1/4 scale Anzani Fan Engine

creast · May 2, 2024

100model said:
That is exactly why I used it for to replace my camera tripod parts that kept breaking. Looks like those parts came out great, silicon bronze seems to flow really well into sand molds.

I was thinking of making a three cylinder like you are making and I have seen a Anzani three cylinder in a local aircraft museum. It has the cylinder center line offset with the crankshaft center line. Why is that?

I really cannot answer that question as the plans I am working from have the cylinders inline with the crankshaft centre line.
Maybe it is a derivative as many variants were produced. Perhaps Ken or others could advise?
Cheers
Rich

creast · Jun 27, 2024

This is just a quick update on the Anzani project.
I decided not to do a true build log as it was getting too tedious to keep a log on things and work on the engine has been a bit sporadic.
Making the con-rods from silicon bronze was probably not the best idea as it is not the easiest material to machine being quite tough and gummy.
Rather than following Ken's crankshaft construction, i.e brazed and pinned, I went for a complete press fit assembly as per most 2-stroke
motorcycles.
Truing the assembly was a new art to me!
The cylinders were fabricated from mild steel and silver soldered at the flange. A little more lapping is needed and one more piston to be machined.
The cylinder head castings need to be finish machined before heat shrinking onto the cylinders.

GreenTwin · Jun 27, 2024

I made the mistake of using boat shaft bronze for bearings one time, and while the material looked like bearing bronze, it was not, and it had a very high stiction coefficient. I had to throw those bearings away and start over again.

"Know thy metals" as they say in the casting business.

Its looking very good; thanks for the update.
.

petertha · Jul 5, 2024

Coming along nice! So the two round crankshaft elements come together on a common crankpin for the 3 rods, is that the layout? Is the mate a permanent press fit thing or is there a retainer method whereby you could later disassemble? Do you put some kind of shim washer between the rods faces or is that somehow incorporated into their bushing area?

Jasonb · Jul 6, 2024

The W type that Mike Cole used to do castings for just had flat edges to the knife and two fork ends. They were steel and ran against each other on a common bearing. Kens drawings that this one is based on are a similar fit but no bush.

creast · Jul 6, 2024

As mentioned earlier in the thread, I chose to make the con-rods in silicon bronze so I could cast them and then machine as required. The reasoning also was to remove the need for bushings but they were a pig to machine, Phosphor bronze would have been better or maybe I should have stuck with mild steel ones. Its a bit late now so I will run with it,
As Jason pointed out, there are no shim washers.
I didn't fancy doing the brazed and pinned assembly of the crank and chose to press fit the crankpin into both flywheel halves. The pin was hardened and tempered and would probably re-press if the crank needed overhauling or failing that I would re-make a new pin.
Hopefully for the little running time this engine will hopefully run I don't see a real problem.
Rich

creast · Jul 7, 2024

Today was what I call a bum cheek clenching day

I decided it was time to heat shrink the heads onto the cylinders.
The big problem was to ensure the orientation for the exhaust valve was maintained so in the end I knocked up a crude alignment jig.
First trial was on a scrap head on a piece of turned steel tube which was almost perfect but froze in place 2mm short so for the real fits I raised the temperature of the head castings to 400 deg C.
Luckily all three worked and are close enough for the alignment although my leather foundry gloves were smouldering!
The parts do need dressing to a finish better than the as cast layer lines but I decided to see how they sat on the crankcase.

creast · 2024-09-07T14:45:32-0400

Yet again, apologies for not providing a running blog but things have been very intermittent on the project and sometimes I am so involved that I don't record every detail.
So, the crank was trued up and now runs within 0.0005". Pistons and wrist/gudgeon pins completed.
Timing gears have been cut, which was an ordeal in its own right as I had never done that before.
I decided to fit Phosphor bronze valve seats/guides to the cylinders as the aluminium cast heads were just too soft and these were shrunk fit into the head.
I could not bear machining the exhaust valves out of solid so I welded the stems to the heads prior to final machining.
The inlet valves are much shorter so were machined in one piece.
Attached are also trial assembly pics.
Still lots to do before I wrap a noose round my neck! Aaarggh!

Olli-Matti · 2024-09-07T16:19:48-0400

Keep up the good work! And try to enjoy it as much as you can, it will be a magnificent looking engine when done!!

How did you make that nice color for the cast heads? Looks superb

1/4 scale Anzani Fan Engine

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