Jump to content

Designer

Mistake with stainless steel fasteners

Recommended Posts

">Website
  • LocationVandemere, NC
  •  

    As has often been seen in this forum, many of the builders share their mistakes unabashedly with the world. In most cases it is just a matter of making a few adjustments or redoing a job and at worst, some time and materials have been wasted. It does help to educate the builders who follow and it is well taken by experienced builders who have made their share of mistakes with a “brother’s in arms” attitude and often share some of their mistakes. In the spirit of sharing information here is one of my screw-ups.

     

    As a professional, we don’t make mistakes! I wish that that was true. We just make different mistakes. One of my short comings is being too familiar and do things for myself that I would never do for anyone else.

     

    I am currently redoing my inside port rings on Carlita. I love the design and they have worked perfectly and look really good. For some reason our marine wholesaler who supplies most of our marine fasteners does not carry #10 x 32 flathead machine screws. They have to be that size to fit the rivnuts already installed. I did not get around to outsourcing the screws until I was rushing to get ready for the Everglades Challenge. I asked Carla to pick some up for me at the local Ace hardware and installed them.

     

    By the time I got back from the EC I noticed that a couple of screws were starting to rust. I replaced them in time but last year I noticed some more were rusting and put it on my mental list to do. While rushing to get ready for my Port Townsend trip I forgot to change them out and planned to do it when I got back. The screws kept nagging at me and I finally got serious about them before the last messabout and discovered that I could not unscrew four of them. I put it off until after the messabout because I did not want to risk putting her out of commission.

     

    I tried to unscrew them again last week without success. I sicced Alan onto them with the same result. My last resort was to remove all of the willing screws and pry out the ply rings forcing them to break at the seized screw and then grab them with vicegrips. It worked well until the very last screw which twisted off.

     

    Luckily I made the original cut files for the ports and it was only a matter of putting some 9mm scrap on the CNC machine and I cut out a new set of rings. They now need their inside edges to be rounded over with 5/16” roundover bit, sand them and epoxy coat and varnish before installing. I still have to solve getting out the sheared screw first.

     

    I ordered up some 316 grade machine screws because I do not want to do this again.

     

    We magnet tested the old screws and the rusted screws jumped to the magnet. The rest of them were mildly magnetic. Of course the new 316 grade screws were not attracted to the magnet.

     

    Had I bothered to magnet test the original screws, I could have taken the bad ones back and had them replaced.

     

    You can see the two left screws were steel with the lower one sheared off. The right screw was also steel. The next pictures shows one of the original with a new 316 grade screw. The other picture is the broken out ring.

     

    I do not know why so many screws were bad but they were in self service bins and perhaps some steel screws were returned and put in the wrong bin.

    Screws.jpg

    screws2.jpg

    Port ring.jpg

    Share this post


    Link to post
    Share on other sites

    Very typical these days.,, Maybe on your next rodeo use bronze machine screws if you have to order them in and just put some epoxy or varnish over the heads to keep them from tuning green, if you want to be anal about it. They would come closer to matching the wood too.  Of course you can cut them off to fit the thickness needed since its hard to buy the fasteners that's probably short enough. If nothing else you should be able to just relocate the new fasteners offset from the current ones with new and even counter bore the back sides of the ring, allowing the leftover threaded shanks to just be hidden. If you need to, use a bit thicker wood for the ring to achieve that. And I have great success with the Loctite[formailly PL products] Roofing and Flashing Sealant which is black to bed the rings to the plywood with just about four fasteners .  And for removal, you can just use a sharp  flat putty knife with some heat to get the ring started and then just razor knife the bedding if you need to remove it.  But you surely would not need as many if you use thicker wood for the wings. Oh and by the way clock your heads please for your finished product.:lol: 

    Share this post


    Link to post
    Share on other sites

    That's odd - I'd stopped purchasing *anything* (fasteners or hardware) from Home Depot or Lowe's as 99% of it is Chinese crap; our local Ace stocks a fastener-palooza and I have no problem finding non-304 stainless, mostly for my bikes and tannic woods like the CAHVG redwood that's our siding.

     

    Near constant salt-water exposure, is 316-grade stainless insufficient for an inner port-ring application?

     

    Mike

    Share this post


    Link to post
    Share on other sites

    When labor and/or the money to pay for it was of no consequence I would go so far as to polish the 316 SS fasteners on a jewelers rouge wheel. (we had one in the carpenter shop at work)  No matter how good the SS, there will always be some crevice corrosion.  Polishing is another step to filling in the crevices. 

     

    For my own boat I would go with Mike's suggestion to use bronze.  I like green.

     

    I don't buy anything from big box stores rattus, even for my house, never mind my boat.  "Real" full service hardware stores usually stock good fasteners, or at least can order them for you.  https://www.jamestowndistributors.com/userportal/main.do is my main go to if I don't already have a better source for something like this.

    Share this post


    Link to post
    Share on other sites

    I've had good luck over the years using anti-seize goop on all threads. Up here in NY they use salt on the roads and it creates quite a corrosive environment. Lot's of broken bolts over the years. My experience with motorcycles transferred to boat and I use this on all fasteners.  A little dollop of this makes anything come apart down the road pretty easily FWIW.

    image.png.c2228b33d088274613ad1434b69a6df9.png

    Share this post


    Link to post
    Share on other sites

    Geek alert!

     

    316 stainless becomes magnetic when it's cold worked (bent, hammered, spindled, mutilated etc.)  You can file a nice piece of non-magnetic 316 and pick up the filings with a magnet.

