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

    I really like the idea. First of all, the fence is shorter, so you won't be making thin boards to edgebow.

    The caution is walking out of the cut. This would happen to dull blades. Another thing is I recommended 220v. Given the absence of it, a high amp draw skil saw is a good idea in knotless or mostly knotless wood.

    Also, need to make sure the guard works. Drop a tricked saw off the ledge and onto a leg and ...
     
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  2. DogCavalry
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    DogCavalry Senior Member

    15841595260516216810026835478635.jpg
    Last few inches of a 2*10*12 from Home Depot. Fingerjointed end, edge I'm ripping from, and temporarily modified saw all visible.

    Certainly I agree about the blade guard. Only fellow I've ever seen lose 4 fingers at once, had driven a shim into the blade guard.
     
    Last edited: Mar 14, 2020
  3. xellz
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    xellz Senior Member

    Essentially a solid diy guide for narrow strips. Sure much more steady than default guide that usually comes with the circular saws. Do you get some circular marks or nothing at all?

    I'm fine now with current setup result, i'm finishing all 4 sides on table saw too. My circular saw also doesn't cut deep enough to cut over 70mm in one go, would like to avoid to do second pass. I'm clamping 2 saw horses together with a board now for more steady feeding. A bit easier now. Circulars marks do appear, but they are not deep at all and visible only at a certain angle. I'm thinking my fence is not perfectly parallel to blade. Would not like to put too many extra holes in timber with screws. My boards are of various thickness and width. As for length, all fits. Could also do outside if necessary. Had some stock over 5m, but cut recently to size for main beams and use offcuts for bulkhead framing.


    For epoxy filling and bonding. Have more confidence now in what i originally thought was right. I finally found fillets in online shop, aerosil silica, roughly 35-36$ per kg, talc 3kg 12$ and glass powder at 24$ per 2kg. Wonder which fillet can work best for bonding flat surfaces. Can't find cabosil in online stores. Saw dust i collected does mix well with pva glue and makes a smooth paste, but it's a bit more fluffy than what you can get from sanding. So mixing sure will be a pain and i don't want to loose time on this when working with epoxy, i will keep it in case for when i need to fill corners.
     
  4. DogCavalry
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    DogCavalry Senior Member

    I bought a high TPI - tooth per inch blade, and am very practiced, so no, no saw marks. Fall guy, you're bang on about walking it out. My helper was doing that some with the first blade: a nasty old demo wreck, with missing teeth from hitting nails. Once I bought the finishing blade, like glass.

    They would let the strip drop off the stock, breaking off at the last few inches of cut, because obviously the grain runs that way. I threw on a few sticks just to catch the pieces for them.
    Nothing a little sand and fill can't cure.
     
  5. fallguy
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    fallguy Senior Member

    On fillers...

    Milled fiber is heavy. Only use when strength is desired.

    Microballoons only use when fairing.

    Cabosil is used in all adhesive operations for your build and in the fairing and strength fills.

    I like using milled fiber and cabosil 50/50.

    Microballoons and cabosil about 3 balloons to 1 cab for fairing.

    Mixing cabosil is about 2.1 to one to epoxy for filleting. A bit less cabosil for certain things where you need flow like through contour scrim.

    Keep all thixo mixes flat on a hawk or board. It is easy to check slump and the most important thing is you won't lose the batch to exotherm.

    Epoxies exo faster than spec when kept in large balls of stuff. I also have good advice for wetting out glass when you get there.
     
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  6. DogCavalry
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    DogCavalry Senior Member

    Most excellent Fallguy. My boatbuilding experience is 30 years old, and strictly traditional carvel construction. I'll be hanging on your every word soon.
     
  7. xellz
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    xellz Senior Member

    Poor luck with the fillers. Found cabosil and it was a bit cheaper than aerosil, but after few days of waiting got the message no stock and money returned. Got aerosil silica and glass powder instead and mix as suggested, took almost a week to ship it compared to promised "within 24h". Finished all the framing preparation, 2 large bags of sawdust. Got a comment from Richard about saw dust, he actually also using it, sieving first to get only fine particles. I was tempted to start the gluing process already, but instead decided to wait and make some furniture pieces i promised my daughter some time ago and do some extra work to get more free time latter on.

    I have a question about plywood epoxy coating, how many coats is usual on plywood for no glass surfaces? From what i could find 3 coats of epoxy is enough before painting, will be applying with brush and rubber/silicone spreaders, found few with different hardness will check which works the best. Sadly no thin foam rollers sold in japan, the thinnest foam size was 13mm which i'm not sure is a good idea to use. I want to avoid doing unnecessary work for cleaning surface from amine blush on each coat, so will go over when epoxy start to gel.
     
  8. Blueknarr
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    Blueknarr Senior Member

    Cabosil is a name brand of fumed silica. Aerosil is simply a different brand of the same stuff.
     
  9. fallguy
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    fallguy Senior Member

    you can use wood flour, but wood sawdust is rather tricky to use and a bit bulky for filleting; if you can screen it really fine; it can work, but bigger bits won't flow well; some places are less important than others for appearances...so inside fillets can use the sawdust, but avoid it in bonding wood to wood and for external fairing

    aerosil is cabosil; just a different name is all I ever knew as a difference

    Neat coat epoxy at 2 ounces per yard. It is a pretty solid number. The rollers are a problem and drive a LOT of waste in a build.

    You must stack projects.

