skidesmond wrote:The little bit of delam you're experienced could be from a number of things. An epoxy with a longer pot life is probably a good idea. I imagine by the time the layup is done and the press is assembled, tighten and pressurized a fair bit of time has passed. The epoxy could start to kick-in by then.
A cat track could also help to even out the pressure across the ski.
Great job! Looking forward to seeing the next pair!
Thanks desmond,
I will know better once I press a pair without the paper. At this point I feel pretty confident that the rice-paper is the issue. If epoxy pot-life were the issue I think I would expect to delams in each layer, and more of them towards the base of the ski (since the lower layers had epoxy mixed earliest).
My local West Systems guy assured me that once a pot was spread out thinly it had plenty of time. All my epoxy was mixed in small batches for each layer of the layup and used immediately - I had a dedicated epoxy helper who never stopped mixing.
I'll let you know when I can try skipping the paper
sammer wrote:How long from the time you pressed them till you cut the flash?
Any warm room post cure in that time?
My bet on your tip delams would be resolved with some post cure heat.
West slow hardener does need a good long time to fully cure.
sam
Sam,
Each ski stayed in the press for 24 hours, then rested out of the press for 24 hours, prior to cutting the flash. I use 105/205 (fast hardener; 70min working time, 8 hours to solid)
The delam I'm seeing is all along the sidecut, the tip and tail have no signs of delam. This further reinforces my belief that the rice-paper is the culprit - since the rice-paper covers all of the wood core, but stops at the tip & tail spacers.
I do agree that my cutting the flash could still be exacerbating the issue though. I use a course fiberglass bit in a jig-saw similar to this: , cutting from the bottom of the ski to follow the edge. This means that if the blade were to catch on anything - it would be pushing outwards on the top-sheet and could create these mini-delams along the edges. I would love to cut the flash from the top of the ski - I will have to think about how I can do this with a jig-saw and follow the edge.
sammer wrote:How long from the time you pressed them till you cut the flash?
Any warm room post cure in that time?
My bet on your tip delams would be resolved with some post cure heat.
West slow hardener does need a good long time to fully cure.
sam
Sam,
Each ski stayed in the press for 24 hours, then rested out of the press for 24 hours, prior to cutting the flash. I use 105/205 (fast hardener; 70min working time, 8 hours to solid)
The delam I'm seeing is all along the sidecut, the tip and tail have no signs of delam. This further reinforces my belief that the rice-paper is the culprit - since the rice-paper covers all of the wood core, but stops at the tip & tail spacers.
I do agree that my cutting the flash could still be exacerbating the issue though. I use a course fiberglass bit in a jig-saw similar to this: , cutting from the bottom of the ski to follow the edge. This means that if the blade were to catch on anything - it would be pushing outwards on the top-sheet and could create these mini-delams along the edges. I would love to cut the flash from the top of the ski - I will have to think about how I can do this with a jig-saw and follow the edge.
After 48hrs at room temp your epoxy is probably not cured.
While it is hard it will still be curing for a while yet.
I still don't think the paper is your issue, but the lack of post cure.
Put them in the warmest room of your house for a week before cutting the flash on your next pair.
Barring that get some sort of heating system, make a hot box or something.
If you look at wests own documentation they show hardness and compression yield are measured after 2weeks.
serious applause for the use of paper clips! haha I never would have thought of that.
honestly, with curing I just go overboard. I was using CPM/CPL and get it as hot as I could for my post cure (usually around 120°F with a combination of wal-mart heat blankets and small space heaters) and just let it go for like 3.5 hours. Their recommendation is 100°F-180°F for 2 hours on post cure. Didn't see any delamination in any of my skis and I was beating the piss out of them.
, cutting from the bottom of the ski to follow the edge. This means that if the blade were to catch on anything - it would be pushing outwards on the top-sheet and could create these mini-delams along the edges. I would love to cut the flash from the top of the ski - I will have to think about how I can do this with a jig-saw and follow the edge.