twizzstyle wrote:
I'm really curious about the description of "brittle". What is it about the board that seems brittle? If you flex it, does it crack? It's a composite, so it's not like it will shatter if dropped.
I was also curious about that.
If you leave a thin sample on a sheet of plastic to cure when you flex it it will snap.
Even the most flexible version of the epoxy I'm using does that although it probably flexes a little more before it snaps.
Once it's soaked into the glass it's a different animal.
The first time you flex your new board it will make all kinds of cracking noises, that's normal. A little unnerving the first time but normal.
sam
You don't even have a legit signature, nothing to reveal who you are and what you do...
twizzstyle wrote:
Also on your tail (the bottom of the full length photo) I see two horizontal lines on the tip spacer that look like maybe they had concentrated pressure there. I see you're using a cattrack, are those marks from some of the cattrack bars? Do you have any kind of material between the cattrack and the laminate (i.e. sheet metal)?
Haha, yeah. Those were from 2x4s when I clamped it up inside the house. The shop was getting cold quick so I was in a bit of panic mode.
I picked up a scale so that problem is fixed.
Perhaps my version of brittle isn't what it should be. Basically I was able to take flakes of left over epoxy and break them like potato chips. The board also made quite a bit of noise upon flexing. It has quieted down the more it work it. If that's normal then I'm not so worried.
Totally normal. Left over bits of epoxy should be as hard as glass, and break almost the same as glass. Be careful too - I've cut myself pretty good on epoxy that broke leaving razor sharp edges! (for what it's worth I use entropy resin now, and it cures VERY hard and brittle)
So basically it sounds like you took it out of the press WAY before it was even close to curing. That was your problem, I think your epoxy ratios and mixing were just fine. If clamping left imprints after you pulled it, it wasn't even close! Next time be patient and just leave it in, if its cold it will just a long long time to cure but you should leave it in there.
I've been mixing my qcm/forrest epoxy by volume since 2008, probably 60 boards deep. I would do a couple things:
1. make a mockup and test your epoxy on known good materials. make sure everything is clean and free of fingerprints, dirts/oils, and mold release!
2. dont ever touch mold release then touch snowboard parts! keep way too many gloves around.
3. check the thicknesses of your core and sidewalls vs. the thickness of your tips, where they meet, if one is more than a few thousandths thicker than the other, it will reduce the clamping force of your press on the thinner material, or eliminate pressure on that material completely.
Its a shame it didn't come out awesome, it looks like you had near perfect alignment. My first 3-4 attempts were far worse!!!
All my skis make little cracking noises the first few flexes, totally normal. I work most of that stuff out before handing them off to someone so they dong freak out. Very nerve wracking the first time though.
I mix QCM by wt. to the gram with great results. The epoxy alone without glass in it is very brittle. I agree with twizz, even if it gets cold just leave it in the press under pressure until you can get the heat back on.
I toss extra partially filled extra epoxy cups outside to exotherm in the rain and cold...when I pick them up later, the stuff is cured and the plastic is deformed.
twizzstyle wrote:
The first time you flex your new board it will make all kinds of cracking noises, that's normal. A little unnerving the first time but normal.
sam
that is good to hear! mine have been doing that and it's been making me nervous.
also, if you ever switch over to MAS epoxy, which is what I've been using for room temp cures, the mass ratio is quoted below from an email between MAS and me. I assumed the densities were similar enough to just go 2:1 by weight, and I was wrong. A product dev. person at MAS told me the ratio is pretty forgiving though
The following are the mix ratios by weight for the 2:1 Epoxy systems: When using the MAS 2:1 Slow Hardener with either the MAS Low Viscosity (LV) Resin or MAS Flag Resin: 100 parts resin to 45 parts hardener (100:45)When using the MAS 2:1 Medium Hardener with either the MAS Low Viscosity (LV) Resin or MAS Flag Resin: 100 parts resin to 45 parts hardener (100:45)When using the MAS 2:1 Fast Hardener with either the MAS Low Viscosity (LV) Resin or MAS Flag Resin: 100 parts resin to 46 parts hardener (100:46)
Took it for a ride on Saturday. Was really floppy but I expected that. I used a router bridge and found the core being sucked into the bit. I suppose I would need to figure some clamping system to keep the middle down. Going to try the planer crib on the next one since I made one of those as well.
It was a good time even though the board sucked. And so did I. Also got a bunch of people asking me about it which was fun.
