Fitting a prop sanity check

leaky

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Update: not going very well :(...

I should've taken a picture but basically I end up with this ~1 inch section where perfect seating is occurring that is in about the middle of the area on the taper that the prop hub covers. It almost gets kinda polished right there, with only fine barely noticable scores across the marker in other places that I don't think qualifies as being seated right.

My layman's view of the process is that the grit mostly gets squeezed right out of that tight spot, which is where you really need to see some material removed. Getting worried I'm going to f something up if I just keep trying how I'm doing it.

If you asked me last night my response would have been f-this, I was banging the coupler off and bringing it to someone to check the fit & lap it, but after some sleep I'm ordering some actual Prussian Blue and a compound that might be better than this permatex stuff and will have a beer and see what I can see/do first. If nothing else by completely covering the shaft with a potentially better dye I might be able to see better what I'm up against.
 

Downrigga

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You dont have to do that leaky. Keep doing what your doing. It kind of a pain but just keep spinning the prop with the lapping compound and it will fit like a glove. You dont need the dye. Just make several long lines with the sharpie all the way around the shaft. Its bull work but it works wonderful.
 

Diesel Jerry

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leaky

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You dont have to do that leaky. Keep doing what your doing. It kind of a pain but just keep spinning the prop with the lapping compound and it will fit like a glove. You dont need the dye. Just make several long lines with the sharpie all the way around the shaft. Its bull work but it works wonderful.

Ditto what he said. Also when the prop starts to “fit” the shaft you will know. It starts to get really hard to lap.

Thanks for the encouragement guys!

Should I be pushing on it with some force? What I was doing is using the nut to calibrate how hard it was seated, one hand on the nut, one on the prop to spin it.

I guess I just expected it to be like the article, went at it like a 30 minute job and two hours later (a lot of it slowly getting myself better setup and trying to use my head better) I just didn't seem to be making headway.

Got that clover lapping compound coming in Thursday & the dye, will turn my attention to something else for a few days and go back at it with a comfortable place to work under there this time and when planning on it taking awhile.
 

Diesel Jerry

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Viexile

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Yeah. I bought a cutless remover/prop puller last year and learnt my lesson on prop removal and replacement. You do NOT want to be standing behind that thing when it finally decides to come off. Because it's still pissed off from being put on the shaft.
 

leaky

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I grab the prop at 9:00 and 3:00 (12:00 and 4:30 for 3 blades) and do 6, 90 degree swipes. Turn the prop 90 degrees and repeat, and repeat until I have made I full revolution. I may do 2 or 3 revolutions before I check it. I apply enough pressure to “cut” but not enough to turn the shaft. If the shaft is really easy to turn I will clamp it some how. Read the grinding compound when you remove the prop. It will show you if you have good contact.
Also don’t “nuke” this. So many people don’t even know about lapping props on. My dad never did any on his own or on boats he finished off. He learned it from me when his prop kept coming loose on the JC.
If you still are struggling let me know. I can take Friday off and come help.

Thanks Jerry! You don't need to take a day off to do it, can meet you over there almost anytime, but I would totally pay you to come down and sanity check. Seems like at every turn lately I run into some odd rigging difficulty, last were exhaust clamp sizes where I land perfectly in between.

Also I guess this is just a bronze test prop, isn't destined to live on there forever just to get a baseline and maybe to sacrifice in the process by having it twisted all around - though I could see it staying on there for a season if it works OK (while I run around in circles and go broke w/ all the other things involved in new boat process), or if it works well I don't know why I would bother changing it.

My shaft is really easy to turn, like I can turn it on the smooth shaft using my thumb and two fingers - hopefully is a sign of my outstanding alignment :).. also though the o-ring collar isn't fit to the PSS right now (is just slid up toward the coupler) so basically nothing is there to cause drag. I've got the coupler tied up to a C clamp on the stringer to lock it, something I did after I realized using the two prop nuts and a wrench again and again and again was getting stupid.
 

