Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[dave parker]

hi all


I am struggling with understanding how to set up my prop shaft and associated parts, before permanently mounting them.


Pics below show where I am.


What can you see is wrong? Anything?










Now. I have the shaft next striped down showing one end has more threads than the other.
I assume the shorter end is for the propeller?














When the propeller  is fully tightened up there are still threads showing so I assume I need to trim some off?


I didn’t realise that the shaft wasn’t fully threaded and so if I get one end wrong the other end won’t tighten anymore!?!


I know you need a slight bit of play between the shaft and the housing but that means that both ends are more or less fully tightened. Is this right?


How do I do it 

[Colin Bishop]

Check this out:

https://www.modelboats.co.uk/news/article/drivelines/27166

You might possibly have to cut a bit of thread off but think carefully before doing so.

Colin

[CGAux26]

A few comments:
-In your second picture the nut on the prop end is meant to be a jam nut against the prop.  Tighten the prop on its threads, then run the nut up against it and tighten it very tight with a wrench.  Very embarrassing if the prop backs off in the middle of the pond.   


-Most of us seem to use a lock collar, held in place by a set screw on the motor end of the shaft, without a nut.  You set up the axial float of the shaft after the prop and its jam nut are tight.  Use nylon washers where your pictures show brass (they transmit the prop thrust to the stuffing tube in forward and reverse).  Push the shaft all the way in and move the lock collar away from the motor until there is no more than 1/32" axial float.  Then lock the set screw.


-Motor to shaft alignment must be as near perfect as possible.  Yeah, we all use flexible couplings.  But the more mislalignment there is, the more vibration, noise and wear results.  When moving the motor up/down and left/right, keep checking the alignment visually from the top and side.  No visible angle is allowed.


-At each step of shaft installation and alignment, turn the shaft by hand.  No resistance should be felt.

[dave parker]

Thank you


With regards to you first comment I thought that was the case but if I tighten the nut back up to the propeller, and then move the tube up to the nut and washer, there isn’t enough thread on the other end to tighten the other nut.


Is this where you are saying to use a collar tightened to the unthreaded part of the shatft???


Cutting the thread down in the propeller end will help but still not enough for the other end to work???

[grendel]

add an extra nut?
 I have a section of exposed shaft on mine so have a much shorter shaft tube, so I have a collar and washer bearing on the outer end of the tube.

[grendel]

I also fine tune my motor position with the motor running and an ammeter in circuit, tweaking the mount position on adjusting screws until the current draw and noise is least.

[dave parker]

Have you (or anyone else) got any pics?


Much easier to understand sometimes

[grendel]

this is my exposed prop shaft, note the collar where it bears on the end of the tube

[grendel]

a couple of videos, its here I have to explain that my internal arrangement is somewhat unconventional, using a model car cv joint at the end of the shaft between the shaft and motor, this has allowed me not to have the motor as well aligned, but I do now have a brace for the cv assembly that i have fine adjustment on.
https://www.youtube.com/watch?v=1hWhTA0WdkE
https://www.youtube.com/watch?v=cA_ZzmIIQjA
https://www.youtube.com/watch?v=BBK8FR4ruKQ

[dave parker]

Ah ok I see, I think


All of your shaft outside the hull has no tube at all
There must be a small tube inside with bearings either end, then the washers and collar on outside to take the strain when running?

[SailorGreg]

Dave, you don't need both nuts to be up against the tube.  What you do need is a locking collar, as suggested in another of your threads.  Many prop shafts have no thread at the inboard end at all, so rely on a collar to take the thrust in reverse.  The inboard nut should be used to lock against the brass insert for the universal joint.  Also, in many applications there will be a little bit of shaft outside the tube inside the boat before the universal joint - it is not mandatory to have everything butting up to everything else.  And you do need to shorten the thread at the prop end so that the nut is hard up against the prop but there is only plain shaft running in the bearing.

Good luck, you'll get there soon!

(And just a suggestion - if you keep starting a new thread for every little wrinkle, you (and us) will soon lose track of what is advised.  Try to keep a single "My Springer Problems" thread going.)


Greg

[grendel]

yes the shaft is about 12" long and the tube that passes through the hull about 6" as it passes up through the keel. as you see there is a support on the shaft just before the prop, and the collar is tight up against the end of the shaft where it goes into the keel, there is another collar on the other end of the shaft, and then about 2 " unsupported until it goes into the bearing block where it mates to the cv joint.

[dave parker]

Excellent Greg thanks


And point taken!

[dave parker]

Thanks Grendel


 

[SailorGreg]

If it helps, here are the two ends of the prop shaft from a boat I am building at the moment.  At the outboard end, you have (left to right) propeller, lock nut, washer and then the bearing in the end of the tube. 




Inside the boat, (left to right) the bearing in the tube, washer, locking collar, short space with nothing then the brass insert for the UJ.  The inboard end of this shaft is not threaded, the insert is locked in place with a grub screw, as is the locking collar.



The only real difference with yours is that there will be a nut snugged up against the brass insert in the UJ.  Note that the motor is aligned with the prop shaft as well as I can make it, the wood mounting plate under the motor is tweaked repeatedly until it holds the motor at the right angle.


Greg

[dave parker]

Greg that is fantastic!
Many ha is
I was nearly there
Collar on order!
I can get my tube fixed in now!!!

[RST]

I don't think you should get confused with needing collars etc. From the pic you posted (same shafts I always use) you don't need a collar with grub screw for a plain shaft end if both ends are threaded!

[RST]

Also, one trick for setting alignment is to connect a 1.5v dry cell to your motor and "feel" for resistance as glue sets. Or use a couple of teeny tiny blobs of something like blu tak etc then set with epoxy after.

[SailorGreg]

I don't think you should get confused with needing collars etc. From the pic you posted (same shafts I always use) you don't need a collar with grub screw for a plain shaft end if both ends are threaded!

Dave, RST is correct.  Looking back at the photos of your shaft and tube (should have done that first!  ), the locking nuts are snugged up to the end bearings, so a collar is superfluous.  Just make sure that you leave a smidgeon of play in the shaft so it doesn't bind, and that the prop and the brass insert are tightened hard against the nuts at their respective ends.  Don't worry if you have ordered a collar - assuming this won't be your last boat, the time will come when you need it!

Greg

[unbuiltnautilus]

There is enough depth available inside your universal coupling to accommodate the longer threaded end of the propshaft, if you don't wish to cut it down. Just turn it around so the shorter thread is at the propeller end of the boat!