Brass vs. Bronze screws

Discussion in 'Wooden Boat Building and Restoration' started by crosscut, Feb 9, 2008.

  1. diagram
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    diagram Junior Member

    TeddyD,

    How do you get a brass screw to hold up just in the installation? They deform or sheer off - not to mention the zinc issue. I realize there are different make-ups of brass but, the stuff I see - marine or residential - not worth my time and I do not even consider it from the outset nor have I for many years. Siliicon Bronze or 316 SS. I don't use Monel except for staples - would definitely consider it, though. 'Pot Metal' seems to come with alot of residential hardware and it is OK but, don't bare down too hard or you'll spend the next few hours digging out the sheered shank and cutting in some good wood.

    Longliner,

    I use Jamestown Distributors in RI. I'll ask about the country of origin. I have not had any issues with their Silicon Bronze but I mostly use SS when given the choice. I agree, the cost - typically is not an issue and I am more comfortable with the end product.
     
  2. longliner45
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    longliner45 Senior Member

    par??what do you suggest? I have see stainles last for 15 yrs in salt water,,,put your zink in the right places,,longliner
     
  3. missinginaction
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    missinginaction Senior Member

    I wouldn't think of using anything else but silicon bronze. Another supplier you might consider is: http://www.mertons.com/

    Mertons is a smaller house than Jamestown, the people there are very helpful.

    Just a thought and for those of you who remember me from last year, yes, I'm still working on my Silverton restoration. I'll post as soon as things start to thaw out and I can get out of the shop!

    Regards,

    MIA
     
  4. Landlubber
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    Landlubber Senior Member

    Par is right Longliner, Stainless Steel is not a good choice for undrewater use, particularly in salt water.

    The premium fastener is monel, followed by silicon bronze, 316L stainless (L is low carbon), any crappy 316 stainless (18-10 is 18% chromium, and 10% nickle), 304 stainless (18-8) (302HQ), brass is at the bottom of the list, and while I am now on about it, it contains no Tin, as someone did say earlier, brass is zinc and copper only. When it has been alloyed with tin, it becomes a bronze.
     
  5. TeddyDiver
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    TeddyDiver Gollywobbler

    I've been using them, or actually my father used them and I assisted (in my youth), in typical scandinavian rowboats (lapstrake) at the bow and stern parts (mostly flat countersunk).
    These boats were used like cars, more tar every spring and when they eventually get rotten we burned (and still do) them in the midsummer party fires:p Anyway the brass screwss holded generally well the whole life of aboat, in this case maybe 15+ years.
    Brass screws need precise prebored holes (pilot hole, clearance hole and counterbored)
    About the precise brass quality used in those screws... not a clue..
     
  6. SamSam
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    SamSam Senior Member

    I like the idea of more or less planned obsolescence and not trying to extend the life of a boat forever by constant maintenence and meticulous care. Not that that path is wrong, it's just kind of a pain in the *** and sort of stressfull for some people.
     
  7. diagram
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    diagram Junior Member

    TeddyD

    Sounds like a good deal from start to finish. I know that one has to drill a larger hole - I still seem to have sheered off a number of them over the years anyway.... I guess it is like many things - if you know what the parameters are one acts accordingly. Happy boating
     
  8. darlian
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    darlian Junior Member

    to save money, try hot dipped galvanized
     
  9. Landlubber
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    Landlubber Senior Member

    well, if you really want to save money, just use mild steel screws, hell, why not!

    Indonesia, China, India.......wot me worry!
     
  10. pila
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    pila Junior Member

    True about stainless screws. not recommended ,especially in salt water. I believe stainless has to be in the open to survive. There is info on that subject but I don't recollect where right now.
    As for brass screws, I can picture how many will break when tightened (torqued) into the wood. Not very strong.
     
