Sheared bolt on anode bracket

[Herman Melville]

Hi I was changing the transom bracket anode and one of the two bolts either end holding it on sheared.

I have been unable to drill it out so far breaking about 6 HSS drill bits in the process.

Worse still the last drill bit sheared in the hole that had begun to be made so now it's even harder to get out.

Any suggestions before I make it even worse than I already have?

Cheers

[Herman Melville]

I don't think the picture worked - have attached it here too - I think..

[paintman]

You might want to consider mig or tig to weld a washer onto the stub & then a nut onto the washer.
The heat helps loosen stuff.
Done it a few times but unless you have the kit you would be best finding a local small enginering company & asking them if they can do it.

You MIGHT be able to drill it out with a tungsten carbide tipped bit - I used some to drill into steel window lintels that HSS bits were struggling with.
Went in effortlessly.
Not cheap but worth it.
www.ebay.co.uk/itm/222556144960
Note that these are NOT the same as tipped masonry bits.

[Herman Melville]

I have drilled and drilled and drilled.

every time i've opened up a decent hole I've got the extractor in there and not joy.

repeat.

Currently I think I am going to either end up going all the way through and putting a bolt in or fix the other end with it's bolt and this end with marine epoxy - will still be able to conduct one end.

It's a nightmare.

[A1an]

Is that an M6 bolt?

I’d be trying to weld a nut on the end of that but if that’s not an option and you’ve had your fill of drilling you could cut a deep slot in the bolt then use a wide flat headed bit on an impact screwdriver.

My gut feeling is that it’s going to need heat whatever you do.

[A1an]

Originally Posted by paintman

You might want to consider mig or tig to weld a washer onto the stub & then a nut onto the washer.
The heat helps loosen stuff.
Done it a few times but unless you have the kit you would be best finding a local small enginering company & asking them if they can do it.

You MIGHT be able to drill it out with a tungsten carbide tipped bit - I used some to drill into steel window lintels that HSS bits were struggling with.
Went in effortlessly.
Not cheap but worth it.
www.ebay.co.uk/itm/222556144960
Note that these are NOT the same as tipped masonry bits.

I’ve got a set of tungsten drill bits, I love and hate them in equal amounts. They are extremely sharp and durable but very brittle and once they snap and get stuck in a hole they are almost impossible to drill out.

[Herman Melville]

its quite recessed so can't weld onto it really.

Cutting a groove might just do the trick.......

[Herman Melville]

problem is that the bolt is tiny , only M6, and the grinder blade will probs be nearly as wide......sos chances of success also low...

[Oldman2]

Mig weld into the hole you have will heat it up some and with repeated welds will build a tit over which you can weld a nut with yet more heat, then cool it some with wd40 or a n other make and try a spanner on it. If it shears, go again, more heat etc. I have lost count of the exhaust manifold studs I have removed that broke well below flush. If you dont have the gear, take it to a welder, he will know what to do. Good luck!

[paintman]

In view of the problems you're having with it I'd suggest taking the 'local small engineering company' option.
Worth a chat to see what they can offer.

[Peter_C]

Could you drill another hole and tap it right next to the current location? Then leave the old one in place, and grind the nub off.

Snap-on Tools cobalt drill bits make holes in stainless pretty easy *shrugs* Sometimes you have to drill the holes out until you can pick the bolt threads from the hole threads, IF the hole is centered.

Heat is always a good trick. Another one is taking a punch and hammer then smacking the bolt before ever trying to loosen it. The hammering shock helps knock everything loose. It is a feeling to learn when something is about to break. An anti-seize compound helps in future removal.

[Herman Melville]

Thanks all.

The hole just a cratered pit now. About 6mm in depth.

Something strange is pitting itself against me. I wonder if the bolt was permanently threadlocked in... I only undid it with a 1/4 inch short 10mm socket - it was soft straight away. I wonder if whoever put it in before knew it was on the 'dick' and locked it and when it suddenly went soft on the tighten just ran away....

Anyway is it not coming out and drilling and tapping the same hole looks like a nightmare as it's slightly off centre. I would also have to do it in place upside down on the ground under the stern becuase I don't have an engine hoist to get it all off and make it more accessible.

I 'could' I supose grind the area flat and drill and tap one next to it...that's joint plan A but I would have to buy cobalt bit which no doubts I woudl break and I don't have any taps.

Alternative in my mind is to weld it full then weld the stainless steel stip on instead of bolting the strip on. Then I can get the anode back on. Problem with that one is I don't know how well the weld would hold up to the salt enviroment.

Cheers

[Herman Melville]

Course if the plan of last resort is weld it I could try tapping a new hole by the side and tapping that then weld it all if it fails....

[Peter_C]

No need to weld anything. That housing is aluminum correct? Just drill and tap another hole in a location that will accommodate the anode. You could even use a different shape of anode if needed. Just look on the other side before drilling.

Aluminum and stainless react together in salt water causing corrosion. You can help slow the galvanic corrosion down by using an anti-seize compound.

A 6mm tap is cheap like $8.00 USD, and most any ole drill bit will make a hole in aluminum.

Another trick when drilling a hardened bolt is to start with a smaller drill bit and keep it centered, then upsize so an extractor can be used. I like the short extractors that don't break. Also lots of lubricant when drilling harder metals.

[Herman Melville]

Thanks @Peter_C

Yes welding would not be ideal and I will avoid.

I have a tap but my HSS drill bits will barely touch the hole - I don't think it's aluminium. I could be wrong but I thought it was stainless steel.

This is a good point I don't 'actually know' for sure what the block is made of to be honest - just that whatever it is seems to be well corrosion resistant. If anyone knows what metal it is then that would be interesting since I would need to know in the event it did get welded....

Anyway in the meantime some cobalt bits are on their way to me now and I will have a go at making a new hole to the side.

Cheers,

[Herman Melville]

Found this on the Yamaha website

"The lower unit is cast with an aluminum alloy (YDC30, Al–Si series) specifically developed to improve corrosion resistance, and it also has the strength and rigidity to withstand impacts with things like driftwood"

So I assume the bracket is made of the same stuff.

You live and learn !!

[Pikey Dave]

Originally Posted by Herman Melville

Found this on the Yamaha website

"The lower unit is cast with an aluminum alloy (YDC30, Al–Si series) specifically developed to improve corrosion resistance, and it also has the strength and rigidity to withstand impacts with things like driftwood"

So I assume the bracket is made of the same stuff.

You live and learn !!

Look up “spark erosion” & see if you have a local practitioner.

[Herman Melville]

Thanks - I didn't know about Spark Erosion.

Will take a look.

[willk]

Oh man....

[Nasher]

I think you'll struggle to find anyone who can Spark erode in situ.

You are more likely to have to strip the saddle etc down so they can put the removed part in/on their machine.