I recently picked up two Atom 500 airframes. One was a somewhat worn out 500R, the other; a low time carbon version. The 500R came with a flybarless head conversion. I stripped both of them down to parts. Tossed the worn out, broken and trashed parts.
So, this thread will pick up with my experience building one airframe. I've built and worked on well over 30 models since 2005. I realize this model is a 2 year old design, but I'll drop in my 2-cents anyway on the design, construction and eventual flight anyway.
To start my rebuilding I always take used or "ARF" models and take them down to nuts and bolts. I check for and clean off any old thread lock. On used models I soak and re-grease all of the bearings using a Greaser, and essentially build it up as a kit. So, I tore these models down, dumped all the hard parts and bearings into rubbing alcohol (70%) for 48 hours. Then flushed everything with water, dried and then started my sub-assemblies.
I decided to start with the tail since I'm doing some modifications to the frames that I'll get into later. Before I tore everything down I checked the action on all of the moving parts, ball links, etc. to get a feel for any inherent binding. The tail in my opinion was not as smooth and effortless as I thought it could be. Upon reassembly I sanded the inside flats of the plastic "H" piece that attaches to the tail case housing with a long pin so that when onserted to the housing there is little to no resistance. Once the pin was installed (need to wick in some Tri-Flow lube to the shaft's hole), this "H" piece moved freely with no resistance.
I then did the same sort of sanding to the inside edges of the pitch plate actuator arm so it would swing freely once pinned to the "H" piece. Again, I'll wick some Tri-flow oil in at the pivot points. These two bits of sanding made the tail action substantially more smooth. Some might say that if left in stock condition, they'd eventually wear in. That may be, but I'd prefer to have a smooth, bind-free tail at the get-go and be more kind to my tail servo.
I rebuilt the pitch plate, re-greased the bearings and installed the pin screws with a small drop of thick CA glue on the threads. I finished rebuilding the tail grips with lubed bearings. I did notice that they have a marginal amount of play on the hub shaft, but figured it wasn't worth trying to tighten them up since centrifugal forces are just going to cancel it out. I used a small smear of high strength (red) thread lock on the blade grip-to-hub M2.5 screws to insure the grips don't come flying off as a result of a loose screw.
Once reassembled, the tail action was substantially more smooth than it had been. I probably could have further improved on it if I had tapped out the tail pulley gear roll pin and pulled out the tail shaft, chucked it in a drill and polished it. Maybe on the next rebuild
I'll be popping the tail case onto the tail boom soon, but I'll be drilling out the two indentations so the "pinch" screws actually screw into the boom.
The frame reassembly is the next major thing to do, but after I modify it
I'll be installing PEM nuts to retain the servos.
More to come and with pictures...