Making Fiberglass Part - From scratch

[P69]

I couldn't find the parts I need in anywhere online or local and the price for custom parts seemed unreasonably high.  So, I decided to make my own parts (Lots of sanding!). I spawn an idea, make a cardboard or styrofoam  mock-up,  make the mold  (or plug), then make the part (or mold).   In some cases, I make a plug, then a female mold, then the actual part. For concave parts, I make the male mold and cross my fingers that I can remove the part with out destroying the male mold. If it's a convex part, I make male plug, female mold, then the part. If concave part, I make a male mold, then the part.  Not yet completed are two instrument/accessory panels for the cockpit.  I am making fiberglass parts (from molds I make) for Instrument panel, recessed cavity for two galley foot pumps (fresh and salt water), and hull stiffener that will also be a wiring conduit bringing wires up from under quarterberth to the electrical panel area by nav desk.  The cockpit panel parts are made, I am just working on details for making instrument installation/maintenance easy once box is installed in cockpit.  The other parts (hull stiffener, foot pump recess) are in the mold stage, not made the part yet.

I didn't put enough taper in the design and/or enough PVA on the mold and had to destroy the mold to remove the part. For second box, I designed more taper and used a lot more PVA. It came of fine, with  minor damage to the mold.  Now that I have the equipment and know how to do this, I keep thinking of other items I want to make.  It's a lot of work, but if a finished product is unavailable for purchase, what's one to do?  Make the think yourself!

http://s1278.photobucket.com/user/scherzoja/library/Fiberglassing%20Parts

[INCOMMUNICADO]

Nice Work.

[P69]

Thanks Allen,

I was surprised by what came out of the mold.  I had never made anything like that before. Excluding all the sanding to get a perfect finish on the male pattern (the piece panted gray), the process was actually fairly simple and it helps to have the right tools and materials.  Once the panel is finished and installed, I'll upload some pictures.

The hardest part was figuring out the basic shape of the part so that it is what I want and at the same time can be released from the mold. A mold can't have any straight sides, all surfaces have to have some taper and there can be no undercuts or negative draft, unless you have a 2-part mold that can come apart to release the part. I haven't done that yet.

For anyone who wants to try this, here is a list of basic steps and tools/materials

First, definitions.

Pattern: Sometimes called the plug. The form of the final part, usually identical to the final part. What comes off the pattern is the mold, usually female
Mold: This is usually the female mold, sometimes a male mold. Either way, what comes off the mold is the final part
Part: the final part.

The resins in part-making are all polyester, no epoxy because 1) epoxy is not necessary and 2) epoxy is not compatible with chopped strand mat (CSM) and gelcoat

Gelcoats:
- Normal gelcoat -
The stuff you see everywhere, color added to white to match existing gelcoat

- Tooling gelcoat-
This is harder than normal gelcoat, used on molds because it is more durable and one can produce more parts from single mold if tooling gelcoat is used, Red or black are common colors


1. Use your noodle to come up with a design (or use an existing part as the pattern)
2. Make a cardboard mock-up
3. Make the pattern out of whatever medium you think will work (styrofoam, MDF, plywood, whatever you can work with to produce what you imagined).  This will have the shape of the final part
4. Finish the pattern to a smooth surface (putty, drywall mud, etc...) and spray with Duratec primer, then sand to smooth finish
5. Wax and spray PVA
6. spray on tooling or regular gelcoat, then build up with chopped strand mat, cloth and/or biaxial. First layer needs to be CSM so it conforms to the mold shape
7. Pop the part off and see what you get. It's usually hard to get the part off and includes smacking with hammer, so make sure you made a strong, inflexible mold.

Tools and Materials
Husky Siphon Feed Detail Spray Gun: (sprayed diluted Duratec and PVA)
  Model # H4910DSG
  http://www.homedepot.com/p/Husky-Siphon-Feed-Detail-Spray-Gun-H4910DSG/203468550

E&S Model 100 Gelcoat Dump/Spray Gun (sprayed gelcoat and Duratec)
  http://uscomposites.com/equipment.html

Duratec Gray Surfacing Primer
  http://uscomposites.com/polyprod.html
   
Orange Tooling Gelcoat
  http://uscomposites.com/polyesters.html

Pure White Gelcoat
  http://uscomposites.com/polyesters.html

PVA # 10 Moldrelease
  http://uscomposites.com/moldrelease.html


Fairing compounds:
  Drywall mud, "Easy Sand 45"
     http://www.homedepot.com/p/Sheetrock-Easy-Sand-45-Lightweight-18-lb-Setting-Type-Joint-Compound-384210/100321610
     I used this on this for gross faring, where I needed quick buildup and low cost. Also, needed to be compatible with polystyrene substrate. Polyester resin will dissolve styrofoam, so you need tocover styrofoam with something (PVA, drywall mud, anything).
     Drywall mud worked really well, but needed to dry for several hours before sanding, usually overnight
     Next time, I'll try Easy Sand 20, which has a working time of 20 minutes, and maybe faster cure-to-sand time


  Wood putty
   Ace Wood Filler, solvent based
     http://www.acehardware.com/product/index.jsp?productId=53380326
     This worked very well on the MDF because it is the same density as the MDF and it sanded really well. I tried ther putty, but the density was different from the MDF; therefore, sanding was inconsistent.

  "foam putty"
     http://www.lowes.com/pd_41405-68-12142___?productId=3033261&pl=1&Ntt=spackle
     Used for final faring on top of the drywall mud. Quck dry, sands easy, sometimes too easy.

   I tested bondo and other polylester-based, bondo-like fairing substances and they didn't work out because they were either too hard to sand or never hardened up and gummed up sand paper


Sanding the Duratec:  The final coat of Duratec has an "orange peel" texture which has to be sanded smooth. It's easy stuff to sand, but  has a hard, gloss surface.
   Grit schedule was: 60, 120, 220, 240 we sand, 600 wet sand. Only wet sand if the what you sanding will not absorb water.
   For example, when sanding the MDF mail plug that was sprayed with Duratec, I did not wet snad becuase that would have ruined the plug.  When dry sanding, I used the same schedule
   When sanding a fiberglass male plug, I wet sanded.
 
You don't have to get the surface perfect (and you won't when you use drywall mud and foam putty) because the duratec will fill minor defects. The duratech surface has to be perfect because any defects in that surface will appear in your female mold (or part, if this is the male mold)
Once female mold was created, I wet sanded with 600, then 2000 grit to get perfect surface. 

The final part also needed to be wet sanded to get the high gloss.

Mold release.

There are two steps to getting the part to release from the mold.
1.  wax the mold with caranuba wax, 5 to 10 coats, depending on how lucky you feel. I tested Mothers Pure California Gold Carnauba and Mothers Carnauba paste wax. Mothers seemed better. The wax fills very small imperfections and is the backup release agent if you have issues with the PVA layer
2.  Spray thin coats of PVA. First spray very light dusting, wait a few minutes between dustings. Then spray increasingly heavier coats, being careful not to cause any sags or drips. The final surface of the PVA coats will be the surface of the final part, so be very careful spraying. If you make a mistake, wash it off (it's water soluble) and start PVA spray all over. PVA does not take too long to dry, so it's not much time lost if you have to start that process over.