NickH
Well-Known Member
People keep asking me about things in other threads, and the information gets fragmented, so I figured I'd start a thread here for questions, and then progress if I make any forward.
From that comment, you can guess this has not been a good day.
I had a little bit of a setback. A couple of days ago I laid up a sheet of 1/4" foam with a BID each side for the HS spar and ribs. The first side went fine, the second didn't. Many areas of the layup were light in colour, obviously not adhering well to the microed foam. I've been using a black pigment in the slurry to help show up imperfections and bubbles when doing the layup, so these bad areas stuck out very well and covered about a third of the sheet.
A little investigation and I could pull the cured glass off the foam. The lighter areas pulled off easily, the darker areas with some effort. The separation happened between glass and slurry with the foam intact underneath (different from reports of how last-a-foam delaminates). My problem is a weakness in the micro, almost certainly a result of a combination of not using enough slurry in the lighter areas and maybe having too dry of a slurry in those which are darker. I have, of course, read comments about divinycell foam taking a lot more slurry, and ending up heavier, and this probably influenced me too much.
The problem now comes when I consider the other parts I've made. My seat looks fine, being the first part I made, and as a result probably slightly wet of a layup anyway. The glass on my fuselage has none of the lighter areas, but I'm still questioning how well the glass is attached, and there are a few scrap pieces that I can start to pull away at the edges. Now that I have doubts, I'm not sure I can trust my previous workmanship.
I've been a little afraid to cast too critical a light on my work, part of the reason I haven't posted any pictures. I've never been too happy about the way some of the foam lines up, where the 1/2" foam is sanded to match the 1/4" foam, and in hindsight I rushed way too much to make some progress. Any doubts about the safety of my workmanship means I need to do over. I previously commented that I wished I'd tried the Fold-A-Plane technique, so now this is my opportunity.
I can treat this as a learning experience. While I've worked with composites before in boat building and other projects, and can lay some decent glass, the foam is new to me, and I've certainly learned a lot about making it work. Since I now have more time on my hands I can start to appreciate this as the project it needs to be, and commit to doing it well. My airplane will be a work of art.
So I'll begin again. Fold-A-Plane should give me better lines, and I'll use a jig to ensure that my bevels are even and straight. More importantly, I'll be more critical and honest with myself about what I'm doing. Better to spend a little on some more foam than have a project that I'm not completely happy with and confident in.
From that comment, you can guess this has not been a good day.
I had a little bit of a setback. A couple of days ago I laid up a sheet of 1/4" foam with a BID each side for the HS spar and ribs. The first side went fine, the second didn't. Many areas of the layup were light in colour, obviously not adhering well to the microed foam. I've been using a black pigment in the slurry to help show up imperfections and bubbles when doing the layup, so these bad areas stuck out very well and covered about a third of the sheet.
A little investigation and I could pull the cured glass off the foam. The lighter areas pulled off easily, the darker areas with some effort. The separation happened between glass and slurry with the foam intact underneath (different from reports of how last-a-foam delaminates). My problem is a weakness in the micro, almost certainly a result of a combination of not using enough slurry in the lighter areas and maybe having too dry of a slurry in those which are darker. I have, of course, read comments about divinycell foam taking a lot more slurry, and ending up heavier, and this probably influenced me too much.
The problem now comes when I consider the other parts I've made. My seat looks fine, being the first part I made, and as a result probably slightly wet of a layup anyway. The glass on my fuselage has none of the lighter areas, but I'm still questioning how well the glass is attached, and there are a few scrap pieces that I can start to pull away at the edges. Now that I have doubts, I'm not sure I can trust my previous workmanship.
I've been a little afraid to cast too critical a light on my work, part of the reason I haven't posted any pictures. I've never been too happy about the way some of the foam lines up, where the 1/2" foam is sanded to match the 1/4" foam, and in hindsight I rushed way too much to make some progress. Any doubts about the safety of my workmanship means I need to do over. I previously commented that I wished I'd tried the Fold-A-Plane technique, so now this is my opportunity.
I can treat this as a learning experience. While I've worked with composites before in boat building and other projects, and can lay some decent glass, the foam is new to me, and I've certainly learned a lot about making it work. Since I now have more time on my hands I can start to appreciate this as the project it needs to be, and commit to doing it well. My airplane will be a work of art.
So I'll begin again. Fold-A-Plane should give me better lines, and I'll use a jig to ensure that my bevels are even and straight. More importantly, I'll be more critical and honest with myself about what I'm doing. Better to spend a little on some more foam than have a project that I'm not completely happy with and confident in.
