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Old Dec 27, 2012, 12:22 AM
Entropy is happening!
Jim.Thompson's Avatar
Australia, NSW, Bellingen
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Tooling Coats.

Quote:
Originally Posted by josh18 View Post
Looking great Jim! What tooling coat are you planning on using?
Thanks Josh.

For the wings which will be steel backed epoxy moulds like my plank, the tooling coat will be graphite and flocked cotton/colloidal silica (Wests 403) mixed with epoxy. Adam has posted the percentages somewhere, I will look them up. Previously, I did not measure the quanitites. It makes an excellent hard surface!

The fuse mould however, will be Vinylester Tooling resin and the surface coat will be normal gel coat. It will also be steel backed and designed for quick slip on clamps made from threaded rod and nuts through 25x25mm RHS steel or hardwood strips. I don't want to fuss with nuts and bolts anymore, especially on a fuse mould. The bolts get glued up with the excess resin and they are too slow to remove should a bladder burst and have to be replaced etc.
Adam showed the way for me here with his little DLG fuse moulding video demonstrating the use of the clamps above.

I've got to make the parting boards for the tail surfaces now.

edit: Adam of WWWorks has a post here: http://www.rcgroups.com/forums/showt...urfac+coat+mix with his recommendation for the surface coat mix.

It seems that 23% of Wests 404 (403) here in Aus!!! - much room for confusion there. And 8% of graphite. All by weight.
He gives slightly different percentages on another thread, but I don't think it is critical.

Jim.
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Last edited by Jim.Thompson; Dec 27, 2012 at 01:11 AM. Reason: grammar/spelling correction.
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Old Dec 27, 2012, 02:23 AM
Arrarrar!
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Australia, NSW, Wagga Wagga
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Thanks Jim. Why the epoxy and Graphite on the wing and Vinylester for the fuse? There are so many conflicting reports on the best surface coat about. I want to re-do my scorcher moulds at some stage. With the first set I went quick and cheap, but if I do them agian I want to go for as near to professional quality as I can get. I'll keep doing my research as I dont think it'll be happening for a long time anyway.
Good luck with it jim
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Old Dec 27, 2012, 03:11 AM
Entropy is happening!
Jim.Thompson's Avatar
Australia, NSW, Bellingen
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Quote:
Originally Posted by josh18 View Post
Thanks Jim. Why the epoxy and Graphite on the wing and Vinylester for the fuse? ..............
Yes, it must read a bit confusing I suppose.
There is no doubt in my mind that epoxy moulds are superior. The vinylester tooling resin ones are next best in my limited experience and reading. They are cheaper and easier to make with chopped strand mat used as the reo. More toxic and smelly though, I do them outside only and with a good mask with fresh cartridges.
The vinylester can be slightly unstable if not laid up in multiple stages to avoid exotherm induced stress problems and such. However, if done carefully and with some practice, they make a good fuse mould. I would not trust a mould made from vinylester sufficiently for wing moulds though, due to the larger cantilevered distances across the chord and the span of the wing. Maybe not justifed and perhaps I am being over cautious here. I could try doing the small tail surface moulds in vinylester. I'm not sure yet.
Also, my method of doing the epoxy wing moulds (If I can call it mine?), with steel RHS backing, is a good compromise between rigidity and economy.
Actually, its not my method at all. I copied "Shaper Dave's" method and modified that somewhat. I used steel where he uses end grain balsa and glass/epoxy capping. It seems that it is important to have rigid flanges on any mould.
The epoxy/glass can be thin in this style of mould. Like my Circa moulds, which were around 5 mm only. The steel frame provides the rigidity. Steel is cheaper than epoxy/glass.

Logical? Maybe in a convoluted way. A less eccentric builder would do them all in epoxy!
Jim.

edit: For your Scorcher moulds (most proffessional etc.), I would follow Adam's examples if I were you. I have not been doing this for long as you know - we are fellow travellers in this learning experience. My method has not stood the test of time and not many parts pulled etc.
Adam's has! His surface coat, which I use, is well proven and I for one would not consider using anything else for epoxy moulds. You do not need another resin sitting on the shelf with it's shelf life etc. for just occaisional use. The 403/404 and the graphite have numerous uses and are cheap.
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Last edited by Jim.Thompson; Dec 27, 2012 at 03:18 AM. Reason: see edit.
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Old Dec 27, 2012, 11:14 AM
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Hi Jim,
Been following the infusion trial's recently that you are doing and its proving very interesting and not quite as I thought might work out !
Jim in the recommendation for tooling coat of yours / Adam's whats the graphite for? and as per Adams video do you use 3 coats ?
The reason for asking is that I have had some problems of when extracting a part from a mold the 1st layer of Tooling coat has delaminated and flaked off.
Have you had similar problems ?
Think your molds look real good.
Hope Christmas went well down under and best wishes for the New Year.
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Old Dec 27, 2012, 02:29 PM
Entropy is happening!
Jim.Thompson's Avatar
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Fubar

"Been following the infusion trial's recently that you are doing and its proving very interesting and not quite as I thought might work out !"

