Help me build my new driveshaft

[MassiveOverkill]

Here is the tubing I have:



The top tube is the stock stainless stuffing tube

The next stainless tube specs has the sticker below it. It's the exact same diameter of the Octora prop shaft, and the flex shaft fits inside tight enough to use this shaft as end stock or even to make replacement prop shafts. It could even be used as a straight shaft it inside the brass tube, but it creates too much friction. It probably won't be used.

The Octora .130 flexshaft is next

We then have brass tube below the flex shaft with it's sticker specs below it. It fits perfectly inside the last brass tube on the bottom and is the same diameter as the Octora prop shaft. It has a larger inner diameter than the new steel tube and will probably be used to replace my teflon liner and to beef up the main brass tube as well as help reduce wobble.

Then you have the teflon tube, which does fit perfectly inside the largest brass tube which I don't want to use (the teflon liner that is)

Here it is put together:



You think this will work?

The Octora end dry spins very freely in the large brass tube. Brass is self lubricating and although I would lubricate it with grease, the tight tolerance should minimize water migration. I am worried about metal expansion of the metal prop shaft vs the brass tube and figure you veterans can tell me if that would be an issue with heat.

The teflon liner has too much slack, but it would be perfectly straight if used inside the large brass tube. I'd rather not use it at all and just use the brass but do you think the flexshaft could rub through?

I hope it's clear enough of what I'm trying to do. Thanks for any tips.

Here's a shot of how much clearance I have:

[MassiveOverkill]

Anyone?

[Remmie81]

Hmm, am I correct that you want to have the propshaft directly into the brasstube?

[MassiveOverkill]

Yes, but the original teflon tube fits inside as well, so it either small brass tube inside of larger brass tube or teflon tube inside of larger brass tube. I like the first setup better because there's less play in the flex shaft. There's no bend in the stuffing tube, it's straight, just like the original, and you only need flex at the tip mating with the motor.

The prop shaft (not flex part) will always be in brass. Now it's a matter of deciding if the flex part itself is in brass or teflon tube.

[Remmie81]

I would go with the teflon liner. But I use always teflon liner.
If it for some reason should worn out, its an easy replacement.

You said in your first post:
-I am worried about metal expansion of the metal prop shaft vs the brass tube an figure you veterans can tell me if that would be an issue with heat.

I dont think the metal will expand, the only thing i would wonder is if the propshaft would not start to vibrate because of the tolerance in the tube.

if you could make a tube that you supply with slide bearings to hold youre propshaft (will minimize heat and wear)
and then on the otherside you slip your brasstube in then you have everything covered i think.

[MassiveOverkill]

Thanks Remmie. The new setup has tighter tolerance than the stock one, so vibration should be less than stock. The stock setup relied on the prop shaft being inside a piece of teflon tube that was then loosely inside the stock steel stuffing tube. The whole setup was loose-fitting and had much more wobble.

The end goal is to get a PVC T-junction and drill a hole in the brass tube about 1/3 the length from the prop and use a grease fitting at the end of the T.

[martin]

I take it thats a 4mm stub & .130" flex, you can run the stub direct in the 3/16" O/D brass tube ok ( this is exactly what Zippkits do on the JAE Mini Sprint riggers. You also want the 3/16" O/D brass tube for the .130" flex to run in when no teflon is used, if you use the next size tube down its to close to the flex (flexes expand when they wind up & shorten in length). Go up to 7/32" tube & the flex rattles around & whips inside the tube. Martin.

[martin]

By the way flexes work better in a curved tube than a straight tube as the curve in the flex & tube stabalizes the flex from whipping around inside the tube.

[MassiveOverkill]

Thanks Martin. Unfortunately, I didn't think about buying some solid stock to just create a straight shaft with a small flex bit at the end. I was still in the mindset of placing a smaller tube snugly around the flex to convert it to straight, but there wasn't tubing small enough to snugly fit around the flexshaft and still fit inside the larger stuffing tube.

It is the 4mm stub for 2mm shafts: http://www.offshoreelectrics.com/pro...od=oct-oc64pkg

I have my stickers mixed up in the photo, the last two should be flip-flopped. The 3/16" is acting as a liner for the flex inside of my 7/32" stuffing tube. The Octura stub fits snugly inside the 7/32" stuffing tube. Sorry for the confusion

[martin]

If your stub fits in a 7/32" O/D then the stub is 3/16" & not 4mm, the one you show from OSE store is a 3/16" stub.

[MassiveOverkill]

Sorry, the one I linked is the one I got. I hate having to bounce back and forth between metric and US.

[MassiveOverkill]

I take it thats a 4mm stub & .130" flex, you can run the stub direct in the 3/16" O/D brass tube ok ( this is exactly what Zippkits do on the JAE Mini Sprint riggers. You also want the 3/16" O/D brass tube for the .130" flex to run in when no teflon is used, if you use the next size tube down its to close to the flex (flexes expand when they wind up & shorten in length). Go up to 7/32" tube & the flex rattles around & whips inside the tube. Martin.

Just to be sure. My main stuffing tube is 7/32" so the stub will fit inside. I have a shorter 3/16" inside of that to for the .130 flex with no teflon liner. I'll take pictures tonight.

[MassiveOverkill]

Pictures as promised:

Old flex top, new Octura bottom:



New stuffing tube:



Motor End:

[martin]

Looks good on size of tubes, dont leave to much gap between the coupling & stuffing tube so as to reduce unsupported flex moving around. Also to stop water getting up the stuffing tube put a piece of silicon water tubing on the motor end of the stuffing tube, the silicon tube I/D needs to be around the flex diameter so its not tight on the flex.

[martin]

Something you wont know untill you run the boat is with the original curved stuffing tube is the idea of the curve is to get the prop drive line parallel with the bottom of the hull. By using a staight stuffing tube the prop drive line is angled down which will hold the bow down.