First run of the season on the first board of the season. It felt very sketchy. Had to lean way back on it to keep the nose up.
have you thought about using a vacuum table to hold the core down for your router bridge? there are a few people on here who've posted pictures of their vacuum table, and I tried to copy this one: viewtopic.php?t=4445&highlight=vacuum+bases. I use a shopvac for vacuum and it works really well. check out the link below for a how-to.
mine needs some work to get evenly profiled cores on the first try (I need to do a bit of adjusting for the last few passes because my router cradle isn't quite perfect), but, for me it's faster to profile w/ a router than a planer. the last few passes on the planer were always pretty stressful worrying about tear-out. with the router bridge you can hear it coming and do something about it most of the time...[/url]
Got number 2 just about cleaned up. Going in for the grind on Thursday. This one turned out much better but still having a couple issues. The delamming around the top sheet when I cut off the flash for one. I did sand and flame everything but I'm willing to accept user error. You can also see that right out of the press it's all white around the fill material. Any ideas? I do cut a rabbet out but only on the core. Pretty stoked to get this one out this weekend as we just got a brand new foot of powder.
I used the planer sled method to profile this one, both top and bottom. This one has a pre-cut camber on it which uses a dedicated sled. Upon final profiling I ended up loosing part of the sidewall. I think this is from the gaps in the adjustable sled so it's time to switch to different design. Took about 4 hours to repair. Bleh. Alignment inserts poked through the base just a little bit. I caught the solution to this error half way through layup and tried to fix it by cutting a hole in the glass. Didn't work all that well but better than the first board. I'll need to cut a slightly larger, deeper hole for those next time.
Not sure if it shows up well enough in the pic but half the edge on the tip and tail didn't press very well. It's the same place on both ends. I think I just need to do a better job straightening the edges prior to bending and not rely on the press to do it for me.
In that second pic it looks quite dry around your edges, could be part of your delam issue.
Also if your not using heat you should let your board rest for more than a few days at room temp to fully cure before you cut it out.
Try a simple bonding test.
Glue some glass and top sheet to a small piece of core. make up 3 or 4 of them.
The next day peel the topsheet off one, wait a couple days and see how much harder it is to peel the next one.
Do this over a few days and you should get an idea how long it really takes for your room temp epoxy to cure.
Overall not too shabby for a second attempt.
Now go ride it until it falls apart or you make a nicer one.
sam
You don't even have a legit signature, nothing to reveal who you are and what you do...
Looking better! Overall the board looks a little dry to me. More resin, and maybe slightly less pressure may help to not squeeze out quite so much of the resin. What pressure are you pressing at?
On the edges where it's coming apart, is it really delam (is the fiberglass breaking loose cleanly from the plastic tip spacer?), or is the fiberglass ripping apart? If the latter, that would indicate a dry layup = not enough resin in the composite. You can try to put a knife or something between the layers to see if its really delamed, which would just mean there is a bonding issue that could be from unclean tip spacer, or un-flamed tip spacer. Comments all apply to the topsheet as well, if its the topsheet separating from the fiberglass. My hunch, based on the photos, is it might be the fiberglass just needs to soak up a little more resin.
You're applying your lessons-learned, which is what this is all about! Each board will get better and better as you fine tune your own processes. Go ride that sucker!
Don't spare the epoxy when wetting the materials out, at least until you get the process fine tuned. Pressure in the tips and tail sections are known problem areas for builders. If the epoxy is thick try warming it up under a heat lamp or some other method. You'll find it saturates the FG and is much easier to wet out the materials.
Spend a little time patching up the board and ride!
Can you find these in the US: http://www.cosyfloor.com/Products/ECOMA ... ments.aspx, 20 GBP for a 6ft length. They will heat up to around 20- 30oC, just plug them into 240v. Per: @ 2.58, create a layup space and put the heater under the fibre, then use them in the press.
If they are difficult to find, use an electric blanket or similar to heat the layup table. I suspect you could cover the blanket with backing (silicone) paper - you just have to be careful not to tear it. Thin cardboard between the two layers perhaps. Carbon Heaters will survive the press, electric blanket won't. This should resolve any issues you are having with the impregnation of the fibre.
I would be a little bit careful about where you are storing parts before you are using them, moisture and cold are working against you. Leave them in the house until you need to bring them into the basement. Ideally, storing the mould and cat-track in the house before use would be a good idea. The more you can preserve the heat generated by the epoxy the better ... well better than dealing with a mould at single digits temp. There was a builder here who used to throw an electric blanket over his press ... not entirely sure about that, I would give consideration to putting the electric blanket between the mould and the cat-track (under inflate i.e. 1 psi) and throwing an ordinary blanket over the press a few hours before use.
Once the epoxy has reached C-stage (gone hard), bring it into the house and allow to cure.
I'm willing to bet it's dry under the top sheet. when I put it on I just smeared it into the top layer of glass instead of adding more epoxy I don't seem to have this problem with the other layers. Pressing at 55psi. Testing on Saturday. Pretty stoked about it.
