Molding a Nosecone Using a Pressure Bladder

[watheyak]

Hi all,

I'm about to move into some unfamiliar territory, at least for me. I'm going to try and mold a nosecone for a sub-minimum-diameter project using a pressure bladder inside the mold. This isn't a new technique. R/C discus launch glider folks have been making fuselages this way for a while now. Essentially I'll be making a stiffer, back-filled mold to handle the internal pressure from the bladder. Then, after the lay-up is done and situated in the mold, a nosecone shaped bladder is inserted into the mold, hooked to a compressor and inflated, pressing against the inside of the nosecone lay-up. Kinda like vacuum bagging in reverse. If you're really interested, here's a 65-page thread covering the whole evolution of the process.

https://www.rcgroups.com/forums/showthread.php?1056468-Fuse-Molding-with-an-Inflation-Bladder
I have some goals for this project I would like to attain which got me started down this path. For one, I want to have a very strong seam, with no air bubbles. I also want to have a nosecone interior that's as uniformly round as possible, as well as somewhat smooth. I also want to it to leave the mold shiny, polished and ready to go. It will involve high temp resin and I don't want to fill or paint it. I also want to make the nosecone out of 5oz 2x2 twill Kevlar. Because it looks cool...

So far I have a nosecone plug that was originally made by Charlie Ogino at Carolina Composites. It's made one mold already, but it has been stripped and modified to accommodate the bladder system. A half-round was added to the back end, as well as a tube for bladder access. It's Pictured here on top of the melamine particle board I'll be using for the parting board.



Tonight I will be cutting the silhouette out of the board. I'll also be using more of the same melamine to build a box around it to give the mold depth. Kinda confusing now, but It'll make more sense as it comes together.

Tomorrow I will spray the plug with tooling gelcoat and commence sanding and polishing.

I'd love pointers and constructive criticism. I'm still wrapping my head around this and there will be a lot of learning as I do. Let me know if thou think of any serious issues that I haven't.

Has anyone here done this? I know I've seen at least one common name over on the RC forums....

Thanks for reading!

 

[kalsow]

I haven't read the R/C thread you posted, but I will. Thanks!

I've been making nose cones from molds for a few years. I try something new on almost every one. I've tried using sticks, spatulas and ballons mounted on a stick to smooth out the flaps that cross the mold halves. I've only had moderate success with these schemes.

I tried making a bladder using heat to fuse the layers of a garbage bag together. It sorta works, but I found it quite difficult to get the bladder to rest properly against the mold. Any snags or bubbles where the bladder meets the epoxy becomes a weak spot that pops as soon as you add pressure. On my best attempt I got up to 30psi before it popped.

My current method is to make a mold with an large opening at the bottom of the shoulder - not appropriate for a pressurized bladder. Then I paint the mold (4 layers is what the manufacturer recommends) with "Rebound 25". It's a two-part silicone rubber mix. You get a custom, open ended, thick, reusable bladder. It's almost magic, but the only thing that this silicone sticks to is itself. It peels right off cured epoxy. Because it's painted directly on the mold, it leaves zero space for the glass and epoxy layup. But since it's rubbery, there's enough give to get everything to fit. I lay up fabric in both halves of the mold. Then I add the flaps that cross between the halves. Only 1/2 of these pieces are wetted out with epoxy. Then I put the silicone bladder into the half of the mold with the partially wetted flaps. I wet out the rest of the flaps against the silicone. It's a nice perfectly shaped surface for the flaps. Finally I add the other half of the mold. If I want to add a little pressure, I stand the mold on its nose and fill the silicone with water. If the silicone is thick enough, this extra step isn't really necessary. The big down-side to this technique is the cost of the silicone. It comes as a kit with two 450g bottles - about a quart. I've found kits for $32, but my most recent one cost $39.

I just built a mold for 8"x24" nose cones. I used 3 of the silicone kits to get a thick enough bladder. A couple pictures are below - mold with a completed nose cone and mold halves with the silicone bladder. A typical 4" nose cone would use about one full kit.

