OAKLAND WOLVERINE             

                           MODEL BOAT CLUB



 

      Building Tips feature 

          ( SCALE GUYS ~ SEE PICTURE BELOW )            

 

     Being that we are in the building season, I thought addressing the subject of

             gluing and sealing would be helpful.  This may seem elementary, but I can

             guarantee you, failed glue joints will ruin your day at the pond

 

            Safety:

                      *Ventilate!!!!! Fumes and vapors given off by epoxy, polyester or CA can

                       be very harmful.  If you are working in an enclosed un-vented area

                       (Basement/garage), it is important that you setup a fan and open a

                       window to expel the vapors.  Epoxy vapors come during the curing

                       process and have minimum to no odor.  CA is really bad stuff!

                       *Wear disposable latex gloves. If you cannot wear latex, uncured epoxy

                       can be  removed from your had with Fast Orange hand soap.

                       *Wear a quality dust mask when sanding.  Almost everything that we

                        sand on our boats is harmful when breathed into your lungs.  When

                        sanding off old paint, always wear a respirator mask.  Paint dust is as

                        toxic as airborne uncured paint.

            Surface Preparation ( The most important part of the process):

                       *Before repairing or gluing items to fiberglass (epoxy or polyester) it is

                       mandatory to remove the glossy finish that occurs in the curing process.

                       Scuffing the surface with a wetted Scotch Bright Pad prior to sanding will

                        help to keep the  sand paper from clogging up.

                       *Before gluing plywood it is also mandatory to remove the oily finish that

                        is present on the outer surfaces.  This can be done by sanding with a fine

                        to medium grit paper.

                       *Surface preparation for other types of wood should be the same as

                         plywood.

                   *Before gluing Styrofoam ( use only high density ) it also has a coating on

                        the outer surfaces that needs to be removed.  This can be done by

                        sanding with a fine to medium  grit paper.  I would strongly recommend

                        cutting it away.

                       *After sanding, remove all dust. clean fiberglass and wood surfaces

                        with lacquer thinner.  This will assure a good bonding surface, free of

                        oil and other contaminates.  do not use lacquer thinner on Styrofoam

                        unless you want a melted mess.

     

          Gluing:

                       *Although many boaters use it, I personally do not recommend using CA

                        for bonding any joints needing structural integrity. Unfortunately, I have

                        experienced too many failures in using it for applications other  than

                        tacking or non-structural  applications.

                       *Slow drying epoxies are widely recommended for fiberglass or wood

                        applications. They work extremely well on wood hull structural joints

                        and for sheeting hull decks and bottoms.  Clamps, pins or weights will

                        be necessary to hold things in place while the glue cures. When gluing

                        with epoxy, more does not mean better.  After attaching  parts together

                        wipe off the excess.  Big globs of glue not only look bad, they add

                        weight and give no added strength.

                       *Most of the fast drying ( 5-10 Minute ) epoxies, I have used recently

                        performed well in structural joint applications.  I find that it sets up to

                        fast for large  gluing areas like decks.  Unless you want to hold things

                        together, clamps, pins or weights will be necessary to hold thins in place

                        while the glue cures. The big advantage, they expedite the building time.

                        *Soft woods, especially the open ends of cedar and lite ply will wick

                        glue into them and leave what is called a dry joint. These joints are

                        highly susceptible to failure.  Most epoxy manufacturers suggest that

                        you coat these woods with a light  first coat of epoxy that is wicked into

                        the wood.  Once dry, the sealed surfaces are lightly sanded and then

                        glue as normal.

            *I have experienced no failures in bonding to either balsa or Styrofoam

                        with both types of epoxy if the surfaces are properly cleaned and prepped.

                       *Sandbags make ideal weights, especially in contoured areas. Make up

                        multiple sizes to fit your applications.  Cloth bags seem to work better

                        than zip lock bags.  Use wax  paper between bag and surface to avoid

                        accidental bonding.

     

                       Fillets/Sealing:

                       *Fillets can add a lot to the appearance of you hull.  I find an easy way to

                       do them is to mix west system 407 Low - Density filler with any type

                       (slow/fast) of epoxy to a thick paste consistency. i run masking tape the

                       width of the fillet on each surface that the fillet is against.  This creates a

                       nice visual line on each surface and keeps any excess mixture from

                       adhering to the surfaces.  After applying the filler mixture I use a piece of

                       wood with the desired radius on it as a scraper to remove the excess. 

                       If you use long setting epoxy in the mix, you may need to use the scraper

                       multiple times to keep the fillet shape. let all epoxies harden for at

                       least 24 hours before sanding.  Once the fillet is hardened, remove the

                       tape and using sandpaper and a dowel rod, sand fillet to a final shape.

                       *The 407 filler changes the properties of the epoxy and makes it real

                       easy to sand.  Most fillers or thickeners when added to epoxy will

                      revise the laminating and bonding properties of the epoxy. Refer to West

                      Systems technical publications for more info on additives.

                       *Sealing a wood hull is mandatory. A simple accepted method is to paint

                       the hull  with slow dry epoxy and then scrape it with a playing card to

                       remove the excess.  I prefer to use a lint free rag and rub the epoxy in

                       to the hull.  This minimizes the amount of epoxy used and reduces the

                       final sanding effort. Either method works.

        

           Sanding:

                   * When sanding on epoxy, it is not recommended to sand too long or

                    vigorously in the same spot. Like paint, friction will soften the epoxy

                    and it will begin to clog the sandpaper.

                   *To  get a nice flat finish when sanding, you need a nice flat sanding

                    block. An ideal sanding block can be made from a piece of

                    hardwood  or birch plywood. The surface to which the sandpaper

                    will be mounted  needs to be flat and free of imperfections.

                    Attach the sandpaper to  the block using two way carpet tape.

                    Wrapping the sandpaper loosely  around the block will not give

                    you the same results. It is a  little  more work, but the results are

                    much better. Make up multiple blocks  with different

                    sandpaper grits.

                   *3M has come out with sandpaper called "Sandblaster". It comes in

                    colors (yellow, purple  and green) depending on the grit. It does not

                    load up like regular sandpaper

                    and lasts longer. It is a  little more expensive but well worth the money.

                    It is  available  at most hardware centers. Amen

 

              TIPS FOR SCALE GUYS

                SCALE GUYS. HERE IS A GREAT SHOT OF THE DASHBOARD AND

                 WINDSHIELD DETAIL FOR OPEN  COCKPIT  HYDROS. THIS

                 BUDWEISER  COCKPIT COULD ACCOMMODATE TWO PEOPLE,

                 THAT IS  PROBABLY WHY THERE  IS A SISSY BAR.

 

       

 

    

        

    

 

           

 

 

Oakland Wolverine Model Boat Club