Jazz 30, sheathed plywood power cat

Discussion in 'Fiberglass and Composite Boat Building' started by xellz, Nov 17, 2019.

  1. fallguy
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    fallguy Senior Member

    the concern is xellz going about planing all his stock to 45x20....totally unneccesary
     
  2. fallguy
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    fallguy Senior Member

    A lot of your stock looks like it came in at 38mm thick. Is this assumption correct?

    Are you planning to rip them to 45mm on a thin kerf blade and then rerip the 38mm to say 18mm? Is that allowed? You'd be 45x18 then only.

    why did you buy the 38mm lumber?

    Find out Richard's minimums against the 45x20.
     
  3. xellz
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    xellz Senior Member

    All lumber is at nominal 2inch, most of it is near 5cm thickness. Just one large board is 4.5cm, few 4.6-4.7cm. Why i thought about planing or at least surface treating on tablesaw is to remove large grooves from a mediocre bandsaw that appears to be used. Probably i better ask for advice from Richard at this point, way too little to work with now and i will need every piece of wood i can scrap.

    About Edensaw Woods, Richard recommended this place since he got his own stock from there too and also quite a bit of good review i could find, so didn't worry too much. But now that i actually do my research on weight, i see i could prevent this from happening to recheck the stock. At container shipping weight-inn the timber pallet weight was at 490kg, i.e. includes pallet, wrapping etc. 444board feet of dry alaskan yellow cedar should weight roughly 520kg. Pallet is at least 60kg, that brings me to 90kg missing weight. I send all this info to Edensaw already and first answer that according to their papers everything is right and i should re-check my measurement. Waiting for second answer now. At this point what options i even have? I guess i got too used to living in Japan and let my guard down.
     
  4. xellz
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    xellz Senior Member

    Most likely i go with this approach, use most smooth surface as glue surface. However epoxy coating/painting over "hairy" and rough surface will be a pain and most likely i will end up using a lot more epoxy too. Maybe try to run through tablesaw and try to remove just a hair-width to at least get rid of most loose fibers.
     
  5. fallguy
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    fallguy Senior Member

    Just double cut.

    cut halfway, flip over
     
  6. Rumars
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    Rumars Senior Member

    Xellz, I believe your problem is a communication one.
    When you buy "nominal" wood the volume is calculated with nominal thickness and width and actual lenght. That means there always is a difference between nominal volume and actual volume. The weight you find in descriptions is "average dried weight" and actual weight usually varies.
    I don't know what your invoice specifies exactly regarding grading, but unless it says "grade A Select" a few defects are acceptable.
    Please recalculate your board feet and check the invoice for grading.

    Now for the practical aspects. Just sand the exposed faces with 80 grit to remove the offending toolmarks and be done with it. There is no need for the wood faces to be perfectly parallel, uniform and glass smooth. As fallguy said thickened epoxy likes rough wood better.
    If you need extra wood anything in the 450-550kg/cum is acceptable. I don't know what is available there but Douglas fir, all larches, all pines, all spruces are in this range.
     
  7. fallguy
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    fallguy Senior Member

    For sure, all those 4.5cm boards are considered 2" by Edensaw; standard for softwood is different than for hardwood
     
  8. xellz
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    xellz Senior Member

    I did calculate on nominal value too, but even if i was rounding up 5inch wide plank to 6inch (2inch steps) it still added only 7 board feet to my exact calculation. Where i'm missing about 80. Sure, weight varies, i understand this. But the difference i think is too large to cover this variation.
    In Japan it's hard to access clear grain timber, especially strong enough. I did search of course, but had no luck. Something that still possible to buy is about 380kg/cub, i.e. most common species, japanese pine. 4 sides clear is also ridiculously expensive. That's why i went through all this difficult and long process, started in last summer.
    CVG, so it seems one face is allowed to have small defects. I'm not sure if 1.5-2.5cm diameter knots counts as small, but this is a minor problem compared to lack of material. My order process was add 10% to required material from BOM then through mail ask if Edensaw can pull out enough timber based on my list of already processed timber sizes, i.e. how much 2x1inch, 1.5x1inch etc i need in the end. They said yes, they can, but because they don't cut to length/width or height the order increased by another 10% or so due to random length/width and stock is only available in 2inch thickness.