I also built a mold with a 45-degree flange at the end of the shoulder. Made the usual silicone bladder. Then, the whole thing was mounted inside a 2-part wooden box. The space between the mold and box was filled with rigid 2-part foam. Then I made a wooden cap that fit into the flange. The cap had an embedded valve stem and bolted to the box holding the mold halves. With the rubbery silicone on the flange I was able to tighten the bolts enough to get an air seal. I pumped it up to 35-40psi and it held pressure overnight. It worked, but I don't think the extra work was worth the improved resultant product. Maybe if I was making ultra-thin 1-layer nose cones it'd be worth the hassle.

 

[watheyak]

I had looked into the silicone bladders as well. I really like your system. If I cant get this method to work satisfactorily, I'll try that. Balloons are another option, but I can see issues with the pointiness...

As for the popping, the R/C fuselage molds are only using 10-15psi. My lay-up will be made from heavier material, so I may need to bump it up a but. They're also using stretchy plastic these days, and that's supposed to help.

 

[watheyak]

I'm getting ready to spray the gel coat on the plug. This will be my first time using Duratec Gray Surfacing Primer. It's supposed to be really nice for mold plugs, easy to sand and polish.


https://duratec1.com/pdf/DS 707-002.pdf
Spraying a gelcoat is no fun. They're thick, they're cranky and they cure really fast. Cleaning the spray gun afterwords is a serious undertaking requiring lots of acetone and dental picks. It come out in chunks from places it shouldn't. At least that's the way it's turned out when I've done it in the past, others may have had better luck.

This time I'm going to try something different. I've wanted this spray gun for a while now for things just like this. Everything is disposable and replacements are cheap. Pop off the spray head, pull out the cup liner, wipe off the needle and poof, done. Spray heads are reusable for normal paint, but in this case it'll most likely be a one time use.



My medium sized compressor might be an issue. I'm hoping that it can deliver the air need for air needed for this small part. Waiting for the tank to come up to pressure while the product in the cup catalyzes might be too much excitement.

Anyone have any experience with HVLP guns on smaller compressors?

 

[watheyak]

Well, a new compressor and two weeks were all that was required to finally get the gel coat on. It all worked pretty well. There is a bit of an orange peel, but it's going to get sanded and polished anyway. The lighting makes it look worse than it is. Maybe...

I'm also going to try polishing with the foam pad on a Dremel Versa.
https://shop.dremel.com/versa-power...ime cleaning and,inside and outside your home.




I've forgotten how much I hate the smell of polyester. Ick.

 

[stantonjtroy]

I'm getting ready to spray the gel coat on the plug. This will be my first time using Duratec Gray Surfacing Primer. It's supposed to be really nice for mold plugs, easy to sand and polish.

View attachment 419108
https://duratec1.com/pdf/DS 707-002.pdf
Spraying a gelcoat is no fun. They're thick, they're cranky and they cure really fast. Cleaning the spray gun afterwords is a serious undertaking requiring lots of acetone and dental picks. It come out in chunks from places it shouldn't. At least that's the way it's turned out when I've done it in the past, others may have had better luck.

This time I'm going to try something different. I've wanted this spray gun for a while now for things just like this. Everything is disposable and replacements are cheap. Pop off the spray head, pull out the cup liner, wipe off the needle and poof, done. Spray heads are reusable for normal paint, but in this case it'll most likely be a one time use.

View attachment 419109

My medium sized compressor might be an issue. I'm hoping that it can deliver the air need for air needed for this small part. Waiting for the tank to come up to pressure while the product in the cup catalyzes might be too much excitement.

Anyone have any experience with HVLP guns on smaller compressors?

