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isobars
Joined: 12 Dec 1999
Posts: 20935
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 Posted: Wed Jul 29, 2015 12:44 pm Post subject: |
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I didn't realize Ikea made furniture for use underwater, fresh OR salt.  |
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eastfork
Joined: 10 May 2007
Posts: 20
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| Posted: Wed Jul 29, 2015 2:33 pm Post subject: |
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| Those are not brass and will last until the rust |
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whitevan01
Joined: 29 Jun 2007
Posts: 607
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| Posted: Fri Jul 31, 2015 8:29 am Post subject: |
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then use the Ikea nuts in your fins and see how long they last.
brass is not cheap |
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westender
Joined: 02 Aug 2007
Posts: 1288
Location: Portland / Gorge
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| Posted: Fri Jul 31, 2015 5:29 pm Post subject: |
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| Drill it out from the side, use a C clamp to press it out, knock it out with a hammer and punch, soak in vinegar to loosen up the corrosion. Get almost free CGWA fins that include the nut. Get a Dremel tool and grind it out. Shoot it out. Is it fixed yet? |
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isobars
Joined: 12 Dec 1999
Posts: 20935
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| Posted: Fri Jul 31, 2015 8:18 pm Post subject: |
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| Westender comes through again. |
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rigitrite
Joined: 19 Sep 2007
Posts: 520
Location: Kansas City
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| Posted: Fri Jul 31, 2015 9:38 pm Post subject: |
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| Quote: | | You want them soft. In theory in the case of an impact it would fail before ripping your finbox out. I'm not sure how accurate that is in reality... But it is a press fit. So friction is the only thing holding it in... |
Oh shit! a chance for me to geek-out...cannot.....resist.....
So, the thing here is that "soft" and "strong" as it applies to metals are not mutually exclusive. For example, brass is a soft metal; easily galled, easily machined, etc.. However, it is also quite strong. Decent quality brass has a yield strength close to that of some mild steels. So, while some care should be taken when threading brass machine screws (due to galling) they will not yield and prevent your box from being destroyed. The fin material will probably fail first.
The reason that it chosen for what we in the process industry would call "marine service" is it's resistance to corrosion (general attack), which is superior to stainless steels. If you wanted something better, then you'd need to use titanium. The fasteners from IKEA are plated steel, they're cheaper due to economy of scale. Brass is quite cheap to make parts from: easy to cast, easy to machine, easy to braze, but there's just not many of these parts made, so it's the opposite economy of scale.
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johnl
Joined: 05 Jun 1994
Posts: 1330
Location: Hood River OR
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| Posted: Fri Jul 31, 2015 10:07 pm Post subject: |
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| rigitrite wrote: | | Quote: | | You want them soft. In theory in the case of an impact it would fail before ripping your finbox out. I'm not sure how accurate that is in reality... But it is a press fit. So friction is the only thing holding it in... |
Oh shit! a chance for me to geek-out...cannot.....resist.....
So, the thing here is that "soft" and "strong" as it applies to metals are not mutually exclusive. For example, brass is a soft metal; easily galled, easily machined, etc.. However, it is also quite strong. Decent quality brass has a yield strength close to that of some mild steels. So, while some care should be taken when threading brass machine screws (due to galling) they will not yield and prevent your box from being destroyed. The fin material will probably fail first.
The reason that it chosen for what we in the process industry would call "marine service" is it's resistance to corrosion (general attack), which is superior to stainless steels. If you wanted something better, then you'd need to use titanium. The fasteners from IKEA are plated steel, they're cheaper due to economy of scale. Brass is quite cheap to make parts from: easy to cast, easy to machine, easy to braze, but there's just not many of these parts made, so it's the opposite economy of scale. |
Okay so my metallurgy is weak  BUT expain why not BOTH brass nut and screw or why not both stainless nut and screw. Curious minds want knowledge 
Although I now remember it was a US fin with a nut made from plastic with a brass insert that was a breakway (oops). Although I am still curious about my question above... |
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westender
Joined: 02 Aug 2007
Posts: 1288
Location: Portland / Gorge
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| Posted: Fri Jul 31, 2015 11:37 pm Post subject: |
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| Metal transfer. The OP probably had a burr on the top of the nut from the pulled and stripped threads that would need removal before it would come out easy. You can do similar metals but not without lube or anti seize. |
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rigitrite
Joined: 19 Sep 2007
Posts: 520
Location: Kansas City
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| Posted: Sat Aug 01, 2015 9:36 am Post subject: |
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| Quote: | | Okay so my metallurgy is weak Rolling Eyes BUT expain why not BOTH brass nut and screw or why not both stainless nut and screw. Curious minds want knowledge |
That's actually a great question. Why don't we have both brass machine screw and insert. I suspect that the reason is that the board and fin are bought from different suppliers and manufacturers 95% of the time, and that there isn't coordination. Brass fittings are typically a little harder to find; my hardware store has 300 series stainless parts, but very few brass parts. I tend to use stainless machine screws, just because they're not very expensive and easy to find. I use anti-seize with them, and I take everything apart after use. The stainless does corrode, but very slowly. If you leave brass & stainless together in contact with fresh or (even worse) sea water, you'll get both general attack & galvanic corrosion (due to dissimilar metals and the salt content in the water...even fresh water).
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UncleRandy
Joined: 18 Sep 2009
Posts: 63
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| Posted: Sat Aug 01, 2015 8:07 pm Post subject: |
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One way of removing the barrel nut is to press the old one out with the new one Putin the new one in at the same time. Put the fin in a vice or press , a deep and wide socket on the side lube is and just press it out and new one in.
Unless there bur or other problem it should be pretty ez. Make sure the threads are in the right direction. |
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