Shopvac's Skis

[iggyskier]

Practice for the edges I reckon but I'd say all the clamps help too!

That is courtesy of CDW and their prebent edges....which reassemble what you get when you give a drunk man a blow torch, a bunch of skis edges, and possibly the wrong ski template. Takes a good bit of work to get them to fit.

That and my hands just love clamping those bastards 1000+ times a day. Made worse by the fact that all of our templates are now out of 1.25" MDF.....

Bandsaw blade is a 6-10 1/2" blade. We usually get 30-40 pairs out of it before swapping.

[shopvac]

We built another pair last week. Montucky made us 4 new bags that work great. It seems much easier to get the 4 bags on and off and they are slightly smaller in circumference which is better. Thanks again.

The new bags:


The skis are 195cm long using a straight tape from tip to tail.
1.5mm red base
22 oz triax top and bottom
70 cm in the tail of 3" wide 4oz uni carbon from soller composites top and bottom
ash and poplar core
pau ferro veneer with pu coating on top

145-118-125 * 5 dimension ski
45 cm of tip "rocker" we include the tip or tail in this length (2cm rise over first 34cm with 4cm of rise over last 11cm)
18cm of tail "rocker" - mostly continuous tail rise
radius = 25.2m
running length = 131cm
sidecut = 8.5mm
camber = 5mm each ski
weight = 2600g each (I guess the cf didn't make them lightweight!)

The tip turned out a little different than I hoped as we had a new one CNC'd. Oh well. I think they will be fun.

The finished skis:


Close up of the pau ferro veneer we used. They look really nice in person.

[shopvac]

cores are fun. we use a profiling jig like mark made in the photo seen below:


http://www.skibuilders.com/phpBB2/viewt ... t=crib+mdf

We add shims in the front and back to help keep the profiler from losing its shape in the large gaps between the shim at the tip and tails and the area that is screwed together in the middle. I also put 5 - 2" tall pieces of wood vertically below the bottom piece of MDF in the above photo with a piece of plywood below that.

We run the cores through the 13" rigid planer. Both cores are on the crib. On this last pair of skis we built we measured both cores with digital calipers on the right and left side of the core after we were finished.

I made some very simple plots of what our cores look like.


I also made a difference plot using the average of all 4 sides as the baseline. It seems like we are almost always better than +/- 0.2mm which I feel is fairly good for the setup we use. Has anyone else done something similar?



DBS made me interested in trying to "quantify" our core profiling performance after all of his work he did with the jigs he built. I guess what I really need is the actual profile we were aiming for and then do differences from that (if that is possible). Sorry for the crappy quality ... I really need to download paint.net again after wiping my comp ...

[Jekul]

Beautiful wood. I really like that you made the ski's symmetrical.

[brewster]

cores are fun. we use a profiling jig like mark made in the photo seen below:


http://www.skibuilders.com/phpBB2/viewt ... t=crib+mdf

We add shims in the front and back to help keep the profiler from losing its shape in the large gaps between the shim at the tip and tails and the area that is screwed together in the middle. I also put 5 - 2" tall pieces of wood vertically below the bottom piece of MDF in the above photo with a piece of plywood below that.

We run the cores through the 13" rigid planer. Both cores are on the crib. On this last pair of skis we built we measured both cores with digital calipers on the right and left side of the core after we were finished.

I made some very simple plots of what our cores look like.


I also made a difference plot using the average of all 4 sides as the baseline. It seems like we are almost always better than +/- 0.2mm which I feel is fairly good for the setup we use. Has anyone else done something similar?



DBS made me interested in trying to "quantify" our core profiling performance after all of his work he did with the jigs he built. I guess what I really need is the actual profile we were aiming for and then do differences from that (if that is possible). Sorry for the crappy quality ... I really need to download paint.net again after wiping my comp ...

Standard deviation on the last plot would allow you an easy way to compare averages without having to guess. It would also allow you to baseline your process and detect subtle changes with changes in time or materials. If you decided to change your crib, planer, etc. you could easily see if it improved your cores.

[MontuckyMadman]

ahh standard deviation aside.

Shopvac, could you post a pic of your planer crib if you are on this continent?

I have made one similar but am having some difficulty potentially with deflection but I'm not really certain the best way to fix it.


THanks

[Richuk]

I have the same interest - have thought about using a CNC machine to make the crib. More cost effective use of CNC time? I've been getting some exacting results with the crib I have at the moment, but I've not been plotting the same number of points. If I pull something together I'll give you a shout

[shopvac]

not out of the country, so here are some photos, if I remember how ...

this is what the beast looks like. The bottom of our cores sit touching the crib.


