TEENY TINY
by
Bob Holderith

TEENY Tiny is a one half scale version of Elmer Verburg’s Tiny. When I began this engine I had just completed a full scale Tiny. Steve Huck, a regular member on http://www.homemodelenginemachinist.com/index.php, had half scaled an engine that he had built. I thought building one made a lot of sense for me because my ultimate goal within this hobby is to build a small scale internal combustion engine. Teeny took about a month to build. A lot of time was spent figuring out how to hold parts.

Teeny was especially challenging for me at the time because I only had a 6 inch swing lathe and a 15 inch swing drill press. Most hole locations were scribed and center punched. The flat face of the column was machined on a face plate by bolting Teeny to it through the bearing bore in the column. Other challenges included how to supply air to the engine and how to retain the cylinder block. The air problem was solved by drilling out a 1-72 screw and using shrink tubing as an air line. The retention of the cylinder block was solved by a simple collar which is crimped by the use of pliers. The hardest challenge was drilling the port holes. Small drill bits will not draw a part into alignment on a drill press. Therefore, the part has to aligned by hand. To do this a vice was clamped to the table and tapped with a piece of brass until the drill bit wouldn’t show any deflection with the prick mark.

Teeny proved much less difficult to get running than I had anticipated. As with any engine it is important to maintain perpendicularity and parallelism with the moving parts as they relate to one another. The crank bore needs to be perpendicular to the column face. The crank pin needs to be parallel to the crankshaft etc. On a very small engine a few thousandths of an inch error in these areas can make the difference between a runner and a static model. The only major problem that occurred was the crank disk slipped on the shaft. The crank on my full size Tiny was assembled as a press fit. I attempted the same thing with Teeny but had to soft solder it in the end. Once this was remedied the engine ran after a few sticking points in the rotating assembly were worked out.

When I completed the engine it received quite a bit of attention from the members of homemodelenginemachinist.com. It was actually nominated by Steve Huck, of all people, for Project of the Month. I never dreamed that this little engine would receive the attention it did. As a result, this led me to attempt a quarter scale version of Elmer’s Tiny. I had about 70% of it done when a #80 drill bit broke off in the column. That was five days before my youngest daughter was born. As a result, I just shelved the project. The column at a quarter scale is the most difficult and tedious part to make. Having recently completed Dr. J.R.Senft’s Poppin vacuum engine I am debating whether or not to attempt the Ultra Tiny quarter scale version for my next project, or Gail Graham‘s Lobo Pup Twin 1.6 cc diesel.