Resin under base tip and tail at the edges

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Jdline
Posts: 26
Joined: Sun Jan 26, 2020 3:19 am

Resin under base tip and tail at the edges

Post by Jdline »

So, I have made about 10 pairs of ski's in the last year and a have.
And the first hade some resin/epoxy in the base but not so much.
But the laste few i made all had a lot of resin under the tip and tail at the edges.
When i did a full wrap edge it was everywhere along the edges.
Now i did a 3/4 wrap and again puddles of epoxy.

I have tried pre bending tip and tail, layup on another table, squeezing as much resin out of the fabric befor layup.

I use a vaccuumpress, i uses to use a solid MDF mold but now i made an adjustible one and put a 6mm thick plate on in.

Any other tips?

Ps, last pair i traid to grind (beltsander) it out a bit more, but i went to far and the edges gave away and base is very thin, I'll try to cut out some base and edges and re gleu new parts....

https://photos.google.com/album/AF1QipO ... Tm9d6CyCNe
https://photos.google.com/album/AF1QipO ... 0F2pt60vHy
https://photos.google.com/album/AF1QipO ... kcB9dCFKhm

https://photos.google.com/album/AF1QipO ... ajRibbqqft
https://photos.google.com/album/AF1QipO ... SVsyRnyXdZ
https://photos.google.com/album/AF1QipO ... K7Hu_ue6x8
TimW
Posts: 48
Joined: Sun Apr 26, 2020 11:56 am

Re: Resin under base tip and tail at the edges

Post by TimW »

Some resin is unavoidable, when applying vacuum the (low viscosity) air tends to flow out fastest(luckily) and replaced by resin. Next the excess resin flows out into your breather.

If there is more than a film of resin on your base, then somehow.the base does not get pressed onto your mould. It can be that resin gets trapped under your base and pressure builds up, or that the ski does get pressed onto the mould, e.g your top laminate getting under tension.
So make sure that the resin can floor out easily and has a place to flow to, and that all your layers can confirm to the mould.

Removal of epoxy is easier with a scraper than sanding. Also I use rub on wax on my base to reduce the bonding of the epoxy, but make sure to stay away from the edges!

This is what I typically get (vacuum infusion, should be worse than hand lay up + vacuum):
Screenshot_20221214_145028_Gallery.jpg
Screenshot_20221214_145028_Gallery.jpg (109.42 KiB) Viewed 1233 times
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TimW
Posts: 48
Joined: Sun Apr 26, 2020 11:56 am

Re: Resin under base tip and tail at the edges

Post by TimW »

Oh and taping the base should work. I recently glued a titanal top laminate back on a board under vacuum. I taped the base along the edge, and it came out clean. But I added filler to the resin for gluing, which will have helped.
Jdline
Posts: 26
Joined: Sun Jan 26, 2020 3:19 am

Re: Resin under base tip and tail at the edges

Post by Jdline »

Maybe the tip bend of the mold is to steep to puch everything down.

I'm thinking of trying to put a block on top of the vaccum and puch is down with 2 clamps.
The core is only 2mm thick in the tip and tail so that will bend, the topsheet is a wood veneer 1-1.5mm thick.

When i do a full edge wrap, de edges do bend the base at tip and tail, i figured that the vacuum would puch it flat....

I'll try it again at one of my old molds ( full mdf block and less steep tip)


Do you use heat on your system?
I taped the base once befor but do to the heat the tape kind of melted and it was a mess getting it of..
TimW
Posts: 48
Joined: Sun Apr 26, 2020 11:56 am

Re: Resin under base tip and tail at the edges

Post by TimW »

A 2mm wood core will not conform to your mould if there is an abrupt transition to the tip curvature. It may appear so visually,, but conforming it to the tip curvature requires bending moment, and that bending requires some length to build up if you only have vacuum pressure. Not much, but at least a few centimetres the will be no pressure under the core. I do not run my core into the tip, but use base material as tip spacer.

Good point about the temperature. I used flashbreaker tape. If you use a non heat resistant tape you can indeed create a mess. But still better to scrape off than epoxy.
Jdline
Posts: 26
Joined: Sun Jan 26, 2020 3:19 am

Re: Resin under base tip and tail at the edges

Post by Jdline »

hmm, owkey, i'll make the core smaller and the tip and tail filler longer!
(is more 1.5mm core thickness in the core but...)

Thnx for the input Tim
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