Sheared bolt

[dunedin]

Fitting a new windlass motor the bolt for the electrical connection sheared off. Wasn't using a lot of force - with small spanner for access.

Does the metal look like it was sound or was it possibly a defective bolt? Views

 

[Boathook]

Looks defective to me. Who's good with metals on here. Is it @vyv_cox ?

 

[Momac]

Looks like static failure
If not over tightened then it must be weak material.
I had a brass water pump cover screw fail in the same way . The other screws are sill in use years later.
Also studs for a macerator pump which was probably frost expansion causing static failure,

 

[Poignard]

It isn't a bolt. It's a brass stud with a stainless steel nut

 

[pmagowan]

Looks like some kind of sintered metal

 

[Momac]

I assumed its brass if its an electrical connection. Certainly looks like brass stud with a stainless nut as noted above.

 

[Bodach na mara]

Odd looking thing. It looks like a brass nipple (a tube threaded over its length) with a stainless nut and the central hole is filled with sand!

 

[dunedin]

Yes, brass stud with s/s nut. But metal at break does look very odd to my (non-metallurgist) mind

 

[pmagowan]

Take an image of the other side. I guess a sintered metal with brass outer and there was a flaw in the sintering process which has left it weak.

 

[dunedin]

Take an image of the other side. I guess a sintered metal with brass outer and there was a flaw in the sintering process which has left it weak.

The other side ....

 

[awol]

If you are trying to claim faulty material with the aim of redress, good luck! May I suggest cutting a nut in half and using the bits on the remaining stud. Or you could develop some muscles (or back strain) by lifting your anchor by hand?

 

[pmagowan]

Might not even be metal. Not sure as you would need to read instructions but normally an electrical terminal will need a good conductor for the ring terminal to clamp down on. Can’t see that in the pics as may be below the nut. Stainless nuts/washers are not good conductors and are normally only used to clamp the conductors into a good connection. You need to check that you were using the correct layup of nuts, washers etc. No harm getting in touch with the manufacturer to claim defect but they may say the fill in the terminal is not designed for the force you applied.

 

[vyv_cox]

Not a failure mode that I can identify from two photographs. It has failed at the first thread of the nut, normally the highest tensile point. Looks more brittle than ductile. No sign of fatigue beach marks. The sintered suggestion might well be correct, coupled with over-enthusiastic spannering.

 

[dunedin]

Not a failure mode that I can identify from two photographs. It has failed at the first thread of the nut, normally the highest tensile point. Looks more brittle than ductile. No sign of fatigue beach marks. The sintered suggestion might well be correct, coupled with over-enthusiastic spannering.

Vyv. Thanks very much. What does “sintered” mean?
And for a non expert like me, is this simply over tightened (by a wimp like me) or is there a likelihood that it was a faulty stud?

 

[dunedin]

If you are trying to claim faulty material with the aim of redress, good luck! May I suggest cutting a nut in half and using the bits on the remaining stud. Or you could develop some muscles (or back strain) by lifting your anchor by hand?

Sadly my barge weighs twice as much as your elegant little Contessa

Does anybody have any suggestions for an auto electrical place in Oban that might be able to strip the motor and replace the stud?

 

[AngusMcDoon]

What does “sintered” mean?

Metal munged together from powder.

 

[Bodach na mara]

Sintered components are usually porous to a degree and are made by filling a mould with a powdered form of the material to be cast with a critical distribution to grain sizes and shapes. The mould is then heated to the point where the points of the grains which are in contact fuse and a fairly weak but porous solid is formed. Or as Angus said above much more simply!

I have encountered the products myself only in laboratory glassware where the process is used to make filters, but I was told once that it was also used to make bearings, which could absorb a lubricant. All of which is irrelevant in connection with a connecting stud!

 

[pmagowan]

Copper is expensive so might be a simple threaded tube with another material internally. Sintered stuff is just a cheap way to mould things. As described above they take a powder and heat is until it sticks together. Often used in metal components as actual casting is more expensive. I can’t find out how you are supposed to wire the motor. IMO there should be a good conductor on the base and both nuts and any washers should go on the outside but it seems like you have the wire terminal (or had) between the nuts. Perhaps they are not stainless because stainless steel tends to be a poor conductor which heats up under load. Like on a battery terminal all the SS bits should go on top of the wire terminal not between it and the lug. Might be different with the windlass but online manual doesn’t seem to say much on the wiring.

 

[AntarcticPilot]

Not a failure mode that I can identify from two photographs. It has failed at the first thread of the nut, normally the highest tensile point. Looks more brittle than ductile. No sign of fatigue beach marks. The sintered suggestion might well be correct, coupled with over-enthusiastic spannering.

Very much a shot in the dark, and I defer to @vyv_cox ! But assuming the colour on the first photo is right, it looks very like copper oxide, not copper metal.

 

[cpedw]

Does anybody have any suggestions for an auto electrical place in Oban that might be able to strip the motor and replace the stud?

You could ask Robert Desadler 07799143888. He's based at Lerags south of Oban but travels in the area. He deals with boat engines and electrics but has been talking of retirement.