+xThanks for the reply Matt!
I'm glad you don't think the pattern material is a problem, I couldn't see how it would be either but it's just one of those things.
Laminating and bagging technique are potential issues, though as you know I do have good experience working with pre-pregs so I'm quite confident. I think I do need to come back and complete another course though, I hate feeling like my knowledge is past it's use-by (although to be fair, I've been itching for an excuse!). I did however laminate most of these moulds sort of as I would a component. I'll post some pictures this evening to help this make sense, but I did use some fairly large pieces on the larger moulds, as these are fairly simply shapes. The complex areas I did do lots of small pieces, ensuring any tight corners had material butted into the corners first before lapping with several other pieces. Similar story for the flanges. I made extremely sure that there was no bridging in these areas, and there were no creases anywhere either. I can't really see how doing the larger sections with smaller pieces of material would help as there really wouldn't need to be much relative movement there, but take a look at my pictures and feel free to tell me otherwise!
Again, bagging I'm confident with. The first 4 or 5 moulds I made, I paid really close attention. I did rush the last couple that I made, but surprisingly these were actually the moulds with the best results! There were some small voids in the tighter features as I would have expected with a small amount of bridging, but really nothing that worries me at all. These two moulds only had a couple of small voids exposing the scrim on the main surface, although there are still quite a lot of very tiny pinholes as well. I'm not too worried about those tiny pinholes really, I think by the time I've applied my semi-perm system there won't be too much issue. I'm more concerned about the voids that expose the scrim, as not only will these effect the surface finish but I'm also worried about release issues from mechanical locks etc etc.
Cure cycle and out-life should be non-issues. I've really stuck to the guidelines with the cure cycle, and the material was only a week or so old when it was cured so shouldn't be a problem. Do you have any thoughts regarding doing a warm debulk? I can't really say I've noticed any difference, but I have been debulking at 30 degrees for a couple of hours just because it is fairly cold here at the moment (around 15-20C anyway... That's freezing temp in Aus!), so it just helps prevent the surface ply from lifting. Though if you think that may cause issues with the scrim 'wicking' and messing with the surface finish then that could be something I look at?
I am following the bicycle frame build with great interest! It is really what convinced me to purchase some of the XT135 and give it a go. I assume all of the moulds were produced from epoxy tooling board patterns?
I can't really see how doing the larger sections with smaller pieces of material would help as there really wouldn't need to be much relative movement there, but take a look at my pictures and feel free to tell me otherwise!
I agree, the small sections are only necessary for the tighter, more intricate sections, not the flatter areas.
Though if you think that may cause issues with the scrim 'wicking' and messing with the surface finish then that could be something I look at?
Yes, this is worth looking at (especially because it seems we're running out of other explanations). The warmer it is, the more the wicking will happen. At 30 degrees I think you'll see this happen a lot. You should be fine getting the material to take to the mould at 20'C (normal temp for us).
Also, it's worth considering whether the XT135 could have been exposed to high temperatures on its trip over to you? - As you know we're subject to ambient temperatures on the flight over and I just wonder whether the material spent a few days in a very hot customs container or storage area on its way to you. If it was hot enough, this might be all it would take to take away the 'dry' breath-ability of that scrim layer.
I am following the bicycle frame build with great interest! It is really what convinced me to purchase some of the XT135 and give it a go.
Yes, it's an exciting project, in fact, the very first bike frame is in the oven at the moment on a debulk before the main cure today so we should see the first frame by the end of the day!
I assume all of the moulds were produced from epoxy tooling board patterns?
Yes, all machined from EB700 epoxy tooling board.
Matt StathamEasy Composites / Carbon Mods - Technical Sales