Need fastener recommendations please

Discussion in 'Wooden Boat Building and Restoration' started by flyingvranch, Jan 23, 2017.

  1. PAR
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    PAR Yacht Designer/Builder

    Dipping the screws in epoxy doesn't work, as it just wipes off as the screw threads its way into the hole. It will improve the "bond" slightly, as the last few threads will retain some goo, but it';s not much of an improvement. More importantly is the remaining buried threads will see moisture/electrolysis gain/lose, which are the real issues.

    The wood has to be encapsulated and the holes properly treated, though admittedly many taped seam builds don't bond the fastener holes, though do cover over their heads with epoxy fillers and don't seem to experence nearly as much problems. This is likely because the wood isn't moisture content cycling, which keeps it away from the fasteners and more importantly, most of these types of builds are trailer borne, limiting exposure.
     
  2. Scot McPherson
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    Scot McPherson Senior Member

    well how is this for an idea...and it's just an idea.

    pre-drilling the screw holes to a precise depth, injecting a tested amount of epoxy into the hole, and screwing in behind the epoxy? The pressure should force the epoxy into the wood surrounding the screw and some back up between the wood and the screw. Shouldn't this create that bonded environment for the screw, and potential increase the strength of the fastening I would suspect manifold in the immediately adjecent to the fastener?

    I don't know if that's practical, but the amount of epoxy needed would be dramatically reduced from requiring a full cloth layup to gain that bonded environment, and may allow one to just use a paint over the wood with possibly glassing only those areas that are more likely to come in brisk contact with something under the water such as stems, keels and maybe chines.

    thoughts?
     
  3. PAR
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    PAR Yacht Designer/Builder

    That's a technique I use occasionally on buried fasteners, though not as effective as a truly bonded fastener, certainly improves pullout strength and the fastener's grip on the substrate. How much? Well a bonded fastener (machine screw) is about 5 times better than a simple wood screw into wood. I'd guess a 2:1 improvement in pullout on a epoxy filled hole, as you've described. Of course porosity of the wood, the species employed and a few other variables come to play. Interestingly enough, tests have shown a machine screw has a much better grip on wood in a bonded hole, than a wood screw that had some goo injected into the hole. Basically it's simple physics and the machine screw, has more surface area on the typically finer threads. A syringe is handy for this and I have a bunch I get from a veterinary supply store near me.

    You don't need cloth over a fastener head, though it does help. If you slightly bury the head, wetout any raw wood, then smear a coating of thickened epoxy over the fastener head dent, it'll protect it nearly as well as anything else, assuming moisture isn't getting at it internally (non-encapsulated).
     
  4. daiquiri
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    daiquiri Engineering and Design

    Can't help thinking that sometimes this forum is such an odd place. :D
     
  5. PAR
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    PAR Yacht Designer/Builder

  6. daiquiri
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    daiquiri Engineering and Design

    Just an impulsive rant which I now feel sorry for. One of those bad days. But now the post is there, so...
    It was a reaction to so many repetitive and iterative considerations even after the answers have been given, Paul. But it wasn't directed to you. I admire the patience and dedication you put in every post you write.
    I am more of a "see the reply in this other thread" type. But I do realize that if everyone replied like that, the forum would soon become the dullest place in internet - so you are actually doing a much better service to the community. Have you thought about writing a book about do-it-yourself boatbuilding? Looks like the time is ripe. :)
    Cheers mate
     
  7. PAR
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    PAR Yacht Designer/Builder

    Yeah, I've thought of it many times, two books really. One the obligatory DIY deal and the other, a book of resources, like marine plywood, goo's, etc., maybe with annual updates. You want to be my proofreader and editor?
     
  8. missinginaction
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    missinginaction Senior Member

    There is an idea. Paul's sarcastic wit combined with his knowledge all in one easy to read place. Based on your posts here Paul, you have so many good stories......that read would be a hoot! Probably have to be self published though.

    I for one would buy it. Sign me up.
     
  9. daiquiri
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    daiquiri Engineering and Design

    Somehow I felt that you must have been thinking of it. I consider it a natural step for someone who has so many things to say and share about technical aspects of boatbuilding.

    Your offer is a great honor for me. However, in my opinion there is not a single person in this forum who has more general knowledge and experience than you about DIY boatbuilding. A group of persons, each one with a specialistic knowledge in their field, could do the job (and share the time burden) of proofreading much better. I am very confident that several technically qualified forum members will be available to help you.
    Having said that, I will gladly be one of them, if and when necessary.

    For sure, I'll be one of readers of your work. Good luck with that project. :)
     
  10. Scot McPherson
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    Scot McPherson Senior Member

    Hi daiquiri,
    I have heard the same arguments on other forums and email lists before. My usual response is that discussion is what makes this a forum rather than a wiki. I have put wiki's together in the past, and watched them die unless the topic had a huge following. Wikipedia is the only truly successful encyclopedic wiki out there, followed by gaming wikis and wikis about super popular movies or TV shows like Star Wars and Star Trek among others of course.

    Discussion is what makes a forum, it's what draws us together. If all we had we had was already been said and done, this would just be a place to search for stuff, and rarely any discussion and therefore no community. I think it's nice to talk about stuff even if it's been talked about before. Those who haven't had a chance to participate in the earlier discussion get to work out their thoughts organically. I think there is real value in that.

    Cheers
     
  11. daiquiri
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    daiquiri Engineering and Design

    I absolutely agree, Scot. Like I said, mine was just a knee jerk and I am sorry for that. Caught me in a bad moment, can happen to anyone.
    Cheers mate
     
  12. SamSam
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    SamSam Senior Member

    Off topic, but related to this book thing.
    Forums like this have a tremendous amount of information, I'm wondering who owns what? Is it all owned by the forum owner, are individual posts owned by the individual posters or is everything public property that anyone can use for whatever purposes they want. Such as publishing a book. ?
     
  13. daiquiri
    Joined: May 2004
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    daiquiri Engineering and Design

    http://www.boatdesign.net/forums/faq.php?faq=terms_of_use - check the paragraph named "Intellectual Property Rights.
    It says that any content published by the BoatDesign.net may not be re-published or used for commercial purposes without permission from the authors or owners of the content.
    On the other side, everything that has been published by the users of the BD.net in the forum or other "interactive areas" can be used freely.

    In any case, it should go without saying that it is highly unrecommendable to use the information and claims in the forum for the purpose of writing a book, without a prior verification of their veracity and validity.

    Cheers
     
  14. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The comments and opinions of the posters is their own. Unfortunately, I'd have to fess up to some undesirable ones over the years, though I've made some modest impact. I've also seen comments cut and pasted into other internet sites, to reinforce someone's belief or point of view. Simply put, if you post it, it's yours and you're married to it. This is nothing more than using a microphone in a crowded room.
     

  15. Barry
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    Barry Senior Member

    As there might be some wooden boat builders watching this thread I wanted to pass along some information regarding screwdrivers.
    Many years I was hanging around my friends gunsmith shop and I remarked on the number of screwdrivers that he had on his bench.
    He showed me one and said that there were made specifically for gun screws so that the screw slot would not get damaged.
    The slotted screw driver ends, the flats, ie the wide part and the shoulders were parallel.
    So particular slots in different sized screws required a much tighter fit than a conventional tapered flat and shoulder screwdriver.
    If someone was building a boat or trying to take out hard to extract screws, this type of screwdriver might make the job easier

    I think that Wheeler makes a kit, one driver and several bits and they are not expensive

    https://www.youtube.com/watch?v=E-DurrIEu-o
     
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