Please take a look at my flex shaft alignment

[xlandguy]

Here is a picture. I don't know if this is the best angle to see from, but anyway, does this look good? When it comes to FE's I have the combined knowledge of 2 barge barnacles. I slightly enlarged the motor mount holes so I could move the motor down slightly and it does line up better. I do have a support bracket on backorder that supports the tube between motor and where tube goes into the hull.
shaft_21.jpg

[Darin Jordan]

Sure... it's always a good idea to have the flex exiting as cleanly as possible. Less friction and drag, and less chance of a "hot spot" forming... If you have the adjustment, get her centered.

That being said... what you have there doesn't look like it would be a problem.

One suggestion, if I may... Get a piece of silicone water line that has an ID that is JUST at the same OD as the flex cable (.150")... I think it's 5/32 ID Dubro tubing or similar, and use a piece about 3/4 to 1" long, slide it over the stuffing tube and down far enough to where there is just a small amount of it overhanging and contacting the flex cable. About 1/4" or so. When you grease the cable, it'll grease the inside of the silicone tubing as well, and this will help to 1) Keep the teflon from climbing up the flex cable, and 2), act as a water seal to help keep the cable from drawing water up into the boat.

[xlandguy]

Thanks, I will do that as soon as I get a piece of that tubing. Maybe in some miracle, my local LHS might have some. Thanks again for sharing this "inside tip"

[Fluid]

It is tough to get perfect shaft/motor aligment from an RTR, you've done well from looking at the photo. Another thing you can try is to bend the stuffing tube up a bit and reposition the motor - you can even bend the mount a bit. What I try for in every one of my builds - and I usually get it - is to align the stuffing tube and motor so that as you stick the flex cable through the stuffing tube it will go straight into the coupler without having to push it to one side with your fingers. I usually have a lot less exposed flex cable too - while yours looks okay, if the gap is too long the cable can actually tie itself into a knot. Some don't believe this, but it happens.



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[dana]

Looks pretty good. You might loosen the screws that hold the mount to the hull and see if you can adjust the angle a tad

[JIM MARCUM]

Barge barnicles must be much more knowledgable than I remember from my marine biology class. Your setup is OK, but looks slightly out of alignment in the vertical axis (motor tilted slightly down too much).

Here's a few basic tips when aligning a stuffing tube, assuming a stuffing tube support bracket is installed. If the support bracket can be removed or is yet to be installed as in your case, jump to #4.

1. Keep the length of the flex shaft exposed between the stuffing tube & collet short to help prevent "cable "whip". 1/4"-3/8" is fine.

2. Horizontal alignment. With the motor mounted just tight enough to move it around slightly & the flex drive chucked up in the collet, everything should be as straight as possible from the motor shaft to where the flex shaft enters the stuffing tube. The flex shaft should look straight from above, and the gap between the shaft & stuffing tube sides equal. If not, adjust the motor mount until it does. Then tighten down the motor mount screws.

3. Vertical alignment. three ways to do this.
a. Most motor mounts have adjustment screws to move the rear of the motor up-down. Looking from the side, the drive should be straight and the gap between the flex shaft & stuffing tube top & bottom should be equal. Adjust the motor up/down to adjust the gap.
b. If the stuffing tube support is removable, or has at least 1 1/2" of tubing exposed ahead of the support, bend the stuffing tube gently until it's aligned. DON'T KINK IT!
c. If there isn't enough stuffing tube exposed past the support bracket to bend it, use Stainless Steel or aluminum washers under the motor mount to shim up the motor until it aligns with the stuffing tube.

4. If the stuffing tube support bracket can be removed, or a new one is available, alignment is easier.
a. With out the flex shaft support installed, mount a straight piece of brass tubing the same OD as your flex drive, long enough to fit into both the collet, & slip into the the stuffing tube about 1".
b. Slip the smaller tube into the stuffing tube far enough to have 1/4"-1/2" clearance at the collet end.
c. From the collet end gap, slip the stuffing tube support bracket over the tube.
d. Slide the smaller tube into the collet, leaving the other end inside the stuffing tube.
e. Move the support bracket around until the smaller tube is in line with the stuffing tube, and the gap between the tubes equal. Slight bending of the stuffing tube may be required.
f. With everything aligned, holding the supprot bracket in place by hand, put a few drops of CA glue along the bottom of to tack it onto the hull. After it sets up, clean the hull aroung the bracket with alchol or acetone & let it dry.
g. Finish installing the support bracket to the hull by epoxing 1" wide of strips of flexable tape - or strips of fiberglass cloth - along the support base.

I'm sure there are other ways to do this, and some may suit you better. The methods above are easier than it may look. That's how I do it. JIM

PS: If your flex drive can be removed from the prop shaft end, it's a good idea to put a small lock ring on the flex shaft between the collet & stuffing tube to prevent loosing the shaft & prop if the flex drive comes loose of fails.

[xlandguy]

Wow, that's alot of good advice here. thank you so much. I do have the adjustable tube bracket coming from Kintec Racing. I will wait untill I get that before I decide if I need to bend or further modify. I ran a couple of packs just a minute ago and it seemed pretty good. Boy, I never knew how handy the lake across the road is. I load up my gorilla cart behind my vintage pulling tractor and head to the lake, takes 2minutes from here to in the water. More running this evening, but might go rock crawling with my Summit instead. Gotta make a trailer too for the Summit to pull the MC, that will look nice.

[Bryan73]

if the gap is too long the cable can actually tie itself into a knot. Some don't believe this, but it happens..

For this to happen, wouldn't the flex shaft have to either stretch a good bit or break first, or the strut or motor mount completely break off?

there doesn't seem to be enough slack in the flex cable even without a stuffing tube to bind up enough to knot up without something breaking or stretching first

when I first got into electric boats 20 years ago, I ran a 20" cat with a trinity monster marine water cooled motor (12 cells , 14.4v) direct drive with a 1/8" flex shaft and no stuffing tube (only the teflon tube) from the motor coupler to the strut .. that motor was at 35k no load rpm and ran with an octura x435 prop .. many many runs on that boat and never had any problems with the flex shaft knotting up.

I mean no disrespect in any way, based on my limited experience, it logically makes no sense that a flex shaft would knot up from having a brass stuffing tube too short .. not saying it cannot happen because anything is possible