     

     

    Share this post


    Link to post
    Share on other sites

    If the rivnuts are also stainless steel I second Steve's suggestion.  Use anti-seize any time you have two stainless fasteners in contact with each other.  Some of the mine sites I've worked with up North use groundwater that is saltier than the ocean to wash the equipment down and I've had the anti-seize rule drilled into my head (fortunately not literally) by frustrated maintenance crew.

    Share this post


    Link to post
    Share on other sites
    On 11/18/2018 at 9:15 AM, Hirilonde said:

    ...

    I don't buy anything from big box stores rattus, even for my house, never mind my boat.  "Real" full service hardware stores usually stock good fasteners, or at least can order them for you.  https://www.jamestowndistributors.com/userportal/main.do is my main go to if I don't already have a better source for something like this.

    Been happy with Manasquan Fasteners too.

     

    https://www.manasquanfasteners.com/category/specialty-sharx

     

    Edited by rattus
    added a link

    Share this post


    Link to post
    Share on other sites
    ">Website
  • LocationSalt Spring Island, British Columbia
  • Back in the 80’s I did a test of several products to find out what worked best to keep aluminum and stainless from welding themselves together. Took a piece of aluminum sailtrack and tapped a series of holes in it, screwed a stainless fastener into each one with a different product and torquing them all to the same level of tightness. After 6 months on the splash zone of a dinghy that was used every day each screw was removed with a torque wrench. The winner was LANOLIN. It was sold as LANOCOTE. The runner up was Silicone.Those sheep make good stuff. I have been using it ever since with very good results. That is not to say there are not other things that are as good or better. Just my experience.

    https://www.forespar.com/products/boat-lubricant-lanocote.shtml

    Ken

     

    Share this post


    Link to post
    Share on other sites

    As long as we are talking about SS Fasteners, I have a question about attaching the B & B aluminum sail track to the masts. I'm planning on painting my masts first (after the ramps are made), then drilling the rivet holes and then using the supplied rivets to attach the track. What prevents galvanic corrosion on the backside surface of the rivets? And all of the other attached hardware, whether riveted or bolted, same question.

    Share this post


    Link to post
    Share on other sites
    ">Website
  • LocationNorth Carolina, Raleigh
  • Steve, 

    Easy answer is nothing. The way I see it there is no way to 100% prevent stainless steel touching the aluminum either on the backside (inside) of the tube or in the hole walls if you miss a spot with your duralac or other corrosion inhibitor compound. That being said, i don't think it's as big a problem as most fear. As an example, after the failure of Southern Skimmers lower mast section in the EC the other year I was keen to inspect the inside of Joe and Sally's EC-22 mast which is built to the same specs. We used a boroscope tool with a smartphone to take video of the inside of the tube focusing on the rivets and bolts that poked through and the general condition of the aluminum inside. We found little to no corrosion other than a normal surface layer. Nothing to worry about AT ALL. There was no more corrosion around the threads and rivets than anywhere else. By contrast, Skimmers mast failed because it had a large sleeve of carbon, glass and epoxy glued into the lower section at the tabernacle as reinforcement and insurance just in case the thin wall tube was too much on the ragged edge of the safety margin. The mast never failed but the sleeve kept water from capsizes trapped which corroded the tube badly until it failed. 

    Share this post


    Link to post
    Share on other sites

    Personally I use two types of insolators along with never seeze compound on threads of dissimilar metal applications. This can apply to the masts or trailer parts where you use aluminum trailers.  Go to your hardware store and get the flat sink faucet washers and use between the heads of panhead fasteners if you use screw threads. For machine threads use small hexhead fasteners. I also use nylon flat washers too if you cannot get the correct size of the rubber washers for the hardware.  Of course if you wish to use permatex Loctite, you can do this also . You don't have a lot or surface area to worry about not being able to remove them down the road.

    Share this post


    Link to post
    Share on other sites
    ">Website
  • LocationSalt Spring Island, British Columbia
  • If you plan to use Never Sieze or Anti Sieze look at the formulation. They are not all the same.  Some have more zinc, some more cooper, etc. When I have used a lot of that stuff I tried to find the highest zinc content. My guess is the formulations have gotten more sophisticated since the time I looked into it.  

    Read up on Lanolin and see what others have to say. My experience is that it is amazing stuff and easy to work with. I would smear it on stainless screws before screwing then into aluminum. There is a spray that I would use in hard to reach places  and inside of rivet heads, etc.

    Another advantage to Lanolin is it keeps the sheep employed to create more wool for my wifes obsessive knitting habit.  

    This is my experience and there are probably many others good solutions.

     

    Share this post


    Link to post
    Share on other sites

    Just make sure when you buy SS fasteners, that they are passivated per QQ-P-35, ASTM A967 or equivalent standards.  Cheap SS fasteners, including most of those sold by West Marine, etc., are not passivated and will rust much faster.  I often buy parts and fasteners from McMaster-Carr because they are very specific about the standards for most of their fasteners and they are fast.  

    • Thanks 1

    Share this post


    Link to post
    Share on other sites

    Join the conversation

    You can post now and register later. If you have an account, sign in now to post with your account.
    Note: Your post will require moderator approval before it will be visible.

    Guest
    Reply to this topic...

    ×   Pasted as rich text.   Paste as plain text instead

      Only 75 emoji are allowed.

    ×   Your link has been automatically embedded.   Display as a link instead

    ×   Your previous content has been restored.   Clear editor

    ×   You cannot paste images directly. Upload or insert images from URL.

    Loading...
    Sign in to follow this  



    ×
    ×
    • Create New...

    Important Information

    By using this site, you agree to our Terms of Use.