bleed and feed

Discussion in 'Fiberglass and Composite Boat Building' started by Tungsten, Dec 19, 2013.

  1. Steve W
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    Steve W Senior Member

    Tungsten, i have in front of me an box of divinycell samples and the grooves are 2mmx2mm on 20mm centers with holes of about 1mm at each junction if that helps. You could cut them with a thin kerf circular saw blade or router or even on the table saw depending on size.

    Steve.
     
  2. Tungsten
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    Tungsten Senior Member

    Thanks Steve, that reminds me I have that same Diab sample box in my garage, I had forgotten about that.
     
  3. Tungsten
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    Tungsten Senior Member

    having a look at there site 2mm x2mm is the norm and 20mm spacings.With a long open time resin one could maybe reduce the channel width and put them farther apart.
    Also stop them short by the vac to make a break zone.
    I'll have to fire up a test as I have my infusion resin now.
     
  4. Tungsten
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    Tungsten Senior Member

    I'd like to revisit my question about infusing foam core both sides at once with out perforations or groves.
    I have plain foam.I've scrolled through the PDF groper posted and found nothing on my question.
    My part is about 16' long and 2' wide.I will infuse on a curved bench/mold.

    My questions,from what I've read the foam (1/4") should be tapered on the edges so to reduce race tracking?Can the glass on both sides extend past the foam? In feed line placed on one long side off the part with flow media from both sides under the inlet?Vac on other side so feeding across the 2' side

    I'd really like to do a small test but not sure if I'm on the right path.
     
  5. groper
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    groper Senior Member

    Yes, extend beyond by as little or as much as you like. The chamfered edges of the foam stop it from bridging and racing around the edge of the foam leaving the middle dry. Make sure you push the bag down tight onto these edges even with the chamfer as it will still bridge a little...

    Yes, no problem - provided the flow media is in contact with the feed line, it will flow under the foam via the flow media the same as it does over the top.
     
  6. Tungsten
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    Tungsten Senior Member

    Thx groper,so infeed can sit on the glass and flow media from both sides?What about tapering foam,does it need to be thin at the edge?Like a 1" taper or just a round over bit or...?

    thx again.
     
  7. groper
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    groper Senior Member

    i make a 45deg edge... cut the edge with a circular saw tilted over @ 45deg and run the edge off...
     
  8. Tungsten
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    Tungsten Senior Member

    thanks again,

    I had some bridging/racetracking .

    a pic
    [​IMG]
     
  9. Tungsten
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    Tungsten Senior Member

    After cure I have a little white on both sides right where the flow media ended,the remaining part from edge of flow media was clear.
    Looking at it now maybe my media was to wide or too close to the edge?

    I see why perforations are used now,this also allows you to center feed like most of your pics groper.Not sure but with the holes you don't need a flow media on the tool side then?
    What are your thoughts about having a converging front with perforated core?
     
  10. groper
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    groper Senior Member

    Your bag looks too tight... need more pleats... Put several pleats on every side of the bag so that there is a fold in the bag which runs along every edge of the core. With plenty of slack in the bag in these areas, its easy to press it down firm and eliminate the bridging. Also need to push the glass down tight and perhaps hold it with a little spray tack adhesive - but this isnt strictly nessesary.

    Also pay attention to where your feed lines are... If the ends of the feed line were close to the corners, with a little bridging it would have flowed straight down each side then around the back which has blocked your vaccum path and you get no further wetout - as shown in the pic.

    Its a pretty small test piece, everything would have happened so fast... You need to make long test peices that equal the flow distance to model the actual parts you plan to make...

    The perforated core allows flow in the Z direction. Once it reaches the tool side, its pulled along towards the vacuum. This flow has a lag behind the bag side, typically 2 inches for these types of laminates. It allows a smooth finish on the tool side with half as much waste resin from flow media on both sides. Apart from that, its no different to what yourve already done...
     
  11. Tungsten
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    Tungsten Senior Member

    This was my first try at both sides at once,didn't want to F up a large piece.Ontop of that its -20c right now so hard to get good temp in the shop.

    I'll be drilling holes this week I guess,1" centers at about 1-2mm diameter sound right?
     
  12. groper
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    groper Senior Member

    Didnt mean a "large" peice... small width say 4-6inches, but same length as your full size flow length- proably around 2-3 feet with a 200-400cps resin... this way you know infusion times and flow speeds over the full infusion.

    Yep 1 inch centers, offset to each row, 1-2mm dia...
     
  13. Steve W
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    Steve W Senior Member

    Are you going to join the holes with a small saw kerf like the diab stuff? I wonder if its needed, probably depends on the glass. I am going to need to be drilling some coosa board I will be using for high density inserts in my next project as it doesn't come drilled.

    Steve.
     
  14. Tungsten
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    Tungsten Senior Member

    Thanks,no not doing the saw kerf thing,reading about it seams it goes too fast and uses too much epoxy.Knife cut however has better results from what I;ve read but not sure on depth/spacing.
    Just the perforations alone should save me some resin,haven't done the math but groper says about 400gsm for grooved and drilled so I'd think a large part of that is the grooves.
     

  15. groper
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    groper Senior Member

    Yep steve, i included the coosa board in the infusions where i needed it. I just drilled it by hand using a 1/8th bit - smallest i had on hand. Works great, job gets done in 1 shot and the reinforcements are already in there.

    The saw cut allows you to get rid of teh flow media over the top. I mostly used peforated only foam on my build, and shade cloth flow media bag side. This produces the lightest possible panels. I tried the saw cut foam and its easier to use, flows huge distances (over 2 meters) and there is less waste plastic to deal with. The diab infusion grooved (VR cut) foam, consumes 400grams per square meter extra resin to fill these grooves - hence the added weight. This is in addition to the weight of perforated only foam.

    If weight is not an issue - the VR cut foam is definately the way to go, very painless.

    I havnt tried infusing knife cut foam, i suspect it would be much slower and flow distances would be much shorter. Hurry up and do some experimenting with it already Tungsten, so we can all find out! :D
     
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