Announcement

Collapse
No announcement yet.

Epoxy

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Epoxy

    I am getting ready to do some Epoxy work. JB Weld has long been my friend, but.....

    I did not realize how fiberglass, epoxy, and other adhesives have advanced. West Systems has a tremendous amount of information on applications and materials. There was a lot of info at http://www.westsystem.com/
    and there is a whole set of articles at http://www.epoxyworks.com/ there are other sites as well. I was very interested in metal adhesion and fiberglass blister repairs.

    I know many here are already up to speed on this stuff... but if you have not checked it out lately, then you might go...

    --Jerry

    (no - I don't own the stock or work there- I just using it and getting ready to do a lot more.....)
    dvideo

  • #2
    Yup... One of these days I'm going to place a massive fibreglass, resin, and epoxy order.. I'll probably make a small sailboat hull, a pair of Kayak's, A PsychoKart body maybe, and probably a bunch of other things..

    So many things to do, and so little time to do them!

    -Adrian

    Comment


    • #3
      I was laying up some WestSystem epoxy and glass last night!

      Converting a rudder to an 1 1/2" aluminum tube tiller from an ash tiller with aluminum side plates.

      The new rudder has an epoxy/glass tube bonded to the top of it, then glass is layed over the top to reinforce it. The tube was actually layed up around the aluminum for a super snug, no slop fit.

      Mike P
      Mike P
      1919 13" South Bend Lathe
      1942 Bridgeport M-head Mill

      Comment


      • #4
        I have done some epoxy over fiberglass cloth recently, works very well. 2 tips that I learned. 1) make a squeegee out of an old javex bottle or similar and after applying the resin to the cloth, starting at the centre, use the squeegee to pull of all the excess resin. it might seem like you are taking off too much, but this is how you pull the cloth to shape so that later you won't even see it. work in areas you can handle at a time, once it gets to a certain tackiness, the squeegee starts to lift the cloth

        2) the epoxy dries with wax film - i.e. needs sanding between coats. this is a pita if you are trying to build up (don't want to go through into the cloth when you sand) thickness. make a 30/70 vinegar/water solution and vigorously scrub the surface. this removes the wax and you are ready to recoat
        in Toronto Ontario - where are you?

        Comment


        • #5
          Was looking for concrete anchors in McMaster Carr. Was suprised to see the ones with the highest tensil (pull-out) were a steel stud/epoxy kit.

          Comment


          • #6
            For what its worth--

            When using Fibreglass matt as opposed to cloth, polyester resin will soften the mat and allow it to conform to the shape of the part. Epoxy will not soften the mat.

            Comment


            • #7
              Mcgyver--it works better not to let the epoxy dry between layers of glass. Put it all down at one time.

              You lay your first layer of fabric over the mold, then brush on epoxy. squeedgee the epoxy out (I use old copy cards--they're like credit cards but a little more flexible, because they're a little thinner), then lay down your next layer and repeat. The key with putting on the second layer is to get it down right the first time, because it doesn't want to scootch around once is it's sitting on the first layer of fabric with wet epoxy on it.

              Composite stuff is basically pretty easy, but there's a lot of little tricks and techniques to make it come out right. I'm sure there's lots of people here who know about 1000X more about it than I do, because I only have a little experience with this stuff.

              -Justin

              Comment


              • #8

                What kind of material do the "pros" use for fiberglass molds? For a boat hull, I was thinking of building the hull out of light weight 1/8" ply, then cover with several layers of glass cloth.. The 1/8" ply would obviously be part of the hull.. But if I were to make the hull only out of glass, what kind of material should I build the mold out of? Can I build the mold out of anything and just use wax paper over it maybe?

                Also, I think the itch as developed.. Where do you guys buy your rolls of glass? I saw some on Ebay last year but I forget what the price per sq/yd was, etc.

                -Adrian

                Comment


                • #9
                  I think you are right about the tricks. I have ordered the West Systems booklets - before I do more. Are there useful sites *full of tricks* on the 'net?

                  You can always get Epoxy at West Marine. I will likely get some at Mr. Fiberglass, as well. He has this cool CF rocket page.....
                  www.mrfiberglass.com .

                  I also was looking at heat forming some Polycarbonate (lexan)- so adhesion is a big thing....

                  --jr
                  dvideo

                  Comment


                  • #10
                    The way you build a mold is actually fairly simple. You cut a bunch of cross sections out of plywood (we use 1/4" to 3/8"). In areas where the cross section is changing rapidly you should have a piece of plywood every 6" or so. In areas where the cross section is relatively constant you can make that every 12 to 18".

