Author Topic: Glass fibre mould from the slender plug  (Read 2697 times)

Offline PekkaNF

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Glass fibre mould from the slender plug
« on: June 12, 2018, 09:22:50 AM »
My daughter needs a anime prop: about 1200 mm long sword that has opaque blade. Tried to mould that from PC, but it turned out pretty damn difficult.

Pretty much like on this picture:
https://www.pinterest.nz/pin/598556606695462033

Plan "B" is to use two layers 160 g/m2 glass fibre cloth and clear laminating epoxy to make two halves and then glue them together.

I'm making a practice run with another sword, that essentially is a katana blade. Plug is made from two halves, split, glued on the MDF board, finished and coated with two componenet acryllic paint. Covered it with six coats of release wax yesterday.

I was planning to make the mould with polyester resin (first gel coat brushed and then resin and glass mat), but I read that it the mould would take up two weeks to harden. Is that true?
https://www.ecfibreglasssupplies.co.uk/images/mouldmaking.pdf

"Leave the mould to cure up to two weeks at room temperature is desirable, post curing the mould is desirable but not sometimes practical, less if using low shrinkage tooling resin ( 2 – 3 days), releasing a mould too early can cause distortion to the mould."

Sounds pretty long....My mould would be about 1200 mm long (blade differently and handle separately) protrusions are small (specially with katana, it's only 3 mm for half thickness and planning to use only one thin mat and then two 400 g/m2 mats.

Tempted to use the better laminating epoxy to save least week, but I don't have compatible gel coat for that.

I keep on reading about tooling gel coat and that sort of stuf. They don't have them on the local shop and those materials are hazmat, when it comes shipping them. Aargh.

Pekka


Offline PekkaNF

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Re: Glass fibre mould from the slender plug
« Reply #1 on: June 12, 2018, 03:30:58 PM »
Two more coats of wax. This is Katana type sword that will be for her friend. This is the practice piece and I'm considering mouldin process for this one.
« Last Edit: June 12, 2018, 04:47:25 PM by PekkaNF »

Offline PekkaNF

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Re: Glass fibre mould from the slender plug
« Reply #2 on: June 12, 2018, 04:54:48 PM »
And the somewhat transparent sword has few more tricky parts and I finally made my mind how to make it. Took three prototypes :Doh:

So the blade is symmetrical, plan is to make only one mould for blade and use it for both sides. Because that will require pretty good symmetry I made a single sided jig to use router and bearing/copy bit to make both sides of the plug symmetrical.

Now the blade plug is ready for final coats and to mount on parting board.

Drat, the pictures are on the other laptop....I'll update them when I have it back.

Basically I'm trying to find faster way of making the mold than two weeks.

Pekka

Offline Brass_Machine

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Re: Glass fibre mould from the slender plug
« Reply #3 on: June 12, 2018, 04:58:53 PM »
Have you thought about making the sword out of acrylic or some other clear plastic?

Something similar to this cosplay sword build.

http://chrixdesign.blogspot.com/2015/12/red-from-transistor-sword.html

Science is fun.

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Offline PekkaNF

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Re: Glass fibre mould from the slender plug
« Reply #4 on: June 12, 2018, 05:07:11 PM »
Yes. I tried vacuumforming 1 mm polycarbonate (for two halves) to make lightweight, strong and non offending blade. Proble is that that slender piece needs an long ifrared heater and it is hard to get even temperature distribution. Managed to make decorative twisters, they looked ok in the mold and then twisted half a round when realesd from the frame.

Three tries (and two 1 kW burnt IR heater) later I gave up. I mm polycarbonate would have been pretty good.

Pekka

Offline vtsteam

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Re: Glass fibre mould from the slender plug
« Reply #5 on: June 12, 2018, 11:44:54 PM »
Pekka, what about finishing the plug well and then doing a plaster of Paris mold over? Then varnish the plaster, wax it and mold your sword material in that?