I swear by Duratech. Goes on nice, sands & polishes perfectly and is you mess up just re-shoot and do it again.
I use the same PPS gun for Gelcoat work. 1.8 tip is perfect for the Duratech. One word of advise, do not push more than 24psi of air through the gun, more than that and you can pop the tip off sending paint/gelcoat everywhere. Also moisten the O ring on the tip before install and push it on straight, don't twist it on. I'll have to follow this.

 

[watheyak]

I swear by Duratech. Goes on nice, sands & polishes perfectly and is you mess up just re-shoot and do it again.
I use the same PPS gun for Gelcoat work. 1.8 tip is perfect for the Duratech. One word of advise, do not push more than 24psi of air through the gun, more than that and you can pop the tip off sending paint/gelcoat everywhere. Also moisten the O ring on the tip before install and push it on straight, don't twist it on. I'll have to follow this.

The Duratech is great, I'm sold! It sanded and polished up really easily. Didn't load the sandpaper at all and came out to a nice polish for sure.

To polish it I used 3M Finesse It II and an unlabeled bottle of fine polish I have. A while back while I was wandering around Home Depot looking for a small format polishing wheel I found the Dremel Versa that's pictured next to the polished plug. It's the right RPM and has foam pads available. It worked great! It also does a top-notch job on my glass stove-top. My wife is of course thrilled with my ingenuity.



I also finished the melamine parting board. Now it's time to prep the parting board and plug for release. I'm also going to try another product for the first time, Frekote Mold Sealer. I've had really good result from Frekote 700NC, so I though I'd give the sealer a try as well.



That's it for now. Hopefully I can get the plu prepped and placed in the parting board before I have to go back to work on Wednesday. I work eight days on, six off, so this will happen in bursts.

 

[stantonjtroy]

I've used both Frekote products in the past with great success, I just don't like the price. My go-to mold sealer is Chemlease 2180, (available at freemansupply.com) and Zyvex Flex-Z #5 release (also from Freemen). The Zyvex #5 is stupid slick. Like easy to slip out of your hands if your grip is loose slick. If you're not a fan of the fumes of any of it, Zyvex makes a complete non-hazardous line called "WaterWorks". Great stuff as well. Used it a great deal in the past.
I'm glad you posted this thread. It's a process that I hadn't considered but will solve a problem I have on my own projects. I'll keep checking back.

 

[watheyak]

I've used both Frekote products in the past with great success, I just don't like the price. My go-to mold sealer is Chemlease 2180, (available at freemansupply.com) and Zyvex Flex-Z #5 release (also from Freemen). The Zyvex #5 is stupid slick. Like easy to slip out of your hands if your grip is loose slick. If you're not a fan of the fumes of any of it, Zyvex makes a complete non-hazardous line called "WaterWorks". Great stuff as well. Used it a great deal in the past.
I'm glad you posted this thread. It's a process that I hadn't considered but will solve a problem I have on my own projects. I'll keep checking back.

Hey great, I'm glad at least one person is interested!

I have heard of Chemlease, someone had recommended it to me in the past. So far I've had great luck with the Frekote, but I'm almost out of the 700NC. I might give the Zyvex stuff a shot next.

 

[watheyak]

The mold is all ready for the tooling gel coat and the fiberglass layers. I'll start that tomorrow morning and stay up late so I can get all the successive layers on before the previous one fully cures.

Here's some pics of what led up to this point.

The parting board was beveled with a Dremel to enlarge it a bit. I actually wanted a bit of a gap between the parting board and the plug. Supports were added to hold the plug on the 50/50 split and the perimeter was masked off.



Colloidal silica and micro-balloons were added to epoxy until I got a peanut butter consistency. I spooned it into a zip loc bag, cut the corner off and forced it into the gap around the plug like cake frosting. It was then scraped mostly level, forcing it farther into the gap. After the epoxy in the gap cured, I removed the plug from the parting board and used a sanding block to sand the cake frosting epoxy level with the blue tape. The tape was then removed and the whole thing sanded with progressively finer sandpaper up to 1000 grit.



