and the boss finished off.
The second casting had a buckle in it, so all I could do was make it the best I could and machine bits to get it a bit nearer running true on the spokes.

[mhirst121]

Next up I had a go at the gears. I had to spend a little time getting the new rotary table set up and a chuck fitting to it. This was my first attempt at gears on my home machinery and they turned out very well, even if I do say so myself.
The blanks were machined and some stub arbours made up to mount them on to machine. The drawings called for 18dp gears, but I have substituted these with 1.5mod gears, there was not much difference in the sizes when I chose a different pitch to the ones stated(went from 42 teethdp to 40 teeth mod.) I made extra gears while the machine was set up, this will leave me some spares to use on another project, and I think it is as easy to cut three of each as it is one of each.

[Bertie_Bassett]

looks like good progress there !

and the gears came out very well indeed

[Don1966]

Nice set of gears you'll made Martin............


Don

[b.lindsey]

Those gears look better than a store bought tuxedo on Tennessee Whisky Martin!! Seriously nice work there.

Bill