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Learning experience/ with cost
today was a cluster mess.. I found my lost prop had to put a reward on the thing the guys at the mariner found it. Cheaper than purching a new one or two. +++++++ The shaft broke it was 2 1/2 inch thick. The new shaft arrived yesterday indtalled the new shaft bolted it to the coupler and off we went to slide the prop on. The shaft was made to hatteras specks as to what came on the boat got the speck sheet from Hatteras. The company that turned the shaft said he should check the prop to the shaft. (past experience told him mis fit props broke shafts) Well have at it and he did the prop was off that was what caused the shaft to brake. With that in mind nothing to do but check the other shaft and prop. After removing the prop he put a red bye on the shaft and a crack in the exact same place as the other broke. After a bunch of bull and talking nothing to do but purchase a new shaft. My point
When purching a boat eaven with all you know and the best survaror in the business will miss that .
Probley will not eaven think about checking it it cost 2 shafts 8000 plus hall out 300 plus labor to remove and install 2 shafts and fus cut the props to properly match 3000
total cost about a 12000 hit .
Outcome slick and smooth .There was a small vibration at about 1600 to 1800 not enough to really worry about if you got one find the problem if you are thinking about purching. Do not just sluff it off Tim
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Re: Learning experience/ with cost
Quote:
Originally Posted by
tIM pOWELL
today was a cluster mess.. I found my lost prop had to put a reward on the thing the guys at the mariner found it. Cheaper than purching a new one or two. +++++++ The shaft broke it was 2 1/2 inch thick. The new shaft arrived yesterday indtalled the new shaft bolted it to the coupler and off we went to slide the prop on. The shaft was made to hatteras specks as to what came on the boat got the speck sheet from Hatteras. The company that turned the shaft said he should check the prop to the shaft. (past experience told him mis fit props broke shafts) Well have at it and he did the prop was off that was what caused the shaft to brake. With that in mind nothing to do but check the other shaft and prop. After removing the prop he put a red bye on the shaft and a crack in the exact same place as the other broke. After a bunch of bull and talking nothing to do but purchase a new shaft. My point
When purching a boat eaven with all you know and the best survaror in the business will miss that .
Probley will not eaven think about checking it it cost 2 shafts 8000 plus hall out 300 plus labor to remove and install 2 shafts and fus cut the props to properly match 3000
total cost about a 12000 hit .
Outcome slick and smooth .There was a small vibration at about 1600 to 1800 not enough to really worry about if you got one find the problem if you are thinking about purching. Do not just sluff it off Tim
Welcome back to boat ownership.
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Re: Learning experience/ with cost
What exactly was wrong with the prop to shaft fit? I've never heard of this problem.
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Re: Learning experience/ with cost
Quote:
Originally Posted by
davidwigler
What exactly was wrong with the prop to shaft fit? I've never heard of this problem.
Lapping the prop to shaft and checking the fit it has been mention here many many times and is all over boat diesel Tony has a Tip section on it good read. I lap mine every time they come off regardless of how many times prior they have been done. Also you need to check the key way fit and make sure its not hanging up on it.
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Re: Learning experience/ with cost
I lost a prop the same way. It was an expensive lesson.
I had both props removed and reinstalled by a diver without pulling the boat. While being reinstalled, they got hung on the key apparently, and never fully seated. A year later one broke off just in front of the prop. I checked the other and it too was cracked and would have failed.
Bottom line is this: Always haul to do the props. Always fit the props with lapping compound. Use coarse compound first. Apply it liberally, snug the nut slightly, then spin the prop on the taper. As you spin it, it gets looser. Tighten the nut and spin it some more. A lot more. Take it apart, clean it up, then apply fine lapping compound - again, liberally. Repeat the process.
Finally, install the prop. Remember, the key does not carry the prop. It only aligns it. The prop must be fully pressed against the tapered shaft. Also, use the big nut to press the prop on, then once on, remove the big nut and put the smaller nut onto the threads and tighten. Finally, put the big nut on last and tighten. Don't forget to put in a new cotter pin.
