Story and photos by Paul Adams, EAA Chapter 675 President
In Part 1 of making this BIG propeller, I wrote about the purchase of 271 pounds of cherry wood and the activities associated with turning this stack of wood into a 75-pound billet for the making of a prop for EAA’s 1927 Pheasant biplane. A lot transpired between parts 1 and 2.
So here is Part 2’s report: the making of the BIG machine, the duplicator.
The story starts with Mary Joe McCurry. Simply put, Mary Joe broke her leg and was in need of Dave’s support. So instead of moving to my house for the making of the duplicating machine, Dave and I worked in his workshop. And, I might add, I should thank Mary Joe, Dave’s shop was the better space to do the work. You see a BIG propeller needs a BIG duplicating machine! Here’s a picture of Dave’s original duplicating machine. It was designed to make smaller props and props without the severe scimitar shape of the Pheasant prop.
Better yet, here are a couple of pictures of Dave’s machine with half of the Pheasant prop. That half was to be our pattern, sitting in the bed of the old duplicator.
As can be seen, there’s not enough room, especially since the scimitar shape needs to curve both directions so both sides of the pattern can be used. So, with that, Dave and I, with our shopping list, set out for Menards to buy materials for an enlarged duplicator. Upon returning to Dave’s house, we immediately started cutting out parts in his driveway.
Then next came building the table with the side rails. This duplicator will be going to EAA, so we decided to make it a little more upscale than originally thought. The new duplicator may be used in some form at a future AirVenture.
Dave is also figuring out the axles which are to be used next.
The “truck” came next. The truck is the rolling parallelogram that holds the router for cutting and the stylus for following the pattern. I had a router that I donated to the project. Dave made the stylus from some Menards half-inch round aluminum stock. Holders for both the router and stylus were made and mounted to the parallelogram at a precise distance, 13 inches apart. To help balance the parallelogram which helps when carving, we repurposed some of my son Dan’s old weights.
Next, a mounting plate was added that raises the pattern and blank above the table and more importantly, has mounting holes for both the pattern and the blank which are at the precise 13-inch separation. As an added note, Dave’s duplicator had a distance of 6 inches between the router and stylus. Did I ever mention this was a BIG scimitar shaped prop! You might have already noticed the new bed is way wider than Dave’s duplicator bed. We added some odds and ends like supports and travel stops on the rails for the truck. It would make a long day if the truck fell off the end of the table during use.
Everything was varnished and we were ready to go. Time to make a bunch of chips. Part 3 next week will discuss the machining and finishing process.
Finishing, ugh! That means varnishing! Not my strong suit! And you will learn the final weight! Did I mention lots of chips? Stay tuned