Felgiebel 16,6

[F-DS]

 

[Mechanicboy]

Too much moisture in the mold. Let it dry in some days before cast if you do not have drying oven for mold. It is not necessary to have high silicone in aluminum from piston, aluminum from cylinder head or water pump is good enough for casting.

 

[aka9950202]

I have cast aluminum using a gas fired furnace and with a charcoal / bricket furnace. The charcoal was a failure as i could not control the temperature. The castings seemed to have a grainy structure and cavities which were large enough to put a pencil into.

My first gas furnace was a square of firebricks and the heat source 2 mapp gas torches. It allowed better control with perfect results.

Cheers,

Andrew in Melbourne

 

[F-DS]

I did the (perhaps last) casting of the crankcase today. The shape of the casting looks fine, there is only one defect on the casting, namely a cavity in the space on the crankshaft. The cavity is about 3 cm deep and 1.5 cm wide. Fortunately, the cavity doesn't matter, it was probably caused by a bad vent channel, which was filled with aluminum too soon and the air from the bearing space no longer had how to escape from the mold. I subjected the risers cut from the casting to mechanical tests in the form of bending and malleability. The alloy looks like it's already fine, it's definitely not brittle and it's not very soft either. I am satisfied with this casting.

 

[F-DS]

Casting with risers.

 

[F-DS]

This is what the last casting looks like after cutting the risers and light grinding. It can be seen that the casting has an excellent surface and shape geometry. There will be no need to mill the mounting feet and the crankcase will be easy to polish.

 

[F-DS]

I photographed all my previous castings backwards and then I wrote to them (in Czech) why I was forced to cast another specimen. Maybe it will help someone save work with similar research.

 

[F-DS]

Again, I photographed the model for comparison.

 

[F-DS]

I already have the crankshaft ready.

 

[F-DS]

I started machining the crankcase. I pressed a bronze sleeve into the case, ground the crankshaft into a plain bearing and custom-made the propeller carrier on the crankshaft so that the crankshaft had an axial clearance of 0.5 mm. For the first time, I put a propeller on the shaft. In the photographs after machining the inner space of the crankcase, it can be seen that the casting is really high precision casting, the thickness of the crankcase wall is the same everywhere (within a small tolerance).

 

[aka9950202]

Nice work. Great to see someone making their own casting.

Cheers,

Andrew in Melbourne

 

[Rudirk]

It looks perfekt.

Rudi aus der Eifel

 

[F-DS]

Thank you Rudirk and aka 9950202.

 

[F-DS]

I finished the crankcase, made the rear lid of the crankcase, I made a protrusion on the lid, through which the lid can be screwed to the crankcase upwards. In this way, the lid and crankcase form a stronger unit.
I ran a motorized crankshaft in the crankcase.
I made paper seals.

 

[F-DS]

I pressed the piston pin into the piston, pressed the safety brass lenses. I cleaned the individual parts in gasoline and kerosene and then assembled the engine.

The engine rotates quite lightly without installing the spark plug, it does not bite. After fitting the spark plug, the engine has excellent compression in the combustion chamber. I put an aluminum seal 0.5 mm high under the cylinder head. The pre-compression in the crankcase also seems excellent to me. The engine is only oiled with kerosene, the compression is not increased by the added oil.

 

[Mechanicboy]

Hi, never use the E clip to lock the connecting rod on place. The consequence is that the connecting rod can force the E clip to rotate so that the E clip can be throwed out from the crank pin due to centrifugal forces and cause greater damage to the engine. Let behind the back cover / piston to hold the connecting rod in place on the crank pin.

 

[F-DS]

I was hesitant to use a paper clip, so I kept the original solution in reserve, drilling a hole with an M3 thread through the pin and leaving a gap between the pin face and the lid so that I could put a suitable washer secured with a screw in the pin axis. So I'll put the clip away. Otherwise, the groove for the staple is made in such a way that the staple does not rotate spontaneously in it and is still sprung, so I thought that this fixed mounting of the staple could prevent its rotational movement.

Would the engine be able to operate without any protection of the lower connecting rod eye?

Other engines do this as usual, but there is a gap between the connecting rod and the crankcase cover over 2 mm, so the connecting rod cannot "lean" on the cover.

 

[F-DS]

Can this clamp be used? I can't imagine her spontaneously slipping, it runs almost around the whole pin.

 

[Mechanicboy]

No problem, but i prefer the back cover are holding the conrod at place on crank pin.

 

[F-DS]

I replaced the clamp on the lower eye of the connecting rod with another, which better encloses the pin. I had to grind the second clip 0.15mm to fit it smoothly into the groove of the pin.