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Re: Learning experience/ with cost
i agree with bob about how to lap the prop. when i'm done lapping the prop, i mark the shaft at the fwd end of the prop, then install the key, and make sure the prop makes it all the way on the shaft up to the mark that i made without the key. this insures that the prop isn't binding on the key.
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Re: Learning experience/ with cost
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Re: Learning experience/ with cost
Quote:
Originally Posted by
tIM pOWELL
today was a cluster mess.. I found my lost prop had to put a reward on the thing the guys at the mariner found it. Cheaper than purching a new one or two. +++++++ The shaft broke it was 2 1/2 inch thick. The new shaft arrived yesterday indtalled the new shaft bolted it to the coupler and off we went to slide the prop on. The shaft was made to hatteras specks as to what came on the boat got the speck sheet from Hatteras. The company that turned the shaft said he should check the prop to the shaft. (past experience told him mis fit props broke shafts) Well have at it and he did the prop was off that was what caused the shaft to brake. With that in mind nothing to do but check the other shaft and prop. After removing the prop he put a red bye on the shaft and a crack in the exact same place as the other broke. After a bunch of bull and talking nothing to do but purchase a new shaft. My point
When purching a boat eaven with all you know and the best survaror in the business will miss that .
Probley will not eaven think about checking it it cost 2 shafts 8000 plus hall out 300 plus labor to remove and install 2 shafts and fus cut the props to properly match 3000
total cost about a 12000 hit .
Outcome slick and smooth .There was a small vibration at about 1600 to 1800 not enough to really worry about if you got one find the problem if you are thinking about purching. Do not just sluff it off Tim
Sorry to hear about this Tim. Hard way to start when you have done all that research and careful surveying. Let's hope it's a long while before another major problem/cost shows up.
Good luck Mate!
George
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Re: Learning experience/ with cost
Quote:
Originally Posted by
krush
blue check?
No, no, no!
That would suggest that parts can be made so they can be assembled without hand fitting.
A concept that hasn't been invented yet.
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Re: Learning experience/ with cost
Quote:
Originally Posted by
Bob Bradley
I lost a prop the same way. It was an expensive lesson.
I had both props removed and reinstalled by a diver without pulling the boat. While being reinstalled, they got hung on the key apparently, and never fully seated. A year later one broke off just in front of the prop. I checked the other and it too was cracked and would have failed.
Bottom line is this: Always haul to do the props. Always fit the props with lapping compound. Use coarse compound first. Apply it liberally, snug the nut slightly, then spin the prop on the taper. As you spin it, it gets looser. Tighten the nut and spin it some more. A lot more. Take it apart, clean it up, then apply fine lapping compound - again, liberally. Repeat the process.
Finally, install the prop. Remember, the key does not carry the prop. It only aligns it. The prop must be fully pressed against the tapered shaft. Also, use the big nut to press the prop on, then once on, remove the big nut and put the smaller nut onto the threads and tighten. Finally, put the big nut on last and tighten. Don't forget to put in a new cotter pin.
Bob I must agree never use a diver, After checking i found that a diver did this work in florida befor i purchased the boat.
A small vibration caused the owner to pull the props and have them ballanced, Diver did the work...
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Re: Learning experience/ with cost
Yup.
At least it sounds like you got your prop back. I lost mine at 17kts running in 40fow. And yes, it did make a big bang as it departed. Also cut a major slice in the bottom. Thank God its a Hatt; a lesser hull would have been breached.
I had a diver do my old Chris (gas engine, 1-1/4" shaft) many times with no problem. I did find a prop loose once or twice. I guess the stresses of a much bigger power plant on a much bigger boat and running gear are substantially different. Before all was said and done with new prop, two new stub shafts (got them free from a generous site member, but paid big bucks to have them reconditioned), and a couple haulings and propscans to get everything perfect, I figure that mistake cost me north of $6k.
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Re: Learning experience/ with cost
Tim- I dont think you could have forseen that problem. Hopefully the boat bucks stay in your wallet for a while. Hopefully when we die it will be with a big smile on our face from all the enjoyment our Hatteras' brought us. Enjoy your boat...life is good.
