Visit our Popular Forums

delmarrey · 20-11-2006, 18:40

Sorry mates! I screwed up! A morse taper is .625" (5/8") per foot. It's the American pipe thread that is 3/4", like the prop shaft/hub. But still considered a self-holding taper.

I'm gett'n old. Can't remember the numbers anymore. I've been working this off topic gravy job too long. ~~~~~~~~~~~~~~_/(

BBill · 22-11-2006, 16:12

Quote:

Originally Posted by Alan Wheeler

Woooow up. Hang about BBill, we aren't talking about the accuracy of the key. The exact tolerance of the key is not the issue.
It's the shaft/prop taper we are stating MUST BE exact in it's machining. 100% exact. I think you would agree with that. The exact tolerance of the taper and fit between shaft and prop is and has to be spot on. I really don't care what other experts (and I would have to say "so called experts ")if they don't get that fit right, do or say. We have all heard of stories of the "credible" making mince meat of jobs. Speaking as a qualified engineer and I am confident Del will agree with me here, there is no room for era of the angle of that taper. There can be slight era in the diameter which results in the prop sitting at a different point of the shaft, but there can be no era in the taper angle.
Now, as an engineer, I am suggesting that you use gease or any "anti-sieze" very sparingly. Wipe it on and wipe it off. It requires very little to do the job and to much of a flim, I REPEAT, will stop the mating of the prop tpaer onto the shaft taper. If you don't want to believe that, well that's upto you, but this is my suggestion from an engineering point of view.

Wheels,

I think we are speaking the same language but from different sides of the wheel. Since you pulled qualifications out. I think I'm qualified to have an opinion too...Bachelors + mech tech degree, 25yrs in engineering (mechanical & facilities), 3 USCG ratings with MMD card, yada, yada. Officially retired in 2003 and recently took a pt marine supply job just to be active around boats.

I believe someone asked it filing a key as ok and I was commenting on that. The bit about filing the key was to make it fit the keyway. It's done everyday. Keys are cut in the field from common stock and filed to length/taper. If a so called prop expert hasn't done that yet he really doesn't have a lot of experience fitting props. Heck, I'm just a boater and have carried spare key stock in my tool box since my first major project in the early 1960s. Learned how to do it at a prop shop.

One question in the string was what material to use for the key. Technically (if you want to pull out the "engineer" card) is to use a key only to align and use a softer key to prevent possible damage to shaft, coupling, prop, whatever the major part is. However, what we have been seeing work perfectly on boats is same material key. Against the general engineering book but well proven in the applied engineering arena. The prop nut should also be torqued to value but who does that?

For lube on shafts, again, engineering wise...tapered generally not lubed and straight shafts lubed (However, some equipment mfgs spec to lightly lube tapered shafts). Yet you will find lubed tapered boat shafts everywhere that have no problems.

Whatever happens, happens.

Regards,
Bill

fstbttms · 22-11-2006, 17:27

I called my prop shop today (Bay Propeller in Alameda, CA) to ask what they recommend regarding lubrication. They said not to use any lubrication, that metal-to-metal is best. But he cautioned especially against using an "anti-sieze" product, as these typically have a graphite component which can set up a battery situation.

So I learned something new today and will not bother to grease any future props I install.

**Alan Wheeler** · 22-11-2006, 19:09

BBill, sorry mate In wasn't trying a pissing contest with "qualifications. Please don't take it that way, I was just plain meaning I work in that feild and not just a boat owner with a hammer and spanner.

fstbttms, it is possible that anti-sieze has Graphite in it, or there is a Graphite anti-sieze, but the two most common ones I come across are either copper or nickel. Copper is fine on the Bronze prop, but not the SST shaft. Nickel is fine on the SST shaft but not the bronze prop. And yes I know, the SST is against the Bronze prop so what's the diff? I dunno, but I gaurantee it can cause a problem. so I use Lanocote for most anti-sieze applications such as on turnbuckles and bolt threads and stuff.

delmarrey · 22-11-2006, 20:13

Quote:

Originally Posted by fstbttms

I called my prop shop today (Bay Propeller in Alameda, CA) to ask what they recommend regarding lubrication. They said not to use any lubrication, that metal-to-metal is best. But he cautioned especially against using an "anti-sieze" product, as these typically have a graphite component which can set up a battery situation.

So I learned something new today and will not bother to grease any future props I install.

That's good to know about the anti-sieze I had used it on the threads but will remove it now. But is makes sence being metalic and all. It's back to the water proof grease on the threads.

But this is why we hang out here on the Cruisers Forum, we all have something to learn now matter how long we've been around.

