Planer crib

[hegan]

I have access to a planer and plan on using it. I have spent the last couple of days researching how to make a crib and I got all the basics besides on key fact. How to figure out what sizes to make the blocks for the crib, I'm going to be making 3mm tip to 12 mm mid foot to 5 mm tail. In order to get these specs should i slowly work my mid point of the crib to 12 mm for the midfoot ?

[MontuckyMadman]

you dont want a 5mm tail.
If using linear taper draw it out and measure it.

[vinman]

Use this spreadsheet to help figure out your core profile. It takes some work to figure out how to manipulate the dimensions in there but it will help you get started.

I have not played with that sheet in a very long time. Someone one here made it awhile back. If you search the forum you might find some kind of info on how to use it.


http://www.mediafire.com/?w2zhdmuzkam#1


Tip 1. You want your tip and tail measurement to equal the thickness of your tip spacer material in order to get a flat base at the transitions from the core to the spacer material. Tip spacer material is 2.2mm thick.

A 5mm thick tail would not work for 2 reasons, WAY TOO STIFF and your bases would not be flat.

Take a look at some commercially made stuff. The final ski thickness in the tip and tail is maybe 5-6mm. But that includes base, glass layers and spacer material and that ever else they put in there.

Base 1.4 mm, spacer 2.2 mm glass layers ~.6-.8 mm each, top sheet maybe 1mm depending on type of material and some VDS, and you've got 5-6 mm right there. And that is on a ski without a metal layer.

[hegan]

I downloaded the excel file, wasnt for me. So I made my core in snocad and brought it in to a drawing program flipped it horizontal and started at the thinnest point with 2 in gap and worked my way through the core and ended with this. I plan on fine tuning it some more and then all I have to do it write down the specs of the blocks.



As well the core are now 2.5mm x 10mm x 3 mm.

[vinman]

You missed my point on base flatness. If you are planning on using plastic tip spacer material then yo need to taper to 2.2mm with your planer sled or by hand after with a belt sander to fine tune the final thickness at the transition point between the core and tip spacer. If you don't your bases won't be flat.

Btw a 10mm waist with a 3 mm tail is likely going to be a noodle with a very stiff tail. Thickness changes in the order of a couple tenths of a mm will be noticeable both in hand flexing and performance

[hegan]

The cores are not going to have spacers going to be full wood core.

[hegan]

[quote=

Btw a 10mm waist with a 3 mm tail is likely going to be a noodle with a very stiff tail. Thickness changes in the order of a couple tenths of a mm will be noticeable both in hand flexing and performance[/quote]

Would 2.5 mm 13mm 3 mm make more sense for an all mnt/pow ski?

[vinman]

^^that profile would be very stiff.
There is a good discussion of the in the Why Not thread in journals right now.

When usin 19 oz glass: For me if I'm making that kind of ski for a normal sized person say 150-180 lbs and they want a stiffish ski I'd go with 2.2-12-2.3

I'd adjust in tenths of a mm if they are heavier or lighter and/or I'd add some carbon tow to the lay up. If the person is heavier or wants a stiff ski I'd bump the waist dimension to 12.2 or 12.3 plus some extra carbon tow.

Or stiffen things by using heavier 22oz glass.

Literally 1/10 of a mm makes a difference. I know it sounds incredibly small but if really does.

After you make a few pair you'll start to feel the differences. Do your research and then just go for it. Learn something from every pair.

[hegan]

Ok, thanks

I'm going to go with a 2 mm nose 12.5 mm mid foot and a 2.5 mm tail.