Author Topic: Glass fibre mould from the slender plug  (Read 426 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.

We're all mad here. I'm mad. You're mad.

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