    For now my plan is to use thinnest plank as 2x1, i.e. 45mmx20mm finished is acceptable. So i'll go with suggested sanding only, first sand a bit then cut 1inch. It's 5.2 inch wide, so i should get decent 5 strips.
     
  9. xellz
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    xellz Senior Member

    I would like to add, all input is appreciated. It's my first build so to compensate for lack of experience just was going follow plans directly. Like slightly rough surface on timber should be fine, i also didn't see a problem with at least table-saw edge finish, but to be sure wanted to plane it smooth at the beginning.
     
  10. Rumars
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    Rumars Senior Member

    Did Edensaw provided a detailed inventory like X feet 2x4, X feet 2x6, etc.? That's the only way to determine if some boards have gone missing.
    Letting the merchant determine how much wood you need was a mistake. They do not know how you are going to cut it. But it's to late now.
    Sanded to 80 grit is enough for epoxy, no need to go finer. Only exposed pieces need to actually be perfectly smooth (cockpit framing, etc.). After the first coat of epoxy the surface will be hairy and sharp (don't slide your bare hand over it) because fiber ends will stand up and solidify. Another quick pass with the sander will cut them down, then you can proceed with the other 2-3 coats and paint.

    Just out of curiosity, what does a japanese carpenter or cabinet maker do if he wants some wood other then japanese pine? I always tought that the most common commercial domestic species there is japanese cedar (sugi) and Japan is said to be the biggest wood importer in the world.
     
  11. fallguy
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    fallguy Senior Member

    None of the timber is exposed. It is ply boat sheathed in glass.

    Nominal is thickness. All softwoods go up thickness to nearest 1/4.

    So any 45mm board counts as a 2"; not 1 3/4. Least that is what I learned. A 44mm board is thin and counts as 1 3/4.

    I doubt they take a 5" board up to a 6" board, but if so; you probably are short on rules.

    A 10% waste rate is super low. If you cut 1/8" for each 20mm rip; that is 15% on kerf alone. And real waste is higher because the kerf calc assumes perfect starts and finishes, but if you have a 10mm board left; you only get a cleat from it in the end. For sure, buy an ultra thin blade. If you don't have a tablesaw; you absolutely need one now because you will really struggle to make accurate rips with a skilsaw and you will probably waste more. The last cuts will be impossible. I am very experienced woodworker. (Did not say great)

    Make sure and get Richard's minimums. You might have some wiggle on bulkhead reinforcements or a few others. Just ask him where you can deviate. If he allows 18mm on bh reinforcements; you can board select or rerip, etc.

    Another thing to consider is BH reinforcements are not as critical as other bits. It might be wise to extend your stock by using local wood where possible(2nd Rumars). Getting another 10% is probably very wise.

    Do not mix timbers on scarfs. Treat the cedar like gold.
     
  12. fallguy
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    fallguy Senior Member

    Do not plane or joint the lumber; you will put it all into shavings. You only plane on the hull as needed for ply fitment. You are framing for ply; not building fine furniture.
     
  13. xellz
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    xellz Senior Member

    Small update. Corona virus started to affect even my project. First it took me quite some time getting dust mask and filters, people don't care much if it's effective or not, they buy everything. Then when i started schools and kindergartens got closed though all Japan, i'm taking care of kids alone now so even less time on the boat.

