Old Sckool 5 cc model Diesel engine build

[911hillclimber]

With the crank done, it was time for the connecting rod.
It is to be machined from what feels like En1, but cut well. The critical dimensions are the centers of the pins and the radii of the big and little ends. Simple.

And so it was! The compound slide made easy work of the critical holes, all reamed out and a very nice snug fit to the pins.

Time then to fit the crank and be sure it is free to spin, the rod to the crank pin and finally the whole lot articulating correctly.

The last bit was a problem.

The drg shows two relief cuts for the rod, but mine were nowhere near open enough to allow the lot to rotate so a few hours with the dremmel and a carbide tip ground the inside of the casting to clear the rod.

Possibly, if i had removed more metal off the shank of the rod less would have had to be removed, but all done now and it is free to spin or rather turn.

The back cover fitted and tightened gives the crank end float of about 4 thou, 0.1mm which feels about right (?).

For something totally different i think I'll tackle the carb and tubes and needles fuel bowl etc next before lapping the cylinder and making the piston.

L o n g way still to go.
Can't help thinking I'm making this engine in the wrong sequence.

Some pics as ever:

[911hillclimber]

As a respite from steel, decided to make the 'carb' from the brass rods supplied.
Machining the brass need some keen or new tools and the parts are quite fine and certainly awkward to make true and straight.

Drilling some of the tube with a 1/16" dia drill for over 1" is a heart stopper at times, and near impossible to keep it straight over that length.

Had to buy some 4 BA taps and die for part of the job, but this part has AF/BA/ISO threads all over it.

The carb is made from 3 turned parts, two are silver soldered together, the third is essentially the jet which the 1/16" dia needle sits into, the lot fed from the tank I have yet to machine.

Anyway, bar one thread it is all done, nut not my best work.

I'm quickly realizing this fine machining is not my best skill...even if I had a new Myford!

That lot to one side, started to make the lapping tool for the cylinder. The lapping grease now here.

[911hillclimber]

Bit frustrated now, so stopped, cleaned the bench and lathe and having a cup of tea.

Needing to work smarter than harder.

Two tasks done (almost) this afternoon.
First task was to lap the steel cylinder to smooth out the rough finish which I thought was quite good, but...
Made the honing bar from aluminium and tapped the ends M6, one for the chuck arbor and the other for the 'expanding screw'.
Here, the trick is to drill and tap the adjusting tapping with a taper tap and use a screw to run into the taper and so expanding the bar, cut down the bar with a hacksaw. Works a treat.

Bought some 320 lapping grease off ebay for a few ££ and ran the lathe and the cylinder holding the latter by hand. Slowly occillate to and fro to run the past along.

20 mins later got bored but also improved the finish.

Pleased with that moved to making the piston and contra piston using the bar of cast iron supplied. Never ever machined cast iron before, felt and smelt very Victorian.
That all wnt quite well until the milling of the con rod internal opening to allow full articulation of the rod on the wrist pin which drilled and reamed really well.

The slot needed is 3/16" wide and all i had was a 1/8" slot drill and working sideways and almost blind (god, would love a small milling machine) the slot was anything but right.

That's when i ordered a nice new 3/16" slot drill.

This job needs stacks of small tools.

[911hillclimber]

Chipping away at this project still, maybe 60% of the way there now.

Finished the piston and it turned out oddly accurate, actually goes up and down the cylinder, BUT, maybe too slack. There is a lack of real compression, so I might make another to get it tighter.
The contra piston is far too loose and follows the piston (oiled) down the cylinder on the down stroke. Sigh...
I will need to get some more cast iron bar, maybe tomorrow from Hemmindways.

Moving on, did some more to the 'carb' and with the arrival of a 4BA tap and die made the needle valve jet which screwed together well, and then the tank to follow. The tank was machined from the remains of the Alum bar i had over so is a bit small, but it only has to hold a small volume of diesel to prove it runs.
It will never get into a plane.

Lathe needs a bloody good clean, alum swarf everywhere, very irritating.

Question, do I REALLY need a tight fitting piston?

[911hillclimber]

While I wait for the fine lapping grease and some fresh cast iron for the piston thought I would do some boring bits.

The needle itself has been made as my friend suggested, in the chuck and with a grind stone in the dremmel (and it at maximum rpm) shaped the needle point quite well.
Turned a needle collar and soft soldered the needle and collar together with little fuss.

All screws up and down with some nice resistance which I hope will resist the fine vibration of this turbine like engine...

Next came the top of the cooling head and decided to add some more fins as the rest of the sleeve, more heart-stopping parting off tool work, what a din!

Soaked the steel cylinder in citric acid solution, 20% crystals and had a good coat of bubbles on the cylinder after 10 mins. all rinsed and it looks much better, but still needs some swiss file work.

Oddly, now ground to a halt, little else to do until the iron and grease turn up.

Can this adventure (to me) actually be drawing to a close?
Plan was to have it ready to run (really?) by my birthday, end of this month.

Will i make it?
Doubt it!

[sladey]

Nice work

[911hillclimber]

Thanks Mark, but i must admit it is not really to my liking.
Dissapointed at my level of handywork, it is scruffy in the detail in exposed places, but overall not to bad maybe for my first shot at precise machining on a 100 year old very basic lathe that has lived a life in a village garage.
The Myford compound slide has been the real star of the project and all this so far would be impossible without it.

Can't get some cast iron bar to remake the pistons until Monday earliest so will have to do some jobs on the 911 and the Lola!

[hot66]

Are you going to fit this to something or make something for it to power ?

[911hillclimber]

No James, it will end up as part of my small collection of engines.

I do fly model aeroplanes, still a leaner, but all are electric, just so easy to live with.