I then mocked up the whole mold. At this stage it's sorta like a "mold for a mold". The side dams were cut and it was all screwed together.



Once I was satisfied with how it all fit together, I unscrewed the pieces and applied the mold sealer and release to the boards and the plug. Once that was complete I filled a few small gaps between the plug and the boards with clay. The whole thing was wiped down again with the mold release and set aside for tomorrow.

 

[watheyak]

First gel coat applied. 127 grams of Aeropoxy, 4 grams of tint and 4 heaping tablespoons of colloidal silica. The color is hideous, right?

After applying I carefully ran a heat gun over it to help pop any bubbles. I didn't actually see any pop, but I think I was able to get it mixed pretty bubble-free. One thing that is stressing me out is the fact that I can still see tiny chunks of the colloidal silica, despite forcing it through a sieve prior to mixing.

Once it's tacked up a bit I'll add the second coat.

 

[watheyak]

More progress-

A second coat of gel coat was added, after which I added carbon tow to the corners and wet it out with neat Aeropoxy.



After the tow, a third and final layer of gel coat was added. While it was still fresh, the fiberglass was applied and wet out. It ended up being 2 layers of .75oz, 2 layers of 1.5-ish oz, 2 layers of 4oz and 4 layers of 8.4oz. The every other layer of the 8.4oz was on a bias. This wasn't exactly as intended, but it'll work. This build thread is helping me keep track for the second half. And future molds...



After this it's time for the heavy metal.

 

[watheyak]

This mold needs to be super rigid so it won't flex when the bladder inflates while things are curing. It will also be clamped together with a dozen 1/4-20 bolts. These next steps help with all that.

1.5" tall plywood spacers were glued in place with lots of epoxy. In this case it was thickened with colloidal silica. In hindsight, I should have added some cotton flox as well.



Next, 1" square steel beams were added. They were cut with an angle grinder and cleaned with acetone until no more black was coming off on the rag. They were then roughed up with an angle grinder and hit with an 80-grit sanding disc on an RO sander and cleaned again. After that they were smooshed into place on a bed of epoxy thickened with colloidal silica and cotton flox. Not only will the iron keep it rigid, it will also be the clamping surface. The holes for the bolts will be drilled through the mold halves, through these bars.



Then 254 grams of epoxy was mixed and 950 grams of pool filter sand was mixed in. It was about the consistency of sandy peanut butter. Not quite pour-able. The sand was left out in the Arizona sun in for an afternoon to remove any moisture. That took two tries. We have neighborhood stray cats......

It was troweled into the cavity between the bars. Pictured is two of the batches described above. I am going to do the second half tomorrow before it's fully cured. I'm a little worried about exotherm.



It's been a long day. Bed time.

 

[watheyak]

All filled up with sand. Side one done. I'm going to let it cure for a few days, pop off the sides and the parting board and start side two. That'll be when I get home form work on the 30th.

 

[watheyak]

De-molding went pretty well. the sides came off very easily, but the actual parting board stuck a bit. This makes some sense as the parting board had been sanded a bit. Still kinda odd. The bits that are left behind scrape off pretty easily and the second half shouldn't stick to it.

The good news is the part that matters (the nosecone cavity) is nice and shiny and in great shape. The seam edge is the best I've made. Pretty happy with the outcome.

And it only weighs 20 lbs!





One last chore is to trim the excess gel coat off the bottom.

 

[n27sb]

Beautiful mold.
I usually do not use water thin releases when making tooling.
I prefer Partall #2. You can put it on smooth bare wood and get a release.
You can also follow up with PVA.
I also find that brushing gel coats can cause release issues and stuck molds.
Especially with polyester gel.
Looking forward to seeing your first part.

 

[watheyak]

Beautiful mold.
I usually do not use water thin releases when making tooling.
I prefer Partall #2. You can put it on smooth bare wood and get a release.
You can also follow up with PVA.
I also find that brushing gel coats can cause release issues and stuck molds.
Especially with polyester gel.
Looking forward to seeing your first part.

