Mandral jig

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diesel
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Mandral jig

Postby diesel » Sun Jan 31, 2010 9:01 pm

Well guys last week I built a rocket stand ,So this week I decided to have a crack at fiberglass body tube so I made a mandral jig.Image After preping the PVC tubes ( greaseproof paper and all that ), I got started to laminate it Image Thats as far as I have got so I will post more later 8) Image
Last edited by diesel on Sun Jan 31, 2010 9:06 pm, edited 1 time in total.
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Re: Mandral jig

Postby Scoop1261 » Sun Jan 31, 2010 9:04 pm

Great to see folks stepping up to "Rolling their own"

Keep us informed how it turns out for you, and if you need any tips, don't be shy to ask! 8)
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Re: Mandral jig

Postby diesel » Sun Jan 31, 2010 9:08 pm

Mate you inspired me to have a go.. 8)
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Re: Mandral jig

Postby EMiR » Sun Jan 31, 2010 10:57 pm

good stuff mate, I'll see you next launch, let me know how it goes

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Re: Mandral jig

Postby diesel » Tue Feb 02, 2010 8:58 pm

Well guys as you know I attempted to laminate my own body tubes, it dident go so well it stuck to the PVC pipe, so I will attempt it again after talking to scoop for advice as he is the ( Yoda and I am the apprentice ) ... So once again I will keep everyone posted.
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Re: Mandral jig

Postby Scoop1261 » Tue Feb 02, 2010 11:03 pm

diesel wrote:Well guys as you know I attempted to laminate my own body tubes, it dident go so well it stuck to the PVC pipe, so I will attempt it again after talking to scoop for advice as he is the ( Yoda and I am the apprentice ) ... So once again I will keep everyone posted.


I ain't no Yoda!.....thanks all the same......that honor should really go to PK.....Now there is a man who knows his way around a PVC mandrel and fibreglass cloth!

Patience young Padawan!
The trick for players trying this most interesting step is preparation

Amourall is your friend!

A generous application to the mandrel is required, let it dry then give the whole thing a wipe with light cloth (oh yeah...it helps if your mandrel doesn't have any scratches or scars on it too).

Greaseproof paper is hard to applying by yourself

The tick here is to get a nice even overlap (spiral) that is no more than about 10 - 15mm wide .....OK maybe 20mm...but that's it max!

4 hands are better than 2......a friend is a useful tool in the making of composite tubes.

Take note of the direction you wrap the paper!.....Everything!....And I do mean everything must continue in the same direction....critical....no if's or but's!

Don't try to take the tube off too early, a green tube will bunch and get stuck....if you need to twist, it must be twisted in the same direction as the wrap, or the greaseproof paper will "unwind" and bind on the mandrel.
Generally, a light tap on the ground will loosen the tube from the mandrel.

The best form of release is no release at all!

I would suggest perfecting your laminating skills by adding layers of glass to a cardboard mandrel (ie reinforcing BT) before stepping up to the complete composite stuff......but hey PVC tube and FG cloth are reasonably cheap....have a go....it just may work first time.....and you will have some fun in the process!

Don't give up Diesel!
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Re: Mandral jig

Postby PK » Wed Feb 03, 2010 12:10 am

Scoop1261 wrote: as he is the ( Yoda and I am the apprentice ) .

Anyone got a pic of Dave looking a little green? :-)
With PVC, the ways it goes wrong are:

You get a scratch in the tube that causes the glad bake (accept no substitute) to bunch up and the tube gets stuck.
You get some tape stuck under it that causes the glad bake (accept no substitute) to bunch up and the tube gets stuck.
You get some moisture ('cos you left it oustide overnight) under it that causes the glad bake (accept no substitute) to bunch up and the tube gets stuck.
Aim for the minimum amount of overlap in the glad bake.
Make the tube shiny (armourall)
Keep it dry.
Try to cure it hot and pull it out when it's cool, the coefficients of thermal expansion for PVC vs glass will work for you....


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Re: Mandral jig

Postby OverTheTop » Wed Feb 03, 2010 6:52 am

Would plugging one end and filling the PVC with ice-water help? Dry Ice?

I have a source for liquid nitrogen that I could use!

Sounds like something I'll have to try in my spare time...
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Re: Mandral jig

Postby rocket_troy » Wed Feb 03, 2010 8:02 am

I've probably laid up a hundred or so composite tubes over the years - which have all been donated to the rocket gods BTW! I used to use baking paper with a bit of extra lube to assist with the tube removal off the mandrel. To ensure the reliability of that combination as a release agent/layer I found I needed *at least* 2 coatings of baking paper. The lube helps stick the layers of baking paper together making the process quite manageable for 1 person.
However, these days I much prefer a more foolproof, cleaner and simpler method that always results in a very effortless slip-off removal. This simply involves laying 1 or 2 coats of newspaper around the mandrel and coating that with packing tape - ensuring the entire area to be coated or laid up over is totally sealed with the tape. In fact, as Wombat knows, I'm quite a fan of packing tape for composite tubing work and not just that application! Applied correctly (and there is an art to it), it can literally cut hundreds of hours off the entire process of making a finished tube.

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Re: Mandral jig

Postby Scoop1261 » Wed Feb 03, 2010 9:01 am

PK wrote:Anyone got a pic of Dave looking a little green? :-)


PK


Any of those sort of photos would have been "doctored"................... :mrgreen:

Honestly!
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Re: Mandral jig

Postby PK » Wed Feb 03, 2010 9:20 am

OverTheTop wrote:Would plugging one end and filling the PVC with ice-water help? Dry Ice?
I have a source for liquid nitrogen that I could use!..


Probably, but its unnecessary. A little bit of care and practice and it'll slide off every time.
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Re: Mandral jig

Postby The Wombat » Wed Feb 03, 2010 12:10 pm

it's a pity that extra-large heat-shrink tubing isn't commonly available or cheap.
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Re: Mandral jig

Postby PK » Wed Feb 03, 2010 12:17 pm

The Wombat wrote:it's a pity that extra-large heat-shrink tubing isn't commonly available or cheap.


But release coated heatshrink tape is. You can spiral, perforate and shrink.


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Re: Mandral jig

Postby Scoop1261 » Wed Feb 03, 2010 1:53 pm

Apologies for the large photo, but the resolution is required to see the detail............

Wrapping the mandrel, is definitely an art, and the photo demonstrates the overlap you are looking to achieve and the angle of the paper to the mandrel to get the spiral.

The other effective means is to use mylar, and is applied entirely differently.

Image
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Re: Mandral jig

Postby The Wombat » Wed Feb 03, 2010 8:31 pm

Is that being wound on 'dry'?
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