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vacuum bagging in Singapore - for building airplane wings - my experiments

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    vacuum bagging in Singapore - for building airplane wings - my experiments

    some of us (not sure how many, har) are glider enthusiasts.

    some of us are scratch building enthusiasts

    well there's the rarer few that do both (like me)

    anyway I've been trying to do cheap vacuum bagging

    vacuum bagging is a method of adhering balsa wing skins to foam cores or getting fibreglass to stick to the foam wings using as little epoxy as possible...

    biggest problem is getting a reliable vacuum pump

    so here's what I managed to find...for $2.90 somewhere in Ang Mo Kio...

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    this is a ball pump. there are 2 ends. the pointy end is where the air comes out to inflate your soccer balls, basketballs, etc

    the OTHER end has holes for the air to be sucked in

    what we need is to seal up these holes with epoxy and then make ANOTHER hole for the check valve to go into.

    now, you need this device called a CHECK VALVE. (for those of you dabbling in aquariums and planted tanks, you would know what I'm talking about). it only allows air to flow in 1 direction.

    drill a hole in the pump and push the check valve in. make sure it's in the right direction (when pumping, you still can feel some suction). seal all gaps with epoxy or sealant.

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    the other end goes into a bottle cap with another check valve on top. I use aquarium tubing to connect them. There is another type of aquarium tubing, black ones that are more rigid but I used regular ones (the black ones are for CO2....for planted tanks)

    and now I crush the bottle with atmospheric pressure....


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    a regular bottle to compare, duh

    now you need a proper vacuum bag. I am fond of using the 2 dollar daiso vacuum bags for storing clothes..... they seem rather tough.

    now what I did is get another bottle, saw off the neck area and put it in the vacuum bag. then using your bottle cap, screw it over once you made a hole. I'm really bad with words here, but just take a look at the picture, you would get it.

    I'm still fine tuning the results but it seems you need an O ring for better results...... ah...

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    in this pic I'm 'bagging' a scrap piece of foam. no biggie there, I was just testing how tight was the pressure.....

    note to self, do not use too big a bag.

    Qn: Y U NO USE Converted Aquarium pump???

    I did, but bought the wrong type. It said 'vacuum pump' but it was a 'water lifter', more for doing little fountains for terrariums...

    I might use an aquarium pump, but I do not wish to risk a good $20 on something that may end up useless.....so any people willing to donate their old pumps to me are most welcome.

    We can talk about our other hobby....'fishkeeping' and 'aquariums'= p

    Qn: in RCgroups, there is extensive mention of 'caulking'. Where can I get it? I have not been able to find it in Singapore.

    Ans: Well......this looks like what you need. Block 412A Ang mo kio hardware store. do note...it's 12.90. horrible.

    go for ziploc bags instead la....

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    "Always fly with a responsible attitude. You may think that flying low over other people’s heads is proof of your piloting skill; others know better. The real expert does not need to prove himself in such childish ways..." - the Multiplex Build Manual

    #2
    Stick to your bike pump! ...them aquarium pumps usually can't create the vacuum necessary for successful bagging.

    Professional vacuum bagging pumps looks like aquarium pumps but the pressure created are not equal.
    Seriously running out of ...Storage space !

    Comment


      #3
      i tried bagging using those space saver bags and the pump which comes with it. The pressure seems to be sufficient as I get a good lamination.

      The problem i face is in getting mylar sheets and mold release wax. Following are what didn't work for me for your consideration so u don't waste $$:
      - Normal car wax didn't work for me.. due to the long period the wax is in contact with epoxy, i think the wax gets dissolved..
      - waxed paper from supermarket was also not good enough..epoxy soaked through...used baking sheets (bakerite) which is silicon based and i get a decent barrier. This cannot give a glossy finish

      Do share if you found sources for wax and mylar

      This is how the glider built looks like....kind of e-blaster inspired. Pod is 2pc FG joined using a joggle so i can work on the internals.

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      Comment


        #4
        Good stuff, gecky

        where do you get those space saver bags? now totally can't seem to find and believe me, I've looked

        I have a roll of cellophane wrapping paper, totally transparent. seems to have some potential as a mylar substitute

        think I got to try next week....

