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Edge Gaps after Pressing

Posted: Sun Dec 02, 2018 5:32 pm
by falls
Hi Everyone
Just pressed up a new pair of skis and annoyed to find two sections of the edge eased away from the base material by 0.5mm-1mm over about a 10cm length in each case. Hopefully shouldn't be a deal breaker in terms of function but still a disappointment after never having this happen in the previous 20+ pairs. I clamped and superglued every tang in the tips and every third along the running length as usual. Think I waited usual 20 min with it clamped to the template for glue to set. Checked edge fit after pulling off the template and no gaps at that time.
Layup was slow and my theory is the epoxy on the base material had started to thicken and when squeezed out under pressure had more force outwards squeezing between the base and edge than the thinner watery epoxy if I laid up faster. Can't really think of any other possibilities - other than bad superglue or I dodn't leave it to set as long as I thought, or maybe I was too miserly with the amount of glue?
Anyway if anyone has any thoughts or fixes for this that I have done wrong would be happy to hear.
I have tried to file down the bulged areas a bit to smooth the sidecut out. Might even give some more edge grip a la magnetraction?


Posted: Mon Dec 03, 2018 2:03 am
by mammuth
Nice design!

What comes into my mind:

edges/base not clean
pressurized too fast
like you said superglue bad

Superglue can need long time to completely dry if the parameters are not good. Did you begin your layup after these 20 minutes?

If your epoxy did start to cure before you applied pressure it could be a part of the problem, for sure.

Posted: Mon Dec 03, 2018 11:19 am
by MontuckyMadman
Ive seen way worse on many large production models.
Line, rossi etc.
I bet it will grind out to be barely noticable.
Ive never had this issue myself but the superglue did not bond for some reason.

Posted: Tue Dec 04, 2018 2:24 am
by falls
thanks for the replies
The base came from Miller studio in Seattle likely off a roll they use for their commercial ski company jobs. It looked clean and I am pretty careful with the surface preparation and cleanliness.
The edged bases were spray glue adhered to the cassette after the 20 minute superglue dry and sat there for probably another 1.5 hours before layup.
Maybe bad superglue? Maybe too conservative with the amount of glue in each dab? Probably did pressurise pretty rapidly after a slow layup and wanting to get it finished - with gelling epoxy I think it might have just overcome the hold of the superglue as it started to get squeezed out.
It's always something.

Posted: Tue Dec 04, 2018 4:17 am
by vinman
The only time I have seen this happen is if I did not put enough glue on the teeth. I generally put a small dab on every 3rd tooth.

CA glue can go bad with time, shelf life is generally about a year.

Posted: Tue Dec 04, 2018 1:26 pm
by falls
Thanks Vin
I think that it maybe it.
The bottle has been in the shed for a year or more I would say. I also use a fine tip on the end to give better control and it felt like not as much glue as usual was flowing through this tip on the day. The bottle felt stiff to compress so low glue is possible. Also when positioning the ski on the cassette and lifting it up again to reposition a small section at the end of the ski came up and I reglued it down. It isn't near where the other problem occurred but I think probably weak glue bond is likely as I have never had any lifting of edges of the base in the past.
2 solutions:
1. Buy new superglue for each pair
2. Build skis more than 2-4 times a year!

Posted: Tue Dec 04, 2018 5:17 pm
by MontuckyMadman
If glue gets too cold like freezing it goes bad as well.
I don't know if that's an issue where you are down under.
I forget who it was on here maybe twizz used very little glue one time and got magnatraction sorta.

Posted: Wed Dec 05, 2018 12:34 am
by chrismp
3M has guidelines on storing superglue. For longer periods they recommend storage in the fridge (not freezer) to extend the shelf life. However, if you start using the glue more frequently they recommend to keep it out of the fridge in order to avoid condensation inside the bottle (moisture makes the glue go bad).

Posted: Wed Dec 05, 2018 3:24 am
by falls
It gets cold and hot where I am. Probably 28F winter nights and 113F in the summer. Think it was probably not enough glue at each of the glue spots. Stupid mistake.

Posted: Thu Dec 06, 2018 6:23 pm
by vinman
having old glue is defiantly an issue as is glue that gets frozen. The stiffness you felt was the glue polymerizing...old

Posted: Thu Dec 06, 2018 7:09 pm
by falls
thanks vin
I normally buy a new bottle before each pair, but didn't this time. I think I will start labelling all consumables when they were bought/opened so I can keep better track of the need to replace stuff. I remember headmonkey's site has a lot of stuff about keeping track of your inventory so you know how old it is etc + testing each batch or resin before you use it.
This is the second pair I have had where little things just kept going wrong and you got the impression they didn't want to be made. I had everything ready and laid out to layup and poured the resin in the cups ready for mixing etc then poured the hardener into the dispensing bottle and it was all lumpy! Rang the distributor and he said if I strained the lumps out of it it would cure fine and it was probably due to exposure to air. I was pretty skeptical but had everything ready including edged bases on the cassette and getting new resin of this type in Australia needs shipping from Europe by boat. So went ahead and they were right - it cured as solid as ever. Everyhting bonded and flexed OK so far. Skis are in Bali now (!) on their way to Japan so will see how they hold up.

Posted: Sat Dec 08, 2018 12:27 pm
by mammuth
Strange, i did lookup on my superglue, there is no expiration/production date at all. And its minimum two years old and still working.... I hope so, pressing right now.
Loctite Professional in 10 or 20gr tube.

Posted: Mon Dec 10, 2018 4:42 am
by gav wa
What type of superglue are you using?
I use Loctite 406 and never have any issues.
It is a bit pricey but lasts forever in the fridge and has crazy strong hold.

Posted: Mon Dec 10, 2018 7:21 am
by mammuth
Feedback on my old loctite. It was holding strong and the first two boards pressed fine.

Like said its min. 2 years old, storage was in the workshop (10-29 deg C during winter/summer) and the bottle i used up was opened last season!

Posted: Wed Dec 12, 2018 9:49 am
by skimann20
I'm with Montucky, these will grind out fine.

I too just had an issue with my SG not holding (pre-press) but this was in the tips. My thought: Sometimes when I put to much glue initially, then i don't get good bonding. It doesn't set well. perhaps this was your issue, you used too much SG?