1/4-Scale 5 HP Red Wing: Part 2


| December/January 2004

  • Engine frame and jig attached to the lathe
    Photo 1: Engine frame and jig attached to the lathe in preparation for boring.
  • Governor-side flywheel
    Photo 4: Extra work must be done on the governor-side flywheel.
  • Engine frame and jig
    Photo 2: Engine frame and jig mounted at 25 degree angle in preparation for facing the mating surface of the bearing caps.
  • Bearing cap removed
    Photo 3: With one bearing cap removed, you can see what the surfaces should look like.
  • Homemade tool
    Photo 6: Here is the homemade tool in action.
  • Broaching spacers
    Photo 5: Small broaching spacers were fabricated with sheet metal.
  • Cutter speed and Feed speed list


  • Engine frame and jig attached to the lathe
  • Governor-side flywheel
  • Engine frame and jig
  • Bearing cap removed
  • Homemade tool
  • Broaching spacers
  • Cutter speed and Feed speed list

Editor's note: This is part two of a four-part series. Read Part 1 

Last month I told you about how I became interested in model engines. We also went over a few milling steps that let us get started. This month I want to mill the engine frame as well as bore the cylinder. I think there will even be time to work with the flywheels, so let's get started.

Before the engine frame can be milled any further, it has to be attached to a jig. Some of the milling steps require that the engine frame be held sideways or at an angle. Because of the irregular shape of the engine frame, it would be very difficult to do without some type of jig.

Fabricating a jig
The jig I made is simply a flat piece of 3/8-inch steel that has been milled square on three sides. I made it about 12 inches long and 7 inches wide so there would be plenty of room for the jaws of the vise to grab. By having the three sides milled square, I just have to let the jig touch the bottom of the vise and it will square itself with the table.



With the engine frame attached to the jig, I decided to bore the cylinder. It is important to bore the cylinder before some of the other machining on the engine frame can proceed. This is because the cen-terline of the bore is used as a reference for some of the other steps.

I started by attaching the jig and engine frame to the lathe table. As you can see, I had to use several V-blocks and plates to center the bore with the center of the lathe.



SUBSCRIBE TO GAS ENGINE MAGAZINE TODAY!

Gas Engine Magazine A_M 16Gas Engine Magazine is your best source for tractor and stationary gas engine information.  Subscribe and connect with more than 23,000 other gas engine collectors and build your knowledge, share your passion and search for parts, in the publication written by and for gas engine enthusiasts! Gas Engine Magazine brings you: restoration stories, company histories, and technical advice. Plus our Flywheel Forum column helps answer your engine inquiries!

Be sure to take advantage of the Square Deal Subscription Program.

  • No Missed Issues.

  • No Renewal Notices.

  • No Additional Cost.

The Square Deal Subscription Program is designed as a paperless transaction with automatic renewals at a preferred low rate.   With advanced electronic notification, a 100% satisfaction guarantee and an easy opt-out plan, the Square Deal Subscription Program is the best value, risk free, eco-friendliest way to subscribe.




Facebook YouTube

Classifieds