Actually, since you seem to do really nice work in wood, what's wrong with a wooden sword? Traditional for practice and children's swords, I believe.

If you really want, you could glass the outside for some wear protection. -- it does take more finish work, but far less mold work, so they're about even.
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eskoilola

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Re: Glass fibre mould from the slender plug
« Reply #6 on: June 13, 2018, 12:09:08 AM »
Yes. I tried vacuumforming 1 mm polycarbonate (for two halves) to make <snip>
Polycarbonate is not very good material for vacuumforming. I does not get really soft and when it does, it already starts to decompose. I made a swarf shield for my tiny lathe from this material and it was an excersise with heat gun. The result is not pleasing but it does the job.

I quess acryl or ordinary PVC might be better.

eskoilola

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Re: Glass fibre mould from the slender plug
« Reply #7 on: June 13, 2018, 12:16:55 AM »
<snip>
Actually, since you seem to do really nice work in wood, what's wrong with a wooden sword? Traditional for practice and children's swords, I believe.
<snip>
Do You actually believe that a small wooden sword would have any chances of survival in the hands of a viking ?
The idea of making the thing out of polycarbonate has some appeal to it as that material is virtually indestructible.
One might consider using the vacuum to fill in the particle wood sword with polyester resin. I have used the polyester resin to repair housings of old tube radios which were broken and were made out of the particle wood. The resulting composite is actually very strong.

Offline PekkaNF

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Re: Glass fibre mould from the slender plug
« Reply #8 on: June 13, 2018, 02:21:17 AM »
I should have clarified few things:
* Both swords have to somewhat transparent, therefore something bit more opaque that wood is needed. I normally would make the core out of foam and epoxy glas fibre veil to it to give some strength and surface to finish, but that does not work on this one, because there is no transparent core material (or it is unobatanium).
* All anime props must be pretty harmles, they must have no "live" (read "real") metal and maximum strenght is "wood" or the prop is not allowed. Puts some limit on materials.

We made a halberd out of closed cell foam, plastic electrical conduit, some plywood on structurally critical parts. It's about 250 cm long and has all detachable spikes (three when assembled) and few spares. Weight very little and breaks if you poke anybody with it, but looks very menacing. That was easy.

Plaster of paris came to my mind, but the mould would be 1,2 m long, least 200 mm wide and some depth....probably shrinking would be a factor and on those dimenssions POP might need some serious inforcement. Think I'm going to go for polyester. Digged out the gelcoat, resin and noticed that the MEK bottle had leaked....what a mess. Luckily the plastic box I had all of them had contained the mess.

Pekka

Offline vtsteam

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Re: Glass fibre mould from the slender plug
« Reply #9 on: June 13, 2018, 10:55:49 AM »
Hi Pekka, I think you meant translucent in the first and last post -- not opaque, hence the confusion.

eskoilola, re. "Do You actually believe that a small wooden sword would have any chances of survival in the hands of a viking ?"

Depends on the viking (or in this case samurai, not to mix up our cultures) and the type of prop use. If for costume show primarily, wood will certainly do. But if the proposal is for actual clashing with replica-looking blades, any hard plastic will also dent pretty bad and even break. Light weight hollow soft plastic like polypropylene would be more appropriate and safer.

And btw to go along with Japanese culture, bamboo swords are quite durable, even in practice battles. Not that they are particularly safe if of scale proportions. Tubular blades are much safer.

Pekka while you may not prefer to use plaster of Paris for other reasons, it can be reinforced just like any modern plastic resin would need to be -- and you can use easily obtained or scrap wire or screen or mesh, as well as set into a wooden box for support. It cures very quickly, and no, it does not shrink, which is why it is traditional for molding. Vaseline (petroleum jelly) is a great release for it, all easily obtained and inexpensive materials.