I have formed the conclusion that vacuum resin infusion is not suitable for flying parts due to the poor strength weight ratio.

"Jim in the recommendation for tooling coat of yours / Adam's whats the graphite for? and as per Adams video do you use 3 coats ?"

I have been using only 1 coat. From memory, I thought Adam used 2 coats. I will look at the video again if I can find it. My memory is flawed, so no doubt you are correct.

"The reason for asking is that I have had some problems of when extracting a part from a mold the 1st layer of Tooling coat has delaminated and flaked off.
Have you had similar problems ?"


The tooling coat should be allowed to tack off only, this takes around an hour or so, depending on the temperature. This will ensure a good chemical bond between it and the subsequent epoxy / glass layup. I've never had any problems, in fact, it would be extremely hard to lift some of the surface coat on my moulds.

"Think your molds look real good.
Hope Christmas went well down under and best wishes for the New Year. "


Thanks (Chris?). All the best to you.
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Old Dec 27, 2012, 03:21 PM
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Thanks Jim.
Chris
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Old Dec 27, 2012, 03:26 PM
Entropy is happening!
Jim.Thompson's Avatar
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Say Chris, have you got the link to Adam's video handy?
If so, can you post it here for me please?
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Old Dec 27, 2012, 05:08 PM
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Quote:
Originally Posted by Jimbello View Post
Say Chris, have you got the link to Adam's video handy?
If so, can you post it here for me please?


Making And Applying a Surface Coat for Epoxy Molds (4 min 56 sec)
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Old Dec 27, 2012, 05:14 PM
Arrarrar!
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Australia, NSW, Wagga Wagga
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Hey Jim, thanks for that. Do you find the graphite powder makes for a harder surface finish than just epoxy/ filler? I also read from Adam that the graphite aids the lubricity of the mould. Have you noticed this?
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Old Dec 27, 2012, 06:55 PM
Entropy is happening!
Jim.Thompson's Avatar
Australia, NSW, Bellingen
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Quote:
Originally Posted by josh18 View Post
Hey Jim, thanks for that. Do you find the graphite powder makes for a harder surface finish than just epoxy/ filler? I also read from Adam that the graphite aids the lubricity of the mould. Have you noticed this?
I have not done enough to know Josh. Besides, I think that is the only surface coat that I have tried with epoxy moulds.
Note that the cotton flock and colloidal silica mix (403/404 or the equivalent) is not just a "filler" like microspheres or talc is/are. It is added usually to enhance adhesion, and in our case, hardness. At least, that is how I understand it.

Jim.

Thanks for posting the link Chris!
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Old Dec 27, 2012, 10:51 PM
Entropy is happening!
Jim.Thompson's Avatar
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Tail parting boards

I cut out the tail surface parting boards today. The resin trap trench spacers have been glued on.
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Old Dec 28, 2012, 02:13 AM
Entropy is happening!
Jim.Thompson's Avatar
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No Graphite!

Chris and Josh,

Did you notice that there was no graphite included in the mix Adam used in the video?
It must have been an old one. He definately recommends graphite added at around 8% from memory.

Jim.
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Old Dec 28, 2012, 03:11 AM
Entropy is happening!
Jim.Thompson's Avatar
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Support for splooge parting board fill.

I wrapped the tails with cling wrap and sat them in position in their respective parting boards. Then flipped them over and applied some acrylic filler/grout along the LE and tip to form a bead. This bead will later on provide some support for the splooge fill that will go between the plugs and parting boards and stopping it from simply falling through.
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Last edited by Jim.Thompson; Dec 28, 2012 at 03:12 AM. Reason: grammar/syntax
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Old Dec 28, 2012, 03:28 AM
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Yes Jim , I noticed, have some graphite on the way to try out in a mix with some W.S 404.
You say 8 % by weight of The total.
I will be using it in combination with Freekote. Will let you know how it goes.
Adam can you confirm the quantities if you are about please ?
Chris
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Old Dec 28, 2012, 03:38 AM
Entropy is happening!
Jim.Thompson's Avatar
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Chris,
See link in post #361.
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