Question about Prop lapping
Printed From: CorrectCraftFan.com
Category: General Correct Craft Discussion
Forum Name: General Discussion
Forum Discription: Anything Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=47759
Printed Date: April-29-2024 at 3:59am
Topic: Question about Prop lapping
Posted By: *mtrbtr*
Subject: Question about Prop lapping
Date Posted: July-17-2019 at 2:01pm
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New to me 2006 SV 211 Last year. Been messing around with props trying to decide which one I like better. The original prop that was on the boat (856) got a bit of a ding in it first time out this year, so I had it rebuilt. I had a rebuilt (644) backup prop that I bought form NP over the winter, so I put that on. I plan on taking the boat to a church function where I will be pretty loaded next week so I decided to put the fixed 856 back on. I did the lapping procedure found on this site both times. I also came across a screaming deal on a "never used" 644 prop so will probably sell my rebuilt one. I am also doing some testing with RPMS to see which prop I like better (644 vs 856). My questions are: Is there a limit on your shaft as to how many times you should lap a prop. Once a particular prop has been lapped and then removed, does it need to be re-lapped? Just wondering since I have been playing musical props here lately. ------------- 2006 SV 211 (sold) went to the dark side 97 Sport Nautique (sold) 89 PS 190 (sold) 05 Four Winns H180 (sold) 89 Four Winns 180 Freedom (sold) 75 MFG (sold) |
Replies:
Posted By: 8122pbrainard
Date Posted: July-17-2019 at 2:38pm
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Johnathan, There's no limit to lapping . The material removed is very small and really won't change the geometry of the taper. Once one prop is removed, you shouldn't need to lap it again UNLESS the next prop lapping removes a significant amount of shaft. Really the only way to check the fit is to use the Prussian Blue. The Nibral material of the prop and the stainless material of the shaft are very close in hardness so when you lap, you are removing the small amount of material on both surfaces. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: tryathlete
Date Posted: July-17-2019 at 2:40pm
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My theory is that when you lap a bronze propeller onto a stainless shaft, the softer metal propeller is going to be the half of the equation that does the actual dimensional change. This is purely speculative since I’ve never measured the very small changes that occur in this very low speed lapping operation. I think you can lap to your heart’s content. I like the idea of the very cheap brand new 644! That sounds like a real nice find. |
Posted By: 8122pbrainard
Date Posted: July-17-2019 at 2:44pm
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Peter, I think you should look up some material Rockwell harnesses.  ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: tryathlete
Date Posted: July-17-2019 at 2:53pm
Pete, we machine Nibral impellers as well as stainless steel impellers on a production basis all day long. There’s a whole lot more to wear pairs than hardness. Lapping is an abrasion process where the compound does the work, not the metal to metal action. It takes a lot longer to lap the shaft bore of stainless impellers than the bronze. 😏 |
8122pbrainard wrote:Posted By: flyweed
Date Posted: July-17-2019 at 5:40pm
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just got done with my new prop and "lapping" procedure...Piece of Cake! ------------- '93 Ski Nautique NWZ, Air Boom Tower Drink Tonight..for tomorrow We Ride! |