My UH12R : Miscellaneous

Miscellaneous construction details

						This is the hot-wire cutting bow that I used to cut out the rudder and trim wing shapes. It consists of a piece of highly resistive wire such as nicrome (as is in the case here) or steel such as guitar or piano strings strung between two rods of spring steel like the kind used for model airplane landing gear.
						This is a close-up of one end of the bow. Notice the alligator clip that brings the power from the cutter box. The clip can be moved back and forth on the wire to allow the cutting wire to get hotter or cooler.
						This is an internal view of the cutter box. It contains an AC transformer, a fuse, a wall plug, a switch, and a reostadt (sp?) which is a standard household dimmer switch. This particular cutter was build by an electronics tech/electrician friend of mine who really likes to wire things up complicated. The transformer used here has several secondary windings that supply varying levels of power but a transformer with a single secondary winding works fine and simplifies the construction considerably.
						Here is a (very) rough drawing of how the hot-wire system is put together. The dimmer switch (reostadt) functions as the cutter power switch and heat adjustment. Turn it up to set the wire hotter and turn it down to set the wire cooler. The lines going to the plug are the primary (input) leads and the lines going to the cutter are the secondary (output) leads. If anyone wants to contribute information on the construction of a better cutting system, feel free to contact me and I'll replace this. *NOTE* I am not responsible for injury resulting from the use or construction of this cutter. This cutter uses AC voltages that are sufficient to cause serious injuries or death. Do not cut styrofoam in an enclosed area or without a respirator.
						A (very generous) friend of mine gave me his old garden tractor knowing full well what I intend to do with it (*play 'Taps' here*). Fact is, this is the last time that this tractor is going to know what it feels like to have a Briggs & Stratton 11HP electric start engine vibrating in its belly.
						This is what the engine looks like. UPDATE!: After rebuilding the carburator and fixing an oil leak, I mowed my lawn with it about 6 times. After showing my father the mower and telling him what I planned for the engine, he just couldn't let a perfectly good rider go to scrap so he offered to buy me a brand new engine in trade for the mower. "Okay, if you insist", I said and ordered myself a new Tecumseh 10 HP lift engine with recoil and electric start and a 3 amp alternator. :-)
						And this is the new lift engine still in the box. Ain't she a beut!?! BTW, This model of Tecumseh is also EPA approved.
						After I had installed the lift system, the craft was too heavy to hang from the ceiling in my garage so it came time to put my baby outdoors under a tarp. That very week for a couple of weeks in a row, we had temperatures exceeding 100 degrees. When I looked under the tarp to check on the craft, I had found that the very top of the thrust duct had expanded and split. Evidentally, I had allowed an air bubble to remain between two styrofoam layers that form the duct and the bubble had expanded in the heat and had essentially 'popped' splitting the top of the duct open. These pictures are of repairs I had to make to the damage. I basically hacked out the foam and filled it with expanding spray foam and sanded it level with the rest of the duct. I had also discovered another bubble that ran down from the top along one side which I drilled several holes in and pumped spray foam into the void to prevent this from happening again. I then coated the (really pourous) spray foam with epoxy filler and sanded it smooth and then laid a layer of glass over the area. You can see evidence of the damage in pictures in the thrust system section as I hadn't painted over it yet.
						A week later (after repairing the thrust duct) I came out to check on it again as we were still suffering from 100+ degree weather. You can imagine my joy (massive sarcasm) at seeing that the nose of the craft had wrinkled up and shrunken like a prune. Technically, it would have worked fine but I just couldn't feel good about the craft with that kind of a blemish after working on it for a year and a half. So, partially in a fit of rage and partially for repair reasons, I hacked the white bead foam, that had formed the nose, out. I laid down layers of pink foam until I felt that there was enough to form the lip and I cut and sanded and filled with spray foam until the shape I wanted appeared and then I coated the whole area with epoxy filler, sanded some more, filled some more, and then glassed over the area and painted it. You really can't tell that the damage had even occured.
						This is a close-up of the trim wing actuator. It's operated via a marine shifter/throttle cable. I've since beefed up the arm.
						This is a close-up of the rear steering pulley. It pivots against spring tension to keep the cable tight.