Re: Resin volume placed on foam
You bring up good point, Rob. The $200 million dollar question. What is the best Inspection?
Thermography? Water Ultrasound? X-ray? Nordam found out the hard way that dealing with Gulfstream
can cost a lot...bankruptcy of an entire division...when that question is not fully agreed on first (IN WRITING).
For us the reliable old Silver Dollar ring is good enough..but the on-going battle for Inspection has yet to be
fully resolved. Yet another place where fortunes can be made. Whomever invents the final standard for composite
construction Inspection will live very comfortably.
From: main@Q-List.groups.io <main@Q-List.groups.io> on behalf of Rob de Bie <robdebie@...>
Sent: Tuesday, March 30, 2021 4:35 PM
To: main@Q-List.groups.io <main@Q-List.groups.io>
Subject: Re: [Q-List] Resin volume placed on foam
Thanks for the explanation! I never did autoclaving myself, although I prepared some fiber-metal
laminates to be autoclaved.
A related question: AFAIK, a low percentage of voids (below 3-4%) has hardly any effect on the
material properties. Would it be right to say that it is then more an indicator for quality control?
On 30 Mar 2021 11:57, One Sky Dog via groups.io wrote:
> In an auto clave the usual cure cycle begins with full vacuum to expand the air bubbles so they move
> laterally between the plies. The pressure is applied to reduce the size of any voids left and drive
> remaining gases into solution in the resin.
> Blender scheduals are calculated to not remove to much resin.
> My you tube channel
> On Monday, March 29, 2021, 1:30 PM, Rob de Bie <robdebie@...> wrote:
> I really like this as a thought experiment. And I see some parallels with autoclave processes.
> In an
> autoclave you can apply pressure without the vacuum turned on. Therefore this is sort of similar to
> what you propose. I haven't figured out yet whether this leads to different amount of resin flowing
> into the bleeder - but my gut feeling says it will have a considerable effect.
> And now that I'm thinking about it, a typical autoclave pressure *could* make the resin absorb
> air bubbles. At least that's what I see in resin casting, using polyurethane resin. In that process
> one can take one of two very different routes: vacuum casting or pressure casting. In former you
> 'pull out' the air bubbles, in the latter the pressure makes the resin absorb the air bubbles.
> tonight I hadn't seen the parallel. But it has nothing to with building a Q1 or Q2 :-)
> On 27 Mar 2021 21:40, Bruce Crain wrote:
> > Just a thought. Would it help to vacuum bag parts and then put sand or lead on top of the
> > bagging material to use weight to press the resin and glass together tighter into the weave? It
> > would be messy and you would have to keep the mold from creeping but what does the group
> think and
> > does any one have any experience to share about that? Just thinking outside the box.
> > Bruce Crain
> > ---------- Original Message ----------
> > From: "Stuart Grant" <smgrant@... <mailto:smgrant@...>>
> > To: main@Q-List.groups.io <mailto:main@Q-List.groups.io>
> > Subject: Re: [Q-List] Resin volume placed on foam
> > Date: Sat, 27 Mar 2021 07:18:37 -0700
> > Here is a link to a YouTube video where Cozy Girrl Randi explains about how Cozy Girrls make
> > composite parts, including mixing epoxy, mixing micro, using gloves, low pressure vacuum
> > peel ply, sanding etc. The video was recorded at Sun-N-Fun 2019 and the beginning has a lot
> of noise
> > from the air show but Randi has great tips. https://youtu.be/fmuDOWTr_3c
> <https://youtu.be/fmuDOWTr_3c ><https://youtu.be/fmuDOWTr_3c <https://youtu.be/fmuDOWTr_3c>>
> > If the link doesn't work search YouTube for
> > Cozy Girrrl's LoVac Composite Tools & Tricks