Douglas Fir or Hemlock Fir

[gketcham]

Does Douglas Fir or Hemlock Fir make a good core? I looked at its density, modulus of rupture/ elasticity and it seems like it would make a good flexy core. Has anyone tried this, or know why it may be good or bad... Thanks for the tips

[MontuckyMadman]

fir, harder to machine, tends to splinter more, doesn't hold a screw all that well in comparison to other species.

Has good mechanical properties for flex patterns, weight to strength and stiffness.

[skidesmond]

The last pair of skis I made we a combo of maple and pine. The pine was from a 2x4. Construction pine is typically spruce or hemlock.
I haven't skied on them yet but they are noticeably softer than an exact pair I made from ash. Which is what I was looking for.

I think you'd get good results w/ fir, it is usually very straight wood grain. I would use hard wood in the binding area like my build below. Or re-enforce the binding area w/ metal or something to keep the binding screws from pulling out.

I'm making skis for my daughters and will be using fir, because it's light weight and fairly strong.

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[gketcham]

Thanks for the advice guys, with the 2x4s did you cut them down to 1" widths or did you leave them at 2"

[skidesmond]

Depends on how fussy you are about grain patterns etc. If you don't care too much about it then just cut the 2x4 to the dimensions you want and try avoid using any of the knots. If the knots are tiny and tight, may not be much of a problem, otherwise get another 2x4.

The best way to do it is to look at the grain on the end of the 2x4. Ideally you want the final cuts to have the end grain run up and down as opposed to left and right. Does that make sense?

[Dr. Delam]

I used some vertical grain fir on my last pair of cores. I got it free so I threw it into the mix with some oak and bamboo.

Like MM said, it can be difficult to work with. I was trying to shape it with my router before attaching sidewalls and it kept splitting, even with a brand new router bit. Insert cuss words here. Straight rips on the table saw are fine but I don't recommend using it for sidewalls or anything that needs to get cut with the router parallel to the grain.

[skidesmond]

Thanks for the advice. The side walls will most likely be maple or ash, along w/ the binding area and the fir will be in the middle. I'm working on a jig to shape the the center of the core before I add the side walls. I've seen some others do this as well. Then I'll profile the core.

[SRP]

I have also used cvg fir for cores. As others have also said I have used maple and bamboo as stringers for binding screws and as side walls. Overall, I think fir has very good strength to weight ratios.

[gketcham]

I have noticed on the skibuilders (howto) page that they have 'black ash' and 'paper burch'. I don't know different woods by that specific of a name, are these two common? Has anyone used these and would they be good for a binding area?

[skidesmond]

I have noticed on the skibuilders (howto) page that they have 'black ash' and 'paper burch'. I don't know different woods by that specific of a name, are these two common? Has anyone used these and would they be good for a binding area?

Yes. I'm not familiary with all the types of ash and birch but both are good types of hard wood and suitable for skis.

I just bought a 4x4x8 douglas fir today for under $20. I should be able to get a few pair of skis out of it if I use hard wood for sidewalls and the binding area.

[gketcham]

Should the core of Douglas or Hemlock be thicker than say an ash or maple? to give it more strength?

[Skierguy]

I would leave the core thickness the same. IMO The bigger issue with Fir as a core material has to do with binding retention rather than overall strength of the core. Adding core thickness will not help binding retention. If you are going to use a fir core I would recommend using binding inserts as they will give you more 'bite'. Loosing a binding is no fun at all.

[skidesmond]

Should the core of Douglas or Hemlock be thicker than say an ash or maple? to give it more strength?

This is the art/fun of ski making. You could try that. Or you could use inserts like Skierguy suggested. Or use hardwood in the binding area, fir else where.

IMO, decide what you want the ski to be first. If you want to use fir because it's light that's ok, but then decide how to over come the short comings of fir. Inserts are a good way to over come tear out. I've never used them. If you have any moving of the core when you press your insert alignment could be off. But if you have core movement under control try inserts. If you don't, maybe consider hardwood or extra layer of glass or metal....