At 5cc a suitable plane would be large, maybe 80" wingspan, and thus take up a lot of room somewhere. but I have non to use, everywhere is full.

I do like building them though!

[911hillclimber]

Slowly making my way through the magic world of cylinder/piston lapping...
A bit of a folk-law subject, but getting there.
Lots of opinions, all experienced, so good, and I think I have the solution sorted. Now awaiting 1200 grade silicon powder for the final finish. You mix this with engine oil and go for it.
The surface finish you need is a near polished grey sheen.

Fresh lump of cast iron arrived, so when the honing is done, time to make a new piston which has to be almost an interference fit at the top of the stoke, but 1/5 thou loose at the bottom of the cylinder. and round of course!

Easy.

[911hillclimber]

Lapped the cylinder using fine cutting compound I've used on car/bike valve seats, and what a difference that made!

Changed the look of the surface, but removed a lot of the imperfections.

Have ordered the 1200 powder for £6 off ebay.

Thought I would try 'expanding' the piston by heating to cherry red and quench. Did that twice.

The previously slack piston would now only enter the cylinder 1/2 way, so the growth was far greater than I expected. Started to mess about with the lower part of the piston as it was the tightest only to find 2 hair line cracks in the 'skirt', so now scrap.



Further wait for the 1200 powder to arrive and then can progress I hope.

[911hillclimber]

The fine 1200 grit powder arrived 2 days early, so mixed some with a drop of engine oil and set to polishing the bore some more.
I really doubt i can improve it further, so have called that a day, and started turning the cast iron piston.

I'm experimenting of getting a good chatter-free cut as I reduce the bar, and may have found the happy spot of cut, feed, tool overhang and angle.
Quite a few variables but will try some refinement tomorrow starting with a fresh tip.

Plan is to make a new 'tight' fit piston by lunch tomorrow.

[911hillclimber]

Not a good day at the lathe today.
Wasn't quite in the mood, but pressed on.

Made a piston 'blank' that seemed a good fit in the cylinder, tight'ish at the TDc and slightly loose'ish at BDC.

Drilled and reamed the wrist pin hole 3/16", no probs.
Re-aligned the piston in the cross slide and started milling the inside of the blank to take the con rod.
I happened to machine it 90 deg out, so no slot for con rod to articulate.

Ok, turned the piston to allow correct slot position.
Machined the 3/16" slot which sounded not quite right....
Removed the piston to find the cutter had gone throu the piston and was 1/16" off-set.

Got my arithmetic wrong.

God, I'm good at this stuff.

Made another piston, all thou or so tighter (practice makes perfect), drilled holes, milled slots all in the right position. (practice makes perfect).
Assembled the lot together and the movement is tight, cannot see any touching points of the con rod to the case to the cylinder etc so reversed the piston on the rod. Same condition, so something not square.

I cannot see how to find and get rid of this high friction point, so seriously thinking of tarting the outside of this lump of metals, and put it on a stand.

I finally think I'm a mechanic not a machinist.

[911hillclimber]

Having slept on this problem and taking advice from Those Who Know on a model aero plane forum, set to to find why the engine is in bind.

After 10 mins it was found, the problem that is, and the solution was easy enough.
The cylinder mounting flange to the crank case was out by 10 thou, the cylinder was thus at an incline to the crankshaft.

Solution was to place a razor blade under the rear half of the flange and nip the nut up and the engine rotated freely.

The blade is 10 thou thick so I needed to machine the cylinder (very high risk option) or to reface (by hand) the crank case face by good old files.

This was quite easy and I crept up on the change until all was good.

So, the lot assembled and tight the crank/piston etc all are smooth. I've marked the front of the piston on the crown just in case this lot has to come apart after running in.
Similarly the con rod as it can go onto the crank pin 2 ways.
I'm pleased to say the exhaust ports are fully open when the piston is at BDC, I hope this is correct.

After a good clean of the lathe of cast iron granuals and a good oiling of the bed, I took a look at mounting the crazy large diameter wood propeller.

Decided to make a sleeve nut, tapped M6 to suit the crank shaft and 8mm dia to suit the hole in the prop.

Not a sensible idea as this would leave very little wall thickness to the sleeve of the prop nut, so that nice piece of alum bar which was perfect is now scrap.

A visit to ebay again for some bar, but also for some diesel fuel and start-up (or an attempt) is not far away.

Need some gaskets first...

[911hillclimber]

A lot concluded today.

The Last Chapter is opening on this project.

The Myford compound slide is back in it's box. Best £17 I spent on this lot. This means No More Milling.

The cast iron scrap pile I hope/think is finished, this lot represents a lot of wasted time and a few bob on cast iron.

The tube prop nut is made and holds the huge prop. Will try to get a smaller one from Penn Models when open on Tuesday, they have a 12 x 6 in plastic. £10 and 1/2 the price of the wood one.
Will get 1/2 litre of fuel too.

Did the final dry fit up on all the parts and thus just the fiddly gaskets to make, later this afternoon/tomorrow's task.

Thoughts turned to running the thing.

Found a nice piece of 10 mm alum plate, so cut that to suit the engine mounts and then 2 M6 bolts to attach to the work mate. I guess this will need tethering to the lawn (if it starts...)

Made the wood starting 'aid' from a piece of dowl to keep my small fingers being chopped-off even smaller.

Found an old engine stand I bought a very very long time ago , but it is so nice shame to butcher it for this thug of an engine. Little Enya engine is seized.

So, what can possibly go wrong over the next days?

I have little confidence it will run. I do not feel a lot of compression, and if it does run not sure if all the parts will tolerate the shock, let alone me.

I want to get a picture of it running, clean it down of fuel and put it on a stand.

Only then will I have proof that you can get by on a 1924 Drummond round bed lathe.