No worries about thread hijacking.... its actually all relevant to the discussion at hand. I wish I had half of the understanding of this stuff as the two of you do! I think the back and fourth discussion helps continue to broaden the awareness of the capabilities of brushless in our hobby. I keep seeing more and more people try them out, and the more people that use them the more experiences for all of us to learn from. Those magazines are awesome! Are they for your Gridley? I am still trying to figure out magazines for Uritski..... I have all (I think) of the torpedo made except for the magazines and breeches. I just hope it works as planned.
Actually, I'm printing him a gearbox to go with the little tiny motors and gears I'm using. Pics to come!
I must say I envy your 3d printer! That's just far too cool! I had no idea that some of those things could print in stainless!?
Ahhhh, The untold joys of stator winding....... There's a reason why they are untold..... no one wants to re-live the electrical shorts, lost counts, electrical shorts, sore fingers, electrical shorts, blurry vision, electrical shorts, miles of wasted wire, electrical shorts, aggravation over electrical shorts, consideration of having oneself commited over electrical shorts........ the list goes on and on.... most of it in one way or another relating to electrical shorts..... Below we have a rotor/ outrunner can combo as discussed previously, an unwound stator, another unwound stator with the only method I found to effectively limit electrical shorts (cover teeth in heat shrink tubing), and the main mount for the stator. After the stator arrived I had to open up the center hole to provide enough room for everything else to fit. I used a piece of scrap in the lathe and turned a bore in it just barely big enough to fit the stator in, then bolted the stator to it without removing it from the machine. I then milled the hole to the desired size. I avoided turning the hole to size because I was concerned it would de-laminate the rotor.
I like to refer to the actual winding of the stator as my sleigh ride to hell.... I tried numerous methods to eliminate the electrical shorts. I first tried winding carefully to avoid damaging the coating that came on the rotor and the wire..... that failed in a remarkable way. I tried wrapping several different materials around the rotor to pad it's corners from breaking the wires coating.... fail. I tried coating the rotor with west systems epoxy.... fail. I tried polishing all corners of the rotor with a dremel, THEN coating with west systems... fail!!! Uuuggghhh!!! Im starting to feel like Charlie Brown here.... I'm sure if Snoopy were here he could wind this stupid thing on the first try, then dance off in happy abandon!! Below is my first sucssesful wind. I don't remember how many turns it was, but it was 25 AWG wire, and was wound in a star (wye) pattern. It worked too well.... It hit 32,000 RPM before the reflective tape for the laser tach flew off!! Next to it is the stator I tried to polish and coat. The epoxy mess had been mostly removed by this point. I Wound another stator with 28 AWG wire (not shown) and was rewarded with a nice functional 19,800 RPM. The strange looking device on the right with the hole in the end is the winding tool I made after removing most of the skin from my fingers trying to wind stators. The wire passes through a larger hole on the tool about where your thumb would be during winding, and comes out the hole in the thin protrusion, You then control the tension with your thumb. Worked pretty well.
Ah yes, that brings back memories. It's amazing how the surface tension of the epoxy pulls it away from the sharp corner that you want to coat. The best insulator was molded nylon covers for the stators. These look like they are still available from gobrushless.com when you buy the stators. Kapton tape was also supposed to work well, but I never got around to trying it. I like the tool you made, simple and effective.
Drat! Looks like the nylon covers are only for the 20mm stator... mine is the 18mm I may actually get the 25mm that is under 2mm thick... might save some space. Thanks for the pointer on the kapton tape, I will experiment with it on my next wind. That's one thing I don't think I tried, and I have a ton of it lying about in a few different widths.
Here is a shot of where the stator mounts. Its held down with a small nut I made that has a small boss on it. It was hard to keep everything short enough to fit under the rotor, so some parts (like the nut) weren't functionally optimal once they were made to fit in the allotted space. During the redesign I will make a little more room for everything.
Here is a little better exploded view pic I came across. The stator mounting nut is under the 3 electrical terminals.
Ok, I finally have all but one part revised and built to try a different precession system on the gyro, with any luck i can be ready to re test tonight. The original design did not provide enough precession to balance properly enough for me to even tell if it was precessing in the right direction, so I redesigned to provide more of a direct friction precession system. (Which I fully expect to precess in the wrong direction). I haven't bothered to try to explain this whole precession thing much because I wanted to try to get it right before I posted erroneous info. I am also very close to torpedo testing, I just need to build the breeches and barrels. I am still doing a bit of experimenting in tight radius bends to try to clear the deck. The first version is a little difficult to build. I finished making the latest (and simplest) apparatus to bend with, hopefully I can try it tonight!
The new Gyro frame is ready to go, just have to put the gyro itself on it. The old Precession system (on left, shown upside down) attempted to use the rocking of the gyro cage on the precession pivot (which had clearance built in to allow a small amout of rocking) to cause friction in the slot, since the cage would rock and the gyro and shaft would attempt to remain in its previous location. This was intended to cause the spinning shaft to attempt to pull itself along the slot as it rubbed on it, causing the gyro to rotate on the pivot (forcing precession). There just wasn't enough friction available for a number of reasons, so I came up with the new cage. On the new one, (on right, rightside up) the top of the cage will be mounted to the boat, and when it rocks, it will more directly and with more force press against the shaft, which should provide more of a precession. Time will tell (fingers crossed).
I really really hope it works, just because it looks too freaking AWESOME to fail. Really, it looks like military-grade hardware.
Thanks Tugboat!! In reality, I expect it to precess backwards, just because that would require a major redesign to correct. There isn't a lot of good UNDERSTANDABLE reference on this sort of thing. The stuff that isn't technical enough is of no use, the stuff that is technical enough is soooo technical that my little brain can't wrap itself around it. On the upside, it IS cool looking.... maybe if it fails I will just carry it around and look at it.
Well, I wanted to arm Uritski with torpedos. The easiest way to do it would be to use extra parts from the cannons I had built for Emile Bertin. So I tossed around ideas and figured to save space, I would use a common accumulator for each side of the ship, even though they could be fired independently. I started to lay out the real estate requirements..... Drat!! They are waaaay too long, and waaaay too heavy! The MPA-3s weigh a ton and take up tons of space!!! Both ball valves and their accompaning hardware, placed at the shortest possible distance, yet still needing a copper accumulator between the two:
So I came up with an alternative plan. The "Torpedski". Forgive the garbage picture, I don't even have all the components finished, and some of the ones that are aren't here right now. The white plastic valve body is a standin for the other Lexan one which is at a friend's house. I put it in the pic size comparison. The white one is also the first generation. There have been 2 revisions since to get to the lexan unit. The valve bodies are Lexan because I wasn't confident in the Delrins ability to take a shot, and since Uritski is so small, I'm not sure the internal armour will be all it can be, so I stepped it up to Lexan. The accumulator is ABS.
I incorperated the MPA valve into the Ball valve to save space and weight. It added very little to the overall length of the ball valve, and since it is a slightly bigger bore diameter than a MPA-7, punches the valve open much easier than the MPA-3 did that i was planning on using. The two new valves together weigh less than one of MPA-3 ball valve assemblies. I still need to build the breech, it has been a bit of a challange. It will fit into the outlet hole you can see in the brass piece sticking out of the side near the bottom. There is one on each side of the valve so I will have two barrels per side, Each valve serves one side of the ship, meaning both barrels from this valve will fire to the same side.