But of course everything we do must appeal to us, and if epoxies and glass fiber are what you want to work with, that's the way to go. I'm jus throwing out possibilities to consider.
I love it when a Plan B comes together!
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Offline sparky961

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Re: Glass fibre mould from the slender plug
« Reply #10 on: June 13, 2018, 06:30:35 PM »
I'll bet your daughter just got tired of you bugging her and decided to give you a project to keep you busy. :P

Otherwise, your daughter has a pretty damn good dad!  Or maybe she's a little spoiled.... ;)

Offline PekkaNF

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Re: Glass fibre mould from the slender plug
« Reply #11 on: June 14, 2018, 02:46:51 AM »
She is spoiled, but there are few chores she has to do in and around he house to free my time for these projects. Most of the stuff I only show few minutes how to do and then leave her to finish the work for two hours. But glasfibre work is something I don't do routinely and I'm not sure. Last summer she helped me to pave front of the garage and booked up a hotel and drove her 300 km to convetiond and stayed there two night to see that she is safe, fed and all that parenting thing. Good deal.

Steve, I see. This has to be somewhat translucent. Like, if you hold the blade, you must see vaguely hand outline, but no need to see any details.

I might try POP later on smaller detalis, specially if I need only one-off part....I am bit sceptical on that parting off wax, I never had good results with vaseline or automotive waxes. Once I brought some aclaimed release wax from USA and transported it home on my lugage (those were the times!), and it worked ok, but needed really many layers and the can dried in the end. Karnauba fourniture wax worked well in my youth and solvent stink was bening.

Anyways, Resin rep. told me that with their resin and on my case, I need to wait one and half day and then the mould should be usable. So I layed up gelcoat, some thickened resin, chopped strand mat and finally twill to tidy up. I am rusty. Took really long to do all the stuff. Check this morning (less than 6 hrs of sleep) and it still is a litlle greenish and would have been time to cut edges off, but desided to leave un disturbed.

Now: 1) Will it release? 2) Will it have voids? Noob mistakes.....I don't feel too confident, but first on this decade (actually closer to 20 years.....) is first. :lol:

Pekka

Offline PekkaNF

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Re: Glass fibre mould from the slender plug
« Reply #12 on: June 15, 2018, 04:44:12 PM »
So....my big mistake: Went techno and tried new one can 2K paint to cover the plug.

All went initially well....mould popped open easy, but from filler. Not from separation wax layer....damnhik!

Called the wax manufacturer and they were rally helppfull, All should have been fine.

Then called paint manufacurer and explained the situation. We had a really nice chat. It perspired that in order to keep that paint from setting in the can they have mixed the acid hardener in water. Therefore the after spraying the water has to evaporate off the paint layer before it hardens and it might take 7 days and has to be open all that time....a chemist is going to call me on moday and explain it fully.


Offline PekkaNF

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Re: Glass fibre mould from the slender plug
« Reply #13 on: June 15, 2018, 04:46:19 PM »
Anyway, because the chemical reaction did not finnish in three days, layers separated on competely wrong place and there was not end to my fustration.. I used some sanding paper to remove MDF, then acetone and wood spatula to remove the unhardened 2K paint and all started to look better.

After a little more polishing pad all started to look pretty good, found one hairline fracture and few little pores. Easy to fill with epoxy/microbaloons.

To be continued tomorow...

Offline PekkaNF

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Re: Glass fibre mould from the slender plug
« Reply #14 on: June 16, 2018, 08:23:58 AM »
Sanded down to gelcoat and then polished the mould.

Offline PekkaNF

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Re: Glass fibre mould from the slender plug
« Reply #15 on: June 16, 2018, 02:57:09 PM »
6 coats of release wax + layer of PVA release film

2 layers of 160  g/m2 twil and SP106 laminating epoxy. Hope it works, but it did not go around the corners that great. Hope it does not have exsessive amount of voids.

Pekka

Offline PekkaNF

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Re: Glass fibre mould from the slender plug
« Reply #16 on: June 18, 2018, 04:15:59 AM »
All went pretty ok, but:

1: I don't use gelcoat to keep the whole thing translucent, therefore back of blade side corner was not crisp. probably have to laminate veil and think of using a perforated separation film and pressurepad or slight pressure or vacuum on it.

