Nobody has mentioned ZippKits' "Super Collet". Joe P. introduced this
product just last year and I think round collet fans agree that it
has more grip. Perhaps a similar (extra length) round collet is available
from other sources? I don't know.

zippkits.com/~zippkits/index.p...products_id=368

Note: The link above is broken. At the ZippKits site look in the
"Engine Accessories" for the Super Collet.

One thread at JRCBD which has lots of info on square drive flex shafts is:
"making square end on flex shaft".

Sounds like you've got the sweet spot dialed in for your set up, Craig!

Me, I can't get issues of thrust on engine & stuff tube out of my mind...
so am leaning towards square drive. What the heck!

Checked out info @ rcboat.com/sqdrv.htm
and www.modelpowerboat.com/content...a-RC-Model-Boat

Then read Captain Seebolds reply above, which kind of focused my concerns,
(Thank you, Steve!), and I think I'm ready to try to apply heat and solder to ferrel and flex cable.
Wish me solder luck, Craig... I think I'll need it! Let's see now, if it let's go
nothing at bottom of lake, but, I'll be left with maybe fuzzy thrust?

When you solder your ferrule, be careful not to get it too hot.

Hi Gerry
Firstly Good Luck with your project.
The links you mentioned are very helpful I think.
As Steve said don’t over heat the joint to be silver soldered. If you are new to silver soldering I would recommend doing a test job on two bits of spare stock to get the measure of what is required.

Most of all it is critical to ensure that the components to be joined are totally clean and free of any residues (especially grease/oil) etc.

Any neglect in this respect makes it very difficult to get the solder to run into the joint no matter how much heat is applied. And with too much heat you risk making the components brittle and prone to breaking.

Do let us know how you get on as I hope to hear a success story here in due course!
Cheers
Craig

Just tried out my Zipp collet today on my mono and they work great. Think I am going to put em on all my boats!!