Thanks, I'm excited to see it too. And a little nervous. I think this method is going to take a bunch of tries to get nailed down.

I haven't ever used the Partall #2 I don't think. But I've definitely used PVA quite a bit and it's always worked. I started using the Frekote when I needed to bake prepreg tubes and until now, the Frekote has worked like magic. It worked great on the sides that had just plain melamine, but anywhere I sanded is where it stuck. This also wasn't a true polyester gel coat, just laminating epoxy thickened and tinted.

The Partall #2 is just like a regular wax? "Wax on, wax off"?

And congrats on your new record, by the way!

 

[n27sb]

This also wasn't a true polyester gel coat, just laminating epoxy thickened and tinted.

I caught that. I have used that method as well.

The Partall #2 is just like a regular wax? "Wax on, wax off"?

Aie Danielson.
But it can also fill pores and holes. It actually works better with epoxy than poly.


Following your progress

Thanks for the congrats.

 

[watheyak]

The second half of the mold is done. I ran out of epoxy at the last batch of sand. Not a big deal, I can top it off later. There's about a gallon of epoxy in this mold. I've mixed so much epoxy that I think I have a mixing stick blister.

Does anyone else keep mixing sticks? I've had the same 6" bamboo skewer for years. Weird, I know.

I was definitely nervous and excited pulling this one apart. Lots of work went into this, and this was either the payoff or the disappointment.

All the sides popped right off-




And the payoff-





It looks pretty good to me. Some minor cleanup and a little sand and it should be all set. The alignment pins got a little messed up. I did them the way the article I linked at the beginning of this thread suggested, rather than my normal method. They'll be ok after some TLC.

Now the party can start.

 

[kalsow]

Looking good!

I used 4lb/cf urethane foam to back fill my one mold that uses a bladder instead of sand and epoxy. According to the seller's web page, it's good for 90 psi in compression: https://www.uscomposites.com/foam.html

For your next mold, maybe...

 

[watheyak]

Looking good!

I used 4lb/cf urethane foam to back fill my one mold that uses a bladder instead of sand and epoxy. According to the seller's web page, it's good for 90 psi in compression: https://www.uscomposites.com/foam.html

For your next mold, maybe...

Whoa hey! That stuff looks great. I absolutely would have used that instead of the sand. It never popped up in any of my research.

Out of curiosity, where did you learn about it? I'm still trying to gather as much information about bladder molding as I can. A lot of what I have found is 8-10 years old.

 

[kalsow]

Out of curiosity, where did you learn about it? I'm still trying to gather as much information about bladder molding as I can. A lot of what I have found is 8-10 years old.

I started with the same video that you posted. I didn't find much else. I looked into custom bladders. Apparently big time industrial places use them. They're not cheap!

 

[JLebow]

Awesome thread, with some interesting ideas. The Duratec and Accuspray look like awesome products.

I've used the modeling clay in the past to seal the gap between the plug and parting board. Next time I will try the epoxy and microballoons.

Did I understand you post correctly: you sprayed the Duratec onto the plug, and brushed the first coat of gel coat (Epox, tint, colloidal silica) into the mold? I've wanted to experiment with spraying in the first coat into the mold (like they do on youtube with the polyester tooling gel coat) to avoid air bubbles, but it looks like you have achieved a very good surface.

I have really good success with partall #2 wax. Wipe on with a rag. Let it is for 5 minutes are so, and buff out the surface with a rag. I usually do 3 or 4 coats to avoid "dry" areas. I then use a Badger Airbrush to spray PVA. The first two coats go on very lightly and look rough. The last coat is a bit thicker. Once dry, everything smooths out. If you get pooling of PVA, you did it too thickly. Was with water to clean and start again. I've never had a problem with parts sticking or surface quality using partall and PVA.