2: Turns out that two layers of 160 g/m2 twill is thinner than I anticipated. Anyway, glued them together on the mould to see if can be done and keeps straight.

The release wax and PVA works, it even gives an early release....now went to other end of the extreme...look and learn I guess. Maybe just a dab of film on the nearly vertical feature of the mould (back of the blade).

Think that I'm going to put just a little mictoballoon or silica thickened resin at the very back of the blade section before veil, to keep it in shape, also very tempted to add some of that micture at the very blade edge to give more surface for gluing it. Might even need to make it two steps.

I got pictures, but they are boring and they donät actually show much....paper thin one meter katana type blade at this point.

Pekka

Offline PekkaNF

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Re: Glass fibre mould from the slender plug
« Reply #17 on: June 23, 2018, 04:50:41 PM »
Started working on another sword mold. Can't get my head around it, but think I'm going to build it in two part and need two moulds: blade/handle and cross piece.

Now the interesting part is that I am not very familiar with polyester resin. Information I read is a little confliking.

One major thing is: Some information emphasis putting a veil over gelcoat, let it dry (to various harness, often completely dry and then continue with structural layer. Some videos people seem to build pretty much (or least seemingly) the whole mould laminate on one go.

Which way it is and why? I never build that thich laminate, taht it will heat up.

I get that adding stiffeners to wet laminate will shine trough, but those I could add day later.

Any advice on mould laminiation sequence?

Pekka

Offline vtsteam

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Re: Glass fibre mould from the slender plug
« Reply #18 on: June 23, 2018, 07:58:42 PM »
Pekka, general purpose polyester resin (also sometimes called "finishing resin") generally has wax in it so that it will cure hard on the surface. Wax floats to the surface before cure, insulating it from air. Best for all-at-one-go type work, or as a final coat on a molded part IF you don't plan on attaching anything else to it, since a wax surface isn't good to adhere to. Polyester resin is a poor glue to any hard surface or material. Epoxy resin can be used to glue to polyester, if any surface wax is removed. But polyester itself will not work well with an already cured polyester surface, even after wax removal.

Laminating resin doesn't have wax in it, so that it can be added to by subsequent polyester layers or attachments in a mold. Even cured, it is still tacky on the exposed-to-air-surface, so subsequent layers of polyester WILL stick to and and cure it. Polyester without wax is an air-inhibited cure resin.

Gel coat also is air-inhibited cure, for the same reasons. subsequent layers need to adhere to it. However it does cure (harden) against the mold surface, since that side is not exposed to air.

Because laminating resin stays tacky on the surface, even when cured, you can add subsequent layers without having to rush it or build up too much thickness all at once. If too much thickness is built up all at once, all the resin will cure at the same time and get hot and cause other problems.

Is that any help?
I love it when a Plan B comes together!
Steve
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Offline PekkaNF

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Re: Glass fibre mould from the slender plug
« Reply #19 on: June 24, 2018, 06:22:40 AM »
Thank you Steve very much!

That clear my confusion completely. Now I feel pretty stupid....I had read and "knew" all details, but could not connect the dots.

I knew the difference on gelcoat and topcoat, but never knew the fundamental difference on polyester resins. I was baffled, because when I was young I helped one motobike racer to build fairings and cowlings on my summer holiday...I remember him planning everytihing beforehand, and some stuff had to done when "green", some when hardened and some demended peel off ply. Pretty sure he always used tooling resin, because backside was always stricky and had to topcoat it in the end.  I think we were building only molds and remember him showing how different the parts were when laminated from epoxy or polyester.

This was exactly why I had this confusion, because my previous experience did not match my results.

That shop where I bought my resin had only one type of polyester resin. The plan is to use this can of that resin for next mould (will be build on one go then!) and try to find laminating resin for the next week.