        I have this 'mold release spray' I got from Art Friend. not so sure if it would work...
        "Always fly with a responsible attitude. You may think that flying low over other people’s heads is proof of your piloting skill; others know better. The real expert does not need to prove himself in such childish ways..." - the Multiplex Build Manual

        Comment


          #5
          Originally posted by gEcky View Post
          i tried bagging using those space saver bags and the pump which comes with it. The pressure seems to be sufficient as I get a good lamination.

          The problem i face is in getting mylar sheets and mold release wax. Following are what didn't work for me for your consideration so u don't waste $$:
          - Normal car wax didn't work for me.. due to the long period the wax is in contact with epoxy, i think the wax gets dissolved..
          - waxed paper from supermarket was also not good enough..epoxy soaked through...used baking sheets (bakerite) which is silicon based and i get a decent barrier. This cannot give a glossy finish

          Do share if you found sources for wax and mylar

          This is how the glider built looks like....kind of e-blaster inspired. Pod is 2pc FG joined using a joggle so i can work on the internals.

          [ATTACH=CONFIG]112361[/ATTACH]
          very nice.

          I used a space saver bag for bagging my balsa sheets to wings, so its up to the next level with epoxy fibreglass skins. thing is....vacuum cleaners are loud and I have an infant in the house and I can only build late at night. so.....no go

          what did you use for mylars? bakerite? the finish still looks quite satiny

          wax - same as you. looked at things like auto wax, kiwi neutral, beeswax (expensive!) and so on.... haven't tried yet, ridiculously expensive

          by the way, what's the fuse made of?
          "Always fly with a responsible attitude. You may think that flying low over other people’s heads is proof of your piloting skill; others know better. The real expert does not need to prove himself in such childish ways..." - the Multiplex Build Manual

          Comment


            #6
            The left wing is bagged with wax paper stucked on pvc sheet. The epoxy soaked through parts of the wax paper and I had to painstakingly scrap off the bits..The right wing is with bakerite and it peel off without much fuss.

            The finishing looks satin but is still far from the glossy mirror finish most would expect from vacuum bagging.

            Got the space saver bag (the clothing one like those in daiso) and manual pump from ebay. It helps to use the vacuum cleaner to draw out most of the air before manual pumping out the last bit though.

            For wax, I have tried some Japanese paste wax and liquid turtlewax, both didn't work... the pvc sheet literally got laminated together with the core and glass.

            Fuse is glass with portions of CF+kev cloth. Only got it right on the 3rd/4th attempt

            Comment


              #7
              Fuse photo before painting:
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              Comment


                #8
                good stuff

                I think I'll test bag the horizontal stab later this week

                will let you see how the mold release works

                so I think your glider should fly quite well?
                "Always fly with a responsible attitude. You may think that flying low over other people’s heads is proof of your piloting skill; others know better. The real expert does not need to prove himself in such childish ways..." - the Multiplex Build Manual

                Comment


                  #9
                  Horizontal stab out of foam?

                  For experimenting with the system, you might want to start off with some cores that are scrapped...

                  Maiden was just over wkend... flew ok, still trimming out and prob need to change out the control horns as the mini-servos not giving enough resolution. Then, this morning i got a brown out and the thing plunged from 25+m at 45deg... got a few cracks in the fuse and wing pylon broke off. All fixable but will take time.

                  Comment


                    #10
                    H stab out of 2mm balsa
                    "Always fly with a responsible attitude. You may think that flying low over other people’s heads is proof of your piloting skill; others know better. The real expert does not need to prove himself in such childish ways..." - the Multiplex Build Manual

                    Comment


                      #11
                      Guys, any light silicone lube - a spray in an aersol can - at your local hardware shop will work well for mold release. Usually below 12 bucks.
                      sigpic
                      ... Why does everything I think I need always come with batteries?
                      John Mayer

                      Comment


                        #12
                        heey it's the chemist!

                        thanks! you're a genius! (but I told that to you already in person so you probably know already)
                        "Always fly with a responsible attitude. You may think that flying low over other people’s heads is proof of your piloting skill; others know better. The real expert does not need to prove himself in such childish ways..." - the Multiplex Build Manual

                        Comment

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