Search found 48 matches

by TimW
Sat Aug 26, 2023 11:36 pm
Forum: Ski/Snowboard Design and Layup
Topic: Turn second layer og twi-axial fiberglass
Replies: 4
Views: 972

Re: Turn second layer og twi-axial fiberglass

I'd like to add that from a mechanical point of view it is best to have the 45° layer facing the core. The biax layers have a lower apparent stiffness in the main direction of the core, which will result in less shear stress at the bonding interface between core and laminate and help with longevity...
by TimW
Wed Jun 28, 2023 12:00 pm
Forum: Equipment and Tools (e.g., ski press, core profiler, etc)
Topic: Cheap Snowboard Press
Replies: 1
Views: 779

Re: Cheap Snowboard Press

Vacuum I built my first board (successfully!) on an MDF plate, bent it a bit to provide camber. Fastened it on top of a wooden bean to hold it in shape. Sealed the plate surface with epoxy(to hold the vacuum since it's porous). Made some ramps for the nose and tail that I placed on top of the plate....
by TimW
Wed Mar 22, 2023 11:34 am
Forum: Ski/Snowboard Design and Layup
Topic: Tip and Tail Fill for Rockered Skis
Replies: 4
Views: 1037

Re: Tip and Tail Fill for Rockered Skis

With a long and gradual tip/ tail, you can just do a continuous core.
by TimW
Thu Mar 09, 2023 12:43 pm
Forum: Ski/Snowboard Design and Layup
Topic: Vacuum infusion snowboard layup
Replies: 17
Views: 6679

Re: Vacuum infusion snowboard layup

I put rub on wax on the base, except for the last few mm from the edge. I take most of the epoxy of with a scraper (home made one, about 100mm wide). The last bits come off in the base grind. The wax makes the epoxy come off easier, and I figure that epoxy would also fill the pores of a sintered bas...
by TimW
Tue Feb 21, 2023 2:34 pm
Forum: Ski/Snowboard Design and Layup
Topic: Resin under base tip and tail at the edges
Replies: 5
Views: 1260

Re: Resin under base tip and tail at the edges

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...
by TimW
Mon Feb 20, 2023 12:34 pm
Forum: Ski/Snowboard Design and Layup
Topic: Resin under base tip and tail at the edges
Replies: 5
Views: 1260

Re: Resin under base tip and tail at the edges

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.
by TimW
Mon Feb 20, 2023 12:22 pm
Forum: Ski/Snowboard Design and Layup
Topic: Resin under base tip and tail at the edges
Replies: 5
Views: 1260

Re: Resin under base tip and tail at the edges

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...
by TimW
Mon Feb 06, 2023 12:13 pm
Forum: Ski/Snowboard Design and Layup
Topic: Top sheet replacement
Replies: 6
Views: 1404

Re: Top sheet replacement

Considering how hairy it is, too little epoxy seems plausible. If the topsheet came off without force, you'd expect a smooth surface if enough epoxy was used.

I recently had a titanal sheet come off (should have respected storage time and condition). That left a perfectly smooth finish 👌.
by TimW
Fri Jan 20, 2023 7:28 am
Forum: Ski/Snowboard Design and Layup
Topic: Delamination OR something else?
Replies: 14
Views: 2196

Re: Delamination OR something else?

I did not mean to imply that mechanical properties go up with higher post cure temperature. I was comparing to no post cure at all, as I understand from RealMcCoy that he just did a room temperature cure. Regarding the Sicomin resin, I just checked the datasheet. Be careful with the interpretation o...
by TimW
Thu Jan 19, 2023 1:41 pm
Forum: Ski/Snowboard Design and Layup
Topic: Delamination OR something else?
Replies: 14
Views: 2196

Re: Delamination OR something else?

Your total fabric weight should be ok. But the spec is a bit vague. :-). Glass fibers come in different qualities and with different sizings(= surface finish) suitable for different resins. Epoxy is quite easy going in this, but the fabric is probably far from optimal. The floating of the fabric in ...
by TimW
Sat Jan 14, 2023 1:27 pm
Forum: Ski/Snowboard Design and Layup
Topic: Delamination OR something else?
Replies: 14
Views: 2196

Re: Delamination OR something else?

Ah yes because you mentioned cure maybe I focused a bit to much on that. If your fabric was also old and not stored dry (humidity), the fibre sizing may also be the culprit.
And as said it could simply be insufficient strength.
by TimW
Thu Jan 12, 2023 2:46 am
Forum: Ski/Snowboard Design and Layup
Topic: Delamination OR something else?
Replies: 14
Views: 2196

Re: Delamination OR something else?

It is not just the Tg that goes up with post cure, other mechanical properties increase as well, especially compression. You simply increase conversion of your resin, with that the matrix strength, and compression properties are directly dependent on that (as it stabilizes the fibres, without resin ...
by TimW
Sun Jan 08, 2023 7:16 am
Forum: Ski/Snowboard Design and Layup
Topic: Tip and tail rise
Replies: 2
Views: 993

Re: Tip and tail rise

I also use less to tip height on my snowboards than I typically see in commercial boards. 40-50 mm on a typical snowboard shovel, 20-30mm on alpine snowboards (with tip length similar to skis). 15 years ago the 25mm rise got some weird looks, but nowadays most alpine snowboard manufacturers use some...
by TimW
Sat Jan 07, 2023 1:19 pm
Forum: Ski/Snowboard Design and Layup
Topic: Delamination OR something else?
Replies: 14
Views: 2196

Re: Delamination OR something else?

That looks like compression failure of the laminate (compression stress in the laminate from bending, not the pressure of your feet). Compression strength would suffer from insufficient matrix strength(mixing ratio, cure cycle?) or poor fibre interface strength( fabric moisture? age/ storage?). I've...
by TimW
Tue Sep 20, 2022 11:16 am
Forum: Ski/Snowboard Design and Layup
Topic: Sidewall profile (also new)
Replies: 4
Views: 2133

Re: Sidewall profile (also new)

Usually I cut the outline of my core first, then glue the sidewalls, and then profile the core + sidewalls in one go. But I have also profiled the core first and the glued the (unprofiled) sidewalls to the core. With a hand planer you can easily plane the plastic down to the core's thickness/profile...