    I tried to stop pursuing everything to perfect finish and somehow work started to move a long. I'm getting used to handling expensive and not readily available materials, i did sweat quite a bit during my first cuts. Ripping large timber perfectly clean with my setup proven to be impossible, originally i wanted to make long narrow table flush with table-saw. Now simple saw horses will have to do the job. Difficult to feed steadily long and heavy timber from saw horses on uneven floor, so i do get some circulars marks (example of ripped surface attached), fence on ~500usd table saw isn't that good either. But it's smooth enough and i just continued, going to be painted over anyway.

    Portable makita table-saw handled 70mm thick yellow cedar with ease, i guess unless it's hardwood don't need to worry.

    So far i only finished cutting out all bulkheads and started cutting bulkhead framing. Speaking of which, once i started to read about epoxy bonding again i got kind of confused and now in doubt what is correct way. In photo bellow is how framing will be glued latter. Originally i thought it should go like this, wet-out with epoxy both surfaces, apply thickened epoxy apply pressure. In my case, stainless steel fastenings used. But is the thickened epoxy really needed unless surface is really rough? And is there any reason not to use yellow cedar saw-dust collected in table-saw bag as fillet?
     

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  14. fallguy
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    fallguy Senior Member

    Epoxy is not an exceptionally good flat surface bonding material because clamping pressures are very good at squeezing out the epoxy due to viscosities we enjoy for wetting glass out.

    The ideal bonding/filler agent is fumed silica or cabosil or aerosil. For a project your size; you would need about...-20 pounds. I am around 25 pounds on the Skoota.

    wood sawdust can work, but large wood particulates leave voids which can collect water and have the potential for ingress,,,can be done

    Personally, sawdust tends to be hard to get to lay down smooth. Do not use it between stacks of timber and ply.

    For most of my wood stacks; I use a 1/16" vee trowel. I just did today and ran 24 oz epoxy. I usually run my batches at about 2.1 parts cab to epoxy by volume. So a 10 ounce batch of epoxy would get 21 ounces of cabosil...start lower and adjust as you see fit...I mix all my thixo on a board to make it more homogenous and prevent early kicking by keeping the epoxy in less than a 100g mass. It is also easy to slump test the mix. Pile it up and if it sags; you are too thin.

    wood is resin thirsty as well,
    All wood to be bonded requires prewetting to prevent dreaded drysucking of the joints...get some very cheap 1/8" nap rollers and cut them down to 3" and use them on a 3" roller frame. Roller drink the costly resins; so prewet and squeegee out the epoxy before pitching the rollers. They are not reusable. The squeegeed epoxy can be used for some of the thixo if you work fast.

    So, here is how.

    1. Prewet both surfaces to be bonded. It helps to label things to avoid prewetting wrong sides. Prewet at a rate of 2oz per sqyd of area. Get medicine cups for tiny batching.
    2. Apply thickened epoxy to the joint; I generally use the 1/16" v trowel. For vital strength items like beams, both sides should get thixo. For something like the BH timbers; one should do it as long as you prewet both surfaces.
    3. Clamp. Never too hard. Max vac pressure is about 10" HG. 9 is better, but I can't control that low. Absent vac; use clamps, but avoid overclamping. A 1/16" vee will result in about 0.032" or so glue joint.
     
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  15. DogCavalry
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    DogCavalry Senior Member

    My only comment to fall guys about rips is this. Speaking as a 35 year carpenter, I make my rips with a skillsw, or circular saw. Long accurate tips with a table saw are possible, if you have an extended deck, which requires huge space, and a feather board. Otherwise they are extremely difficult. I have a really cramped shop.

    I built a tiny shelf on one wall, and I screw my stock to that through one edge, so it sticks out from the wall like a shelf. I have a couple skillsaws, so I took one that's battered, but with good bearings, and I screwed a long smooth block of wood to the underside, so it can only make 1 width of rip. My helper, an absolute beginner, can make perfect rips consistantly at ⅝". About 1 a minute from a 2*10*16. No skill, no space, no cost. Perfect pieces.

    I also finger fingerjoint the ends of each board before ripping, because its enormously faster and less wasteful to fingerjoint than to scarf.
     
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