PROBLEM, HOW TO - open up an inaccessible hole in 10mm s/s?

The best thing for opening up a hole in stainless is a step drill. They're designed for exactly this purpose, and are quite short (in comparison with a drill bit of equivalent size).
How wide is the gap between the cheek plates you have to work in?
 
Irvine_himself said:
Not necessarily true if the inner forestay has been seriously weakened by the use of an incorrectly fitted pin.

After a few years as journeyman, I went off to Uni to avoid having to file holes in SS. Subsequently I worked as an R&D Engineer, vainly believing I could thus avoid H&E. When I dropped out to become a dog handler, I still found myself being assigned as the designated Safety officer.
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it sounds like you have found your true vocation
 
colhel said:
I'd be surprised if the 11mm pin is nothing more than 7/16" used more for convenience than anything else. If I was in this situation I wouldn't hesitate in using 10 mm
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Yes to use a smaller pin would simply mean I put a sleeve or similar into the Highfield lever hole to 'bush' it out.

Many thanks for some educated info from all.... food for thought over the hol's!

S
 
bignick said:
The best thing for opening up a hole in stainless is a step drill. They're designed for exactly this purpose, and are quite short (in comparison with a drill bit of equivalent size).
How wide is the gap between the cheek plates you have to work in?
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That was my first thought, but the plate is 10mm thick. The ones I own have steps about 5 mm deep. I can imagine the bit for the job, but not sure I could source it. I stand by my original suggestion. Stick a nicely fitting 9mm pin in and sleep soundly. If you believe that the intended size of pin has been calculated by some super-precise formula you have more faith than me. I have had rigging quotes from different suppliers in the past, and their recommendations have differed by far greater margins. This is not the stay holding the mast up.

It's true that lots of things on a boat could break and kill someone, and very many boats have bits whose size was determined by owner's eyeball judgement. That's why we have so many yachtsmen killed by breaking stays I guess. It is also possible that the person who does have the one in a million accident may be unfortunate enough to be minced by the insurers or courts. We do need to take all reasonable precautions, but we also do actually want to go sailing.
 
sailorman said:
it sounds like you have found your true vocation
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Perish the thought, it is the most thankless job I can possibly imagine. You get grief from all sides and are the first to be blamed if anything goes wrong. Also, while I do think safety should always be a major consideration, half the time I have really got to wonder what planet some of these bureaucrats live on.
 
Irvine_himself said:
Perish the thought, it is the most thankless job I can possibly imagine. You get grief from all sides and are the first to be blamed if anything goes wrong. Also, while I do think safety should always be a major consideration, half the time I have really got to wonder what planet some of these bureaucrats live on.
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i have done method statements & assessments & handed them over in meetings, they are them put in a folder without a glance, only to be used for ammo "IF" anything was to go wrong. others just ass covering @ my expence
 
If it were my boat I'd simply weld a 10mm chain link cut in half to the top of the plate.In a windless day Tig welding would be possible and the weld would be as strong as the parent metal providing it's done properly.Actually that's what I have on my Fulmar.I made a new central cleat out of an old 25mm propshaft and welded a half chain link on top to which the removable stay is attached.
 
30boat said:
.......... the weld would be as strong as the parent metal providing it's done properly..........
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A common myth!

The subject is very technical, with many variables making it difficult to be specific, but, quoting figures off the top of my head. The filler metal of a butt joint, properly vee-ed, in mild steel with a good quality stick, will only have about 75% of the strength of the parent metal, [basically the weld is too brittle,] and, over time, this butt joint will weaken due to hydrogen accretion and other factors.

Generally, stick welding, (and oxyacetylene,) give far superior welds to MIG or TIG welds, which are used primarily for speed, but result in very brittle welds.

The big problem with welding stainless steel is that chromium compounds precipitate out during the welding process leading to very weak welds. The high frequencies associated with TIG welding help to break up these compounds. Historically, before the wide adoption of TIG, good welders could achieve the same effect by lightly tapping the weld as it cooled.

With all its chemical problems, a SS weld is never going to compare favourably with a similar mild steel weld.
 
Irvine_himself said:
A common myth!

The subject is very technical, with many variables making it difficult to be specific, but, quoting figures off the top of my head. The filler metal of a butt joint, properly vee-ed, in mild steel with a good quality stick, will only have about 75% of the strength of the parent metal, [basically the weld is too brittle,] and, over time, this butt joint will weaken due to hydrogen accretion and other factors.

Generally, stick welding, (and oxyacetylene,) give far superior welds to MIG or TIG welds, which are used primarily for speed, but result in very brittle welds.

The big problem with welding stainless steel is that chromium compounds precipitate out during the welding process leading to very weak welds. The high frequencies associated with TIG welding help to break up these compounds. Historically, before the wide adoption of TIG, good welders could achieve the same effect by lightly tapping the weld as it cooled.

With all its chemical problems, a SS weld is never going to compare favourably with a similar mild steel weld.
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Can you give us a reference to this information? It is very different from my understanding and at least some of it I know to be incorrect. This reference http://www.bssa.org.uk/topics.php?article=147 says about welds in stainless steel:
Butt welds
The design strength of a full penetration butt weld may be taken as equal to the design strength of the weaker of the parts joined,
 
alahol2 said:
You will note that I enhanced the proposition by the insertion of 'high tensile' and by supplying a link to extra reading on the subject.
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That looks like good stuff, high nickel and molybdenum enhances 316 strength and corrosion resistance no end. Both are expensive metals so the cost may be rather high but for a single bolt no doubt affordable.
 
;4521249]Can you give us a reference to this information? It is very different from my understanding and at least some of it I know to be incorrect. This reference http://www.bssa.org.uk/topics.php?article=147 says about welds in stainless steel:
Butt welds
The design strength of a full penetration butt weld may be taken as equal to the design strength of the weaker of the parts joined,
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Unfortunately. not easily, they were rules of thumb that I learned as an apprentice in a general engineering workshop during the early seventies and, since it was a trade I eagerly gave up around 1978, I will most certainly bow to your greater knowledge.

I would say that however, from the point of view of the technical expertise of the people on this forum, that you missed some very important caveats from the BSSA article


The design strength of a full penetration butt weld may be taken as equal to the design strength of the weaker of the parts joined, provided that the weld satisfies the recommendations outlined in the introduction to this article, and that an electrode of minimum specified tensile strength at least equal to that of the parent metal is used......
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I do not think I am being pedantic when I say that from the point of view of both DIY and in a lot of general purpose engineering workshops, the latter condition at least, would be fulfilled only co-incidentally. In other words, it would be welded with whatever electrode was available.

But, having said that, I freely and gracefully concede that my previous post was garbage.
 
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