Re: [ATM] making carbon tubes

["Peter" <peter@kitgear.com>]

Hi,

I have this book and it does not explain the detailed method very well.

I tried to make a composite tube on a mandrel and it also wrinkled once
vacuum bagged. I recall watching the process and I observed that the vacuum
created high points (wrinkles or channels) where the epoxy existed more
readily from the cloth causing the outer layer to slide - hence the wrinkle.
My inner layers stayed put and made for a very nice inner surface finish.

Cord, the other problem I had was removing the CF tubing off the mandrel.
The vacuum applied so much pressure that I had trouble removing it.

Shane, perhaps you would consider sharing some of you experience in this
area? Much appreciated!

Peter

-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net]On Behalf
Of James P Crombie
Sent: February 1, 2006 10:49 AM
To: atm@atmlist.net
Subject: Re: [ATM] making carbon tubes


If the tow is wound tight the the vacuum bagging will not affect it.
The main reason to vacuum bag it it to remove the excess resin from the
fibres and to help the fabric conform to the mold or substrate.  The
resin should pass through the peel ply (release fabric) into the
breather material. With your previous efforts with fabric,  if it was
not in tight contact with the alum tube then when the vacuum was applied
it may have moved and resulted in the wrinkes you got.
  There are several books availabel on vacuum bagging for hobbist,
mainly for model aircraft types.

I found this on a google search
http://www.jamestowndistributors.com/product;part;14778;process;search;ID;,F
iberglass,Vacuum.Bagging.Supplies

Cord Scholz wrote:

>Hi Matt,
>why would a spiral layer of tow not wrinkle when vacuum bagged?
>
>Best,
>Cord
>
>
>-----Original Message-----
>From: matt [mailto:electro_optic@bellsouth.net]
>Sent: Wednesday, February 01, 2006 4:41 AM
>To: Cord Scholz; atm@atmlist.net
>Subject: Re: [ATM] making carbon tubes
>
>A cheap and simple way to make tubes is not out of fabric but out of
>unidirectional carbon tow.
>Need to wrap the mandrel in a spiral layer of tow, then apply a second
layer
>of longitudinal unidirectional tow uniformly distributed around the
mandrel,
>then wrap it all in a top spiral layer of tow.
>Advantages are no seams to deal with, can be vacuum bagged and oven
>postcured, and tow is the cheapest type of carbon per weight available.
>Also, you decide how much you need in the longitudinal direction and how
>much strength in the hoop, rather than use some woven cloth or biaxial at a
>preset ratio. The whole tube is going to have a continuous fiber structure
>rather than a bunch of cuts .This will result in the lowest weight to
>strength ratio , so this is no tradeoff, you get it both strongest and
>cheapest at the same time .
>
>
>best regards,
>matt
>
>-----Original Message-----
>From: RodShea <RodShea@comcast.net>
>To: Cord Scholz <cord@astro-image.com>; atm@atmlist.net <atm@atmlist.net>
>Date: Tuesday, January 31, 2006 9:50 PM
>Subject: Re: [ATM] making carbon tubes
>
>
>
>
>>Cord,
>>
>>>From what I can tell, tubing is often made by wrapping the
>>mandrel-composite-(?bleeder+?breather+release ply) with heat shrink
>>tape, instead of vacuum bagging it.  This might give you better control
>>of the fabric.  I have not done this, but it seems reasonable.  I would
>>also have thought it would work better to cut unidirectional CF to
>>exact width, equal to diameter, for each ply, or to do all the layers
>>of uni as one piece, rolled around the mandrel.  I'm guessing  the
>>wrinkles come from excess width material, meaning > diameter, that
>>becomes a problem when the vacuum decreases the effective diameter of
>>the mandrel plus whatever thickness of cloth is under the ply that
>>
>>
>wrinkles?
>
>
>>Rod Shea
>>
>>----- Original Message -----
>>From: "Cord Scholz" <cord@astro-image.com>
>>To: <atm@atmlist.net>
>>Sent: Tuesday, January 31, 2006 9:01 AM
>>Subject: [ATM] making carbon tubes
>>
>>
>>
>>
>>>Hi all,
>>>I'm trying to make a carbon tube using an aluminum tube as a positive
>>>mandrel. Does anyone know ho to prevent the carbon cloth from
>>>wrinkling
>>>
>>>
>in
>
>
>>>the vacuum bag? In my first attempt I used several cloth pieces that
>>>were about 1" longer than the circumference of the tube and moved the
>>>seam
>>>
>>>
>from
>
>
>>>layer to layer a few inches, the result were several nasty wrinkles
>>>in
>>>
>>>
>the
>
>
>>>cf part.
>>>I know that there must be a way to do this with a positive mandrel
>>>
>>>
>because
>
>
>>>I
>>>have a sandwich tube that was made this way but I don't how it was
>>>done exactly.
>>>
>>>Cord Scholz
>>>www.astro-image.com
>>>
>>>
>>>
>>>_______________________________________________
>>>ATM mailing list http://www.atmlist.net/
>>>
>>>
>>>
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>>
>
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