Building a CF Tube

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Aquaman33
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Re: Building a CF Tube

Postby Aquaman33 » Tue Jul 23, 2019 2:22 pm

joeman wrote:RE: PVC
I've been unable to find 76mm tubing...only 75 mm tubing.

hence Aluminum


Maybe a few extra layers of Glad Bake will get the PVC up to 76mm :D

joeman
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Re: Building a CF Tube

Postby joeman » Wed Jul 24, 2019 4:22 pm

That is a lot of gladbake. :lol:

I'm going to give TR-104 MOLD release a go.

https://www.kirkside.com.au/wp-content/ ... -Wax-r.pdf

I'll wind a small 500mm section, something good enough for a payload tube...and see how it fairs.

Cheers

Joe
L1 - Callisto (H133) - 11-Jan-2016
L2 - March Fly (1633K940) - 18-Mar-2018 - RSO

joeman
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Re: Building a CF Tube

Postby joeman » Fri Jul 26, 2019 12:05 pm

Hello,
I've put a lot more thought into this.

Firstly, if I could get cardboard tubes easily and cheaply, I'd probably use that. But I can't.
I like Aluminum tubes because I can if necessary (potentially) use dry-ice, is readily available local product and It is fairly forgiving(strong).

Kirkside have recommended using TR 108 mold release , possibly in combination with PVA Mold release agent.
Going to go for both...I want to give myself the BEST chance of it coming off. I suspect it will work without having to resort to dry ice which will be a great thing, because it takes up more time and isn't cheap. Yes, it will mean more Mandrel preparation, but, that is just what is required.

In my investigations, I think one of my BIG mistakes was letting the heat-gun keep the winding warm for about 4 hours post wind. This really sped up the curing and resulted in even tighter fit, sooner. Next tube I will ONLY heat for about 10 mins max, to extract excess Epoxy. After all, most of the excess epoxy removal occurs in the first 10 minutes when it still has the consistency of honey.

Hope to do a small 500mm test in 1 or 2 weeks time.

Will let you know how I go!!

Hopefully then I'll be closer to my next rocket Build!

Thanks to everyone with thoughts and support.

Cheers

Joe
L1 - Callisto (H133) - 11-Jan-2016
L2 - March Fly (1633K940) - 18-Mar-2018 - RSO

joeman
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Re: Building a CF Tube

Postby joeman » Fri Aug 16, 2019 9:49 pm

Things happen slowly, but they do happen.

I've got some TR-108 "wax" to apply to the Mandrel and I'm likely to try and use some Graphite as a lubricant.
So
- Aluminum Tube - sanded to 2000 grit - then Brasso - then cleaned with Metho and paper towels.
- Then 8 layers of TR-108 - ~1hr between each application.
- Then dusted with Graphite
- Then Cash Register Tape
- Then Packaging tape

.... and then I can do the actual winding!

Yes, a lot of things to do. Hopefully it pays off.

Hopefully in the next few days I'll have a 500mm long tube ...removed WITHOUT dry-ice...

Will let you all know.

Cheers

Joe
L1 - Callisto (H133) - 11-Jan-2016
L2 - March Fly (1633K940) - 18-Mar-2018 - RSO

joeman
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Re: Building a CF Tube

Postby joeman » Sat Sep 07, 2019 10:25 pm

Hi
I finally got a chance to do another winding.
Only a 500mm winding.... but just wanted to test removal from mandrel.


I :-
- reduced tension in the filament,
- used tr-108 wax on mandrel
- Didn’t wrap docket paper around as tight (I could slide it before doing winding)
- only ran heatgun for 10 mins
- removed from mandrel 8hrs... rather than 12 hrs later


It was so easy to remove. Almost single handed and no dry ice. WOW! Such a massive contrast from before.

The surface finish has waves in it.... in some places...I didn’t apply tape as well as I should have. But I have an idea on how to fix that.

So next is 2m tube!

I will get there eventually!

Thanks for all support and suggestions.

Joe



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L1 - Callisto (H133) - 11-Jan-2016
L2 - March Fly (1633K940) - 18-Mar-2018 - RSO

joeman
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Re: Building a CF Tube

Postby joeman » Fri Sep 13, 2019 10:26 am

Did another run - 500mm, single layer, 45 degrees.

Aim was to improve surface finish.

Removal off mandrel was SO easy.

Surface finish excellent inside and out.

IMG_9464.JPG


Image

Will look at applying an external coat next week to give the lovely look.

Definitely getting better at it.

Got 2.5 m aluminium tube. Closer to making the airframe.


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air.command
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Re: Building a CF Tube

Postby air.command » Fri Sep 13, 2019 10:40 am

That's looking really good joeman! What is the wall thickness?
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drew
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Re: Building a CF Tube

Postby drew » Fri Sep 13, 2019 10:40 am

Awesome work Joe!
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Re: Building a CF Tube

Postby joeman » Fri Sep 13, 2019 11:09 am

Cheers!

About 0.6mm thickness. About what I expect for 12k.

Been a slow journey.


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air.command
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Re: Building a CF Tube

Postby air.command » Fri Sep 13, 2019 11:56 am

How long do you think the winding will take for a 2m tube? Also what is the pot life of the epoxy you are using? Do you mix it as you go and add more, or can you make the whole tube with the one batch of epoxy you mix up at the start?
(Sorry if you already answered some of the questions earlier in the thread. )
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joeman
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Re: Building a CF Tube

Postby joeman » Fri Sep 13, 2019 12:26 pm

Previous tube of about 1.8m (that I couldn't remove) took 2 hours. So probably about 2hrs 15mins to roll a 2 meter Carbon Fiber tube - 4 layers.

The K3600 doc (from memory) says a pot time of 90min +/- 10min at 25 degrees, that number means nothing up here in Cairns where it is 30+ in the workshop. I measure out resin prior to the wind...then as required, I add hardener, stir for a minute and then add to the Resin bath. It is a fiddle, but it works. Another thing to remember is that a 2 meter tube requires about 700 grams of CF, so theoretically need 700 grams of Epoxy...way more than my bath can hold.

I have the whole procedure documented...and continue to refine it. It has some calcs that I perform to work out batch size and # of batches and I have everything measured out before I begin. All like clock work. Clean-up takes a while, but so far the Resin bath has been used for about 5 tubes so far of varying sizes.


As aside, I just realised the new Aluminum mandrel is 80mm diameter! not the 76.2 mm I ordered. Glad I picked that up early on!


Cheers!

Joe
L1 - Callisto (H133) - 11-Jan-2016
L2 - March Fly (1633K940) - 18-Mar-2018 - RSO

strud
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Re: Building a CF Tube

Postby strud » Sat Sep 14, 2019 6:55 pm

Persistence conquers all :-)

Well done indeed.

Can you source a slower hardener for the K3600?


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