Infusion Plan

Discussion in 'Fiberglass and Composite Boat Building' started by jorgepease, Jun 4, 2012.

  1. jorgepease
    Joined: Feb 2012
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    jorgepease Senior Member

    I pulled a vacuum on the bag today. The xtra air lines and that big pump pull the bag down fast but the worst thing that could have happened, happened - A leak in the core, I am pretty sure on a joint.

    I don't have good access to patch it from behind so I had to make the decision to yank all the laminate and tomorrow I am going to re-coat all the joints and overlap by a couple of inches just to make sure.

    The bag pulled down tight (25" hg) and I could not detect any leaks in it so maybe I didn't do as bad a job with it as I thought .. although who knows what would have happened at full vacuum.

    Looks like infusion will be pushed back to later next week or weekend. :( On the bright side, I am going to take this opportunity to run air lines along edges this time.
     
  2. jorgepease
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    jorgepease Senior Member

    I have re-epoxied all the joints, if its still leaking it has to be a screw but I don't think so. I think it was the wood flour I used with the filler or maybe the coosa board??

    Anyway I switched the air hoses to be along the edge. They are broken into 4 sections bow, stern and each side so I can clamp them off individually if its not an even flow. I can't see how it wouldn't be, I have been meticulous with everything.

    What I am wondering is would you stop the infusion flow media farther from the vacuum hoses? If so, how far away? It was mentioned earlier that I can stop it before the vac hoses to let the resin front catch up.

    As per the pics, I have stopped it just before the flange ... about 2 inches from vac hoses.

    Thank you

    [​IMG]

    [​IMG]
     
  3. groper
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    groper Senior Member

    I stop it 2 inches from the edge also. Slows right down then finishes more evenly. Can clamp off before this point usually aswell , the remainder will infuse with the excess resin already in there.
     
  4. groper
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    groper Senior Member

    I use about 3-4 inches of peel ply between the vac line and panel edge for a resin break, it allows the vacuum a media to pull through so you need to add this and wrap it around the vac line.
     
  5. jorgepease
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    jorgepease Senior Member

    Ok, I will add the peel ply strips around the vac line though the lines are just about to the edge of the laminate already. I will probably pull some resin out but that is okay, too late to build a bigger flange.

    Thanks a lot!
     
  6. jorgepease
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    jorgepease Senior Member

    I have done another vacuum test. Pulled down to 30" then isolated the pump. in 15 minutes the pressure dropped to 25". I can not hear anymore leaks ... I don't have a leak detector.

    Do you think my pump can infuse this hull Welch 1397, 17 cfm at it's current rate of fall off?

    [​IMG]
     
  7. tunnels

    tunnels Previous Member

    Just interested to know

    Why are you infusing this boat ?? what is the mater with just laying the glass normally ?
    I am just interested in the reasoning !!:confused:
     
  8. groper
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    groper Senior Member

    your in a position i often find myself in... i also do not own a leak detector...

    What i do is a drop test at 25inches, and see how far it drops from there. For some reason, it can almost stop dropping from this point, yet at 100% vac it will drop quite quickly. Very tiny leaks are difficult to find and there can often be many of them, but if it stops dropping from 25inches, i figure they are too small to worry about and proceed with the infusion and look for bubbles once the resin is being pulled in (if any).

    Once the resin goes in, monitor the bag for bubbles and be ready to plug any pin holes in the bag with tacky tape. Look around the resin lines and inlets especially. If you have leaks in your core, this is teh worst case because theres nothing you can do. If the leaks are small, damage will be minimal and youll still have a laminate better than hand laid, but if the leaks are large, you may have to repair part of the laminate where the leak was. i doubt this will be a problem if its dropping as slow as 30- 25in in 15mins. my reasoning is its quicker to do a repair job, rather than pull the whole setup to peices and redo everything again, STILL WITH NO GUARANTEES HAHA! - you may find still more leaks... oh the joy...

    The pump CFM is massive, i use a little 2cfm pump to infuse everything i do... upto 140sq ft so far...
     
  9. jorgepease
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    jorgepease Senior Member

    I should have mentioned that it seemed to level off at 25, interesting. Maybe water is boiling off at higher vacuum ...

    Yes this pump kicks butt, I pull a full vacuum on the bag in less than a minute and went from 25 back to 30 in seconds, I love this thing! Only $800 including shipping on Ebay.

    Thanks, I will go over all my hoses again but scheduling infusion for Thursday.
     
  10. jorgepease
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    jorgepease Senior Member

    This was a learning project.
     
  11. groper
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    groper Senior Member

    BTW, i cant see where your inlets and outlets are... make sure they are at opposite ends or middle and each end etc... not both at the same end etc as the resin starts flowing outwards nearest the inlet first and will reach teh vacuum first if the outlet is placed nearby. I try to get them as far away from each other as practical.

    You have 2 main feeds (backbones) down the center.... why? youll have to open 1 side first, then once the resin front passes the other main line (opposite the front direction), open the second line too. You will get a dryish/void rich laminate between these 2 main lines if opened at the same time as the dissolved air in the resin will be trapped there as it flows in and blocks the vacuum to that strip between those 2 lines.

    Most of teh dissolved gas in the resin, races to the vacuum and exits the job through the flow media or areas of high permeability. It stays in the job, when the vac path is no longer there, and prefers to collect in places of high permeability such as resin lines, bridging of the bag, channels and other places which will form resin rich areas or pathways. Unless you degas the resin before starting, there is always some air in the resin which needs to escape or will expand under vacuum and remain trapped in places like this, which is why we need to design strategies that fill evenly with no parts of the layup becoming encircled by resin and thus cut off from the vacuum pathway.
     
  12. jorgepease
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    jorgepease Senior Member

    My 2 resin feeds are on the far end and I have four exits. The air lines surround the boat but I can clamp each one off individually if I need to.

    The reason I have two feeds is because I wanted to pull the resin quickly, feed them from the same bucket and I did not have cross T's. I figured the 3" between them would fill no matter but thanks for pointing that out, I will delay opening one line. At least I have control of the air so I can shilut one side off a little early. I know, its a mess, next time will be better!
     
  13. groper
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    groper Senior Member

    i infused a flat panel similar to this yesterday... i only used a single back bone, but had 2 inlets into the same backbone. worked great.

    Whatever you do, dont open those 2 lines simultaneously! it will only take about 2-3 mins before you can open the second line, after the resin front reaches it.
     
  14. tunnels

    tunnels Previous Member

    ok i can live with that !and what have you learned so far ?? :confused:
     

  15. jorgepease
    Joined: Feb 2012
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    jorgepease Senior Member

    Groper and everyone who has commented, thanks, this forum is loaded with knowledge and I could not have progressed this far without all the help

    Tunnels, I am a quick learner but as in any new process, there are tons of details, tiny details, of which so far I have learned maybe one hundred, just ten thousand more to go LOL!!

    The one trick that evades me is how you control the kick time of epoxy when its in a big bucket. It seems to me you either need to make a special very thin and long bucket which can vent the heat or you need to empty that bucket as fast as possible which means more and more resin feeds.

    If this hull infuses well I am going to try to infuse some 4x8 sheet of corecell with fast hardener using the same feed layout (but only a single line with two inlets) except I am going to space the legs only 10" apart (5" between them).

    I bought the slow and fast and was going to mix them but after my first experience doing that, I am going to use just slow on this hull and I need to use the fast up on more controllable pieces.

    Cheers
     
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