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PostPosted: Tue Aug 01, 2017 8:00 pm 
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Joined: Mon Apr 17, 2017 1:46 am
Posts: 249
Location: Sweden, sjöbo
Greetings!
I am having trouble to find stainless 1/4-20 allen socket capscreews minimum 3" long for my project.
I am replacing the original bolts for the aka crossbars on my TI but need longer bolts, minimum 3"
(I think the original bolts are 2-1/4)
I have searched the internet but I cant find screws that are long enough.

Anyone who has a tip?
Best regards
/Gustav

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PostPosted: Fri Aug 04, 2017 3:24 am 
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Joined: Sat Aug 31, 2013 1:54 am
Posts: 7
Location: Sweden
Hello !
Göteborgs skruvcenter http://skruvcenter.se

had this longer screws but not with philip head when i checked a few months ago. Too big nut heads for my old crossbar but maybe it works for you.

greetings


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PostPosted: Fri Aug 04, 2017 3:54 am 
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Joined: Sun Apr 20, 2008 6:18 am
Posts: 2983
Location: Sarasota,Key West FL
Just curious why your looking for marine grade stainless, (usually 4x to 8x the price), as far as I know the bolts are the same materials , It's just the marine grade bolts are dipped in acid to remove the iron content from the surface only , ( thus the grey appearance), all stainless bolts have a small amount of iron content, (any iron trapped below the surface is safe from corrosion btw). You can buy regular stainless bolts and dip them in acid yourself, (I've done this with pool acid) Actually I don't even bother doing that. I just buy standard stainless bolts ( Home Depot or Lowes) and just use them as is with no issues.
Keep in mind marine grade fasteners don't prevent galvanic corrosion, really the only difference is the marine grade doesn't form a thin superficial layer of red surface rust, which doesn't hurt a thing.
I always spray all my stainless bolts with krylon clear coat as I'm putting them in, then soak around the bolt or rivet head with krylon clear coat, ( locktite also helps prevent galvanic corrosion on the threads).
If you can prevent the salty water from penetrating into threads and body in the first place it goes a long way in preventing galvanic corrosion especially into aluminum.
Just tryin to help here
FE


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PostPosted: Mon Aug 07, 2017 6:33 pm 
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Location: Sweden, sjöbo
winduser wrote:
Hello !
Göteborgs skruvcenter http://skruvcenter.se

had this longer screws but not with philip head when i checked a few months ago. Too big nut heads for my old crossbar but maybe it works for you.

greetings


Thanks for the tip mate I will check it out.
:)

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PostPosted: Mon Aug 07, 2017 6:47 pm 
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Location: Sweden, sjöbo
fusioneng wrote:
Just curious why your looking for marine grade stainless, (usually 4x to 8x the price), as far as I know the bolts are the same materials , It's just the marine grade bolts are dipped in acid to remove the iron content from the surface only , ( thus the grey appearance), all stainless bolts have a small amount of iron content, (any iron trapped below the surface is safe from corrosion btw). You can buy regular stainless bolts and dip them in acid yourself, (I've done this with pool acid) Actually I don't even bother doing that. I just buy standard stainless bolts ( Home Depot or Lowes) and just use them as is with no issues.
Keep in mind marine grade fasteners don't prevent galvanic corrosion, really the only difference is the marine grade doesn't form a thin superficial layer of red surface rust, which doesn't hurt a thing.
I always spray all my stainless bolts with krylon clear coat as I'm putting them in, then soak around the bolt or rivet head with krylon clear coat, ( locktite also helps prevent galvanic corrosion on the threads).
If you can prevent the salty water from penetrating into threads and body in the first place it goes a long way in preventing galvanic corrosion especially into aluminum.
Just tryin to help here
FE


Greetings!
:)
I use the term "marine grade" for SS with the AISI 316 or A4 (EN 4401/4/6) spec (steel that can endure some acid corrosion pretty well).
In Sweden we call theese types of SS "acid resistant". They endure the saltwater perfectly and do not rust at all.
AISI 304 or A2 (EN 4306/7) SS is mostly cheeper but is pretth worthless in marine environments. Starts to rust pretty fast.
The diffrence is in the steel alloy and has as far as I know nothing to do with "dipping in acid". The A4 has an alloy containing Molybden that does the "magic" and also explains the "magical" price.
I was not aware that "marine grade" had any other meaning? The color is not at all important for my project only durability.
Oh sorry I have to edit the post a little. Color does matter. Rust even a thin outer layer is NOT ok in my book. :) Just hate it! :)
If you have some info of a suplier/retailer that has longer 1/4-20 bolts with hex/allen cap heads it would be helpful! :)

To prevent galvanic corrosion is hard. As you are stating the only way is to try to elecricaly isolate the materials and /or use an anode.
I usually try to use silicone greese between aluminum and SS. Helps a bit but is not the perfect fix. Plastic/rubber washers help but cant be used if the forces/loads are to big. Its just a pain in the neck you have to live with.

Thank for the help!
/Gustav

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PostPosted: Thu Oct 26, 2017 3:34 pm 
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Joined: Fri Aug 11, 2017 9:16 am
Posts: 18
Location: San Diego, CA
I'm probably late here, but I usually find what I need from McMaster-Carr. Here's the screw you were looking for: https://www.mcmaster.com/#92185a557/=19zhckp


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PostPosted: Fri Oct 27, 2017 5:14 am 
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Joined: Mon Apr 17, 2017 1:46 am
Posts: 249
Location: Sweden, sjöbo
domr wrote:
I'm probably late here, but I usually find what I need from McMaster-Carr. Here's the screw you were looking for: https://www.mcmaster.com/#92185a557/=19zhckp


Thanks a lot for the tip!
I will order from them if they can ship overseas.
:D
For now I have mounted the aka crossbar with new longer stainless A2 bolts but I now they will slowly rust as I will head out on longer trips next season without possibility to clean the kayak with freshwater for up to 3-4 weeks.
All the best!
/Gustav

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