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Propeller taper
Posted: Sat Jan 07, 2012 4:51 am
by johnp
On 1 1/4" propeller bore the taper goes down to 1" is it correct that it's a 2 degree taper?
Re: Propeller taper
Posted: Sat Jan 07, 2012 5:20 am
by farmerden
I have been looking for the perfect propeller and have yet to find it at a price I want to pay
But what I have noticed is the different lengths of the hubs -3.5 in to 4.75 in .The accepted taper for shafts up 5.5in. is 1 in 16 or 3/4in to the 1ft. The small hole will always be approx. 1in to allow props of different hub sizes to seat at the small end in the same position to allow the nut to have enough room to be threaded on.Is that what you were looking for or did I ramble?
Den
Re: Propeller taper
Posted: Sat Jan 07, 2012 11:05 am
by Lopez Mike
Whooo, boy. I have fought this to a standstill so many times. First, read this:
http://www.propellerpages.com/?c=tech_info&f=tapers
So now you know enough to be dangerous!!
The reality is that it is impossible to set either a lathe compound or a taper attachment to a correct taper using the scales on them. The fit is far, far to sensitive to teeny changes in the angle. You have to set up your lathe by trial and error using a piece of scrap shafting. This involves rough setting with a dial indicator and then getting it just right with test cuts.
I can post or email more specific instruction if needed. I do this more often than I care to think about. When possible, I have the customer buy a ready made shaft. Actually cheaper than I can do it.
But sometimes I need to put a big prop on a small shaft and then I end up making a tapered split sleeve.
What is really weird is that the key is not doing a thing if the prop nut is tight and the key damages everything if the nut comes loose and the prop moves. Keyways are a really weak spline. If the nut was torqued down properly, you could then take the nut off and the prop would never come loose. I wish I had a buck for each time I have chased the customer away so that I could use my REALLY big maul to get their prop loose. And I have a good puller. A 3/4" to the foot taper after being seated properly will allow you to lift up the boat by the prop without coming off.
Hmm. Way more information than you asked for. Sorry.
Mike