Thursday, October 27, 2016

Window Frame Mold and Installation

We built a fiberglass mold to make fiberglass window frames for Noel. 

The eleven window frames are made with polyester resin and gel coat, and they are bonded to the boat with west systems epoxy resin, and tabbed in with fiberglass around the outside. We pulled a fairing fillet around them, with Awlgrip Awlfair and then primed with Awlquick and 545 until they were blended in with the rest of the primer on the boat.  The windows will be bonded in to the window frames.  No leaks, no seams.  Noel is making the transition from a wooden boat, to a cold molded boat and associated maintenance.   No leaks!  

The plug was made with MDF plywood done in two layers. 

                                            We sealed the plug with Duratec Primer. 
It was sanded out and polished. 
  We waxed the plug, and sprayed gel coat over it.  

We laid up the mold, and then let it sit for a few days before glassing iron pipe to support it on our saw horses and keep it flat.

We pulled the mold the next day, and cut the flange straight.  

Mold read to lay up parts. We waxed it ten times with Partall Paste wax. The mat is up on rolls to make it easy to pull over the mold.  We used both 1.5 ounce mat as well as veil for the skin coats.
First part, skin coat being laid up.  The skin coat extends to the edge of the flange to make the part pull easier.  The window frames have perfectly plumb sides, with no draft, yet they pull out of the mold very easily with the flange left intact.  Polyester shrinks when it cures ever so slightly, which means on shallow molded parts you can have with zero draft angles like this.  We back filled the molded parts, in the mold with a mixture of polyester resin and chopped glass fiber with glass microballoons to keep them fairly light.  To get a flush surface on the top, we broke the part loose from the mold, but left it in the mold for support, and then ground down until we saw gel-coat on the flange.  We made one every two days, to let them set up long enough to stay straight when pulled from the mold.  Each took 10 layers of 1.5 ounce fiberglass mat, laid 3 layers at a time to keep the heat from distorting...  before being back filled with roughly a gallon of filler.

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