Custom Extended Swim Platform

Discussion in 'Boatbuilding' started by tpenfield, Jan 8, 2019.

  1. tpenfield
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    tpenfield Senior Member

    Yes, as I understand it, the flow media allows the resin to move across the piece and the peel ply allows the resin to move downward into the layers of fiberglass.

    So, do I have the layering correct in the image I put in post #58 above?
     
  2. ondarvr
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    ondarvr Senior Member

    What I see possibly happening with that stack is resin flowing through the flow media and across the the surface before it starts to wet out the glass.

    This can leave pockets of glass that no resin touches.

    That’s why people try to not use products like CSM or roving when infusing, they don’t wet out well.

    They can be used to control flow, typically to slow it down so resin has time to flow elsewhere in the part.
     
  3. tpenfield
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    tpenfield Senior Member

    OK . . . it just seems that from the information that I have gathered, that would be the proper 'stack' for VARTM. Probably not the proper stack for RTM though . . .


    It looks like I will be needing to run another test (or two) before setting up for the platform mold infusion. The 3 layers of CSM that I had planned on using will only yield a thickness of about 0.055", (1.5 mm) based on my test. So, I'll need to 'bulk up' the laminate a bit.

    I may try running a test with some wood strips in the laminate as ribs, to see how the resin flows.

    Also, I should have some TBC soon, so I could test that out as an inhibitor. The MCP worked fine as far as slowing the gel time, but the final cure was not as 'hard' as the MEKP activated resin. I'll see if the TBC/MEKP combination is any different.
     
  4. fallguy
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    fallguy Senior Member

    Can I just ask a question here?

    Are you walking away from the lattice or the chunks of core for a solid core now?

    Also, did you remove the air from the mix before infusing?
     
  5. tpenfield
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    tpenfield Senior Member


    Yes, of course . . . but actually those are 2 questions :D

    1) The lattice/truss core is for the part. I am still working on the mold, which will not have much of a core . . . only some stiffeners. The 'part' will have the 'navtruss' core that I had mentioned a while back, but I am thinking I will not infuse the core and final glass layers. I just will infuse the first 3 layers (1 CSM and 2 layers of BDM1708). Then I'll do a hand layup and vac bagging of the core and final 1708 layers, which I think will be less risky, considering I am a rookie at infusion.

    2) I waited for a few minutes after mixing before infusing, but did not do a degassing procedure, if that is what you are asking.
     
  6. ondarvr
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    ondarvr Senior Member

    If the part wasn't as hard as it should be, it would be from the thin laminate. MCP reduces the peak exotherm, which will extend the time until the ultimate cure is achieved, but the final cure will actually be better than with just straight MEKP.

    You aren’t doing VARTM or RTM, the rules for straight infusion are different.
     
    Last edited: Feb 26, 2019
  7. ondarvr
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    ondarvr Senior Member

    Most of the time people don’t de-gas the resin, and MCP will produce even less gas than MEKP.
     
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  8. tpenfield
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    tpenfield Senior Member

    Thanks Ondarvr, I'm not sure that I am following any rules. :D . . . Just as long as I can get it all to work.

    I noticed that the MCP caused very little exotherm, as compared to the MEKP. I used a small amount of resin (0.75 fl oz) in a 'pot' test, pitting MEKP vs. MCP, both at 2%, to see how long the resin would stay liquid before starting to gel. The resin started cold ( 55 F) . . . but the MEKP activated resin started to gel at 30 minutes and reached about 140 F, while the MCP activated resin started to gel at 70 minutes and only reached about 75 F.

    If the final cure of the MCP is going to be better, then I'm all for that.

    So far, I do like vacuum infusion vs. hand layup . . . the results come out better and a lot less fumes to deal with.
     
  9. fallguy
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    fallguy Senior Member

    So, I am lurking here, offering little, but wanting to learn.

    In all my epoxy work; I have rarely enjoyed laminating anything with 55 degree resin. I can't imagine wetting out 1708 at that temp. A few times we had the shop open in the fall during cool weather and my resin cooled into the 60s and we required quite a bit more resin for wet bagging and I knew it was the darn temp. Laminating work is always long sleeves and we were enjoying some human comfort..good air, etc.

    Was the low temp done by you to slow the cure time absent the inhibitor? If so, why? Or just a miss? For the mek mix, it would make sense. So, if you use mcp, will you start warmer?

    Then, aren't you planning a core? So, are you going to sample pulling both sides with a core?

    I do apologize for my awful curiousity and wish you all the best success.

    The fact you have ondarvr here helping you is a real feather in your cap. He is an encyclopedia of moulding knowledge.
     
  10. tpenfield
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    tpenfield Senior Member

    All good questions, which I appreciate as they help to avoid 'tunnel vision' on a project like this.

    I'm on Cape Cod, MA and the outside temps are 20 - 30F currently. I'm working in my garage and able to keep the temperatures in there at about 60-65 F. The garage had cooled down during the past week or so, and therefore everything was a bit colder.

    When I was making the plugs with epoxy, I was able to keep the garage at about 68 F, which seemed fine.

    The lower temperatures (55 - 60 F) are fine for keeping the resin in a workable state, but do seem to delay the curing process extensively. As I have done in the past, when working in colder temperatures, I could heat up the piece once the resin is laid out (or infused in this case) to move the curing process along. In fact, I did that with the test piece that I ran a few days ago. I am also considering the same with the platform mold, if I cannot get the garage to a reasonable temperature.
     
  11. fallguy
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    fallguy Senior Member

    the viscosity is my concern
     
  12. tpenfield
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    tpenfield Senior Member

    Yes, I have not tested the viscosity, but do have a basic tester. So, I can probably see what 55-60 F looks like vs. 65-70 F. If I got my work area to 70+ F it would be a miracle at this time of year. :)

    My preference would be to get the resin infused a bit on the cold side, as long as there was not a huge trade-off in viscosity, then do some heat 'flooding' of the mold to kick things in gear.
     
  13. tpenfield
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    tpenfield Senior Member

    Update on the mounting design . . .

    Taking a page out of the boat manufacturer's book (Formula Boats), I decided to eliminate the struts. Formula does not use them, and I tend to agree, based on my force calculations.

    Here are a couple of updated drawings, showing 'U' channel stainless steel for the mounting brackets and eliminating the struts.

    ESP7C.png

    ESP7B.png

    Clearance at rest is a decent 4"+, so I don't think it will be a 'dragger' upon take-off.
    ESP7A.png
     
  14. ondarvr
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    ondarvr Senior Member

    You are starting off with a very high viscosity resin for infusion, then by infusing at a lower temperature it will increase the viscosity even more.

    It will have a much more difficult time flowing, and may not fill the part completely.

    At 77F a typical infusion resin has a viscosity in the range of 100-150 cps, this resin will probably be around 400 or so at 77F
     

  15. tpenfield
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    tpenfield Senior Member

    I should see about getting some infusion resin. I have regular poly resin for the hand layup portions, which will be the stiffeners, etc.
     
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