Post first build questions

[falls]

Now that I have built the first pair I have a few questions about finishing and cleanup.

1. I used aluminium sheet metal for the cassette which I waxed with mold release. There are small pieces of epoxy firmly or not so firmly stuck to the bottom cassette. I am thinking a plastic scraper to get them off without scratching the aluminium too much. Any tips?

2. I finished the skis with a jigsaw which left some epoxy on the side of the edges. I then had to belt sand this off before I had a clean surface to run the router bearing along. I think this is pretty standard but do people actually run the jigsaw blade against the edge? And does a bandsaw blade allow you to trim the ski back to the edge?
I ask because on a lot of finishing videos it looks like they go straight from the bandsaw to router. If I had have done this I would have ended up with a wavy sidewall and still epoxy on the side of the edge.

[skidesmond]

A scraper will remove the epoxy. Just give it a little whack and it should pop off.

I run the jig saw as close to the edge as I can then use a belt sander where necessary. I've used a chisel as a scraper if I have just a little bit of epoxy to remove.

I think the vids you see of people using band saws are experienced ski/board makers IMO, or very experienced band saw users.

[Alex13]

I've got a quick question to add to this: How reusable are the aluminium skins for the cassettes? Is it hard to bend them back to flat, or fairly easy since the camber curves tend to be pretty gentle?

[skidesmond]

Good question. I'm still using hardboard that has a finished side to it that is smooth white. I want to upgrade to sheet metal, more durable. But I have the same questions.

[falls]

Pretty reusable.
My sheet has a slight bend at the tip end that won't pose a problem laying up the next set. I got a bit of denting where the ends of the 3/4 wrapped edges were forced to bend.
Aluminium is pretty expensive for it to only last a couple of pressings.
It looks like using sheet that is slightly thicker might be more durable. I have 1mm sheet. It looks like people like icelantic use thicker stuff, maybe 2-3mm and prebend.

[twizzstyle]

Scrape what epoxy you can off the aluminum, then lightly sand to get the rest off. Scratches won't matter.

We use parchment paper on top of our sheet metal. That way there is no clean up, you just throw out the parchment paper after each layup.

And on trimming the ski. I use a band saw, and run the blade right up against the edge. You have to be careful, if you put too much pressure, you can cut into the edge, but there is a sweet spot that'll keep the blade running right along the edge without cutting into it. I still go at it with the belt sander before routing though, just to clean it up a little better.

[Richuk]

If you want to get back to new, wet and dry will polish it up once you've removed the excess.

I've used a scribe to lightly mark a centre line (across the width of the cassette and at the tips) and no impression on the base at 60 degrees C and 60 psi. I'm expecting to get more than a few pressing out of the 1/16 sheets (1.5 mm), but I will need to put them through a slip roller at some point - I put a fold in the top sheet when pressing a test piece. Maybe i will need to up-grade in the future ... one thing I will do next time is use the old packaging tape - epoxy on the base is a pain.

What's the issue resolved by pre-bending the cassette? Is it just a loading issue? Isn't tricky to load everything into a pre-bent cassette.

Hope the penny opinions are helpful.

[SHIF]

.. one thing I will do next time is use the old packaging tape - epoxy on the base is a pain...

Packaging tape is a total pain in the ass to remove from the base after cooking in the press. I made that mistake on my first ski build, never again. I use 6 inch wide 3M blue painters tape to protect my base and top sheets. I press at 36 psi and 85 degrees C (185F) and the painters tape peals off clean and easy.

I tried the parchment paper once too. I found it difficult to work with and impossible to create a dam to prevent epoxy from getting all over the place. I prefer to use 1 mil polyethylene sheeting on top of the press plate, and then wrap this sheet around the lay-up like a burrito.

Epoxy on the base... a little is OK, it cleans off when base flattening on the wet belt (Wintersteiger tuning machine).

I trim away the flash with a jig saw too. Then use a 40 grit flap wheel sanding disc in my 4.5" angle grinder to square-up the sides flush with the metal ski edges. Last step in the process is using the router bridge to bevel the sidewalls leaving about 6mm vertical walls above the edges.

Cheers,

[Richuk]

Sorry all - I meant the blue stuff, bought it after reading one of Shif's posts. It's all in the detail

[falls]

thanks all
I thought the benefit of the bandsaw would be that you hit that "sweetspot" and end up with no/minimal material left on the sidewall before router bevelling.
I think by the 4th edge on this first set I had found a much better jigsaw blade and had my eye in a lot better for cutting very close to the metal edge. The 4th edge only needed a light hand sand in a few spots before I had a totally clean side edge.

Rich: I think prebent cassette really just for ease of loading. Some of the ones I have seen are just bent a little bit, but this means less bending to load and also I reckon bending the flat cassette into the press is when a lot of the bad core/base shifting would occur. Bending the edged base around a paint tin seems pretty easy and laying up the glass is just like a flat cassette. The core is usually ok by the looks of things too because most of the radical bending is in the tip spacer section anyway and you can prebend that too. The kingswood skis layup video on youtube/vimeo shows a nice approach to prebent cassette layup.
My press "mouth" (fo want of a better expression!) is pretty small, maybe 3 inches, so getting the flat cassette in is ok, but at this stage a 2 person job.

[falls]

one more if you don't mind!

What do you use for cloth to clean base/edges etc before layup. I started with methylated spirits (same as denatured alcohol in the USA I think) on cotton wool. The rough surface of the base material pulled the cotton wool apart and I ended up with it stuck all over the base material and edge teeth. I ended up using a cotton face washer, but still got a little residue stuck on edge teeth.
I was thinking lint free tissues like they use in laboratories?
thanks

[MontuckyMadman]

I find that edge cleaning to be very technique oriented to get clean but keep from shredding the cleaning cloth.

I have a technique but don't know if I can desribe it. Trial and errror.

[falls]

just a cotton cloth/rag though montucky?

[Alex13]

Have you tried Acetone? I used that and a rag to lightly wipe the base and edges before gluing. I don't think you'd want to soak the base material with it though, could melt the plastic.

I also lightly sanded my edges by hand first.

[falls]

I read a few posts on here about how acetone is maybe overkill for the home builder. The main concern is that the acetone actually can carry the materials it dissolves deep into your skin/body. All this after I spent most of my weekends last year stripping paint from aeroplane wings using acetone and dodgy rubber gloves (stupid!).
I am happy using the methylated spirits. The question was more what type of cloth people use. I think maybe I just needed to go slower and be more delicate around the edge teeth to avoid snagging the cloth and probably my choices of cotton wool and face washer towel type cotton were both destined to snag on rough spots. A tighter weave cotton fabric rag is likely the way to go. I think I will try some lint free tissues too (Kimwipes here in Australia). I'm probably being a bit pedantic really!