"Lapping" for new prop

It's super common place to see props loose on the shaft. When customers boats used to come in the first thing I would do is to grab the prop to see if it was loose or the shaft didn't spin easily.

More common on castle nuts than nylock (I have always ran a Nylock) mine is always right on the shaft other then when my dumb ass bounces it off the bottom of the lake.

I've had a few slide right off too. That's not to say it wasn't installed well enough. Did you have any vibration issues before?

I think some late strong reverse while loading could loosen it up on the taper, purely speculation though. In summer they seem to be tighter than in cold weather. Again, probably not enough of a sample size to hold water but I've had good running smooth props come off w/o the need of a puller before...

Only 1 prop really fought me for more than 2 minutes and it was severely damaged.

I'd venture a guess most people here don't lap at all, let a lone spot check. I wouldn't waste an hour of my day to get the prussian blue.

IAughtNaut wrote: DrCC wrote: Yeah,    I would not want a pinned key.    I would assume they drill all the way thru the shaft so you can remove the pin, thus making an un-necessary weak point. unless I'm not following this correctly (which is very possible) the pin is part of the key. they sell them with or without, depending on which kind of shaft you have. because of this, only about 1/8 inch needs to be drilled into the shaft in the keyway. I'm no engineer but I wouldn't think that small hole would introduce much weakness at all.

I agree that any added weakness is minimal and not a concern. The hole doesn't need to go all the way through the shaft.

now, you can put the key in backwards and line up the pin with the key in the wrong spot, but if memory serves, if you do that you can't get the prop over it so it becomes obvious quickly

How well does the permanent marker work compared to the high spot blue? Could save me an hr of driving.

shierh wrote: there is absolutely no need to pin the key

Why not? Since many have an issue with the key riding up on the shallow portion of the keyway it sure would help them. You don't feel the simple addition is helpful?

My regular shaft with press coupling has a pinned key AND is spoon cut. I never saw a 1" shaft spoon cut before but the machinist is a friend and went a little overboard.

just when you had pinned keys all figured out too...

General Propeller did the roll pin key thing on my double taper, non ARE shaft from them last year... I also though it was slick It goes in the key and there is a hole in the slot on the shaft so that the key stays in its place on the shaft.

That's Alan A's roll pin.   I'm not sure I like the idea of a pinned key.   I like my keys to slide in the prop and in the shaft keyway.

lapping prop and key ride are 2 different issues.
lapping is simply honing the hub to the shaft using valve grinding compound after this you put prop on shaft with nut but NO key. mark how far down the shaft the prop sits then take off and install with key. if it doesnt hit the mark you made then its riding the key. Hone the key down until the hub no longer rides it.
Remember the Key is only for alignment, the taper holds the prop in place, better lap job the better it holds.

now it sounds like you're talking about a point, not an edge

Why not just put the key in the shaft keyway before sliding the prop on? Having a burr on the prop face would be perfect for preventing the key from sliding all the way through the prop. Or am I missing something?

still not sure what inner means. the edges riding along the shaft?
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or the edges against the nut
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Hollywood wrote: i'm a little confused on what you mean al

Removal of burrs from broaching the keyway at it's two intersections to the tapered bore and face of the hub.