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Mast resin infusion

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kostantin
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Re: Mast resin infusion

Postby kostantin » Tue Feb 28, 2017 8:07 am

downunder wrote:Ok,

cool, thanks for that. Question, where does a peel ply go? Peel ply would be used for vacuuming but not for infusion as I understand?

D.
If you don' use peel ply you have to sand a lot more to get anything sticking on the part. In any case use peel ply

tks

Kosta

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Re: Mast resin infusion

Postby downunder » Sun Mar 05, 2017 11:05 am

Hej guys,

resorted to a well known vacuuming :)

Have a look at 4x fast vid:

phpBB [video]


Basically, I've learned hard way not to touch anything with carbon when laminating the mast. This 'jig' enabled me to quickly swap the sides and more importantly, to have a mast with LE vertically, so I could put some tension on carbon down to LE.

Only UNI was placed horizontally on mast as seen on a vid, all the rest vertically touching a LE first. So much easier and faster with a jig.

Used 130ml epoxy for this job. All together 8 layers (4 each side), 2x 45degrees, 1x UNI, 1x big squares finish layer. Will see.
IMG_0034.resized.JPG
Post curing on 45C (ambient temperature is 38C atm :) Tropical cyclone developing up north, no kiting for a week :(
IMG_0036.resized.JPG
Enjoy

D.

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Re: Mast resin infusion

Postby downunder » Tue Mar 07, 2017 6:16 am

Here it is, I've cut the mast from carbon excess (not finished yet), and this is the weight:
IMG_0037.JPG
About on target. The complete foil target is under 2kg. I think this is achievable.

The torsion needs to be tested. Preliminary test is very very promising tho, and after seeing Levitaz mast twist, nothing to worry about :)

So one day I might master the infusion...

D.

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Re: Mast resin infusion

Postby plummet » Tue Mar 07, 2017 7:40 am

Now flex test it to see if its too flexi or not. If yes, slappo more carbon on. If no, carry on as planned.

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Re: Mast resin infusion

Postby tahoedirk » Tue Mar 07, 2017 6:25 pm

Nice one DU. Can you tell me about that spread tow cloth, what weight, where from and is it easy to work with , expensive?
thanks , Dirk
Good luck on mastering!

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Re: Mast resin infusion

Postby downunder » Wed Mar 08, 2017 2:49 am

Thanks guys.

All carbon is about 200g/mtr^2.
With tow cloth it's not easy to achieve a perfect squares as seen on this pic.

Squares with a stabilizing binder between 6-10mm Carbon 12K Plain Weave 195gsm x 1000mm = $25.94 / mtr in year 2014, Australia ( Dirk, I suspect you do not want to buy from here:)
It must be rolled for shipping. All irregularities on this pic are because of folding :(

The epoxy is Araldite K3600. First time using it and very happy with 70min pot life on 25C ambient temp. But, post curing is a must. I did post cure on 60-80C for first 5 hours, next 5hrs on 45C. After 10hrs done (was done after 5hrs, but the specs says posturing on 40C for a week will give maximum epoxy properties). The wood core (or a closed cell), must be sealed for this application if post curing on 80C temperatures. Otherwise, the project might be ruined.

The mast, of course, will float. I am already building a shorter one, with a Nomex Honeycomb core (a sandwich build tho, similar to this one). Expecting 350grams weight for 500mm length :naughty:

D.

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Re: Mast resin infusion

Postby faklord » Thu Mar 09, 2017 10:17 pm

Hey Downunder,
If your doing another mast (strut?) I'd be interested to see a photo of the setup for the vacuum process.
Eg:
1) The orientation of the strut: vertical - leading edge up, or flat.
2) Do you use your jig during vacuuming, If so how to deal with sealing around the pegs at the strut ends
3) Where is vac hose connected.
All the points above are concerned with how to get the unsupported carbon at the trailing edge symmetrically in line with the centerline through the aero foil? By unsupported, I mean the carbon that extends beyond the core. My experience is this tends to sag, giving a rudder like effect. Obviously this can be sanded to give symmetry but you may not end up with the intended finished profile.

Just curious?

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Re: Mast resin infusion

Postby downunder » Fri Mar 10, 2017 2:44 am

The mast is not in this jig when vacuuming. The jig is simply to put the carbon on without touching any surface the carbon might stick to, pickup some dirt, or similar. Not sure about the 'pegs'?

Also, the jig will enable you to put the mast on an angle, any angle you make simply with a few nails (click on a pic, you'll see them). This will obviously work only with some sort of support, as I have SS 6mm bolts going deep into the mast ending in a brass insert:
IMG_0033.JPG
IMG_0032.JPG
Vacuum bagging is simple. No magic here. I would strongly advise to everyone, your peel ply must be first and must be 'soaked' with epoxy. That is where the jig kicks in as well, I did put the mast LE on an angle, and than added more epoxy under the peel ply where needed. Gently used my hands over the top of peel ply. When all completely wet, done.
The SS bolts stay on. They are waxed, no issue with taking them out after.

IMG_0035.JPG
I understand the problem with a 'sag'. And it did happen slightly but way after the blue sticky tape where I actually need to cut the carbon excess. I think this might be due to the carbon setup. If having only a few (ie 2-4), carbon layers and they are all UNI directional carbon, than nothing is opposing to bending forces when applying a vac. Hence it might sag.

I have 45 degrees two layers first, than only one UNI, than big squares tow. With this there are 3 layers supporting UNI not to 'distort' in UNI direction.

Will take a pic of a LE&TE when ready. U bit stuck with other stuff atm.

There is one thing tho, the both mast sides are a bit wave-ish, with a 'wave' square on a LE, every 10mm or so. Not sure why this happened where there is NO carbon in this direction. No idea. You can see that on the above pic, middle right section, strait lines on a vac bag. Where from?

Otherwise perfect.

Hope this helps.

D.

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Re: Mast resin infusion

Postby GrantL » Sun Mar 12, 2017 11:41 pm

downunder wrote:
Fri Mar 10, 2017 2:44 am

There is one thing tho, the both mast sides are a bit wave-ish, with a 'wave' square on a LE, every 10mm or so. Not sure why this happened where there is NO carbon in this direction. No idea. You can see that on the above pic, middle right section, strait lines on a vac bag. Where from?

Otherwise perfect.

Hope this helps.

D.
There is a solution to get the final twill layer looking perfect.
First laminate and vac the mast as you have done excluding the twill layer. Sand profile etc.

Secondly to hold the top twill perfectly brush on a thin layer of resin onto the mast and wait till it is about to tack off. Only then carefully lay the twill onto the resin , gently pressing into the tacky resin. This will hold the laminate perfectly.

Finally wet lay quickly as you are doing and vacuum again.
Works every time

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Re: Mast resin infusion

Postby downunder » Mon Mar 13, 2017 2:03 am

^
Awesome tip, thanks Grant. I think for this a 'jig' is a must, coz once you touch epoxy which is about to tack off, there is no going back :(

Cheers


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