bleed and feed

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

  1. Tungsten
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    Tungsten Senior Member

    So I've managed to get some shade cloth,not sure on the % as the retailer was unable to tell me.

    Its about the same speed as 3 layers of door screen.So compaired to the green flow media its very slow.

    What has worked best so far is the green 75,I've just been pinching the inlet line for the first 5" or so to slow it down.If I don't the front races ahead quickly.Once the the first 5" is completely wet out I open the feed line fully and this seams to slow the front down.It still travels on the top with complete wet out falling behind but it seams to work.

    Considering my vacuum is less then maxium and my resin is thicker then ideal ontop of that my laminate is quite thick.

    My next test will have flow media on both sides,this should speed things up.I'll try the shade cloth on both sides and see what happens.
     
  2. Jim Caldwell
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    Jim Caldwell Senior Member

    I pulled another small part yesterday 3" X 24" with a 7" X 28" resin field. 150 CPS, 40 min. pot life with green mesh and Strechlon bagging film.
    Layup is 1.5 oz PW fiberglass , 2 layers of 6 oz carbon, 1.5 oz PW fiberglass and peel ply with a 1" gap between green mesh and vacuum line for a resin break.
    The resin line was only 1/4" ahead of the saturation line at 22" of mercury.
    We will see what the results are later today but that is much better than the 1/2" separation I was getting.
    Maybe I should try slowing the flow as you did for the first few inches also.
     
  3. Tungsten
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    Tungsten Senior Member

    I did another today but changed my layup to solid stiched,got rid of the WR.Slowing down the first 5" again really seams to work,the air from the feed line gets a chance to get ahead of the front.My distance also increased by getting rid of the WR.

    Jim,What are you making?I will be trying CF later for some interior bling.
     
  4. Jim Caldwell
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    Jim Caldwell Senior Member

  5. Tungsten
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    Tungsten Senior Member

    Playing around with more tests,Panels 6"x 28" with a resin feed in the middle and vac on each end.Surprised to see my distance double,I've been feeding on one end and vac on the other.I'm now getting the resin to cover the 28" in the same time it took to do 14".Great news.

    I'm using shade cloth and 4" of green mesh just under the resin feed.This seams to shoot the resin out each side 6" or so in the first minute.After that it slows down but still fast enough to reach the 14" or so on ea side in 15 minutes.

    Shade cloth short of glass +/-2" and peelply about 4" after the glass to the vac.

    Just playing with when to clamp the infeed.Just as the resin hits the break or should I wait until then end of glass?My first try I did it when it hit the end of the shade cloth,it still moved through the rest of the glass but it looks a little dry at the ends.
     
  6. Tungsten
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    Tungsten Senior Member

    Well its cured now and yes there is some dry looking areas at the end,clamped to soon I'd guess.I was also surprized to see the same under the inlet,just a little bit of that green mesh was enough to let it shoot out just to quickly making it look just a little too dry.
    I've come to the conclusion that my resin is just not thin enough@ 350 ish,green flow 75 is just too fast and shade cloth is just too slow.Guessing that maybe a much thinner resin will flow much better making the shade cloth work.

    I have no idea why this green stuff was invented as it clearly has no use in infusion??

    So on the look out for some infusion epoxy but can only find some around 250 on the viscosity chart that can be shipped to me within reasonable $'s.Open time or gel time is at 300 minutes or so??Is this normal?Ill have to ask if theres somthing faster.
     
  7. groper
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    groper Senior Member

    Dont know about the green flow mesh - never tried it.

    The dry spots at the end are more likely from the flow front being kind of elliptical from the resin feed line center. This means the resin has to travel farther at the extreme corners of the panel. I run an additional strip of higher flow media - you could use the greenflow mesh for example - from the resin feed line ends out toward the corners to help promote flow to the extreme corners of the panel and prevent the dry corners happening.

    The resin i use is 350CPS @ 25deg C. The viscosity doubles with a reduction in temperature of about 8 degrees C. So with you being in canada in winter and all, i suspect you find it slow becuase the temperature is cold and thus your viscosity would be considerably higher than 350cps.

    Where i live, my resin rarely goes below 25degrees. Often its up around 30degrees when i infuse. So for me, the 30% shade cloth works great - not too fast and not too slow.

