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Thread: Coquina

  1. #76
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    Just thinking about structual ply Rob maybe I've been looking/buying the wrong stuff do you have a brand name and grade. Think I'll keep looking as ply would be better than MDF or chipboard me thinks.

    It would be a disaster if I missed a pulled screw and a lap springs a bit.

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  3. #77
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    Default Scarfing Ply

    Hm after the euphoria of Tuesday the stuff up fairies decided I needed to be brought down a peg or two and disaster stuck at 8.37 pm 13th May, well actually just a minor setback.

    Pulled the cauls off the glued up scarfs tonight, first sheet looked reasonable although I wasn't happy with a little ridge at the glue line but a tentative scrape and sand revealed a usable sheet.
    Not so the bottom sheet the small ridge had developed into a +1mm mountain and a very tentative scrape soon confirmed a redo.
    Fortunately I foresaw such an outcome and cut the sheets long so I have one more go before I reach for a replacement sheet.....I bought a couple extra just in case.

    A few things I noted that contributed to the failure.
    1. The first batch of glue was mixed with too much filler making it to thick.
    2. I put the glue on too thick, I have made a comb for future jobs.
    3. I did not screw the cauls down to the benchtop/waste ply thus not exerting enough pressure on the joint.

    So if it doesn't feel right stop and correct things don't hope for the best, so endeth the lesson.

    On a brighter note got to try out the cordless saw works a treat and I glued the inner stem last night all went well I'll leave it for a couple more days yet before unclamping.

  4. #78
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    have you been to this Coquina build blog?

    Breeze

    This section covers mast step, transom and stems.

    Transom, stems and maststep

    Brian

  5. #79
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    Hi Brian,
    Yep beautiful job of the build and the website, I refer to it often.

  6. #80
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    Mike,

    with gentle use of a varieable temp heat gun you can soften the epoxy in the scarph enough too pull it apart. Most marine epoxies have a heat distortion temp in the mid 50 degrees C. Just put one end in the vice and apply mild bending pressure and heat and she will come apart no problems.( don't ask me how I know this!) Give the scarph a sand and start again.

    I always pull the scarph pieces apart from each other just a fraction when gluing as you will have some glue in the joint ( hopefully) and it can cause a slight lump if you align the two scarph pieces right at the scarph line.

    BTW, there are not enough pictures on this thread and we'd all like to see more!

    regards,

    AD
    www.denmanmarine.com.au
    Australian agent for Swallow Boats, Bruynzeel Multipanel Plywood and Barton Marine Products

  7. #81
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    Andrew you have no idea how much your post cheered me up.

    I guess that's one of the the differences between you and us weekend warriors you know how to recover from the mistakes.

    Pictures, you want pictures.....they are coming.
    I am thinking about doing one of those time lapse movie thingos only trouble is I'm not sure I've got enough tape to show any activity.

    I should be out in the shed redoing the scarfing.

  8. #82
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    Default Scarfing ply

    For those of you following this thread and are yet to tackle a scarf joint in ply here is a pic showing how it shouldn't look. The pic is of the off cut from my bad joint laying next to the redo prior to scraping(much better). For those of you who have done them before you can just chuckle.

    Attachment 137219

    Instead of trying to glue up multiple joints I set up one at a time realising my first attempt was perhaps a little ambitious for a beginner. I followed Andrews tip about setting the edge just back a mm or so from the scribe line and all worked well, thanks.

    The stems have been glued over the last few days. I didn't think I would need as many clamps while I was making the jig but I'm glad I made provision because I found to get an even clamping pressure around the curve the number was necessary.

    Attachment 137264

    The stems came out of the jig and rough sanded ready for thicknessing. I did run them over the jointer tonight but the thicknesser is a bit noisy so that will wait for daylight.

    Attachment 137265

  9. #83
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    Fantastic presentation Mike (but I did spot some dust under the thicknesser). Very tidy glue-up! - and those laminations seem to be gap free. Are they about 3mm thick?
    What caused the Pacific War? A book to read: here

    http://middlething.blogspot.com/

  10. #84
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    Howdy Rob the laminations are 4mm. I cheated a bit as I've got a drum sander which makes thicknessing thin bits easy.

    Attachment 138035

    Today I glued up the transom boards and coated the ply. I have been debating about doing this for some time as I'm not sure if it's a good idea to pre coat on a glued lap or not. Most of the builds I've looked at seem not to coat or do it after.

    I played around with some time lapse video today a bit of fun. It shows me cutting out the transom, jointing using a router and straight edge, cutting and routing for a spline and some very fast coating.

    [ame="http://www.youtube.com/watch?v=oHQRuM_V0y4"]YouTube - Coquina Build 290510.wmv[/ame]

  11. #85
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    Man you work fast. Should cut down on the coffee
    What caused the Pacific War? A book to read: here

    http://middlething.blogspot.com/

  12. #86
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    What did you use for a camera Mike?

  13. #87
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    Wish I did work that fast and if it wasn't for the coffee nothing would get done.

    Groggy I have Sony Handycam which until reading recently did not realise it has interval recording controls. Set the camera to take 2 secs every 1 minute then when downloading to the movie edit software play recording at fast forward speed.....easy

  14. #88
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    Thought for the day.....One must become accustomed to dealing with errors.

    In the interest of full disclosure I need to document this little gem.

    Yesterday I was zooming along with things and decided to start the stem bevel checked the plans again, read the reference in the book yep got all that.

    Here is a pic of the stem fit to the mast base pretty good I reckon.

    Attachment 138197

    So first step is the mark the stem width with a marking gauge cut excess on the band saw then refine with spokeshave and block plane fairly straight forward in fact should be simple right.

    Wrong, somehow I managed to miscalculate misread or misinterpret well actually I just plain stuffed up when setting the marking gauge instead of a 3/4" width I managed to mark out 1/2".

    So there I am merrily planing away when terror struck that does not look right. Recheck dimensions
    Attachment 138195

    OK don't panic it might be salvageable as there is still plenty of meat it's only right at the forward edge I've got a problem and that's why they invented epoxy to fill the gaps. So if I pin a batten finished to the correct width I can finish off the bevel and all will be well.

    Attachment 138193Attachment 138194


    After mucking around for a while I decided a redo was in order and surprisingly I'm not really upset plus I milled a new set of laminations in less than an hour.
    The good part is I will have a practice stem to set the molds up with and test cut for the hog.

  15. #89
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    Not much to report this week apart from sanding 40' of ply.

    The transom glue up seems OK so planed and scraped then set out for marking, it still needs a bit more work which I will complete when it's cut out. I have been using some acrylic offcuts to protect the plans and thought I'd join them through the transom centre line as they would be useful to check the grain. I have been careful to sticker the boards as I've been caught before leaving wide stuff sitting on a bench in winter. This transom will hopefully remain flat not cupped.
    I have been wondering if I should epoxy coat the cut out transom now or after the planks have been glued or if I should coat inner side and varnish outer, any thoughts.

    Then onto marking out on the inner side (larger) after marking the centre line on both sides.

    Attachment 138704Attachment 138705
    Mike
    "Working to a rigidly defined method of doubt and uncertainty"

  16. #90
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    Nice to see the odd snippet of plan drawing. They look to be of very good quality and clarity. Lovely timber too.
    What caused the Pacific War? A book to read: here

    http://middlething.blogspot.com/

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