  11. OCEANSELEVEN
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    OCEANSELEVEN Junior Member

    Brass has been used for a long time in boatbuilding. I had a cypress, cedar stripped boat at Lake Seminole that was built around 1890. That was in the sixties. I bet its still around
     
  12. OCEANSELEVEN
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    OCEANSELEVEN Junior Member

    In addition, I have both salt water and fresh water wooden boats I have built.
    I always use brass and with no filler. The brass is exposed only to the painted surface and the wood of course. I do not use any 'modern' boatbuilding techniques, no resins, etc. I do use a porch and floor enamel with urethane though. Its as hard as a piece of glass. Colors like yellow and red do tend to fade after 10 or so years in the sun. The paint is inexpensive and easy to apply with a brush. I use brushed techniques rather than spray simply because of the volume of paint you can get on the surface. With this system no water reaches the fastners, whatever they are made of or no matter what kind of environment they are in.
    Whats my problem with the 'modern' fastners?
    Number one: Without fillers, with the head of the screw even with the surface of the wood, if you hit a 'modern' fastner with your sandpaper, its over. The paper gets shredded. If you hit a brass screw it just sacrifices a bit of metal and you just continue right on sanding.
    Having had boats over 100 years old made with brass, I just cant see a problem.
     
  13. PAR
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    PAR Yacht Designer/Builder

    This is a subject that has been tested and discussed many times and there really isn't any debate.

    Bronze is an alloy of copper and tin (gun metal for example, is 88% copper, 19% tin & 1% zinc), usually the zinc is tossed in to improve machining qualities.

    Brass is an alloy of copper and zinc (typically around 65% cooper, 35% zinc). Sometimes tin is added to improve it's hardness or lead to improve it's color. Un-tinned brass doesn't "stand" before a tool, giving a sure indication of it's strength. Chuck some up in a press and try to mill a few thousands off it's perimeter and you'll see what happens "before the tool". It just balls up and makes a mess real quick.

    As a rule bronzes are generally more rich in copper and their color reflects this.

    Monel is a naturally occurring alloy of nickel and copper (about 70% nickel and 30% copper). It is better in every regard to bronze, but is costly.

    Some small canoes, kayaks and other very lightly loaded craft have used brass fasteners. These work in these applications, because of the light loading. Also in this same class of vessel are the facts they are usually kept dry, hand ported, overly framed and fastened.

    Many people, including skilled welders and metal workers, can't tell the difference between brass and bronze. Of course, these are folks that don't work with these materials very often.

    Without question, brass is the red headed step child of the copper alloy family, in regard to hardness, strength, durability in salt water, in wet wood, ductability, machineability and clearly is the fastener lowest on the list of preferred materials, even below mild, untreated/coated steel.
     
  14. Landlubber
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    Landlubber Senior Member

    Thanks PAR, I read this yesterday too and decided to just let it slip, i seem to become too arguementative in my writings, but gee mate, it is sad that people accept some of the crap here as being good advice.
     

  15. alan white
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    alan white Senior Member

    Just a word about brass. Chris Craft boats of the fifties at least used brass screws for planking and decking, and no doubt bottom planks as well. It is important to consider that there are brass screws that can and do hold up because they are correctly alloyed. They are nowhere near as strong as well made bronze screws but they don't need to be if there are enough of them (often the need to seal a batten seam well means using closely spaced fasteners that aren't stressed as much as widely spaced ones).
    Any failure will occur upon fastening or refastening and not in use. Therefore it is important to use well alloyed brass screws and to profile the holes with precision. I think this is the secret to good fastening. With bronze or stainless, there's a lot of forgiveness of poorly profiles holes but when the metal's softer, more attention must be paid. The ideal hole is tapered if the screw is tapered, straight where the shank is, and exactly the same angle at the head. No need to super-torque the screws with a driver, just firmly set them.
    Corrosion is another matter and the difference between fresh and salt water is huge. A boat that spends all of its time in fresh water AND is fastened correctly with proper spacing can use well made brass screws and they will last indefinitely. I would say it's probably just as true if the fasteners are poorly made bronze screws.
    The innerds or your toilet tank are brass and they can last a century under fresh water.

    Alan
     
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