A lot has happened since my last post. I had the large parts commercially stripped using glass bead blasting to remove all the old paint, hot glue and most of the oxide. This prepared the model for soldering. I built the jigging that would hold the heavy pieces in alignment so soldering could proceed without too much handling. I started soldering the first set of main struts in place and ran into a brick wall. The bronze parts are so massive in relation to the pieces being soldered to them to make them almost unsolderable. I use "almost" because my problem was simply not generating enough heat to get the joint to solder temp before the bronze sinks all the heat away. I actually resorted to using two torches simultaneously; one a MAP torch and the other propane. This didn't do it. Then, one of the Heritage team members brought his acetylene/air torch and it's 2,700 degree flame was sufficient to bring the joint up to solder flow. I was still not satisfied. I talked to a tech service person at Harris Metals, a major solder and flux maker here in the USA and he suggested using 60/40 solid core solder and their high temp flux so it would stay put during the long heating session. I'm waiting for this new stuff to arrive.
Here's how the plane parts looked after glass beading; a far cry from how it looked before. At least now I had a chance to get it desoldered.
I constructed the jigging using 3/8" threaded rod, nuts and b body washers. The jig let me align all these heavy parts and not have to worry about them moving while I'm fitting up all these heavy pieces.
My first joints were decent, but didn't meet my standards.
The landing gear were missing. In the original installation, the landing gear were load bearing and held up the front part of the model. The rear was affixed with a 3/8" threaded lug. At some point after 1988, the gear disappeared and the model was supported with three lugs. I've re-created the landing gear using a hybrid of 3D printed parts and machined brass. I first was going to do the entire deal with 3D printing, but the long strut was too weak. So I designed the print with a 1/8" hole down its length which I would fill with a piece of brass rod. My first print had too much uncured resin in the bore and after hardening, formed a hardened plug that I attempted to drill out. The drilling out process destroyed that gear. For the next one, I drilled some tiny drain holes at the base of the strut so I could flush the recently printed resin out before hardening. This worked and I was able to insert a 1/8" brass tube down the entire length to reinforce it. I also reinforced the mounting lugs that would hold the gear to the fuselage wall by inserting a 3/64" brass rod into previously drilled holes. In the process of pushing this rod into a tight fitting hole I pushed too hard and blew the entire thing apart losing the reinforced strut. I still had the entire lower portion. I then made the struts out of brass and created the hybrid assembly. If this didn't work, the last resort was to print the parts in casting wax resin and have them investment cast in brass. We had a source to do this if necessary.
I didn't have much clearance to drill the 1/8" holes in the fuselage to accept the reinforced lugs on the gear legs. I was looking to buy and angle drill, but then remembered that I had a Dremel right angle drill attachment. I hadn't used it in years. Today it was worth the wait.
I measured twice before drilling the holes in the fuselage to accept the gear. I knew that the spacing was accurate since, even though the drawings were very rudimentary, I was able to at least got those details correct.
The last thing I did was drill out the wooden shafts from old props from the engine fronts and then bored out the props to accept machined hubs which I'm now in the process of turning on the lathe. Originally, it looked like the plane didn't have variable pitch props, but later iterations showed Hamilton Standard HydroDynamic props and their distinctive hubs. I'm going to make something in between. I was concerned that my drilling of the props could destroy them. I hand drilled a centered pilot hole and then used the drill press to open it up to a #2 drill. I was careful and was rewired with clean centered holes ready for the new hubs.
Once I get the new solder and flux, work should proceed fairly quickly. Until next time...