A learning day

Today was filled with a lot of learning. I’ll start with the simple stuff and move into the more complicated.

I’m not sure how I feel about Gorilla Glue in certain applications. Right now we’re using it to piece together the chainplates and the bow-web. It seems to work pretty well – in a distructive test it was stronger than the foam – and it sands easily enough. What bothers me about it is the nature of the glue – it foams and expands as it cures. This can be a good thing in some instances (like where the G10 tubing meets the foam). Originally I was hoping to use this to glue the foam together after planking the hull half – but having to do THAT much sanding because of the expansion seems a little silly. I’m starting to think a mixture of resin and microballoons will work better for this. It can be smoothed out and it won’t expand as it cures.

The chain plate is assembled and hanging up to finish drying. Just need to sand down the HD foam to match and laminate it once the carbon fiber arrives.

Also started working on the bow-web. Not a very good picture of it here, as I have some HD foam clamped and drying.

Time spent: about .75 hours each

We also did the first resin infusion attempt today. Started out with just a bag against the MDF as a table :

Unfortunately, this didn’t seem to work too well – we were having some real sealing issues. Not sure if it ended up being the MDF or something else, but in the end we decided to just Go For Broke. I figure if you’re going to succeed – do it big, and if you’re going to fail, do it big.. 🙂 Consequently, we decided on trying to infuse both sides at the same time.

Built all the layers up after drilling holes in the foam and created a bag around the entire piece. Ran a simple resin channel on one side and a vacuum channel on the other. Here is a picture with the infusion almost complete. You’ll notice a dry-spot in the laminate. At some point during the infusion, a careless mistake caused an air leak which we never could isolate completely and resolve. Vacuum was still good, pulling around 26″, but I was not happy with the dry spot.

After the resin eventually hit the gel stage, I remembered that as long as the resin wasn’t fully cured it will still chemically bond. We decided to un-bag the laminate partially and squeegy some resin in the dry spot (thru the peel-ply) and allow it to gel. I don’t have a picture of this, but the result seems to be fine.

Pulling off the disposables and looking at the bulkhead for the first time:

Completed bulkhead shows a few things to learn from as well. Carbon from the tracing paper shows perfectly fine thru the completed laminate (2 layers thick in half of it), but magic-markers bleed badly and I won’t use them again under the fiberglass.

A different angle:

If you look hard enough, you might notice another little “goof” in the corner of the bulkhead. It should be two layers here, but part of the corner folded back in the bag and wasn’t caught. Lesson learned here is to make sure the layers are proper in the bag before beginning. It will be corrected before actually getting installed in the float.

Last big lesson learned today was to be more careful about the sizing and cutting of materials that go inside the bag. Next time I will be more cautious about the sizing of the peel-ply and the RDM. I had RDM in a place where I shouldn’t so excess resin collected there, and the peel-ply could have been a little smaller as well.

All-in-all, not too bad for flying by the seat of our pants using basic information off the net. Hopefully Steve’s CD will be here sometime during the week so I can read and educate myself a little more on this procedure. Even with things going Not Very Well as far as the infusion goes, the part that resulted looks SO much better than a hand lay-up. I also left one corner of it a little larger for a destructive test to verify everything is glued properly. It will get cut off and tested when the pattern is cut out with the jig-saw.

Time Spent: 6 hours (a lot of which was thinking, making two other test-bags and hunting for leaks)