gbritnell

13 inches 330 mm. It's 3 tenths full scale

While not a kit from a box but still a kit in the sense of filing sanding and fitting the pieces. I started this Ford model A engine a couple of months ago. The project involved many hours of searching online for dimensions, pictures and information to compile the necessary data to create the Autocad drawings which were then transformed into solid models in Solidworks. At that point I started 3D printing everything. 3D printers are quite accurate but not to the point that you can create two adjoining parts with what you expect they will fit together without adjusting the models at least once and sometimes twice. The model was printed with PLA and has all the internals, crank, rods, pistons and camshaft. The transmission has all the gears and shifts accordingly. It's gray because if was from an earlier builf. In all with the preliminary drawings, CAD models, printing and fitting I'm guessing somewhere in the neighborhood of 100 + hours.

Looks and works great Chris! I built a 2" scale pickering governor from bar stock with a balanced valve. It turned out fine except I could never come up with a spring combination that would work properly at that scale. I used the flat blade springs similar to the full sized version.

Even if a horizontal rotary table with ardino was used it would need to be synchronized with the X axis of the mill. You have to advance and rotate at the same time. The milling head would also need to be tilted to match the helical angle. Seems like a dedicated motorized fixture would be the way to go but then its like making a cam grinding fixture. By that I mean for the time spent how many helical gears or camshafts is one person going to make?

How about this Chris. I'm not an electronics guy but someone who is could use an Ardino like they did for the rotary table drive with stepper motor. It would have a sliding block guided by 2 stout bars, say .625 rods. The spindle would be mounted with a bearing on the drive side and a close fitting bushing on the work end. The sliding block assembly would be moved in and out with another stepper motor operating a ball lead screw. The control would allow the the travel and rotation to be synced to whatever helix is required. It wouldn't have to travel more than 1.00 inch. That would be a pretty wide gear.