1-1/2 HP Gade Scale-Model Engine, Part 3

Modeler's Corner

| March 2005

  • 03-05-017-gear3.jpg
    Cam and crank gears installed
  • 03-05-017-gear2shim.jpg
    Detail shot shows the plastic washer made from a milk jug and set between governor collar and crank gear.

  • 03-05-017-gear3.jpg
  • 03-05-017-gear2shim.jpg

Hello again, everyone. Last time, I discussed the governor and the ease of making the small pins, and how I had purchased some small bolts to build the governor spring weights. Well, if I had only checked the parts packages sent to me by Roland Morrison, I would have found he had already made the governor spring bolts!

Gearing up
I have pressed the gear onto the crank, which was a snug fit. I used my small arbor press and a deep-well socket to get it into place, then drove in the small 3/32-inch key-stock shim. This all went together with no delays or snags. I then went to install the governor collar, but remembered that small metal pieces with oil between them - like the crank gear and governor collar - will sometimes stick together, so here I performed one of my old tricks again.

To make sure the crank gear and collar wouldn't stick together, I took an empty, clear plastic milk jug and cleaned the inside thoroughly. I?cut out one side of the jug, hole-punched a 1/2-inch piece out of it, then centered and punched a 5/16-inch hole into this. I then placed this small piece of plastic between the crank gear and the governor collar. It is almost invisible, and it works great as a bearing between the two metal pieces. The plastic from clear-type no. 2 milk jugs is very slippery, and I have found it very useful in many different applications.

I also fabricated the cam gear pin using a small electric motor shaft; it is good metal and smooth turning. This went well until I wanted to fit the pin into the hole in the base. If I had to fabricate another pin, I think I would undersize it some to get a better fit into the base and the cam gear, another part that Roland supplied. I had to take the cam gear and open it 0.0015-inch with a no. 12 drill bit. Roland furnished the gear pin set screw, which is a 3-48 square head. I then used some fine grinding compound on the teeth to show me that the cam and crank gears were in fact squared up. Next time I might slide another small piece of plastic between the base and the cam gear just to slow wear and give it some cushion.

I have also bolted the connecting rod and rod cap together using some paper shims, and bored and reamed my 0.3750-inch (3/8-inch) hole and also drilled for my grease cap. I then drilled and reamed for my wrist pin a 0.1875-inch (3/16-inch) hole, and finished it off using a no. 1 center drill to allow for oiling. I drilled this hole toward the meat of the connecting rod instead of in the center so oil gets into this area easier. Next, I will finish the piston and hopefully the rest of the governor assembly. Is this hobby great, or what?