Fibreglass Molding on a Budget

[Jackson T]

I've wanted to make something out of fibreglass for ages, mainly because that would allow me to make new shapes and curves that I couldn't with balsa. After hearing about plaster molds, I found some cornice cement (a building material similar to plaster) at home, and set to work making a sample plug. I covered the plug with tape, but that left imperfections in the mold where the tape wrinkled. I will try painting it next time. I placed it on a taped wooden board and 'spooned' on a thick mixture of the cornice cement with a paddle pop stick. It popped off the board nicely after it dried and the plug came out almost as easily. I didn't want to buy proper mold release, so I did some research and tried some $3 boot polish. I wiped it on with a rag, let it dry for a while, then repeated 2 more times before laying up the fibreglass. It took a little encouragement, but wasn't a hassle to get out. Pics below. The black stuff on the mold in the last photo is paint. I don't think it made any difference though, so I won't be painting the next one.

 

[Tench745]

I've done some fiberglass layups for a couple of projects. I've sanded, filled, painted, then turtle-waxed male moulds. That works ok. For my fiberglass glider fuselage I splurged on some PVA mould release from the marine store and it worked far better than the turtle-wax ever did.

 

[leaded50]

I've done some fiberglass layups for a couple of projects. I've sanded, filled, painted, then turtle-waxed male moulds. That works ok. For my fiberglass glider fuselage I splurged on some PVA mould release from the marine store and it worked far better than the turtle-wax ever did.

Mould release agent is what i found function better than anything ells too.

 

[Jackson T]

I've done some fiberglass layups for a couple of projects. I've sanded, filled, painted, then turtle-waxed male moulds. That works ok. For my fiberglass glider fuselage I splurged on some PVA mould release from the marine store and it worked far better than the turtle-wax ever did.

Thanks for the input, I'll have check the local PVA price again sometime . How did you lay the glass and keep it from lifting up from the plug? I was thinking about glassing straight off the plugs first, but that would get tricky on some of the things I want to make, like a scale glider's nose.

 

[JustPlaneChris]

Over the years I've probably used 10 gallons of epoxy making molds and parts. I've tried pretty much every method to "shortcut" the process, and the only one that has come even close is the "mud molds" similar to yours using a plaster-like substance called Ultracal (or Hydrocal). Those molds are great for hobby peeps like us, and are good for several parts as long as you don't drop them.

Recently I have been seeing people 3D printing the molds for one-off parts. There is still some prep work required to make the inside surface smooth, but it's still less work than making a plug and pouring or laying up a mold! That's going to be my next venture in composites.

Here are some links you may find interesting or helpful.

My projects:
Custom canopy mold for MSH Mini Protos Heli (commissioned by Lynx Heli)
Experimental transmitter case (mud mold)

Discussion links:
Composites Fabrication forum on RCG
Ultracal molds (a few pics from me in this one too)

Chris

 

[Tench745]

Thanks for the input, I'll have check the local PVA price again sometime . How did you lay the glass and keep it from lifting up from the plug? I was thinking about glassing straight off the plugs first, but that would get tricky on some of the things I want to make, like a scale glider's nose.

Not sure I understand the question. I use lightweight glass cloth which is pretty flexible and can wrap to most curves pretty well with minimal cutting. If the glass hangs over an edge and will get trimmed later, I make sure the plug has some kind of mount to give the ends enough room not to get pushed away. I have heard of people using plastic cling-wrap to apply pressure to something like a glider fuselage while it cures, but I haven't tried it myself.

 

[Jackson T]

Over the years I've probably used 10 gallons of epoxy making molds and parts. I've tried pretty much every method to "shortcut" the process, and the only one that has come even close is the "mud molds" similar to yours using a plaster-like substance called Ultracal (or Hydrocal). Those molds are great for hobby peeps like us, and are good for several parts as long as you don't drop them.

Recently I have been seeing people 3D printing the molds for one-off parts. There is still some prep work required to make the inside surface smooth, but it's still less work than making a plug and pouring or laying up a mold! That's going to be my next venture in composites.

Here are some links you may find interesting or helpful.

My projects:
Custom canopy mold for MSH Mini Protos Heli (commissioned by Lynx Heli)
Experimental transmitter case (mud mold)

Discussion links:
Composites Fabrication forum on RCG
Ultracal molds (a few pics from me in this one too)

Chris

That's a lot of epoxy! Thanks, I'll check the links out.

Not sure I understand the question. I use lightweight glass cloth which is pretty flexible and can wrap to most curves pretty well with minimal cutting. If the glass hangs over an edge and will get trimmed later, I make sure the plug has some kind of mount to give the ends enough room not to get pushed away. I have heard of people using plastic cling-wrap to apply pressure to something like a glider fuselage while it cures, but I haven't tried it myself.

That's pretty much what I meant .

 

[Jackson T]

I have (finally) decided to make a 1.8m scale ASK 21 glider. I was planning on making a 2.5m Discus 2 but decided to make something smaller and simpler to reduce the investment on this experiment . While I like the Discus 2 much more than the ASK 21, the Discus has a higher aspect ratio (skinny) wing so it won't scale to small sizes nicely.

 

[cyclone3350]

Over the years I've probably used 10 gallons of epoxy making molds and parts. I've tried pretty much every method to "shortcut" the process, and the only one that has come even close is the "mud molds" similar to yours using a plaster-like substance called Ultracal (or Hydrocal). Those molds are great for hobby peeps like us, and are good for several parts as long as you don't drop them.

Recently I have been seeing people 3D printing the molds for one-off parts. There is still some prep work required to make the inside surface smooth, but it's still less work than making a plug and pouring or laying up a mold! That's going to be my next venture in composites.

Here are some links you may find interesting or helpful.

My projects:
Custom canopy mold for MSH Mini Protos Heli (commissioned by Lynx Heli)
Experimental transmitter case (mud mold)

Discussion links:
Composites Fabrication forum on RCG
Ultracal molds (a few pics from me in this one too)

Chris

Thanks for sharing. I have done a composite vacuum forming from polystyrene plastic over a carved and sanded and painted balsa molds and then fiber glassing over the parts. OK for one off small parts, but now I am ready to start trying vacuum bagging and moving up to larger fuselage type parts. Ultracal looks like a good path for going to the next level.