Lapping a prop

[Capt Rich]

Has anyone done it without removing the shaft from the boat?

 

[Brooksie]

No problem. Don't get the grinding compound in the cutlass.

 

[Rambler]

No problems doing it with the shaft in place.

 

[LACI GALE 31jc]

just take off prop and keyway and get some ''vave lapping compound'' . put some lapping compound on shaft and in side of prop without keyway turn the prop round and round back and forth remove prop to check for even wear. wash with soap and water real good.

 

[SameDirection38]

We do this at our yard for every new prop, or if we feel it should be done. We always do it with shaft in the boat.

1. Remove spurs (optional, I find it easier). Key should be removed. Clean shaft and inside of prop hub completely. Tape around cutlass or wrap a rag around it.

2. Lock shaft so it will not turn. Apply generous amount of heavy grit lapping compound. Rotate prop back and forth 1/4 to 1/3 turn, Rotate prop around shaft as you do this.

3. Repeat steps with finer grits until the prop gets harder to rotate and almost feels like it is catching.

4. Thoroughly clean shaft and prop hub and apply pursiun blue (I know I messed up that spelling I am to lazy and it is to cold to run to the shop and look at it). Put prop back on shaft with out bumping the shaft around inside the hub. Remove prop and check contact pattern. Repeat lapping process if necessary.

5. Clean inside of prop hub and shaft again. Slide prop back on shaft untill it is all the way on (still no key) and mark around the shaft at the back of the hub with a sharpie.

6. Remove prop install key. Prop should slid all the way back to the mark. If it doesn't it is key bound and you need to clean the key, shaft, prop hub, and check for burs.

7. If not key bound put on big nut and tighten to press prop onto shaft. Remove big nut, then install little nut, tighten, big nut, tighten, and last the cotter pin.

If you arms feel like noodles you did it right.

 

[YankeeFPT]

We do this at our yard for every new prop, or if we feel it should be done. We always do it with shaft in the boat.

1. Remove spurs (optional, I find it easier). Key should be removed. Clean shaft and inside of prop hub completely. Tape around cutlass or wrap a rag around it.

2. Lock shaft so it will not turn. Apply generous amount of heavy grit lapping compound. Rotate prop back and forth 1/4 to 1/3 turn, Rotate prop around shaft as you do this.

3. Repeat steps with finer grits until the prop gets harder to rotate and almost feels like it is catching.

4. Thoroughly clean shaft and prop hub and apply pursiun blue (I know I messed up that spelling I am to lazy and it is to cold to run to the shop and look at it). Put prop back on shaft with out bumping the shaft around inside the hub. Remove prop and check contact pattern. Repeat lapping process if necessary.

5. Clean inside of prop hub and shaft again. Slide prop back on shaft untill it is all the way on (still no key) and mark around the shaft at the back of the hub with a sharpie.

6. Remove prop install key. Prop should slid all the way back to the mark. If it doesn't it is key bound and you need to clean the key, shaft, prop hub, and check for burs.

7. If not key bound put on big nut and tighten to press prop onto shaft. Remove big nut, then install little nut, tighten, big nut, tighten, and last the cotter pin.

If you arms feel like noodles you did it right.

Same way we do it here at Yankee.

 

[Capt Rich]

Wow!
Now that's an answer!!!
Thank you all!!!
Rich

 

[Toolate]

THis video was posted in another thread a while back about straightening bent shafts- I thought it looked interesting but have no idea if it is really the right way to do the job (all looks good to me except the small/big nut order). Results certainly look clean and he has a touch for the materials that only comes with a life of doing something. I like people who use old tools and do things by hand.

Looks easy on the lathe, I can only imagine how many turns it would take by hand.

Lap & fitting Props Part 1 - YouTube

Part 2 should come up if you search this. His other videos are pretty good too.

 

[Capt Rich]

Yep ,
Keith Fenner.
Only know him from YouTube ,
Looks easy on the lathe.
I like his videos!
I was thinking of spinning the shaft with an electric motor and a belt.
Didn't completely think about the details on building something yet .
We'll see how the new prop fits, I'll probably do it by hand.

 

[tunafishhkg]

The main takaway from Kieth Fenner's video's is a graphic instruction of how to check and what to look for when done right. Most lap jobs are done on the boat like the excellent description by SameDirection38. You would be surprised that it really does not take that long unless you have a badly beat up prop that would REALLY benefit from the time and effort of lapping.

 

[captainlarry84]

All correct a piece of cake. If I might add when lapping put on one prop nut just in case of a OPPS the wheel will not hit the ground. Murphy's law. For clean up I like soap & water followed by a acetone whip & all new clean cloth's. Once done a finial spray of WD 40 and a new clean cloth.

 

[huetis]

That was cool, here I am looking for some sort of boat porn, lapping a prop, really?? ,,, and I just spent the last 1:45 minutes looking at a bunch of cool Keith Fenner youtube videos. This site is great.

 

[Toolate]

That was cool, here I am looking for some sort of boat porn, lapping a prop, really?? ,,, and I just spent the last 1:45 minutes looking at a bunch of cool Keith Fenner youtube videos. This site is great.

Made it to the mermaid section yet? haha.

Welcome!

 

[SameDirection38]

I can't take credit for that, YankeeFPT taught me how. Also to quote him "If it takes a torch to get it off you did it right"

 

[tunafishhkg]

That was cool, here I am looking for some sort of boat porn, lapping a prop, really?? ,,, and I just spent the last 1:45 minutes looking at a bunch of cool Keith Fenner youtube videos. This site is great.

Like CaptLarry and many others, he is willing to share his knowledge which is priceless and with all the selfish Aholes in this world, a shinning light.

 

[captainlarry84]

Like CaptLarry and many others, he is willing to share his knowledge which is priceless and with all the selfish Aholes in this world, a shinning light.

our too kind.... feel the love

 

[huetis]

Actually I've been torturing CaptLarry for a while now. Information and what to look for is amazing and hopefully I'll be able to put it to practical use shortly. Used to be when someone said shaft size I went to the mermaid section.

 

[captainlarry84]

Actually I've been torturing CaptLarry for a while now. Information and what to look for is amazing and hopefully I'll be able to put it to practical use shortly. Used to be when someone said shaft size I went to the mermaid section.

IN you make the trip to N/C maybe stop & the Betty Ford Clinic for a quick hello....

 

[huetis]

hahah lol, that was about 14 years ago but thanks for the check....