Repairing prop and shaft

[Marire]

Hey everyone,

We have a problem with our prop slipping on the shaft. Unfortunately, we have a variable pitch prop made by Hundested. In order to repair the taper and keyway which we imagine is at fault, we need to break the shaft and replace it, as it has corroded and siezed into the variable pitch control box.

My question is- to avoid all this, would it be possible to fix the prop to the shaft by another means? We have tried drilling, tapping and fixing 3 grub screws around the hub to the shaft, but these sheared almost immediately.
I am happy to lose the variable pitch on the prop, and fix it in the drive position, as our alternative is to replace the prop with a standard fixed prop, but this also means a new shaft.

This is all a bit too expensive for us right now.

Someone has mentioned welding the prop (bronze) to the shaft (stainless steel). Or just welding the prop so it is no longer variable pitch.

Does anyone have any suggestions as to how we could;
A) fix the prop to the shaft
B) fix the props pitch

If it's a terrible idea, then we will just wait and save up, but we really miss sailing.

Many thanks in advance,
James

 

[Mrnotming]

I have not come across this brand of variable pitch propellor.
However, it would always be a best solution to completely dismantle everything (with the aid of a knowledgable engineer if necessary) and re-machine/rebuild to the origina specs.
Anything else is a bodge and will not really inspire confidence at sea.
Not probably what you want to hear?
A few photos posted here will help those more versed in engineering than myself to offer more advice.

 

[Lon nan Gruagach]

Hundested do spare parts for all their products http://www.hundestedpropeller.dk/service/. So worst case would be dismantle prop as far as possible then cut off the last bit, you save the shaft and most of the prop.
Although, once it is dismantled you should consider taking it to a machine shop where they might be able to press out the shaft (with plenty of heat on the bit of prop that is still stuck).
Have you tried a few kettles of boiling water on the prop only (not shaft), it can work wonders.

 

[vyv_cox]

Very difficult for me to picture the arrangement, as said, photos would help. What has corroded and seized to what? If bronze against stainless steel I cannot imagine it being so solid that it cannot be separated. If the prop is slipping on the shaft presumably the two are not seized together, can they not be separated?

The best 'weld' you could manage is a fillet braze, which is not very strong and likely to fail.

 

[Neil_Y]

Have a look at these, they show breakdown of hundested props and pitch control. We did rope cutters for a Hundested a while back, nice props.
https://www.youtube.com/watch?v=oVnfLuh6lm0#t=89
https://www.youtube.com/watch?v=7HpcAO5zR2U
I'd get the shaft to a machine shop and re cut the keyway for a larger key and possibly re cut the taper if it's damaged.

 

[Neil_Y]

All from a useful site for this drive set up.
http://svseeker.com/controllable_pitch_propeller.htm

 

[Marire]

Thank you very much for all of the great replies and suggestions!! Here are some photos, I'm not sure why but they've all been rotated, hope I don't crick any necks!

This is the prop with hub removed to show adjusting mechanism

This is the variable pitch control unit where the shaft is siezed into the block

Here's the complete prop

And this is to show the variable pitch control unit box


Once again, thanks heaps for all of your help!

 

[Birdseye]

If the shaft is stainless and the control box is bronze then all that is needed to seperate them is the application of heat since the bronze will expand faster than the stainless. So remove the two together and use a propane torch to heat up the box.