Inline Twin Engine Ep. 11

For the camshaft, I’m staying with the spirit of this engine, as it will be built up of multiple pieces.

I started with the cam blanks, turned and parted off. They are made from 1144 Stressproof Steel.

Inline Twin 165 (800x450)

The second side of the cam blanks are finishe turned:

Inline Twin 166 (800x450)

Drilled and tapped for a set screw:

Inline Twin 167 (800x450)

The two cam blanks, ready for the cam profile:

Inline Twin 168 (800x450)

To set up for the milling of the cam profile, I chucked up a piece of shaft in the collet block, and milled a flat for the set screw.

Inline Twin 169 (800x450)

The collet block is set up vertical in the CNC mill and the cam blank secured.

Inline Twin 170 (800x450)

The profile is milled using a t-slot cutter, to be able to cut both cams in the same program.

Inline Twin 171 (800x450)Inline Twin 172 (800x450)

The process was then repeated for the second cam. The only difference, it is a mirrored version of the first one.

The two cams finished:

Inline Twin 173 (800x450)

The shaft has two flats milled, which need to be indexed 180 degrees. The collet block makes quick works of the indexing.

Inline Twin 174 (800x450)

With the shaft still in the collet block, I engraved a line on the end of the shaft. This will help to time the camshaft.

Inline Twin 175 (800x450)

The assembled camshaft:

Inline Twin 176 (800x450)

To finish up the gear train for the camshaft, I needed the idler gear. When I designed the engine, I utilized stock gears from SDP/SI. SDP has CAD files for all their gears for download on their site, which is a tremendous help in the design process.
For the idler gear, none of the stock gears would fit my application. My solution was to use a stock gear and modify it to my need.

To illustrate the design of the idler, and to adjust the backlash in the gears, I attached a CAD rendering below. The hole in the crankcase cover is drilled oversize, allowing some adjustment.

Inline Twin 185 (800x549)

The stock gear, as received from SDP:

Inline Twin 177 (800x450)

In the lathe, the gear was then bored out to the correct diameter for the miniature ball bearing.

Inline Twin 178 (800x450)Inline Twin 179 (800x450)

Parting off:

Inline Twin 180 (800x450)

A bushing is turned, to hold the bearings, and to mounted it to the crankcase cover.

Inline Twin 181 (800x450)

The gear, bearing, and bushing assembled:

Inline Twin 182 (800x450)

The idler installed on the engine:

Inline Twin 183 (800x450)

The finished gear train, with the camshaft installed.
To note is the line engraved on the end of the camshaft as mentioned in an earlier, for timing of the camshaft.

Inline Twin 184 (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)

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


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