..............................................._/)

SkiprJohn · 03-12-2006, 14:38

Aloha Delmarrey et al,
Friday I spent a few hours hand lapping and wrapping sandpaper around the shaft and spinning the Gori prop hub this way and that and it fits better. It definitely was not a good fit before and was not a standard taper because, as I mentioned earlier, the forward end made contact and the aft end wobbled. Now the forward end and center of the hub make contact with the shaft when I put it on hand tight. No more wobble. I assume that when I install the hub I will wipe the interior of the hub clean and the exterior of the shaft clean the only grease that will be left is from my oily rag and fingerprints.
Thanks to all for your input.
Kind Regards,
JohnL

SkiprJohn · 03-12-2006, 14:50

I posted this on the prop fouling thread also. Sorry if you read it twice.
Aloha All,
I took the shaft into a machine shop, had 2 and 3/4 inches lopped off and a new keyway cut. They also gave me a new stainless key. Nice of them. It cost me an extra two days and $55 but it will fit better and bring the prop hub within two inches of the back of the cutlass bearing. Just out of curiosity, is that a comparable price for the job?
I'm on an outer island and there are very few machine shops to choose from. The nearest marine shop is 100 miles away. The one I chose was only 15 miles away.
Kind Regards,
JohnL

delmarrey · 03-12-2006, 15:13

I wonder which was off, the shaft or hub. If you ever replace the prop you may have to go through that again.

Also if you want to get a better job of lapping, one can buy a lapping compound at most industrial hardware's A 60 grit would cut pretty good without too much of a cris-cross pattern.

And from what I've read to date, if you don't have a perfect match, it's advisable to use a little grease to fill the void.

http://www.gpcprop.com/PDF%20Files/aqualoy.pdf See installation instructions.

BTW Lapping will cut the softer of the two metals more then the other. And the other problem with lapping is it may leave a step on the inside of the hub where the shaft stops. This it where a lapping arbor would come in, providing the shaft is correct. Hope I haven't gone over your head too far. As long as you get a snug fit by hand, without the key in place, you should be OK. Of course, putting the key in place in the final installation.

$55 that's about 3/4 of an hour in my shop, good deal!

SkiprJohn · 03-12-2006, 16:09

Thanks Delmarrey,
You didn't go over my head at all. I believe it was the hub that was off because I had a different prop on the shaft before that fit snug. It was a Michigan Wheel so I figured it was pretty well standard. I wasn't sure about the Gori.
I used some 120 grit lapping compound for awhile then 240 grit. The 180 grit wet and dry sandpaper wrapped around the shaft seemed to take off the high spots on the inside of the hub much better and of course the bronze came off quicker. If I used a 60 grit compound I'm certain the job would have been done more quickly.
It is good to know that my machine shop is charging a good rate. Because they have pretty much a monopoly they can charge pretty much whatever they want.
With the Gori prop if the key fails the nut will spin off with the hub and it'll be lost. Installation of the Gori is a little bit different than regular ole props.
Have you ever seen or heard of key failure?
Thanks again,
Kind Regards,
JohnL

**Alan Wheeler** · 03-12-2006, 19:44

So you do not have a locking nut behind the prop??? If you do, then you should be able to put a split pin through it to ensure it can not spin off.

SkiprJohn · 03-12-2006, 21:57

Aloha Wheels,
No the nut fits deep into the hub with no way for a locking nut. There is a set screw on the side of the hub to dimple the nut and lock it into place but that only locks the nut to the hub rotation so if the hub starts to turn the nut will turn with it.
There are threads at the end of the nut that I can screw in a bolt to help jam it in place but that can't be cotter pinned in place either. I can see why some Gori props have been lost if not really carefully installed.
There is a diagram on one of the Gori problem threads that might make it a little clearer.
Kind Regards,
JohnL

**Alan Wheeler** · 03-12-2006, 22:15

There is often a hole in the end of the nut and a thread in the end of the shaft. This takes a SST Allen key head set screw which locks that nut in place. Use a little locktite on the thread to ensure the Setscrew is locked in there.

fstbttms · 04-12-2006, 09:51

Quote:

Originally Posted by SkiprJohn

With the Gori prop if the key fails the nut will spin off with the hub and it'll be lost. Installation of the Gori is a little bit different than regular ole props.
Have you ever seen or heard of key failure?

I have seen keys in a state of extreme corrosion that I would not trust, but I personally have never seen a key actually fail. I suspect this is a very rare ocurrance.

SkiprJohn · 04-12-2006, 11:08

Aloha Wheels,
Thanks. That clears up why that nut has a threaded hole in the end of it. Unfortunately there is no corresponding threaded hole in the end of my shaft. I suppose I could tap one. Might be hard since I've reinstalled the shaft again.
Kind Regards,
JohnL