robert

Hey...
I am thinking of making a 46 sized pattern ship, but I am having trouble designing a cowl and canopy that I can build from wood. What would be the steps in making a glass set?
The problems for me are that it is a very curved area, and its hard to make with wood.
But, I have no F/G experience...and not alot of tools, and little space....So, how do I do it?
Thanks for the help!!
Robert.

robert

Anyone? Please, I am desperate here!
Robert.

Ollie

The easiest and least costly way is to make them is by the lost foam method. You will need blocks of closed cell polystyrene foam. Pink or blue foam boards are usually available from Home Depot, Lowes or other building supply outlets. You will need several pairs of vinyl examination gloves, a roll of clear packing tape, 30 or 45 minute laminating epoxy, a couple of yards of 1.4 or 2 ounce glass cloth, disposable mixing cups and disposable acid brushes.

1. Carve and sand the foam blocks to the finished shapes of the fiberglass parts allowing 1/32 inch for the thickness of the fivberglass.
2. Cover the foam plugs with clear packing tape.
3. Cover the plug withone piece of fiberglass cloth and trim to shape overlapping the fiberglass by 1/2 inch or so where it meets itself.
4. Remove the glass cloth and using it as a pattern, cut 15 more pieces of 1.4 ounce or 11 more pieces of 2 ounce fiberglass cloth to the shape of the pattern. Orient the patern so that no edge runs parallel to the threads of the cloth to prevent fraying.
5. Put on the vinyl gloves and paint the surface of the plug with laminating epoxy. A stik imbeded and glued into the foam and held in a vise comes in handy to hold the plug while you are working on it.
6. Lay a piece of cloth in the wet epoxy and wrap it around the foam so that it covers the plug in one piece and overlaps itself. Use the brush to work the glass into the epoxy and to work out any wrinkles.
7. Apply more epoxy and the next piece of cloth as in step 6.
8. Continue applying epoxy and glass cloth until the batch of epoxy starts to thicken. Blot off the excess epoxy with paper towels and come back when the epoxy is cured.
9. Repeat steps 6 through 8 until all the pieces of glass have been used.
10. Trim off the glass that overhangs the plug and sand the plug smooth and fair. A proper sanding job won't require any filler before painting. wet sanding with soapy water works well.
11. Chop out chunks of foam untill you can grab the packing tape and pull out the remaining foam and tape in one piece. Sand the edges of the fiberglass piece to final shape and fit to the fuselage.

It usually takes me five or six working sessions of 20 to 30 minutes spaced a day apart to finish a piece. It will take a beginner longer but with experience it will take lass time. If you have questions or run into problems let me know and I will try to help.

robert

Thanks for answering Ollie, I'm thinking of practising by making a piece for a model I already have...And I'll look around the house for all the bits needed.
Robert.

Ollie

Robert,

I just noticed that you are located in Ireland. So, my reference to Home Depot and Lowes is probably not helpful. I think one of the trade names of closed cell poly styrene foam in Europe is Roofmate. It is used as rigid insulation on roofs. It is also used as rigid insulation around concrete foundations and as insulation for walk in refrigerators. I hope you won't have trouble finding a local source.

bullfrog

My Feedback: (2)

Great tread, just what im looking for! I to am a beginner in the art of fiberglass, and im going to try to make a coustom fuel tank for my plane. Is it true some chemicals disolve the blue foam you were talking about. If you can please give me some guidance

Jeremiah

Ollie

Acetone and gasoline are among several solvents that dissolve polystyrene foam. However, they tend to leave a gummy reidue behind. This would be very undesirable. A thorough use of packing tape and a large enough hatch in the tank to allow the foam to be mechanically pulverized for foam and tape removal is the way I would go. This will leave the inside of your tank nice and clean. The hatch can be sealed with an external application of fiberglass and epoxy after the foam and tape have been removed. Use at least four layers of light glass cloth to avoid pinhole leaks.

rsieminski

How about the use of PVA? The stuff works great to release the glass from the mold. Tug at the sides, work it around, and it'll pop right out.

Ollie

PVA certainly has its uses as a release film on shiny molds. On foam plugs, however, packing tape does a better job because it has a more reliable continuity over the slightly textured foam and becaues it makes the mechanical removal of the pulverized foam much easier and cleaner.

bullfrog

My Feedback: (2)

Ollie, you are suggesting making a hatch, for the removale of the foam. Would I just build a hatch cover seperate and epoxy it on or ? Im using this tank with a ys 140 so I need it to be pressure ok. Now would it make a differance if I was using Kevlar instead of fiberglass and how would I go about making the hole for the stopper?

rabosr

I would suggest that when you get near the last coat of fiberglass use a blown up balloon about 10 or 12 inches in dia.
Holding the blown up balloon on top of the mold press the baloon down on the mold forcing the baloon to completely cover the mold while releasing the air in the balloon. This will give you a nice smooth finish for the final layer. End result the mold is covered with the balloon and the air is gone from it.
I have done this method several times for making cowlings and cockpit coverings.

Ollie

Kevlar comes in two weaves, plain and satin. The satin weave drapes easier than the plain weave. Even the 1.7 ounce per yard satin weave kevlar cloth does not drape as easily as light glass cloth so you may have to wrap the wet layup with vinyl electrical tape to compact the layup and keep it in contact with the plug and free of voids. Two or three plies of 1.7 ounce kevlar should be plenty for tanks up to a quart. After the epoxy has cured, the tape is easily pealed off for the next layer of kevlar. There may be slight ridges at the edges of the tape which can be lightly sanded to remove them. Avoid sanding into the kevlar. It just fuzzes up and makes a mess. Before removing the foam, the hatch can be cut by marking the cut line with masking tape and using a No. 11 blade to pierce the kevlar at the cut line. The tip of the blade is used like a saw with short strokes of about 1/16 of an inch and progressing about 1/32 inch at a stroke. After the hatch has been cut away and all the foam and tape removed, the brass tubing is epoxied through holes in the hatch and the inside tank plumbing is added. Then the hatch is put back in place and tacked with a drop of thick CA in three or four places around the cut line. Cut ring shaped patches of kevlar to cover the cut line and overlap it about 1/2 inch on both sides. Simply epoxy the patches in place with enough epoxy to fill the cut line and puddle very slightly inside the tank. Orient the tank hatch side down while the epoxy cures. Take care not to epoxy the clunk or flexible tubing to the inside of the tank.

bullfrog

My Feedback: (2)

Ollie, really thanks for your time. This info is like gold to me, I am starting the project very soon and I will let you know how it comes out.


Rabosr-- not sure if the balloon pertains to my application or not but I am interested in this method, please do tell me more.