Cutlass Bearing Extractor ...

[walmsleyc]

Just a FYI thread about building a home made "shaft in place" cutlass bearing extractor. The basis/idea for my extractor is from someone else out there who had posted some pictures of an extractor composed of two wooden blocks with suitable holes, and two threaded rods and a pair of pusher sleeves (so, thanks to whoever that was!)

My extractor is composed of:

• 5/8- 20TPI threaded rods (x2) & nuts (x6)
• 2 quarter sawn Fir blocks of wood, one of them split, with appropriate holes
• 1/2" carriage bolts with washers and wing nuts
• Set of sleeves with I.D. 1", and O.D. ~1.23", ~5" long

Construction was fairly straight forward. Key construction details:

• Split wooden block has a 1" hole for the shaft and two 5/8" holes for the rods, plus two 1/2" holes for the carriage bolts that hold it together on the shaft in front of the strut.
• The split forward block also has a recessed location for a 1" I.D. washer that takes the brunt of the compression from the split sleeves so the wood doesn't compress and get damaged (the washers did flex and bend a little in use).
• The solid wooden aft block has the two 5/8" holes, but the centre hole is 1 5/16" (just a shade larger than the O.D. of my bearing. The 1 5/16" hole has a 1/2" deep section that is 1 1/2" in diameter. This fits over the strut, and properly centres the block of wood (carefully doing this on a drill press keep the holes properly aligned)
• For the split sleeves, I found a piece of 1" I.D. pipe, and had the outside machined down to the ~1.23" so it would just fit inside the strut (and then cut in half lengthwise)
• I used double 5/8" washer between each nut and the wooden blocks, and put some white grease between them as a bearing surface (turned out to be very effective)
• I used double nuts of the aft end of the rods locked against each other with loctite added. For the forward nuts, I just clamped a visegrip on each nut (which would spin until it was blocked by the shaft) to secure the forward nuts from turning.
• I used two pieces of 6" velcro to hold the sleeves in place while assembling the extractor.

Take a look at the video for the extraction process:

• Quick Video:
• Temperature was cold (-10C) and that might have made it easier to extract the bearing
• Barely 25 minutes from start to end
• The 20tpi rods required many turns (slow), but did provide the necessary power
• At the beginning, the bearing "popped" as it moved, every 2 or 3 half turns of the bolts, but as we progressed, the popping occurred every turn, and eventually went away as we were over 2/3s done and the extraction became continuous.

Total cost was about $80. The threaded rods where the most expensive parts.

The aft block can be reversed, and with a 1" I.D. washer in place can be used to push in a new bearing. The prop must be removed for this, but the shaft can be left in place.

Cheers
Chris

 

[whatfiero]

Where is your rudder I don't see a rudder in video?

 

[Jalepeno]

My strut has a zinc on it. I don't see a zinc is that common?

 

[walmsleyc]

My strut isn't bonded to anything else, and it's isolated from the shaft by the nitrile in the bearing. So there's no circuit between the strut and anything else?

Chris

 

[Allan12210]

Chris,

Very nice tool you have created. I like the feature of flipping the aft block and making it the pusher for the new bearing.

I've posted about one I made with pipe flanges and split pipe that works okay but it takes two men and a small boy to hold the pieces together to get it started.

 

[Tally Ho]

Never would have thought to make it out of wood! I can't do the kind of metal working required to make it out of metal, but my brother-in-law owns a machine shop... and all it took was a rough sketch of what I wanted, and a little begging....and viola! I beautiful custom-fabricated tool...

But I love the idea of making the blocks out of wood. Very creative.

Greg

 

[walmsleyc]

Metal would have been fine/better, but I've got a wood shop and a limited ability to make things out of metal (and I guess not enough of the right kind of friends!) so wood was easy and economical. (nice video! )

Cheers
Chris

 

[rpwillia]

Made this out of some steel plate I had sitting around. Also had one I made out of oak.

 

[walmsleyc]

A point of interest ( I notice there is another thread going on now that references this discussion). My bearing extraction worked well for my bearing. But my bearing had only been in for 8-9 years. It did not come out easily, but with a slow steady "pop" every few cranks on the theaded rods. The wood blocks creaked a little, and there was some compression of the wood in places. We were applying a fair amount of force to the wrenches.

Take a look at this document: http://www.spaenaur.com/pdf/sectionD/D48.pdf

I "think" it indicates that if I applied maybe 80-900lbs of force on a 15" wrench, I might have been generating 5-6 in/lb of torque. Using the table in the above link I calculate that each threaded rod was generating something like 748lbs of compressive force for a total of almost 1500lbs!!! That's a lot for sure!!!

While making mine, we basically made two, because the friend who helped me in the video also had a bearing to extract (and his strut has a slight different shape/profile). The bearing on his boat "might" have been in place for the life of the boat (~20 years), and it has also spent some time in salt water. At the end of the day, we only got his bearing pushed out by about 1/3 before the Fir aft block began to self-destruct. We were applying significantly more torque that we did with mine. We even ended up using a ~20" breaker bar on the socket. Given the above calculations, I'm sure we were applying more than 2000lbs of pressure.

He had soaked his set screw holes in PB Blaster, and we tried using heat as well (cold temps, 50kt winds and propane didn't work very well), but to no avail.

Ray, how thick are your plates? I suspect that they would have folded under the pressure we were applying. Looking at the strutpro plates, I would guess they are 3/4" thick (plus the 3/8" yoke plate).

Chris

 

[seadaddler]

3 years ago I took my shaft out and had the room to remove the shaft and no problem with rudder,I did
go to Mainsails web site and did what he showed and needed some heat getting the coupler off shaft and a little banging with hammer and used a berns o matic torch for heat.
I got every thing off and was not easy but everything came off and all went back on no problems and removed the cutless bearing shown by mainsail with hack saw just like on mailsails web page and had cutless bearing
in freezer and than ice bucket just before pressing back in like butter.
nick