I'm looking forward to seeing what you do next with those balloons. Can you get them to attach to you air compressor to maintain pressure throughout the curing process? Are you going to treat the balloon with a release agent? I don't know if balloons bond strongly with epoxy.

 

[watheyak]

It's been a bit since I've been able to work on this. I've got a few days now.

Did I understand you post correctly: you sprayed the Duratec onto the plug, and brushed the first coat of gel coat (Epox, tint, colloidal silica) into the mold? I've wanted to experiment with spraying in the first coat into the mold (like they do on youtube with the polyester tooling gel coat) to avoid air bubbles, but it looks like you have achieved a very good surface.

I'm looking forward to seeing what you do next with those balloons. Can you get them to attach to you air compressor to maintain pressure throughout the curing process? Are you going to treat the balloon with a release agent? I don't know if balloons bond strongly with epoxy.

Yep, I brushed the gel coat onto the mold with a small foam brush. Three coats, waiting for each one to tack up before adding the next.

Also yes on the attaching the balloon to the compressor. Here's some pics of the attachment-



Once it's all laid up and the mold halves joined, I'll be able to thread it through the hole and inflate the balloon. There will be a valve in the line to allow me to slowly inflate it.



The red is the balloon stretched over the brass tube. The brass tube has small holes drilled along it's length so it's not inflated from the front alone. The front of the tube has also been rounded and polished. All this was done to help keep the balloon from popping, fingers crossed! Holding the balloon on the barb and centered in the hole is black rubber electrical splicing tape. It has no adhesive, but sticks to itself. It's also a little thicker and bulks up quickly.



Another chore I accomplished is making a pattern for the fabric parts. I put a mold half in a vacuum bag. I pulled a vacuum and traced the edge.





It'll be traced on to a board for a pattern to cut the pieces.

 

[watheyak]

Ok balloon time.

I switched to a larger diameter balloon. These are Qualatex 350Q, which means they're 3" in diameter and 50" long.

I fired up the compressor and set the line pressure to 15psi. The little valve I have at the base of the balloon is a plus. While it doesn't completely shut off the air, it at least fills the balloon slowly.



Keep the snickering to a minimum...



So far, so good.



So I deflated the balloon and bolted the halves together. Evidently the halves fit so tight that air can't escape, preventing the balloon from inflating. Or if it was I Just couldn't tell. Someone in some thread somewhere mentioned this problem as well. I'm going to have to figure out a solution. So I backed off the bolts about 1/8" and tried again. The inflated balloon was able to lift the 20lb mold have at 15psi without popping. I'd call that a success!



The only weird issue that I can see is a big wrinkle in the balloon about 8" back. You can kinda see it in the picture above. But other than that, the balloon is a success. I've got a few more things to add to keep the bladder apparatus in place. Next it will be time to start cutting cloth. The first few nosecones will be from fiberglass for practice. All will be made with Cotronics 4461 high temp laminating(ish) epoxy. I want to practice with that stuff the whole time as it's not quite like other stuff. It beads up funny on smooth surfaces and wets out cloth weird.

I'm also going for a staggered wet seam. It's intimidating. But then again, so was this whole thing. Baby steps, man.


(Not my drawing. Totally stolen)

And if you're not bored yet, here's a couple pics of the bolts and blind nuts I added yesterday. Blind nuts are JB welded.

Oh and rubber feets. Like 50 sharp corners on this thing. Fully weaponized.

 

[tfish]

I use a balloon sort of the same way in my regular nose cone molds. I have issues with it pushing and bunching up the layup where the balloon first contacts the layup. I tried inflating the balloon tip into a small ball shape....to encourage that to inflate first..which helped some. Now what I do is to add peel ply into the mold once the halves a bolted together...I watch as I inflate and then release the air and slowly work things into place . This really helps the seams and strength on the layup.