                    The way we form the cross sections is to print it out on a plotter so that the print out is actual size. We cut out the shape, and glue it to the ply wood, rough out the shape on the band saw, and finish with a disk or belt sander. You need to draw three imaginary lines through your part, and mark the location where each line intersects each cross section on your printout.

                    Then you glue chunks of pink insulation foam to each piece of plywood (on the side your printout is NOT glued to) in the thickness of the spacing between it and the next section. Use a hotwire to rough out the foam to approximately the shape of the plywood after it's glued on (be sure to wear a respirator the fumes from this are terribly noxious). Drill a hole at each of the line-locations through both the plywood and the foam.

                    Get a 3 pieces of all thread rod and use nuts to position your cross sections in order. It's useful to use a drill or something to get the nuts all the way down the rod, so you don't have to spin them by hand. After it's all assembled, sand your mold so that it's smooth and flush with your plywood pieces. After this, cover it with a good thick coat of Bondo, and sand the Bondo smooth. If you want a good smooth finish, you'll need to do a good bit of sanding on the bondo.

                    A mold the size of a kayak or so made in this style will cost about $200, take 20-30 hours to build, and weigh 80-100 lb. However you can make a pretty good number of parts with one, with only minor repairs between uses as long as you use mold release.

                    I hope you can follow this post--I realize it's rather convoluted. I'll come back and try and clarify things if it's confusing.

                    -Justin

                    Comment


                    • #11
                      Justin's reply describes a male mold. If you lay up a hull over that 2 things happen 1)the resulting hull is slightly larger and 2) the outside of the finished hull is rough and needs to be finished. What he has described is a good appraoch to making a plug. Then you make a (female) mold off of the plug. With the resulting mold you spray in gelcoat first then layup your glass and or core material over that. When hard pop it out of the mold and the out side is shiny smooth. (assuming the plug was shinny smooth and you preped the mold corectly)

                      Now back to the origional question. The molds in most if not all small boat applications are made of fiberglass. Once the plug is faired to finaly shape it is polished to a very high gloss and caoted with mold release. These are either wax based or polymer based. Then the plug is sprayed with tooling gelcast. After that the mold is build up with multiple layes of fiberglass. A typical 20 Ft sailbaot hull mold has an inch of fiberglas and the a WHOLE bunch of framing to make in a large cart with wheels. Once that is cured the plug is pulled out of the mold. The mold is then polished a lot and the prepped similar to the plug. Now you have a mold capable of making hulls. For a hull and deck for 10 ft kayak maybe $1000 in materials.

                      This is the short (very short) description for making an open skiff. Put a deck on it and the complications go up by 4X.

                      Epoxy over wood is a very attractive alternative. I currently using a duck boat I built 16 years ago out of wood and West system. Strong as h***. West system isn't cheap. $75.00 a gallon mixed. There are some special considerations for putting fiberglass and epoxy on wood. Go get the west system books, they're very good. I always a gallon that around for doing various things.

                      Boat building is part science part art. I think everyone should build a boat in his or her life time. It's a great experience. Good luck

                      Comment


                      • #12
                        <font face="Verdana, Arial" size="2">Originally posted by jburstein:
                        Mcgyver--it works better not to let the epoxy dry between layers of glass. Put it all down at one time.
                        -Justin
                        </font>
                        where were you when I needed ya! I want to make sure I understand you, I only used 1 layer of cloth (this the exterior treatment on a mahogany model boat hull). What I wanted to do was apply a couple of more coats to build up the epoxy thickness so that sanding wouldn’t go into the cloth.

                        I understood that as the epoxy dries it leaves a wax film that seals out the air so that it can cure (is that correct?) and that to apply more epoxy required removal of the wax, either by sanding or scrubbing. If that’s so, and you’re saying do the second application before the first dries, hasn’t the wax surface started to form by the time the first coat is becoming tacky? I guess I’m asking does your suggestion work on applying coats without cloth, and when should you shoot for that second coat?

                        thx

                        in Toronto Ontario - where are you?

                        Comment


                        • #13

                          This thread really needs some pictures...

                          Comment


                          • #14
                            Mcgyver,

                            Generally, epoxies do not have wax in them, because air does not inhibit the cure. Polyesters some times have wax in them because certain ones are air inhibited, they won't cure on the surface. If applying multiple coats of epoxy and letting them cure between coats it wouldn't hurt to rough up the cured surface with some sandpaper to help the next coat "bite into" the previous one.

                            Chris

                            Comment


                            • #15

                              Has anyone else tried making small brackets and small fibreglass items using fine glass cloth and thin C/A? I've made some really great small lightweight structures for R/C aircraft with very fine mesh fibreglass and thin C/A. The thin C/A immediatly wicks into the fibreglass and gives you a really nice result.

                              -Adrian

                              Comment

                              Working...
                              X