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Re: Learning experience/ with cost
I feel your pain Tim. My governor failure cost me 25K. But that's part of the game. I think we are both still in great shape considering what we've got and what we paid for them.
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Re: Learning experience/ with cost
Quote:
Originally Posted by
Scrod
No, no, no!
That would suggest that parts can be made so they can be assembled without hand fitting.
A concept that hasn't been invented yet.
So what's the point of the key way then? To center the bores?
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Re: Learning experience/ with cost
I'd like to know this, too. Does the force to turn the prop come through the key? Or once the prop is lapped on, it's on so tight that the shaft can turn it without slipping inside the prop bore? Hard to imagine, with all that torque.
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Re: Learning experience/ with cost
The key does not drive the prop. All the load is carried on the taper. Basically it's like a wedge which is why it's so difficult to remove once it's seated. I work with tapered drive couplings all the time and a properly machined shaft and bore should fit together and work correctly without hand fitting. The only purpose I can see for lapping, or as krush suggested a "blue test" is to verify that the components are in fact mated properly. However, once that's proven I can only see opportunities to foul things up by repeatedly fiddling with them.
On the coupling end the key would be for alignment since the coupling face is supposed to be trued on a lathe while mounted on the shaft. Hence realigning it in a different position could potentially cause a problem. Props OTOH, are not "trued" on the shaft so there's no need for indexing. The only purpose I can see for the key on the prop end is to keep the prop from spinning while you're torquing the nut. If anybody knows another reason I'd like to hear it. Perhaps there's concern about bending a shaft if it's held in some other place while torquing but since we don't use a spanner to hold the prop that potential exists anyway. Or maybe "we've always done it this way." But frankly, if I ever have shafts made I'm going keyless on the prop end. Keyways are just a potential failure point and a key is an opportunity to put a prop on cockeyed.
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Re: Learning experience/ with cost
Here's a case in point: My 3208 injection pump. All the drive force and pump to engine timing is handled by a tapered drive. If it slips it goes out of time and runs lousy if at all.
No key.... no keyway.
http://i56.tinypic.com/2gsmt04.jpg
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Re: Learning experience/ with cost
scrod, the reason for lapping is that when a prop is repaired with a torch, there is the chance that the heat may distort the bore
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Re: Learning experience/ with cost
What's the point of lapping with out some type of verification...aka blue check? If it's really messed up, you ain't going to fix it with lapping compound anyway. And blue checking can have u chasing your tail because it either touches or doesn't...you can't see how far away it is.
One could just leave the key out at the prop end. Then no worries! Keys are used to transmit power all the time, but it usually is on a straight (read non-tapered) shaft.
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Re: Learning experience/ with cost
Hi All,
Tim....Oooouch that's a big one !!
Jack......Oooooooouuuuuccccccchhhhhhhh !!!!! Holey Moley !! Isn't that almost the cost of a re-build ?
Tim,, As Jack and others have said, have confidence in your research, you have a beautiful boat, well cared for, and it's not something you could have foreseen, and unfortunately we've all been subject to Murphy's law in our passion for our classic Hatts.......
Bill, you said "the reason for lapping is that when a prop is repaired with a torch, there is the chance that the heat may distort the bore""....so does the lapping compensate for the distortion and the key then forces alignment or acts as a lock ?
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Re: Learning experience/ with cost
every since my go cart days racing induro at (vIr) Viginia International Raceway I have never seen a taper without a Key. Please Please not to say you are full of muschutto but i tell you that seemd like a stretch. I wounder through the boat yards all the time getting idears. I see all types of boats at Jarret Bay from their famous 30 footers to 70 footers to some honking big boys. With some funny props 8 and 9 bladed stuff sporting 1000 plus horse power per side and sometime 2000 per side awsom stuff burning 120 gallons per side making 50 plus knots. To yet i have not seen a shft without a key way. I understand your thinking but just can not get it down. One of those 1000 plus
hp engins spinning on a fish i can not belive the prop will not spin on the shaft... If there was some merit to your thinking Hinkley or hatteras or someone would be doing what you are thinking.