    If your flow media is too fast, then throttle the inlet to slow it down. Too fast gives a whitish laminate that looks not properly wetout - this is because the entrained air cannot escape before the flow front passes too far ahead and the vacuum is gone. The fibres need a little time to wetout and the tiny air bubbles need time to escape to the resin front. So in the beginning of the infusion, throttle the inlet with hose clamps until the front slows down a bit (first 5 mins or so) then you can open it fully and let the natural resistance govern the speed from then on.

    Yes, alot of infusion epoxies have extremely long open time for infusion work. There are others which are more "normal" aswell.
     
  8. Tungsten
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    Tungsten Senior Member

    I didn't think about the temp thing.Normally my shop sits at 15c so your right no wonder my resin is a little slow with shade cloth.I have been throttling the inlet back when I use the green mesh but not with the shade cloth as its slow.The day I did the test I had the temp up a little and that little piece of green mesh under the inlet,so a little less vis on the resin and the added flow media made it enter quite quickly.

    So with such a long open time on the resin I can see what will happen.If I clamp off after the glass is wet then it will continue to flow through the 100mm gap of peelply to the vac hose.How much resin is able to get into the spiral if its sitting on one layer of peelply?Or will it just stop at that point?So far all my tests the resin has kicked and stopped just before the spiral vac line.

    Thanks for the help.
     
  9. groper
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    groper Senior Member

    The peel ply only resin brake will not allow much resin to pass across it. This shouldnt be a problem regardless if you calculate the required resin for the job and clamp the feed line at the right time - a little bit before the panel is completely wetout. You will get the feel for this the more infusions you do. The laminate is resin rich near the inlet and dry at the extremities, so after you clamp the inlet, you will see the the front keep moving forward as the resin rich areas near the inlet give up some of their excess and the resin content evens out across the panel. Once the ultimate fibre volume fraction is reached across the entire laminate, the front will cease to move forward. So exactly when to clamp depends on the laminate type and thickness, and the vacuum pressure you have which is dependent on your altitude and vacuum pump.

    Keep going, it just gets easier and easier the more you do :)
     
  10. Jim Caldwell
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    Jim Caldwell Senior Member

    For reference, I am using 150cp resin and hardener from Illstreet with 40 minute pot life (fast).
    I also use the peel ply brake, the green mesh works well with 3 layers of 200gram 2x2 twill and flows much faster with Plain weave. I also clamp off the resin after 1/2 infused for a minute or two and shut it off when it all crosses over the flange before the brake.
    I started at 28C temp for resin and mold which was too warm for my resin and thin layups, I am now at 24C and get 4 to 5 minutes Infusion time of 32" flow.
    I give it an hour then turn on my heat lamps which bring it up to 38C over an hour.
    You can see the resin start to flow again after 15 minutes of heat.
    So temp appears to be very important.
    Grouper, you are so lucky to be fairly constant 25C unlike Tungsten and I. -12C now with -18 on the way.
     
  11. Tungsten
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    Tungsten Senior Member

    I'm looking to do flat panels on a table,looks like I'll need some sort of way to warm my bench.

    Jim are you having any trouble removing your peelply?Or are you using release film?
     
  12. Jim Caldwell
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    Jim Caldwell Senior Member

    No more trouble than usual but keep it below 120F or the peel ply locks in.
    Use razor knife and cut 4" strips all the way through the bag, mesh and peelply and it will reduce the surface area of each piece.
     
  13. Tungsten
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    Tungsten Senior Member

    Yes it does lock in quite well.lol thanks
     
  14. Jim Caldwell
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    Jim Caldwell Senior Member

    Well I typed the above wrong, you don't have to cut all the way through the mesh and peel ply, just a score thru the bag a nick in the mesh will let rip.

    The dangers of putting in 16 hour day to beat the weather, I forgot the mesh in my bag since it was only an area of 52" x 9" flow path I decided to go ahead. In fusion time increased by about 30% but it infused. The only negative was it 10% heavier.
    I was surprised!
     

  15. Tungsten
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    Tungsten Senior Member

    I have thought about what would happen if there was no flow media,thin enough resin with a long open time should flow far enough.Adding more inlets would use less resin then the mesh.

    Jim why did your part end up heavier?
     
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