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Old Mud

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MC35

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Leaky, If you need a hand let me know I`am right here in NH and have done this many many times.
 

Kailua Kid

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Leaky im guessing you have never lapped in valves on an engine. when you lap valves or lap Props what you should be hearing is the lapping compound cutting. Just a few turns and quickly back off and push back on the turn again. It is sometimes a quick process but usually a long one. At least 90 percent of that shaft has to be in contact with the prop. I always shoot for more. All this before you should even touch the key. After finished lapping then fit the key. No loose keys. If it is ,replace it. You should lap the key on a piece of 220 or 320 wet & dry with light oil on a glass or other flat surface to fit. Yes it may take a while but it has to be perfect to be good.

Fit dry without lube. Everything Jerry and others said is correct except there is no place on that job for 5200 or silicone. JMHO.

OH i see Jerry was posting when i was. Disregard my post. :)

If i were not on lockdown I would go with you Jerry.
A good application for 5200: Put a dab about the size of a pencil eraser right on the very tip of your nose (measure twice to get it just right). Let it set up completely. Then, every time you even think about using 5200 on your boat you will have a reminder ...
 

leaky

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Weekends are my Family days so I don’t I don’t do boat work. Don’t worry about paying me either, this forum has done plenty for me, just trying to pay it back. Let me know by Wednesday. You are in NH right? I have a hatch and a switch panel I have been needing to pick up there since last year!

Thanks and will do! I am a little less than 15 minutes from the Merrimacport exit off 495, in Newton NH. It is a haul for you though, 2/3 the trip where your brothers was living or so.

If you want I could grab that hatch & panel ahead of time so you aren't running all over.
 

Diesel Jerry

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leaky

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Leaky im guessing you have never lapped in valves on an engine. when you lap valves or lap Props what you should be hearing is the lapping compound cutting. Just a few turns and quickly back off and push back on the turn again. It is sometimes a quick process but usually a long one. At least 90 percent of that shaft has to be in contact with the prop. I always shoot for more. All this before you should even touch the key. After finished lapping then fit the key. No loose keys. If it is ,replace it. You should lap the key on a piece of 220 or 320 wet & dry with light oil on a glass or other flat surface to fit. Yes it may take a while but it has to be perfect to be good.

Fit dry without lube. Everything Jerry and others said is correct except there is no place on that job for 5200 or silicone. JMHO.

OH i see Jerry was posting when i was. Disregard my post. :)

If i were not on lockdown I would go with you Jerry.

Thanks! Yes although I do have decent experience with rebuilding engines, fitting those parts, deglazing, honing, all was 2 strokes of different types... valve - what is that, is it like a reed maybe, do you mean power valve? :)

I think the key way I went wrong here was, although my technique definitely sucked reading everyone's advice, I anticipated it was quick and having to grind away meant something was wrong. Gonna order more key stock tonight too incase I screw that up twice.

I really do want to learn this.
 

Old Mud

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ArchHibb

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This forum is great, and where I learned the technique.

Pay attention to Jerry’s instructions noting 90-degree increments. If you spin the prop all the way around you just scrape all the lapping compound into the keyway.
 

leaky

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Is it an old prop? Maybe it was originally fit to a bad taper.

No idea really, is a Dyna Quad 21 x 21 from someone on Ebay out of RI who appears to mostly sell props and has all positive feedback. Sold as serviced and good to go, looks it, but kinda a blind item other than not a spec of inconsistencies detected in the bore.

The fit I am getting isn't outrageously poor or anything, not a hair of wobble once it is seated home, just couldn't get it to pass the test and I was doing it all wrong so that is expected :)

I was spinning the prop 360 degrees, which seems to perfectly drive the grit out of the high spot you are trying to work on. May have even been making the problem worse, although my impression is simply nothing was happening beyond initially deglazing the surfaces.

20210111_224312.jpg
 
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