I can attest to one thing loose props or misfitted props will brake shafts. My bank account will prove it. Tim
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Re: Learning experience/ with cost
Think about it. The more torque, the more force onto the taper. As you accelerate, the prop is pushed further onto the shaft and the fit gets even tighter to the point that it will no longer get any tighter.
My theory is that the key just holds the prop from spinning until it is fully seated. You may achieve that just by tightening the nut, but if you don't it will eventually be set completely when you run the boat.
The only other purpose for the key that I could see would be a safety for reverse (but isn't that what the nut is for?)
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Re: Learning experience/ with cost
Quote:
Originally Posted by
SKYCHENEY
Think about it. The more torque, the more force onto the taper. As you accelerate, the prop is pushed further onto the shaft and the fit gets even tighter to the point that it will no longer get any tighter.
My theory is that the key just holds the prop from spinning until it is fully seated. You may achieve that just by tightening the nut, but if you don't it will eventually be set completely when you run the boat.
The only other purpose for the key that I could see would be a safety for reverse (but isn't that what the nut is for?)
I know sky and i concure . I could swallow it if it just went one way pushing on the tapor. But with no key way in reverse the prop is going to spin. I just do not see being tightened enough not to. If it spins in reverse there goes your so called fit. Sorry sky. I kinda associate this with trick i told my wife why the car was shaking bad air in the tires!! Yes she is gullable some times about some things Tim
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Re: Learning experience/ with cost
Quote:
Originally Posted by
tIM pOWELL
I know sky and i concure . I could swallow it if it just went one way pushing on the tapor. But with no key way in reverse the prop is going to spin. I just do not see being tightened enough not to. If it spins in reverse there goes your so called fit. Sorry sky. I kinda associate this with trick i told my wife why the car was shaking bad air in the tires!! Yes she is gullable some times about some things Tim
I know. Theory is one thing, reality is another. My props are off getting tuned right now. When they come back, I will testing (bluing), lapping as necessary, and installing WITH keys. Why? Because that's the way I've always done it and I haven't had a problem.
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Re: Learning experience/ with cost
Quote:
Originally Posted by
SKYCHENEY
I know. Theory is one thing, reality is another. My props are off getting tuned right now. When they come back, I will testing (bluing), lapping as necessary, and installing WITH keys. Why? Because that's the way I've always done it and I haven't had a problem.
What is the saying do as i say not as i do
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Re: Learning experience/ with cost
gene, lapping takes some metal off of the prop(its softer than the shaft) any high spots will sand down, just like lapping a valve in an engine.
krush, i know it is not scientific, but the prop will have shiny spots and dull spots. when a good mating surface is achieved, the prop will be shiny all of the way around the bore.
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Re: Learning experience/ with cost
Sky, I am away from the boat and my notebook today, but do remember exactly what were Jim Bircher's comments at our Hatteras school about prop fitting and lapping? As I recall he was basically against lapping as a solution and seem to feel it could cause issues. Jim is the premier machine shop in these parts and makes shafts for a lot of high end brands, and has some of Tim's former money too. He talked a long time about taper, and proper shaft to prop fit. When I get back I'll see if I can find his white paper on the subject.
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Re: Learning experience/ with cost
So just machining it with out lapping would be like doing a valve job without lapping Right?
Or do you blue the seats put it together and check?
If you lap a prop with fine lapping compound you will see what is making contact after you wipe it off, so using blue is not really needed. It also cleans up any scratch, burr or crud you may have missed remember this is outside under a boat not a Machine shop. It is so easy and cheap why would just go do it since every time you do it it will be a better fit.