Tony

 

[watheyak]

I use a balloon sort of the same way in my regular nose cone molds. I have issues with it pushing and bunching up the layup where the balloon first contacts the layup. I tried inflating the balloon tip into a small ball shape....to encourage that to inflate first..which helped some. Now what I do is to add peel ply into the mold once the halves a bolted together...I watch as I inflate and then release the air and slowly work things into place . This really helps the seams and strength on the layup.

Tony

I'm hoping that the brass tube that stretches the balloon all the way to the tip helps eliminate some of that.

But... That wrinkle 8" back or so makes me think I'm going to have the exact issue you're talking about to some degree in some direction. I'm going to give the balloon a shot, and if that doesn't work, plan B is to make a nosecone shaped mold by fusing together stretch bagging film.

Can you clarify what the peel ply is helping with? Is it keeping the layup stable while the balloon inflates? Or letting the balloon shift while it inflates? All that?

Thanks Tony

 

[tfish]

Peel Ply...even though I thought my layup was fairly dry..once you start squeezing it, liquids would rise up to the surface. The balloon would stick and pull some cloth with it when deflated. I even tried spraying the balloon with mold release..which did not help. The peel ply was an attempt to keep things from sticking to the balloon. It is fairly easy to remove the peel ply from inside the nose cone..

I've been using the insides of nose cone for many years (15) to house my main parachutes. My home made nose cones really had to have smooth inside to keep things from getting hung up in there. For the past few years I've been housing my electronics in there and doing dual deployment via reffed chutes. The inside don't need to be near as smooth for the electronics.. Below is some photos of a new 54mm AeroPac Sport Flyer (my term for my rockets that fly well but not the greatest of altitudes) that I'm currently working on. The electronics are mostly just mocked up at this point..

I'll take some inside photos tomorrow if your interested. You'll see where the peel ply and balloon created some voids..

I'm looking forward to seeing how yours turns out..I hope to learn some new tricks.

sorry if this post is derailing your post.

Tony

 

[watheyak]

I'm cramming electronics and the main parachute/cable cutter in this nosecone. Smooth is needed so the parachute doesn't hang up and so the O-ring that seals the av-bay can do it's job.

I'd definitely like to see pics, no derailing at all.

 

[watheyak]

Ok, first part is in the mold! Very exciting. It's not going to be perfect by any means but I learned a lot and successive attempts will be improved.

For the practice parts I'm using fiberglass in weights and weaves that are similar do the desired final Kevlar material. The outer layer is a 2x2 twill that's pretty familiar. The inner layers are a 4HS weave that is easier to work with for complex shapes. The twill is there purely for cosmetics in the final part, and it's a pain. It distorts very easily and sheds threads constantly. so to help with that, I decided to try a composite fabric. Made with composite fabric..... The twill and some fiberglass veil. I cut two identical pieces and used a very fine mist of 3M77 to stick them together. I'm concerned that this kills the twill's ability to form around compound curves. We'll see how it goes.







Stuck together, hard to tell.





Then I set to cutting out the pieces from the fiberboard pattern I'd made. One set of the twill/veil and four sets of the HS. The twill is the only one with the veil.



I was concerned that the Cotronics 4461 wouldn't lay down on the surface of the mold, especially with the mold release. I was right. This may mean bad things for the finished surface. Usually a laying the first layer of fabric into a nice even coat of epoxy helps eliminate air bubbles and pinholes. I also decided to pre-wet out the pieces of fiberglass with a foam roller on waxed paper. This helped keep everything together and helped position the pieces for the staggered seam. I stacked and wet two of the HS layers at a time.





Then proceeded to stack them in the mold. Looking back at these pics it sure looks more sloppily aligned than I thought or intended. Second fo around I have some ideas to help. The 4461 was also setting muchg faster than I thought. It's a little warm in here, next time I'll crank down the AC a bit. There is also not fabric all the way to the tip. In the final product there will be a phenolic or G7 tip, but it needs to get closer than that. Some pattern adjustment will help.







Reached my attachment limit.