    For example, let's say you want to neatcoat with a roller. Use 1/8-1/4" maximum. Cut them down to 3" wide on a bandsaw for most applications and use a 3" roller frame. This reduces roller cost and cover waste. Basically, I have about 5-20 places running at the same time where I can use leftover thixo or epoxy resin. After you start seeing epoxy losses; you can go a little crzy trying to save it from the trashcan.

    When you have rolled the surfaces. Run the squeegee and get the epoxy back out the roller. The roller covers are not salvageable. You will get 1-3oz of resin out. Stir up a batch of filled epoxy and use it on a stacked project or wet out a small tape. I pay about 80 cents an ounce and threw away a lot of epoxy early on before I got in a habit to attempt saving it. Sometimes it was too risky to a bigger panel worth $1500 to worry about saving $5-10 in roller rpoxy losses. You won't face that in a ply no vac build. Your critical effort will be sheathing the whole hull. Another time to not worry about losing a few bux in epoxy.

    You can also get 1.5" pvc tube (or is it 1.25" can't recall) and use just the pvc for a roller. It takes some getting used to, but you only need to wipe it off at the end and it doesn't suck resin into the cover fibers. I really like using the pvc if we are running two 9" rollers instead of loading two rollers with epoxy. You can try this for neat coats. I have not. It might not even out well. If the pvc won't fit right; use duct tape on the roller to make it fatter. Never soak pvc in acetone...wipe clean with acetone only..

    trivia for you...

    My large panels were wetout at about 110% of glass or so; let's say 400 ounces resin went into the panel...we had typical final ratios of 65-70% of glass. This means we had losses to vac of about 40% of the 400 ounces... or 160 ounces of resin lost to process...this incredible falldown rate is part of wet bagging... the number is sort of a constant throughout the build here...I have used about 275 gallons of resin so far; fortunately or unfortunately; it didn't all go into the boat
     
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  10. DogCavalry
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    DogCavalry Senior Member

    Words of hard won wisdom, Fallguy.
     
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  11. xellz
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    xellz Senior Member

    Perhaps i should rename this project into "series of unfortunate events". Due to Covid19 got stuck for a month outside island in hotel, 2/3 of the time all 4 of us. Another major financial blow and loss of time. Could not be avoided and what most important, wife finally home in most safe place now, prefecture with least infections and island has additional screening. Covid19 is basically death sentence in current condition. Returned from a part with one of most infections in Japan. The timber i'm missing also postponed due to lockdown in US, they didn't made it in time.

    But listening to a famous song "Show must go on" i'm continuing to work on the boat at night :) My first bulkhead framing gluing was quite messy and hectic, at the very least i didn't see any voids and got putty squeezed from both sides. I tried few options of wetting out surface and then spreading thickened epoxy and more or less got the hang of it. First attempt i mixed a bit too low viscosity epoxy putty, it was rather surprising just how much epoxy actually flows. Next bulkheads went much faster, no mess and almost no wasted epoxy. Still not exactly a fast process. Higher viscosity mix allowed for much cleaner work, less waste since it's easy to collect and re-use squeezed putty. Another thing helped that i quickly stopped to care about few extra holes from screws. Quick and even fastenings without use of clamps made the work much easier.

    Is there actually benefit or need in using part of glass? Currently i'm using about 50/50 by weight. Aerosil and powdered glass. 5kg of aerosil has about 3 times more volume than 14kg of powdered glass, both cost about same. Powdered glass is a bit annoying to use, since it's all small clumps that need some preparation for mixing.

    Rollers i will use for large surfaces, i read somewhere that thick rollers could mess up coating due to possible quicker cure in the roller. But seems i don't really have to worry much about it. The waste of epoxy and cost of the roller is quite little compared to the gained benefit.
     
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  12. fallguy
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    fallguy Senior Member

    I almost never use glass fiber.

    I use it on areas where I want strength on edges or if I have a small area of raw core that gets deglassed for any reason.

    by volume; my mix rate is about 2.1 cabosil to 1 epoxy

    I mix it in the cup; never more than 16 oz epoxy ever; then I move it to a flat board or cardboard and trowe it flat to reduce the kick rates.

    when building with wood; you have to either reduce the amount of cabosil or prewet the wood join areas or the wood can drysuck the resins and weaken the joins

    always make sure to have extra projects available because there are times when you have excess epoxy and you do not want to waste it
     
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  13. xellz
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    xellz Senior Member

    I started from 30g and ended up with 60g, a bit over 2 oz per mix. For gluing i think that's the amount i'm comfortable to work with. Any more will call for mistakes.
    First i clean surfaces with acetone, mix small portion and prewet all gluing surfaces, a bit extra epoxy on endgrain, proceed to mix next portion for putty.

    There is one more question i forgot to ask, after about one month i noticed just how much sun still reaching inside shed. I used white polycarbonate roofing sheets, which supposed to have an UV protection layer. Bellow is photo and you see difference in color from framing staying on top of bulkhead while i was away. Just one month caused this much discoloration. How sensitive is epoxy to light? I'm not sure how much time will pass after i start covering hull in fiberglass to painting it over.
     

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  14. fallguy
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    fallguy Senior Member

    Epoxy is very uv sensitive. I have had my port hull sitting by a window for over a year and no chalking, but I can see it is yellower.

    If you have a long period of no work after you are sheathed; you might want a light colored cover. For now; don't worry about plywood discoloring.
     

  15. fallguy
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    fallguy Senior Member

    Also, that acetone wash is a bit overkill unless you have grease concerns. Get a shop brush and a shop vac. All you need to do is vac those surfaces. Sometimes, I also blast with air compressor, but typically I only vacuum real good.
     
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