Another Knucklehead, built via castings, as a Draw-Tech design, upscaled

Foketry · Apr 18, 2024

After seeing the construction done by Mayhugh, I also decided to build this interesting engine in a slightly larger scale.
The pistons of my engine will be 36 mm instead of 1.063 inch (27mm) and everything else will consequently be increased by the same proportion.
I have followed and studied all of Terry's posts, whose technique and precision I admire and I hope to obtain a well-functioning engine like his.
I also asked Terry for some 3D drawings and he kindly provided me with some ,I started from these drawings
After the 18-cylinder Isotta Fraschini, I returned to simpler engines, just 2 cylinders, even if Terry writes that it is not that simple

Foketry · Apr 20, 2024

To make aluminum castings the first step is the 3D drawing of the finished part, then I eliminate all the holes and machining, add the allowance in the milled or turned areas, add an increase that takes into account the aluminum shrinkage .

Finished right crankcase

drawing for casting mold

3D printed mold with parting powder

I generally paint the mold to obtain smoother surfaces but in this one I didn't paint

the sandblasted casting

Foketry · Apr 22, 2024

Other aluminum castings, always with the same procedure , 3D project, plastic model, cast in red sand

Cover cam box and Cam box

Foketry · Apr 22, 2024

left crankcase

GreenTwin · Apr 22, 2024

Very nice casting work !
.

ozzie46 · Apr 22, 2024

looking good.

Ron

Foketry · Sunday at 2:38 PM

The flywheel, brass casting

GreenTwin · Sunday at 3:16 PM

That casting turned out really well.
Do you know the alloy type that you used ?
.

Foketry · Monday at 7:55 AM

GreenTwin said:
That casting turned out really well.
Do you know the alloy type that you used ?
.

It is brass obtained from old taps , I don't know what brass alloy it is, but no particular mechanical properties are required in this flywheel

Foketry · 2024-05-03T03:05:06-0400

The crankshaft

My Knucklehead engine is larger than the Draw Tech project, the diameter of my piston is 36mm compared to 27 mm, 1.33 larger , so everything will be larger than the photos of the components that you have already seen in other constructions. The total displacement of the engine will be 90 cc, therefore all the components that you have already seen in other construction photos will be larger.

I built the flywheels separate from the shaft that carries the bearings, I thus avoided turning many kg of steel and generating mountains of shavings

I turned on the lathe and drilled the 2 flywheels together, then separated them with the band saw, to obtain the central hole and the hole for the connecting rod pin perfectly equal and aligned.

I made the tapered holes for the rod pin with a Morse 1 tapered reamer

Foketry · 2024-05-03T04:38:26-0400

the 2 flywheel shafts have an allowance of 0.5 mm, when they are assembled with the flywhee , connecting rods and the pin , I will do a final turning to ensure alignment and concentricity .
The assembly was done with a press.

CNC turning of the connecting rod pin

the defective pins, 5 before getting the correct one

oil quenching of the connecting rod pin

Vietti · 2024-05-03T11:05:58-0400

Before you assemble you might consider a needle bearing on the con rod, I did it on my Hoglet and it seems pretty good. Also I drilled and reamed a hole at 180 degrees from the con rod hole to insert a dowel when aligning the flywheels, seemed useful.

Foketry · 2024-05-03T16:10:50-0400

Vietti said:
Before you assemble you might consider a needle bearing on the con rod, I did it on my Hoglet and it seems pretty good. Also I drilled and reamed a hole at 180 degrees from the con rod hole to insert a dowel when aligning the flywheels, seemed useful.

For the connecting rods I provided bronze bushings, mechanically the needle bearing are better, they have less friction, but the bushings are simpler and more robust.