I used a drop of Loctite retaining compound to lock them to the motor shafts. I was a little leary of having the two shafts of significantly different diameters because I intend to use tubing as a flex coupling.
If you just glued them on it will not hold. Either solder them on or cut a slot in the sleeve and put the set screw through it. Soldering stainless is not easy.
I used the Loctite shaft retaining compound, it's virtually non removable once it dries. We used to use it to hold bearings in bores if the bores were a little loose. Even with a press they were considerably more difficult to press back out than a properly pressed bearing was..... fingers crossed
I think what Bob is worried about is the vibration & impact torque of hitting rocks, bottom, etc breaking the bond. Then your best case is a free-spinning prop while you drive on the other. Worst case is your driveshaft & prop wind up on the bottom of the pond while you have "flooding in the engine room" through the hole.
The fast electric guys have proven that retaining compound is as good or better that a GOOD solder job. They are running over 500 watts, way beyond what we use.
CA glue will not work. Blue Loctite, or even red is not going to work. I've never used retaining compound, thought it might be the same as red/blue Loctite. It's the back and forth of forward and reverse that will breakdown the hold of the glue. I'll be interested to see how it holds up. What kind of tube are you using for the shaft coupling? Why not a U-joint & dog bone?
Shaft retaining compound is specifically made for this type of application in an industrial setting, red and blue Loctite are not intended for this type of service. The tube I am using will be the tried and true fuel tubing. It seems to work pretty well for some of the fast gun guys, so at the slower big gun speeds I am assuming there won't be any issues. I avoided the u joint or dogbones for a few reasons, all of which I don't remember now, but I think the main considerations were with tubing the motor could be placed closer to the prop shafts to reduce used real estate in the hull, is cost effective, it is supposed to run quieter, less chance of mechanical failure, and it will tend to have a tiny bit of "give" if you get bound up in weeds or run into something with the props. I really haven't tried it myself, but from what I have read from others here, it is quick, reliable, cheap, and easy to install..... time will tell if it works as well for me......
Time to make the stuffing tubes.... Pretty standard, 1/4 brass tube with 1/8 stainless shafts. I purchased some bushings from small parts and modified them to fit into the tubing. Props are from Battlers Connection.
I also plugged the opposite end of the dummy tubes, I didn't want to give pond water a place to hang out. Plug isn't fully pressed into place in this photo.
Prop shaft mocked up prior to soldering. The steel set screws that came supplied with the stop collars were later replaced with stainless ones.
Motor mount and prop shafts installed. I made some alignment sleeves to hold the shafts in perfect alignment while the epoxy was drying. These will be removed and replaced with fuel line tubing during final assembly. Also note the deck hold down magnets installed just to the left of the motor mount screws.
Although not what I was intending to capture in this picture, you can see a bit of a side view of the motor/ shaft install here. A little hard to make out is the fact that the motor mount plate holds the motors at the same angle that the prop shafts are mounted.
Another accidental capture of the install. You get a better view of the angle the motors are mounted on in this one, and how tight a fit it was to get the motors aligned without interfering with the bottom of the hull and rib.
Here is the basic setup for the rudder. While at the local hobby shop hunting for rudder servos that would fit as far back as possible, I was looking at some smaller servos. The clerk at the shop was guiding me away from them, and suggested this low profile unit which has similar power to a full height unit. It turned out to be an absolutely perfect fit. As you can see, there is a hex shaped stop collar to hold the rudder in, as well as provide power transmission from the servo. I also made a servo adapter with a mating hex broached into it that will engage the stop collar. I realize the rudder shaft being straight could be a problem. I ground random flats in it to provide a resistance to spinning before I ever seen that bending the end was an awesome solution.... I may remake the rudder at some point to correct this potential for failure.
