JB weld on ss prop shaft

[BrightAyes]

My prop has a locking bolt that is threaded into the center of the SS prop shaft. The threads are stripped and the hole is not straight so would like to fill it and re tap it. Anyone have experience using JB Weld Steel in an underwater application like this? Will the steel in the JB weld corrode in the salt water environment?
The prop shaft is not easy to remove so I am looking for a solution other than welding it up and so I can re-drill and tap it.

[a64pilot]

Threaded insert?
JB weld in an emergency only when no proper repair can be made, no way it could last long and may fail very soon. (in my opinion)

[model 10]

Too bad the old hole is not straight. A Heli-coil can be installed crooked so you could install one to off set the crooked and stripped hole you already have.
As a safety, JB Weld is probably not safe. The corrosion would probably be on the shaft under the JB Weld, not the JB Weld itself.

[PJOHara]

one of the best products for rethreading an existing stripped thread is called Time-Sert,
do a Google search. Another option could be to go up 1 screw size, drill the holes the correct size and retap them.

[Cheechako]

I wouldn't use JB there. maybe a Helicoil though

[SVJennie]

I'll go with PJOhara's suggestion of using next larger bolt size. I have also found that both stainless steel metric and imperial fasteners are readily available in the States (if that is where you are at), accordingly I would see what minimum size hole could be drilled and try to match the fastener to that. The most difficult part will be to drill a straight hole in the shaft. I recommend making up a collar type jig to ensure concentricity when drilling.

Good luck

[mserafi1]

Not a job to mess around with. Weld it up, blend the weld, use a split collar jig to guide the tap drill straight, and use the second hole in the jig to start the tap. Too important a job to muck around with jbw.

[seasick]

Another option is to switch to a castellated prop nut and drill your prop shaft through from side to side to accommodate a cotter pin.

[Twilite]

Retap existing hole same size? If not, go next larger size checking alignment as you drill..Retap again, flush thread debris out with lubricant and check work.

[Uncle G]

"My prop has a locking bolt that is threaded into the center of the SS prop shaft"

Is the bolt parallel to the centre line of the shaft or at right-angles?

Normally the prop sits on a tapered shaft with a key or a parallel splined shaft and is held on in reverse by a nut of some sort aft.

I don't understand the geometry of your problem.

[GrahamHO]

It's almost impossible to re drill and straighten a hole that is not straight. The drill will follow the original hole. I would look at using a helicoil to repair the thread and live with the hole not being straight. It must have worked prior to the thread stripping. Not ideal but it should work. A helicoil set comes with a special sized drill and tap. Don't forget to renew the retaining bolt. If the hole is out of alignment it will put a strain on the head of the retaining bolt especially if it's over tightened. Use loctite on the new bolt and don't over tighten.

[GrahamHO]

Additional to my helicoil suggestion. When drilling and tapping SS use plenty of cutting fluid and reasonable pressure on the drill. With light drill pressure the SS will work harden. When tapping keep backing off the tap every half turn or so to clear the threads. SS is very hard to tap and you can make it easier by extending the tap holder handles with two pieces of wooden doweling with holes drilled into them to accept the tap holder handles. Been there done that.

[oleman]

I have been attempting to use JP Weld for the past 50 years. It has eventually failed in every application I have attempted.
Pull the shaft, mig up the bad area. Center drill and retap in a lathe.
Only to drill to the center of a shaft is in a lathe.
Any good machine shop should be able to do a proper job

[GrahamHO]

Oleman. Yours is the correct solution but BrightAyes doesn't want to remove the shaft or weld. Certainly JB weld won't work because it is softer than SS and will make a mess that still can't be drilled or tapped correctly. The helicoil way will work with a new lock bolt and using loctite. I'm surprised that the hole is not straight as the shaft end taper, keyway, retaining nut thread and the problem hole must have originally been made in a lathe. I wouldn't be surprised if the hole just appears out of alignment because the thread is stripped. In which case a helicoil will be fine and take maybe an hour including a coffee break.

[tinkrman69]

Hi Brightayes.

Your drilling underwater? I assume with pneumatic drill or Brace and bit? Take planty of bits with you and drill it slow taking out very little at a time. if the first drill starts to drift off center don't go all the way in and slowly start with the next size drill bit holding pressure to the side you want the whole to go. just take it a little you can get it closer with the nest bit. take it up to the size for a heila-coil. If you take your time and pay attention to the alignment with the shafts center line you'll get it close enough to not cause excess vibration from the balance of being off balance. you may luck out and get it right or just close enough to get by till you can pull the shaft. If you pay attention and don't use BRUTE force you'll do fine. just because it's metal doesn't mean finesse isn't necessary.