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captain58sailin · 01-06-2013, 19:21

+1 For lapping the taper, the more surface contact the better. Take your time to get a good fit and it will save you more problems later.

sww914 · 01-06-2013, 19:52

Quote:

Originally Posted by Chas Erwin

I always wonder how does FastBottoms do a well lapped propeller install?

Charles

Underwater!

Sorry, I couldn't resist.

bobconnie · 01-06-2013, 20:04

I don't care how well ya lap em ! 99% 100% they still need a keyway ! I don't much care who you are thats a fact !! You show me a prop installed without a key that will not slip under power sooner or later and I will gladly change my opinion! Ive been doing these type if machine jobs for over 50 yrs and I can't ever remember one ive done that did not work properly ! Thats my 2 cents

model 10 · 01-06-2013, 20:24

Well, what does that say, your work needs a key? Let's give you the benifit of doubt and say you should really have a key if you want your job to last for many years without any attention or it's a boat and it's bound to fall apart so you need a key.

NoTies · 01-06-2013, 20:25

If the extremely small surface area of one side of a key was transmitting the drive then we could all reduce the size of our prop shafts to have the same power transmission characteristics as the key.
Just my 2 cents worth, I'm not a machinist but am a marine and mechanical engineer.

fstbttms · 01-06-2013, 20:31

Quote:

Originally Posted by Guy

Well, I've heard white lead should put on the shaft to make it so you could remove it someday. After all you do have a Key. Ask fastbottom about removing stuck props underwater.

The tolerance between prop bore and shaft taper are tight enough that adding any lubricant to ease future removal may, in fact, cause the prop to not seat properly.

You don't want the prop to come off easily. That's why God invented the prop puller.

model 10 · 01-06-2013, 21:15

No that is not true. White Lead is not a lube but a anti-seize compound that prevents a metal to metal seizing.

fstbttms · 01-06-2013, 21:25

Quote:

Originally Posted by Guy

No that is not true. White Lead is not a lube but a anti-seize compound that prevents a metal to metal seizing.

Umm... sorry, but yes, it is true. Whatever its purpose, you don't want anything between the mating surfaces. The prop is not supposed to come off easily. That's the whole point.

model 10 · 01-06-2013, 21:45

I suppose if you had only 75% contact you would be right However we have been talking about 100%. At 100% you would have 0 chance of getting it off because it would pretty much be a metal to metal siezed joint. Hense the key and a loose joint. No one is sayiing it would come off easly if you used anti-seize compound. You would however be able to get it off. Perhaps you have had foggy goggles the last time you removed a prop that had put on using anti-seize compound but it's very thin. We are talking micro thin after everything is torqued up.

NoTies · 01-06-2013, 21:59

The propellor is held in place by friction between the mating surfaces (taper) The friction is maintained by the propellor nut. The key is there primarily to stop any relative movement between the prop & shaft on initial tightening. This movement would cause galling and destroy the properties of the taper. Any antiseize or lubricant introduced between the mating surfaces will decrease the friction properties of the joint and potentially lead to rapid failure. Personally I prepare all tapered couplings after lapping or blueing by wiping with high evaporation solvent such as acetone then drying with a clean rag.

fstbttms · 01-06-2013, 22:10

Quote:

Originally Posted by Guy

Perhaps you have had foggy goggles the last time you removed a prop that had put on using anti-seize compound but it's very thin. We are talking micro thin after everything is torqued up.

Knowledgeable professionals do not put anything on the mating surfaces of the prop and shaft prior to installation. But hey- knock yourself out. It's your prop.

NoTies · 01-06-2013, 22:15

I don't often flex my professional muscles on here but those advocating antiseize on a tapered coupling are seriously misinformed and are giving dangerous advice.