You can machine the shaft and the prop hub and think its perfect but if you think it is perfect it just because you have not looked hard enough ;)
It not a perfect world where theory works :D
Where have I heard that before:confused:
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Re: Learning experience/ with cost
Quote:
Originally Posted by
GJH
Sky, I am away from the boat and my notebook today, but do remember exactly what were Jim Bircher's comments at our Hatteras school about prop fitting and lapping? As I recall he was basically against lapping as a solution and seem to feel it could cause issues. Jim is the premier machine shop in these parts and makes shafts for a lot of high end brands, and has some of Tim's former money too. He talked a long time about taper, and proper shaft to prop fit. When I get back I'll see if I can find his white paper on the subject.
Proper fit is the key and that can only happen if all the components are matched. When I had my new shafts made, they asked for the props and the couplings to ensure a good fit. You'll have to ask Tim but I'd suspect Jim has more of Tim's money now.
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Re: Learning experience/ with cost
The Earth is flat!!!! I guess if a lot of people keep repeating something it will become fact. This lapping makes a lot of $$ for the yards but what does it really do? These are low RPM shafts turning at roughly half the engine speed. The prop is boronze or nibral for the most part. When you crank the prop up on the taper the hub expands and conforms to the shaft. If their is a fit problem the stress is on the prop hub. If the prop hubs are cracking maybe. But the shaft failing because of unequal compression from a softer metal? Like cutting a piece of glass most shafts (regardless of the application) fail due to scoring or inproper machining without stress releiving the cut area.
Lapping valves has nothing to do with a static fit and is only for compression. The fact that their are pounding thousands of times a minute into a seat I dont see any similarity.
If fitment is such a big problem how about the other end of the shaft at the engine coupling. Heck that just slides on and is squeezed together with a couple bolts. If their was unequal compression anywhere it would be there.
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Re: Learning experience/ with cost
Quote:
Originally Posted by
tIM pOWELL
I know sky and i concure . I could swallow it if it just went one way pushing on the tapor. But with no key way in reverse the prop is going to spin. I just do not see being tightened enough not to. If it spins in reverse there goes your so called fit. Sorry sky. I kinda associate this with trick i told my wife why the car was shaking bad air in the tires!! Yes she is gullable some times about some things Tim
You may have hit on the reason they're keyed. The only way they'll come off in reverse is if the nut is loose. Ask anybody who's ever accidentally tried to pull a tapered drive without removing the nut. It's not coming off. But it may be a redundancy in case of a poor installation.
Quote:
Originally Posted by
34Hatt
So just machining it with out lapping would be like doing a valve job without lapping Right?
Or do you blue the seats put it together and check?
If you lap a prop with fine lapping compound you will see what is making contact after you wipe it off, so using blue is not really needed. It also cleans up any scratch, burr or crud you may have missed remember this is outside under a boat not a Machine shop. It is so easy and cheap why would just go do it since every time you do it it will be a better fit.
You can machine the shaft and the prop hub and think its perfect but if you think it is perfect it just because you have not looked hard enough ;)
It not a perfect world where theory works :D
Where have I heard that before:confused:
Next time you get a cylinder head machined let me know if you see evidence of lapping. Nobody does it anymore. Actually in the case of most (not all) engine valves it's detrimental since the valve and seat are purposely cut at different angles to create a smaller contact area. Lapping would widen that area and decrease seating pressure.
Using a light lapping or a blue test basically accomplishes the same thing. Verifies that the fit is correct. If it isn't, you're not going to correct any significant issues under the boat.
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Re: Learning experience/ with cost
Quote:
Originally Posted by
rsmith
... Like cutting a piece of glass most shafts (regardless of the application) fail due to scoring or inproper machining without stress releiving the cut area...
I have to disagree with you on this point. An improperly seated prop, like one hung on the key and not on the taper puts major stress on the shaft, especially every time it goes in and out of gear. Just like bending a paper clip over and over, it will eventually fail. That's how I lost my prop. And, the other one had started to crack for the same reason. This was confirmed by Randall Hale of Hale Propellors in Old Saybrook CT. Randy knows his stuff.