Pekka

Offline sparky961

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Re: Glass fibre mould from the slender plug
« Reply #20 on: June 24, 2018, 01:40:28 PM »
I performed some significant rebuilding of the coaming on my fibreglass kayak last year.  I was going to use polyester resin because it's readily available.  But after doing some tests with it, I opted for higher quality epoxy resin.  Yes, it cost more.  But it doesn't have the nasty odour typical of polyester, and cures almost transparent - unlike most polyester I've seen.  I used MAS brand after reading through many, many reviews and unscientific test comparisons of brands.  It's less expensive than the oft-touted West Systems, but many people reported obtaining very good results with it.  Though I haven't had a lot of experience with it, I was certainly not turned away from epoxy work after using it.  It actually has such low odour that I sometimes initially forgot to don my respirator - though I tried to do so religiously.

Offline vtsteam

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Re: Glass fibre mould from the slender plug
« Reply #21 on: June 24, 2018, 10:10:39 PM »
Sparky, since you were adding to already cured resin, epoxy was the sensible choice. If you'd tried to use polyester, even with wax removal and abrasion, the bond would have been relatively weak by comparison.

There is a third choice, btw, vinylester resin, which has properties somewhere in between polyester and epoxy when laminating. However it has a very short shelf life, and is mainly used for specialty production moulding.

And just to add to the confusion, there are actually two kinds of finish resins commonly called "gelcoat" - the main and original type is sprayed into a female mould, and has an air inhibited cure. The second and more recent (and unfortunate) usage for the word applies to a color coat applied to the exterior of a male moulded part. And that must be an air hardening type, since it is the final finish exterior coat.
I love it when a Plan B comes together!
Steve
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Offline PekkaNF

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Re: Glass fibre mould from the slender plug
« Reply #22 on: June 26, 2018, 12:21:58 PM »
Interestingly some seemingly large shops don't know or recognize that little difference on wether their resin has wax ot not. Laminating resin seems to be elusive. But found a palce to order black ot red gelcoat for moulds.

Ordered one small sheet of 2 mm acryllic sheet to have plan "B" for the almost transparent blade.

Today I have been making more plugs...need to find out what paint to used to make the MDF plugs smooth and non porous.

Pekka

Offline ddmckee54

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Re: Glass fibre mould from the slender plug
« Reply #23 on: June 26, 2018, 02:42:39 PM »
Pekka:

I stumbled across this youtube channel a couple of weeks ago. 

https://www.youtube.com/user/WJP004

Don't know if it will help or not, but he pretty much walks you through everything.  In various videos he shows all the steps, making the mold, hand laying up the part, de-molding the part, trimming the part and assembling multi-piece parts.

Hope it helps,

Don
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Offline vtsteam

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Re: Glass fibre mould from the slender plug
« Reply #24 on: June 26, 2018, 10:18:27 PM »
Interestingly some seemingly large shops don't know or recognize that little difference on wether their resin has wax ot not. Laminating resin seems to be elusive. But found a palce to order black ot red gelcoat for moulds.

Ordered one small sheet of 2 mm acryllic sheet to have plan "B" for the almost transparent blade.

Today I have been making more plugs...need to find out what paint to used to make the MDF plugs smooth and non porous.

Pekka

Yes, that's often the case -- even pro's sometimes don't understand the basic reasons for what they order for supplies day-to-day -- as long as their usual method works for them. If you understand the materials, though, you can also do something different than what you're used to day-to-day.

Pekka, re finishing MDF (or wood, as I do for patterns) try hand brushing lacquer with a few spoonfulls of baby talcum powder mixed into a pint (not the cornstarch type, but the real talc type). Uhh, I mean into a half liter. You have to keep it stirred if it sits too long.

This dries very quickly and sands beautifully with fine sandpaper. MDF is quite absorbent, so it might take 3 coats, sanding between each -- but it works very quickly. Then overspray with colored lacquer (Krylon regular in rattle-cans, here in  the US is lacquer based). Two coats, then wax, or release agent (PVA is often used.

Hope that helps.
I love it when a Plan B comes together!
Steve
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