Boldly Going Where No Man Has Gone Before. RC Nano-Hydro

[Dr. Jet]

Motor Mount Installed

It's TINY!! Eyeglass screws mount it at the "drive" end, and an O-ring rolls over 2 CF rods at the "free" end.

[Dr. Jet]

I’ve been waiting several weeks for a new chuck to arrive for my lathe. The old one was incredibly cheap and had centering issues that made the first coupler I made less than ideal. While I had the chuck off, I disassembled the carriage, the cross slide and the compound slide. I polished all the ways and gibs, cleaned and lubricated everything, drilled and tapped the tailstock for additional adjustment screws, and ordered a few upgrade parts while I was at it. I spent a lot of time in the re-assembly adjusting the gibs, centering the tailstock and making sure everything was square or parallel. It’s surprising how much a little “blueprinting” does to improve the performance of the machine.

The chuck arrived today and I was about to make a new coupler and discovered I was out of aluminum stock. Once I make the coupler, I can locate the stuffing tube and get on with building the wire drive. I call it a “wire” drive, but in this case, I’m going to use 0.8mm carbon fiber rod. With the low power of this system, it should be more than adequate. I chose to use the carbon fiber as there will be less radial load on the brass bushing in the strut. Less radial load = less friction.

Stay tuned for photos and discussion.

[NativePaul]

I was going to say that carbon will wear really quickly unless in ball races, but as you need to step the size at each end anyway with such small diameters, it should work just fine as long as you step up the shaft to give it a brass bearing surface, rather than stepping down the prop. I like the idea so much I will make some adjustments to suit my requirements, and steal it for my own version.

[Dr. Jet]

I was going to say that carbon will wear really quickly unless in ball races, but as you need to step the size at each end anyway with such small diameters, it should work just fine as long as you step up the shaft to give it a brass bearing surface, rather than stepping down the prop. I like the idea so much I will make some adjustments to suit my requirements, and steal it for my own version.

Actually, I am stepping the size UP at each end with 1/16" stainless steel tube. The carbon will not turn against any surface: One piece of SS tube will be captured in the coupler and the other tube will ride in the brass bushing in the strut. The CF rod will connect these two pieces of SS tube.

[NativePaul]

Yeah that is what I meant. I have had a turn around though, I measured the 2x 1mm carbon rods I have in hand and neither are close to round, 1 is .88 x1mm and the other .99x1.12mm so I think they would wreck themselves on the stuffing tube pretty quick, I may be able to sand the bigger one more round in the dremmel at high speed, but I went to the crappy LHS in my new town, and despite England going metric before I was born, they only had the imperial K&S tubing rack not the metric one, and only a fraction of the sizes in that one too, so I cant step the 1mm up to 2mm anyway. I think at this point unfortunately I think I am going to use a 2mm straight shaft with as low an angle as I can get, rather than any sort of flex.

edit; I just weighed 5" of 2mm piano wire and it is 3.4g, nearly as much as my ESC and servo combined, so that is out of the equasion.

[Dr. Jet]

Yeah that is what I meant. I have had a turn around though, I measured the 2x 1mm carbon rods I have in hand and neither are close to round, 1 is .88 x1mm and the other .99x1.12mm so I think they would wreck themselves on the stuffing tube pretty quick, I may be able to sand the bigger one more round in the dremmel at high speed, but I went to the *!***!***!***!**ty LHS in my new town, and despite England going metric 40 years ago they only had the imperial K&S tubing rack and only a fraction of the sizes in that too, so I cant step the 1mm up to 2mm anyway. I think at this point unfortunately I think I am going to use a 2mm straight shaft with as low an angle as I can get, rather than any sort of flex.

I am going to have the 1/16 SS tube go through the entire stuffing tube and end 1/2mm BEYOND the bottom of the hull. That's where the CF rod begins (actually, it's Loc-Tited in the SS tube the entire length, but I digress). The CF rod only touches the INSIDE of the 1/16" tube, so it doesn't matter if the CF rod is oval, square, triangular, or whatever.



EDIT: 2MM?? That's huge!! I'm using 0.8mm (1/32") music wire in the Atlas and the same size CF in this project.

[NativePaul]

Ahh I see, I thought you were just doing that at the strut. Sleeving up the stuffing tube makes sence from a rotational point of view, having a straight stuffing tube means you get very little adjustment at the prop, but anything is better than nothing.

I know 2mm is huge, I normaly use 2mm for Hydro2's with 50x the power, and 1.2mm for Minis with 4x the power, but without a lathe to make my own stub ends, or tube available locally I may have to resort to it.

[Dr. Jet]

Ahh I see, I thought you were just doing that at the strut. Sleeving up the stuffing tube makes sence from a rotational point of view, having a straight stuffing tube means you get very little adjustment at the prop, but anything is better than nothing.

I know 2mm is huge, I normaly use 2mm for Hydro2's with 50x the power, and 1.2mm for Minis with 4x the power, but without a lathe to make my own stub ends, or tube available locally I may have to resort to it.

Send me a PM. I have a TON of 1/16" SS tube and plenty of 1/32 music wire. I can send you some in a normal envelope. You're on you own for the rest of it, but I think you are a resourceful kind of chap.

[NativePaul]

Thank you, but I doubt the postal services ability to transport it intercontinental and it remaining usably straight. Heck I doubt the ability to get 300 miles from my old LHS to me without bending it, or I would have phoned my order in to them rather than bothering to try my crappy new LHS.

[Dr. Jet]

Finally! Some Progress!!

Well, last night was the Super Blue Blood Moon. Happens once every 87 years or so. My astrological sign is ruled by the moon and today, everything lined up. I finally had everything to make a new coupler, and now it runs true and smooth. Now, I can get on with the business of getting this little thing going again.

Here's the final version of the coupler:

[Dr. Jet]

Carbon Fiber Rod Drive Completed

Here it is: The 0.080" carbon fiber rod drive. Now, I have to figure out a way of affixing the propeller to it.

[fweasel]

Wow, so cool, and tiny!

[Dr. Jet]

Wow, so cool, and tiny!

I still don't know if it will work. It could be a lot of effort for naught.......

[Dr. Jet]

Going Boldly.......

Well, I've mounted the propeller. I made a brass sleeve with a very slight taper such that it takes a LOT of effort to push the prop on all the way. The first half is an easy slip fit, but the last half requires gripping the shaft with some (smooth jaw) pliers to twist the prop all the way home. As a safety measure, I'll put a small piece of fuel line tubing on the stub behind the prop.

[Jerryemartin1958]

Is there an assortment of props available!