Gluing Tivek with 3M 927

  • 01 Jun 2020 17:20
    Reply # 9007066 on 9002951

    Thank you Greame

    For my experiment, I added a plastazote bloc under the system to absorb the choc following the failure test! It was not suffisant. The tub was already half cracked and it opened completely. I had 40 liters on the shed floor to mop !

    Idealy I would have liked to mold the Tyvek but the equipment is too expensive. It would have provided an homogeneous structure.

    I tried Sikaflex 291i but while peeling the mastic was separating too easily.

    Tyvek is also very sensitive to puncture and is very easily cut ! (I will have to avoid any sharp item !)

    I’m happy not to be the only one to test Tyvek; I felt a bit lonely !

    Next step will be to pull on a 10 cm thread to know if it is really stronger than the glue. The sowing machine needle perforates the Tyvek and build a structural weakness : tear along the doted line !

    I’m thinking about a bow mast (I’ve sailed a Finn years ago, a very pleasant and powerful boat) but I’m a little afraid of resonance effect that could amplify the movement of the hull in specific conditions (headwind in confused sea for example).

    https://www.ocqueteau.com/notre-gamme/tilapia-650-cat-boat.html,9,6,0,0,103#.XtUhXsbgo0o        (2.50 mn)

    As a start, I already have a mast on Mingming and will keep it. 

    The demonstrator’s flexible components are here only to push the concept to the limit and show if it’s viable or not.

    As the demonstrator didn’t break while it was built so lightly without reaching the expected failure test, even in high wind, it validated the concept.

    The prototype, Mingling's flexible wingsail will be much more robust with 8mm rod GRP structures and a Tyvek skin.
    Eric

  • 30 May 2020 23:52
    Reply # 9003813 on 9002951

    Hi Eric, when I saw your experiment, I could not resist showing a similar apparatus I used a few months ago to test panels of plywood sheathed with ferrocement.


    Water added 1.0 kg at a time, deflection measured and recorded for each increment.  A good method (except testing to failure results in a real mess to mop up afterwards!)


    I made one of the panels on my SJR from Tyvek.

    The parts were held together with basting tape and I considered leaving it that way, but did in the end run a line of stitching over all of the seams. I have since replaced it and would not use Tyvek again for a larger sail, though tape-glued it should be very good (and very quick) for a dinghy, as the material is very light for its strength. It is not woven in any direction, so next to impossible to rip. It will stretch a little. Lovely and soft to handle. I found, when ripping a seam held with just basting tape, that the glue line was strong enough. The glue would not yield from the surface, but the surface would tear from the body of the cloth, which is what defines the strength limit of the glued joint. Rather like gluing cardboard surface to surface – the glue itself is not the weakness. Tykek is OK to sew – but be careful if you put a hot knife near it!

    edit: I just checked and found the the Tyvek I used was 43 gsm. That was all I could get in New Zealand and I see it is much lighter than the material you are using. 105 gsm sounds like a really practical proposition, though the strength of surface-to-body adhesion is probably no better. I would definitely run a line of light zigzag stiching over the seams, and imagine the result might be very good indeed.  (Once the parts are stuck together, the sewing is the easiest, quickest and most fun part of the whole job). The material, with its randomly dispersed fibres, is nice and soft and seems to have some properties which might be quite good for a cambered junk sail. I see also that in the US you can get Tyvek with some sort of UV resistant component in it, which would be even better. 

    I do rather like the idea of re-purposing domestic components or light industrial materials in boat building , where possible, as an alternative to specialised branded marine products.

    Your flexible rig is a real hoot (approving laughter) – to take your philosophy to its proper conclusion, why not a bendy mast as well? (eg like the old Olympic Finn class). I am guessing the flexible components would not readily scale up to larger sizes – but who knows what the rig of the future will be. Inflatable perhaps!

    (Here is an inflatable wingsail, which I think has been on the forum before. http://inflatedwingsails.com/en/concept/    Variable camber, too!)


    Last modified: 31 May 2020 07:10 | Anonymous member
  • 30 May 2020 14:17
    Message # 9002951

    Bonjour
    I’m experimenting Tyvek (105g/m2) as a prototyping skin for Mingming’s wing.
    I tried to glue Tyvek with 3M 927 in 25mm wide. It is the glue tape that is used by sailmakers to assemble spinnakers made out of membranes and not cloth.
    I made a 10cm test piece.

    I hanged in the shed and hanged underneath a baby tub. I then poured water into the tub 10 liters by 10 liters with a watering can.

    Once at 50 kg of effort, after about 1mn, the test piece split and the tub fell on the ground.
    The glue film parted but the glue didn’t unstick from the tyvek on either side.

    I’ll use it for the remaining panels of Mingming’s wing. It is much easier and faster than sewing long threads.

    Unfortunately, the baby tub, a very old one, split open while falling ground, so I couldn't conduct a similary trial with a 10cm seam. I must first find an other baby tub !

    At least, it seams a good way to assemble prototype.

    Eric

       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

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