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Re: Learning experience/ with cost
Quote:
Originally Posted by
Bob Bradley
I have to disagree with you on this point. An improperly seated prop, like one hung on the key and not on the taper puts major stress on the shaft, especially every time it goes in and out of gear. Just like bending a paper clip over and over, it will eventually fail. That's how I lost my prop. And, the other one had started to crack for the same reason. This was confirmed by Randall Hale of Hale Propellors in Old Saybrook CT. Randy knows his stuff.
Like I said "most" but if the prop was rocking on the keyway the vibration would be horendous and the hub of the prop would get egged out to the point where the vibration would keep getting worse. If things are vibrating its time to stop and figure out what is wrong.
Now if your all getting picky about fitment and keyways dont carry any drive load. What about the muff couplings? their not tapered and no one laps them and the only thing that keeps the shaft ends from spinning is the keys.
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Re: Learning experience/ with cost
Quote:
Originally Posted by
Scrod
Here's a case in point: My 3208 injection pump. All the drive force and pump to engine timing is handled by a tapered drive. If it slips it goes out of time and runs lousy if at all.
No key.... no keyway.
http://i56.tinypic.com/2gsmt04.jpg
Looks kind of like a little V8 diesel itself, doesn't it...
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Re: Learning experience/ with cost
If there was no key wouldn't running the engine in reverse loosen the prop and cause it to slip? then, when you put the drive in forward, it would drive the prop back onto the taper and retighten it again... most of us go through dozens if not hundreds of those cycles a year; if the key wasn't there, the prop would be alternately tight and loose on the taper, which wouldn't be good. Maybe the key is there to prevent that?
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Re: Learning experience/ with cost
Quote:
Originally Posted by
GJH
Sky, I am away from the boat and my notebook today, but do remember exactly what were Jim Bircher's comments at our Hatteras school about prop fitting and lapping? As I recall he was basically against lapping as a solution and seem to feel it could cause issues. Jim is the premier machine shop in these parts and makes shafts for a lot of high end brands, and has some of Tim's former money too. He talked a long time about taper, and proper shaft to prop fit. When I get back I'll see if I can find his white paper on the subject.
I don't know what Jim said exactly. I couldn't bear to listen as I just kept thinking that he was just out to take my money. It all sounded like a big scare tactic to get very high prices for precision work that was more than necessary. I know many like him and he has a good reputation. I just would never use someone like that. It seems to be overkill (the precision and the price).
I just do what I have been doing and it works fine for my old boat.
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Re: Learning experience/ with cost
My props are held on with crazy glue. Crazy, right??
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Re: Learning experience/ with cost
Quote:
Originally Posted by
jim rosenthal
Looks kind of like a little V8 diesel itself, doesn't it...
Yep, and these vintage V-8 Macks even more so:
http://i47.tinypic.com/vyw3r8.jpg
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Re: Learning experience/ with cost
Quote:
Originally Posted by
jim rosenthal
If there was no key wouldn't running the engine in reverse loosen the prop and cause it to slip? then, when you put the drive in forward, it would drive the prop back onto the taper and retighten it again... most of us go through dozens if not hundreds of those cycles a year; if the key wasn't there, the prop would be alternately tight and loose on the taper, which wouldn't be good. Maybe the key is there to prevent that?
If they came off so easily in reverse why would anybody buy a puller? A properly made and installed taper is an extremely strong connection. Watch the next time your yard pulls your props and see how much force is required. They don't come off easily.
Also, if that happened there would be evidence of the prop and shaft "working" on each other. Has anybody seen any fretting, galling, spalling or any of a dozen other terms for wear that would be caused by that?
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Re: Learning experience/ with cost
Trust me they won't come off on their own if properly seated. I have a home made puller make from 1/2" steel - one 12" diameter circular piece with a "U" cut into it and one 12" piece solid. Each has 4 holes for the long bolts that pull them together. I block the blade and tighten the bolts evenly using a very big wrench. They get so tight that the 1/2" cold rolled steel starts to bend, and still the bond of the taper does not break. I then rap the unit with a big hammer and eventually the prop comes free with a significant "pop".
The key is nothing but window dressing. The taper does all the work.