Disappointing... but expected

I pulled a vacuum on the mold this morning. As expected, it was not nearly air tight.
In fact, you could hear air being sucked right through the foam core.

There is no sense in proceeding with that plan.

I'm not really sure what I'll do now, but at the moment I'm considering stripping the mold, painting the inside with some resin to seal it and proceeding with a vacuum bagging solution.

I keep reminding myself that this stage of the build is a lot of testing and familiarization. No harm, no foul and nothing much lost except some time and a small investment in materials.

Still doesn't make for a happy day.

Vacuum Bag Enlargement

After thinking about the problem overnight, I realized I might yet have enough materials to enlarge the bag if I lifted it straight up out of the mold and formed a single fold down the middle (lengthwise) instead of trying to cut along one of the sides and dealing with all the pleated material.
So early yesterday, I pulled the bag up out of the mold and formed a smooth fold along entire length of it. Once that was done, I applied a strip of tacky tape near the top edge of the vacuum bag along both sides of the fold. Then I cut a rectangular piece of vacuum bag film and folded it in half (lengthwise). Afterwards, I carefully secured the long edges to the tacky tape on the existing bag and sealed up one of the ends.
From open end, I slit the original bag between the two long strips of tacky tape and then all I had to do was seal up the last remaining edge. That worked out better than I expected and a light vacuum applied via the vacuum cleaner allowed me re-position the bag for a tight fit into all the corners.

Pink bagging material is the additional piece

It's not very pretty, and with the substandard foam materials and subsequent bag patching I don't expect this mold to have very good vacuum integrity.
However, this entire exercise was all about learning the process through trial and error. Obviously, I still have a LOT to learn - but I can already see a huge improvement in my technique -especially with the bag pleating.

I still have some tree removal and gutter repair to do this weekend, so it may a couple weekends before I get a chance to work on finding leaks and doing the injection.

Beam Mold Model Progress

I worked a few hours on getting the Peel-Ply, Perforated Film, Distribution media and lines installed in the model.


The idea is to inject resin along the floor and directly into the rear corners where the fabric thicknesses are greater. I decided to route the Vacuum plumbing into four zones for testing. One entire side has its own vacuum line, while the other side has two "zones". The top of the beam mold is the fourth zone.

Left side Resin feed line is pushed closer to corner

Left side is split into a front and rear vacuum zone

Stakes to support vacuum lines

Stakes to support vacuum lines

The materials are quite slippery and a bit difficult to work with in this situation. I tried using the green "frog" tape to secure the films, but the adhesive is not strong enough so I switched to some regular masking tape. It worked much better. In the end, I believe you should probably have a decent selection of tapes to use depending on what you're trying to accomplish. AirTech sells a few different tapes with different adhesives, they also sell a double-sided adhesive fabric mesh tape. I think that would work very well in some situations.

I cut the vacuum bag with PLENTY of extra material to go into all the corners, but after an hour of carefully sealing and pleating the edges I found that I still didn't have enough material to reach all the corners with enough slack to prevent bridging.

Inadequate size of Vacuum bag

The problem now is that I only have about 1.5 meters of tacky tape left over, which is not enough to cut the bag and patch in some additional film. So, I'll have to put this away for a while until I can figure out some feasible solution. I'm hoping to pick up a roll of tape from some metal roofing company... That should work for what I'm trying to do.