choice of wood

[MontuckyMadman]

not all bamboo is created equal with regards to ski cores.
Most of the bamboo core I have are very smooth and stable. good for crud and pow and 3d snow. Heavy lots of flex and power rebound.
I thought moment made their skis of pine.

[loganimlach]

not all bamboo is created equal with regards to ski cores.
Most of the bamboo core I have are very smooth and stable. good for crud and pow and 3d snow. Heavy lots of flex and power rebound.
I thought moment made their skis of pine.

most of their cores are aspen/ash, some with aspen/pine. they did some prototyping with some bamboo stuff but I don't think any of it went to production. they've also branched into the world of paulownia along with most people for their light touring skis.

[MadRussian]

bamboo is nice.... Maybe lol. I want to stay with local growing wood for core.

Anybody ever use black locust for sidewall? technical characteristics in a chart showing black locust little bit softer compared to IPE. I'm not all that impressed with IPE performance

[Richuk]

The stuff about the design and layout of the pores of different wood species is good and seems to really be a factor in choosing different wood for what you want from a core.

As a general rule, the more dense the wood, the less sensitively you will need to treat the issuses of resin ratio, resin viscosity/ramp timetable during pressing.

To make progress on the issue, its worth investing in a small USB microscope with a scale a measurement feature ... 20 GBP. It will allow you to compare your results - laminate thickness and resin penetration, against comercial examples. It's an interesting analysis, a bit time consuming, but it cures alot of the guess work.

[Dtrain]

Cough, cough, cough. Sorry ......smokin one......but ...... I think that meant the softer the wood the more resin it will soak up? Haha

[Richuk]

As you appreciate, the issue is 'work', impacting the fatigue resistence of the wood (or not), so the relationship is a little more complex.

Broadbrush ...

Light weight, open pore soft wood ... then you are turning the core into a composite, a wood epoxy composite. This means more epoxy, ideally a little less viscous and giving it time to soak and penetrate the core. The resultant effect is a drop in the overall weight of the ski, except at the tip and tails, but then you've increased the capacity for 'work' within these sections.

The opposite it true for hard and dense wood, inc bamboo, the epoxy bonds to the surface, that's it. You're not affecting the performance of the wood. If the wood is unsuitable for this purpose, expect issues such as delamination.

And then you have foam.

[EricW]

I use poplar with ash stringers for the inserts and edge support. No need to get all complicated.

[Richuk]

Great insight Eric.

You are right, using ambient cure epoxy will simplify the process. Leaving only the calibration of pressure to obtain the desired laminate thickness using an online tool like this: http://www.saertex.com/materialrechner/ ... echner.php

[24Dave]

I really like how poplar cores will bend a long way before breaking. Although it doesn't resist edge compression very well. Here is an interesting read on Ash vs. Maple for supporting edges from the baseball world, seems like ash is more straight grained, and maple may be more subject to having weak spots or failing in a larger way. still pretty debatable, but I see why Ash is a common perimeter core strip.

http://chronicle.com/article/University ... ra/125223/

and some cool tools I found lately:

sliding thickness gauge from Peachtree Woodworking
1562 6" iGaging Digital OD Caliper & Thickness Gauge

flat tape measure
http://www.fastcap.com/estore/pc/viewPr ... roduct=150

better glue bottle
http://www.fastcap.com/estore/pc/viewPr ... category=0