Pins and More Pins!

The first pins we made were the six pins used for attaching the connecting rod to the piston. For this, we simply took 1/8" steel rod and cut it in lengths just short of 1" (To keep it from scracthing the cylinder wall). Then we pressed the rod through the piston and connecting rod to hold it in place. (Picture coming soon)

The next step was to make the crank rods on which the connecting rods are going to ride.

	First step was to grab some 1/4" steel rod and cut it to the appropriate length (1.25"). For this, we used calipers to measure the distance to the cuttoff tool on the lathe.
This picture shows the lathe in action. After the cut is finished, the rod can be slid further out of the chuck so that the next section can be quicly measured and cut. A total of three of these need to be made.
	The crank rods need to rotate with the rest of the crank and cannot slip. To achieve this, we could have keyed this rod, pinned it, or what we chose to do in the end, cut a flat on it. Any of these options would have allowed the torque to be transmitted, but using a flat will allow the most torque without worrying about very small keyway or pins shearing.
The flats were cut in 3/8" from the end of the rod towards the center, at a depth of .1" (not quite a full 1/2 diameter).
	Now we needed to make the same cut on the opposite end of the rod. However, making sure the two flats are perfectly aligned with each other can be a bit tricky, so we made a special tool to locate the part in the vice. If the flats aren't perfectly aligned with each other, they will cause timing problems for the engine.
The tool we made had a 1/2" shank, with the bottom area turned down to just under 1/4". This allowed us to pinch the flat exactly perpendicular to the spindle, and tighten the vice without clamping our tool.
	One of the three finished pins!

We need to make another set of pins for the crank like the one above. However, we will only need two of these, and they will need to be 1.125" long. These pins will run through the bearing supports for the crank. The flats are cut exactly as above, 3/8" in from each end, and .1" deep.

Next Step -> Crank Bearings (coming soon)