What or who's drive dog do you use ??

Is one better than others? Why?

Single screw ? Stainless ? Thin? Thick ?

6 to one half dozen to another.
Twin screw seem like a good choice, if you only use one of the grub screws at a time.
May get more use from them, one thing I have noticed is the use of dis-similar metals which was always a big no no in the aviation industry as they cause corrosion resulting in the two pieces welding themselves together.
I have even made my own drive dog but cut down and slotted a stainless screw for a grub screw, it still hasnt siezed yet.

Only 2 screw aluminium type available at my hobby shop. Have changed the hex head screws for stainless.

Quite a neat fit. Use both screws together.

David

Use stainless steel with 2 set screws. Brass looks pretty, but under heavy loads it is possible to shear the tabs off.

I use the stainless steel with single screw from Prestwich Model Boats with no issues.

One thing I like to do is ensure that the retaining screw is flush with the drive dog to minimise unwanted turbulence or drag.

Craig

I like to use blue thread lock. When I need to remover the lock nut.I heat over the stove for 15-20 seconds.unscrews great.

I use blue too (on most things in my boats) and use small butane torch to release it -- I just use a touch for few secs and comes off easy

Don't take this wrong but just can't agree on simple loc-tite on screw holding dog to shaft

Not stated, but shaft should have a FLAT filed in so set screw has an edge to snag upon preventing spin out and preventing dog from getting pushed up shaft as prop retention nut is tightened

In 35+ years of model boating had plenty of drive dogs Spin, Break / Split, Tear ears off, Slide up etc ...
** ONLY way I found to have a near bullet proof drive to prop is by doing the followings things:
#1) Try and use Steel Dogs that have set screw 90* to drive ears
#2) Use an @ 1/8" wide file and make an ample flat in shaft being @ 1/8" wide and just wide enough front/back for the set screw to fit between bottoming out within the flat.
#3) Use a black iron STEEL set screw, Not SS ( Too soft IMO )

** Then the single most important is adding a small daub of JB weld into the empty set screw hole prior to putting in the set screw. When screw is tightened the JB weld is forced in and around the shaft/dogs clearance and fills the gap between set screw and shaft. Once screwed down TIGHT ( Steel set screw ) wipe the oozed JB weld off from around dog.
If set screw is a tad high / take it to the belt sander flushing it up.

This may seem extreme, but end result is a better balanced assembly, a dog that won't move by tightening up nut, won't break loose under use.

*** For some reason you get a dog fracture / failure take a torch heating up the shaft and dog, remove set screw, place shaft loosely in a vice having dog on top of jaws and lightly tap the two apart.


JMO ...
Scott

Hi Scott.

You wrote: "Not stated, but shaft should have a FLAT filed in so set screw has an edge to snag upon (...)".
Is it possible to file a flat side on a flexi-drive without destroing the small threads in the flexi-drive? Or am I misunderstanding something?
(Please remember that I'm danish, and help me out here)

Cheers!

Woodie.

I file a flat on shaft just like Scott says and I use blue loctite on (black steel) set screw on stainless dog - but I've never tried the JB Weld thing

I have good luck but am just starting to wonder because I have a few new engines that make more power than anything I have had before. Two of them 'hit hard' (rev faster/higher) at higher rpm - then anything I have ran.

I hear lots of stories lately about the 520 rippin up dogs

---

so just wondering if I have just been lucky or what??

Thanks Scott