Almost ready - short of materials

Sometimes you work in the shop for a few hours and it looks like you did something, other times you can work all weekend and not have much to show for the effort. This weekend was one of those.

But on the bright side, I did get my Post-Curing Heat blanket delivered!
:)
The epoxies I am using require an eight hour post cure at 180F (82C) to achieve full strength.
Other builders facing this issue have built insulated rooms or small ovens and free standing infrared heaters to accomplish this, but I am planning to get "most" of my post-curing done via a heating blanket.
There are a couple of manufacturers out there, but I chose to go with Custom Heaters & Research.
I worked with Dave to spec out a 2' x 4' (609mm x 1218mm) blanket that will boil water if needed, but can more realistically be set to maintain a certain temperature for weeks on end and only consumes about 700 watts of power. You can custom order the size (and even the color) you want, but I chose a smaller size that will allow it to be used in tighter locations. (The entire blanket needs to stay in contact with the piece being heated). For the hull, I plan to simply "walk" it down the line every eight hours until complete.

As for actual work done, I did manage to get the High Density inserts put into place which is pretty much the last thing I need to do on the floats before infusing.

On that note, I still wasn't happy with the previous test results so I spent some more time working on a third test. From what I've read in the forums and seen in practice, Carbon Fiber is a bit more difficult to infuse than Fiberglass.
I was hoping to replace the 4" (100mm) strips on top of the stringers with some lighter Carbon Fiber strips, but the uncertainty of getting a good infusion on this size of a part had me second guessing that idea. So, the third test was to simulate the infusion with the materials called for in the plans. I also made an adjustment to the vacuum supply on top of the stringer which worked better, but left room for improvement going forward.

At any rate, the third infusion looks really good and I'm happy with the results.

On another note, I think I have just enough resin left over to do the float half, this really means that I don't have enough materials to do that job since the last thing I need is to come up short of epoxy in the middle of an infusion and end up with a REAL mess on my hands.
Besides that, if I use up all my resin now I'll end up with a completed float half and then I'll be in a work stoppage situation until I can afford some additional supplies...

So after sleeping on it, I decided it would be better to complete all the prep work for the floats, which includes drilling and clearing over 2,000 breather holes in the stringers and making a final check to ensure it's ready for infusion. After that is done, I'll get busy building out some of the "small parts" needed throughout the build starting with the Upper Folding Strut Recess Sides. (See Beams Link)

Custom Heating Blanket

High quality programmable heat controller

Prepping materials for the third test

Infusion almost done.

Resin coming through nice and even

Looking good so far

After initial curing - Removed the vacuum bag.
You'll notice that I switched almost entirely to "Enka-Fusion".
I really like working with this product, it lays flat and there's no chance of puncturing the bag.

Bagging materials removed.
Looks really good 

A line up of all the tests.
From Right to left it starts with a solid block of foam, followed by a drilled core.
Then we move to actual materials but the Carbon Fiber proved to be difficult to wet-out comfortably.
And finally the last piece on the left will be the way to go.

The dry spot on the top was a result of the Resin Supply foam block having too large cut-outs underneath.
In the future I will place a small piece of Enka-Fusion under the Vacuum Supply manifold to better spread the vacuum.

A much better job at eliminating the bridging seen in the other test cases

Blue Composite staples to hold fabrics in place.
No spray glue to interfere with the resin and the staples cannot corrode

Bottom side of stringer shows good wetting

Carefully marking out the locations of High Density inserts

Checked and Double-Checked.
Then went to lunch before checking again.

Then I thought about it some more before making the cuts

Using the cut-outs, I simply traced the shape onto the HD foam and then reinserted with some HD Epoxy to fill the gap.
This really didn't take that long.

Second Test Results

Yep, the top surface is too dry... But I'll take the blame for that, it was OK (solid black) before I left it running at full vacuum for too long (I watched it dry out as resin kept being removed).
I should have reduced the vacuum level once the infusion was complete, I think that would have left things in better shape. There's also a section of bridging that can be seen in one of the corners.
I'll need to make sure the corners are VERY well packed in tightly.

However, the bottom portion of the stringer looks really good and that's the part I'm mostly concerned with.

This weekend I'll start work on laying in the fabric, we'll see how far I get.
I might also do one more test to make sure I'm satisfied with the process.

As I mentioned in the previous post, I found it interesting that the resin spread so nice and evenly out toward the left and right edges of this test panel despite those vacuum lines being pinched off.

Fabric removed.
You can see the dryness of the fabric and the bridged area at the lower right corner.
I'm pretty confident I can fix both of these issues but may do another test to validate.

The all important bottom side.
This looks MUCH better than the previous test attempt

Closeup shot of the bottom side of the stringer.
There is 48oz (two layers of 18oz and one layer of 12oz) of glass between that shiny surface and the foam

Testing - Testing

Besides doing the final prep and sanding of the outer half of the starboard float, I spent the weekend building the interior float stringers and doing a bit more work on the raised deck portion of the inside float half. I should be able to wrap those with a layer of glass next weekend and then they'll finally be ready to mount into the float frames for further processing.

The other thing I spent my time on was a couple of tests regarding the Resin Infusion of the interior of the float, as I mentioned before, I'm really concerned about ensuring the bottom face of the stringer is completely saturated with resin. Once the job is done, you can't check to confirm if all went well, so the process itself needs to be 100%.

