Month: April 2017

Inline Twin Engine Ep. 7

The progress on the engine continues. In this episode I’ll be making the cylinder sleeves and pistons.

The cylinder sleeves are turned from cast iron bar stock. The first side is turned to finish size on the outside and inside diameters. This ensures concentricity.

Inline Twin 101 (800x450)

After parting off, the sleeves are finished on the second side. The small shoulder will create a groove in the cylinder block for an O-ring.

Inline Twin 102 (800x450)

Finish turned sleeves:

Inline Twin 103 (800x450)

…and that’s how they look installed in the cylinder block:

Inline Twin 104 (800x450)

The surface finish in the bore turned out very nice and was cylindrical within less than 0.01 mm. I contemplated to just leave it as is, just turned. But I decided to finish lap the bore. Since the surface finish was already really good, and the bore straight, the lapping took mere minutes to complete (note the cling film on the lathe bed, to protect it from any lapping compound drips).

Inline Twin 105 (800x450)

 

The next parts are the pistons.

I started with turning a boss to hold the blank in a collet for the subsequent operations. The piston diameter is 32mm, too large to go directly into a 5C collet.

Inline Twin 106 (800x450)

Chucked in a collet, the OD is turned to finish size and the grooves for the rings are cut:

Inline Twin 107 (800x450)

Using a collet block, it is over to the mill to cut the recess for the connecting rod:

Inline Twin 108 (800x450)Inline Twin 109 (800x450)Inline Twin 110 (800x450)

Without removing the piston blank from the collet block, the wrist pin bore is drilled and reamed. This ensures the hole is perfectly perpendicular to the milled recess.

Inline Twin 111 (800x450)Inline Twin 112 (800x450)

The last operation is to face off the chucking boss. The piston is clamped very gently in the 3 jaw chuck with some paper to protect the surface from getting marked up.

Inline Twin 113 (800x450)Inline Twin 114 (800x450)

The finished Pistons:

Inline Twin 115 (800x450)

 

Thank you for visiting my shop.

If you have any questions about the engine or any of the other projects, please leave a comment below, or email at yogisworkshop(at)yahoo.com

For other projects from the shop, please check out the Projects Page in the top menu.

Yogi

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Inline Twin Engine Ep. 6

The last part of the crankcase assembly is the cover on the back, or the flywheel end of the engine.

First, I turned the inside of the cover where it will seat an additional ball bearing. I’ll be using a sealed ball bearing (2RS style) to serve double duty as an output shaft seal. Sealed bearings are grease filled and lubricated for the life of the bearing, but I’ll remove the inner seal and use the engine oil for lubrication, leaving the outer seal in place to prevent oil from leaking out of the engine.

Inline Twin 091 (800x450)

The part is turned over, and finished on the outside:

Inline Twin 092 (800x450)

The last operation is on the mill to drill the mounting holes:

Inline Twin 093 (800x450)

The finished part:

Inline Twin 094 (800x450)Inline Twin 095 (800x450)

 

The next parts for the engine are the connecting rods. The big end will house a needle roller bearing, and the small end a bronze bushing.

The first side is machined to the full depth plus a little extra to allow for the second side machining.

Inline Twin 096 (800x450)Inline Twin 097 (800x450)

A set of machinable soft jaws was milled out, to hold the rods for the second operation:

Inline Twin 098 (800x450)

The extra stock is milled off and the rods machined to final thickness.

Inline Twin 099 (800x450)

The finished connecting rods:

Inline Twin 100 (800x450)

 

Thank you for visiting my shop.

If you have any questions about the engine or any of the other projects, please leave a comment below, or email at yogisworkshop(at)yahoo.com

For other projects from the shop, please check out the Projects Page in the top menu.

Yogi