Prop shaft taper angle?

--Trying to machine a taper to match the i.d. of a marine propeller
(12" dia, 21" pitch, 3 blade). Is there anything like an industry standard;
i.e. inches per foot?
--TIA,
Reply to
steamer
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I would measure the bore first.
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Kevin Gallimore
Reply to
axolotl
My recollection is it's 3/4 inch per foot = 1:16.
Googling - propellor taper 1:16 - turned up this page...
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Ned Simmons
Reply to
Ned Simmons
If you can fit the prop in the lathe, use an test indicator to align the compound with its taper. That's the best way to match tapers.
Fred
Reply to
ff
You will find that the prop shaft is most likely .750 inch per foot taper. However, check it first. I used to make prop shafts on a regular basis. Most were .75:12 but every now and then I'd get a different taper. ERS
Reply to
Eric R Snow
========== IIRC The Machinery's handbook has a procedure that uses two different sizes of ball bearings [one to fit at the top and the other to fit at the bottom of the taper] and a depth mike. This assumes the bore is in reasonable condition, and that you have a good square surface [to the bore] on at least one side of the prop.
Unka George (George McDuffee) ..................................................................... The arbitrary rule of a just and enlightened prince is always bad. His virtues are the most dangerous and the surest form of seduction: they lull a people imperceptibly into the habit of loving, respecting, and serving his successor, whoever that successor may be, no matter how wicked or stupid.
Denis Diderot (1713-84), French philosopher. Refutation of Helvétius (written 1773-76; first published 1875; repr. in Selected Writings, ed. by Lester G. Crocker, 1966).
Reply to
F. George McDuffee
--Thanks gang; worked it out with a really simple formula I found after a little googling: C/(A-B) where C is the length front to back of the hub, A is the large i.d. and B is the small i.d. I got a nice, clean number: 16 so I plan to put a dial indicator on the compound slide, mount a test bar and turn the compound until I get a change of 1/2 of 1/16 over a distance of one inch; i.e. equivalent to the taper of one side. Then I can lock the saddle and crank the compound to get the taper for the bushing I'm making.
Reply to
steamer
You will still want to use bluing to check the fit. It's pretty tough to get tapers set correctly without some final tweaking.
steamer wrote:
Reply to
RoyJ
--Gotcha; good idea. Thanks! :-)
Reply to
steamer
We've done that to make adapters to fit snowmobile engine shafts. Set it up, bore out the taper, do the blueing, never seem to get it quite right the first time. Only off a couple thousandths but that is enough to get wobble at high speeds
steamer wrote:
Reply to
RoyJ

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