To that end, I did a couple of tests.

The first one involved a couple of "cheap foam" stringer mock-ups.
One was left solid while the other was drilled out at random (maybe 1.5" (38mm) on center)
The table was coated with some release wax and the fabrics were laid up as per spec.

The first test was to check if the "serial infusion" method might be viable. I like this concept due to the simplicity of plumbing and the ability to stop the infusion at any point if something bad happens. In fact, if something drastic (like pump failure) occurred, you could cut out and clean up the wetted portion of the materials and re-stage without too much effort or loss of materials.

At any rate, the first test did not go very well. I believe the resin flow rate was simply too fast.
I ended up with a few dry areas and overall resin starvation throughout.
However, I did notice that the pre-drilled panel worked much better than the solid panel.

The second test involved use of a real foam mock-up.
This time I pre-drilled on 1" (25mm) centers and changed up the infusion plumbing.
As usual, I looked to Henny for some guidance on the process...
And of course it worked much better!
(No clue what I'd do without that guy, so shout-out to Henny and others who have paved the way!)

The general idea is to run the green-flow resin infusion media over the top of the entire part as usual and then run resin supply lines along each side of the stringer base. The Green-Flow media is then removed from the top side of the stringers. Vacuum is supplied at the top of the stringer and then along both outer edges of the part. The idea is to introduce resin along the base edge of the stringer have it move under, up and over the stringer as it seeks a path to vacuum. The reason for removing the Green-Flow media along the top edge of the stringer is to drastically slow down the resin flow once it reaches the outside top edge allowing plenty of time for resin to "catch up" by flowing beneath the stringer and then up through the pre-drilled holes.

After I got the bag sealed down, I thought it might be a good idea to clamp off the two vacuum lines running along the outer edge of the part. The idea was to focus all the resin movement from the base of the stringers toward the center of the stringer and then open up those vacuum lines again to pull resin toward the outer edges and complete the job. Strangely enough, the entire part infused as though those lines were not clamped off. Perhaps I didn’t kink them enough to shut off the vacuum completely? But still, I didn’t expect it would behave that way.

The infusion itself seemed to work well as planned. I did notice wet spots of resin coming up through the pre-drilled holes from the bottom of the stringer before the entire top surface was finally infused. It took 15 minutes to complete. Once it was done, I think I should have reduce the vacuum level somewhat as I now believe I removed too much resin from the part, it appears to be dry on top. But since it’s still curing on the table I won’t know for sure for a couple of days.

Next time I do this, I will replace the little vacuum puck on top of the stringer with a narrower full-length piece. I think just  that’ll do a better job of distributing the vacuum supply.

Lots of pics:

Gluing together the stringers.
Clamping down with some lumber

All stringers cut for the Starboard Float.
High Density Bulkhead reinforcement pieces are prepped for both floats.

The ends of the longer pieces were cut at 45-degrees.
I went back later and re-cut them to the required 30-degrees.

First Infusion test area being waxed up before laying down the fabrics.

Cutting some fabrics 

One piece is left solid while the other one is pre-drilled

Continuing to build the stack. I'll be using two layers of 9oz Carbon Uni instead of 12oz glass

More fabrics

Peel-Ply

In this picture you can see the blue perforated film sticking out near the top edge of the picture and then the Green-Flow media. This is the "Serial Infusion" test case wherein resin will be supplied along the bottom edge of the part and allowed to flow towards the top of the picture.

VacMobile 20/2 (Awesome machine!)

Interesting how the carbon shows through as a solid black mass when fully wet-out.
You can see how far back the from the resin front it takes for the carbon to be saturated.
(The resin flow was too fast)

I'm pretty sure I did the same thing with this part...
Leaving the vacuum at FULL through the Resin Gel time allowed too much resin to be removed from the part causing a resin starvation situation which can be seen below.

Despite the resin starvation, it's clear to see the perforated part infused much better than the solid part

The all important bottom edge of the stringer.
Fully infused, but starved

Another shot of resin starvation along the bottom edge of the stringer

Back to working on the raised section of the float.
In this picture I have created a High Density radius at the bottom edge of the 45-degree angle.

Once cured, I will follow up with a sanding block to take the edge off the top of that 45-degree angle.
Doing so will allow the fabric to make a smoother transition in this area.

Heating up the next foam test panel in the oven to speed the epoxy glue curing time

Prepping for the second test

Pre-Drilled on 1" (25mm) centers.
This is much more than the previous test

Same layup schedule as before except I added a 1oz veil cloth as a final layer.
The veil cloth adds no strength, but should make the final surface a bit smoother.
This will relate to less fairing in the end.

You can see the blue composite staples used to secure the carbon layers to the foam stringer

Doing a better job of laying in the perforated film.
A lot of this is "on the job" training

Disposable Vacuum supply "puck" made from foam scraps.
Next time I will use a longer, narrower piece to go along the entire top edge of the stringer.

Bottom side vacuum grid cut out with a Dremel tool.
Nothing too fancy

Center feed (Stringer perimeter feed) line for resin supply

Vacuum applied.
After this photo I kinked the two outer edge vacuum lines to encourage resin to flow only towards the center of the stringer.s

I didn't take any more pictures during the infusion because I was using my GoPro to capture the video. Unfortunately, I can't process videos at the moment.

But I'll take a picture of the flow lines and post that with the next update.