Atomic77 wrote:3000hp
Awesome!!! I'm a total gear head at heart, so I love hp and machines in general.
Xanthoman wrote:Steve, are you doing room-temp cures? I can't imagine (well I can...but...) you built an oven for the panels. I'm excited for the next phase. Hope the last panels keep going well!
I briefly considered building an oven until I found a concrete curing blanket sitting in a corner at work. I think it's 1000watts and heats up to around 140°F, which is perfect. The epoxy can be cured at 165°F for 4 hours for an accelerated cure, or 24 hours at room temp, so the blanket really does save a lot of time. It's 20' long, so my mold (glass) lays on top of it and after I infuse, I just throw the other half over the top. It has really worked great through the cold winter days/nights, otherwise it would take a few days to cure at those temperatures. I have a rotary timer that shuts it off when I'm sleeping. Very happy with this setup, but I'm glad I didn't have to buy the blanket - I think it's about $1,000.
mkeogh wrote:With my projects I usually find this to be the case, maybe I'm a bit too optimistic. I'm kicking around the idea of fab'ing up panels like you.
Just wondering, is there any specific step that is most time consuming... like reconfiguring molds, preparing molds for release, etc.? Any tips for how to go faster... like standardizing panel sizes, a slightly different layup and release process, etc.? Also, what makes it more expensive than you anticipated? Is it material costs or equipment investment, etc.?
The answers to your questions can be pretty complicated, M, so I'll try to answer them all as simply as I can. The bulk of the
extra cost for the panels has been in the resin. I calculated that the project would take 4-5 gallons and purchased 6 gallons to start (1 gallon was specifically for prototyping and excess). I ended up ordering another 5 gallons later, which should be more than enough to get me through the entire project. Calculating the resin that will be consumed by the part (the panel) is relatively easy - calculating the waste that is consumed by the peel ply, flow media, tubing, etc... not so easy, especially for a rookie like me. And at ~$100 per gallon, the cost adds up fast. There's a good chance that I'll run short on other things as I get closer to the finish line, so I'm anticipating another order before I finish. My "big" initial order was around $2,000, not including the resin, so I'm over $3,000 into the panels alone. That number will probably make some people faint, but it's not about the money for me. I wanted the challenge and I wanted to do something nobody else has done before.
Making things quicker and cheaper can be summed up in one simple answer: make fewer, larger panels, rather than more, smaller panels. So how, you ask? Well, the limiting factor is the fabric width. Most suppliers sell CF in 50" wide rolls, but you can find it 60" wide. It takes about 9" of extra fabric to wrap up and over the frame (both sides), so if you use 60" fabric, and your walls are 51" tall, and you have a long enough piece of glass, and long enough aluminum mold frame material, you could make your side walls in one piece. That wasn't an option for me because my camper has to sleep 5 and is 60" tall. Having standard panel sizes would speed things up a little, e.g. 3, 3' panels for a 9' long trailer, but re configuring the mold really isn't that time consuming in the grand scheme of things. You could, however, make the walls first and then cut out the door openings after the fact and use manufactured doors to speed things up a little. I'm making my own doors, which means I have to make 8 extra panels (4 headers and 4 footers) plus 2 cabin doors, 2 v-nose doors and the rear hatch.
Not only does each panel take about 1 day to make, it also uses consumables, which increases cost. Consider the MTI tubing and gum tape, which are both used around the perimeter of the mold. If you make 1, 4'x4' panel, you have 16' of perimeter (and you can make the panel in a day), but if you make 4, 2'x2' panels, you'll double the perimeter consumables for the same square footage and quadruple the time needed to make them. You'll also use more of everything else (bagging film, flow media, CF fabric, resin...). So, making more, larger panels vs. fewer, smaller panels is the key to saving time and cost.
Another way to save some time and money would be to skip the clear coat and hope that the "UV stable" epoxy won't eventually turn chalky. I wouldn't recommend that. The other option would be to spray the entire trailer after it's built.
Random thoughts...
60" cloth in my case wold have only created more waste in my case, so I went with 50" cloth. I also splurged for a process called Web-Lock, which I believe is a proprietary process from Composite Envision. If you've ever worked with CF, or even FG, you know how unstable the cloth is if you stretch or pull it, or if it snags. With Web-Lock, you can stretch the hell out of it and it goes right back to it's original pattern. I'm so glad that I spent the extra $$ on it.
Another option that would probably work and would be considerably cheaper and faster would be to just get a sheet of glass to make CF plates (or buy them) and just epoxy your framework onto the plates.
One thing that I do to speed up the process is to pre-cut pieces for the next panel(s) while the current panel is curing. This doesn't work as well during the week because by the time I get to the point that the part is curing, I'm ready to wind down for the night.
If I haven't said so already, I'm using AdTech Marine 820 epoxy.
And the last random thought for the night... The 9 inches of extra fabric to wrap around the frame... 1" up the outside, 1/2" across the top, 1" down the inside, and 2" minimum back towards the middle of the panel = 4.5"... double that for the other side. A picture would explain it a lot better, but since this is just a random thought, I guess you'll have to imagine it for yourself.
Please feel free to ask more questions.
Steve