We found it was important to put shims between the tip and mid and tail and mid. here you can see one of them.


This shows the front. The 0 line is where we want our tip to be 2.0mm. We usually have 4-5 cm of core sticking off the front and back for snipe. The layers are 5/8" plywood, 1.5" tall boards to make it rigid. These were ripped on a table saw and then planed down with our planer to make them super flat and all the same size. This is the biggest difference between ours and Marks I have a photo of above. Then we have a piece of 3/4" MDF, spacers in the tip (we used masonite or some particle board that was the right thickness to make 2-12-2mm cores), then another piece of 3/4" MDF for the top piece. I would use thinner MDF because the darn thing is heavy as hell.


we have changed this to make 3 different length cores so there are a lot of holes in the top. Doesn't seem to matter.


We have a 13" Rigid planer I got for cheap. Changing the knives once (flipping them actually) made a big difference


Some other notes:
1. When building this clamp everything down really well and then screw it together to avoid gaps. Gaps Suck!

2. Make yours lighter with the next size thinner MDF.

3. We use double sided carpet tape to hold down the cores and we do both cores at the same time to minimize core differences and to save time and my back from lifting that sucker. I would say we use 4 strips 1"x3" for each ski (2 in back and 2 in front). No problems with carpet tape so far. It is cheap and pretty easy to get off. I imagine grip tape is better but I think our cores would slip. Maybe I just don't understand the grip tape though. If you can get it to work that is probably the way to do it.

[MontuckyMadman]

you rock and thanks. Looks heavvvy.

[Richuk]

It's been done ... http://www.skibuilders.com/phpBB2/viewt ... e&start=30

[knightsofnii]

Iggy's method of cnc'd planer crib and a good planer is a popular method amongst small/medium factories, even ones who have their own cnc machine!

Its just tough to get the planer(s) dialed for runs of multiple cores. But I think if you simply just have something to gage the tips with, you can come pretty darn close every time if you just do one at a time. I'd like to know what kind of planer iggy has and if its affordable.

[iggyskier]

Iggy's method of cnc'd planer crib and a good planer is a popular method amongst small/medium factories, even ones who have their own cnc machine!

Its just tough to get the planer(s) dialed for runs of multiple cores. But I think if you simply just have something to gage the tips with, you can come pretty darn close every time if you just do one at a time. I'd like to know what kind of planer iggy has and if its affordable.

It is tough to get dialed. It took us about 10 days of pulling our hair out to get it to the point where we got good, consistent results.

One big thing is the have an accurate means to measure the correct height of the planer bed. The dial on the planer won't do it, and those "digital" planer scales are bullshit.

We set up a method of measuring the planer table height to ~ 1/100th" I believe (I would need to go check out the gauge we used). You can see it in the photo below...I won't give too much away, but it allows us to be highly accurate very quickly.



The planer is a Powermatic 15HH with a Byrd Helical cutterhead.

I was going to add....
1) Before we get going, we have Powermatic send out a technician to square everything away.
2) Make sure you lock the planer bed on the final pass. I've talked to a few people who spaced this....

Hope this helps.

[shopvac]

After a long hiatus from skibuilding and with our BTSR approaching a big sideways 8 it was time to get building again. Over the past two weeks my brother and I (with lots of help from our parents) built two pairs of skis and have a third ready to roll hopefully this weekend. We have been skiing our 113mm underfoot skis we built 3 years ago most days and they are pretty beat up. It was time to design and build a new ride for 2011/2012.

My brother's new skis:


The stats on the skis
191cm flat MDF mold length = 188.5cm straight tape measure from tip to tail
135-110-124mm
camber = 5mm per ski
turning radius = 24.8m
running length = 139cm
sidecut = 9.75mm
mounting line estimated at 103.5cm (mounted at 104cm with 916's)
core = poplar and ash (2-12-2)
weight = 2300g each without bindings
topsheet = kingswood veneer from certainly wood
22 oz vectroply triax on top and bottom of core
3 inch wide, 4oz/yd^2 carbon fiber on top of the core only entire length of the ski (from soller)
bases are 1.5mm thick
tip rocker is 34cm including the tip
tail is 15cm

Overall, then look stunning. He put at least 2 coats of Helmsman PU and also treated the Ash sidewalls with teak oil I believe.

zoomed in on the tips:


The cores turned out pretty similar when profiled with our planner.


The skis flex feels pretty nice. I am going to build a pair that will have 1" wide 4oz carbon fiber in them next. I think that will be fine.

We also built a pair of cross county skis for my uncle. They are 183cm long and have 80-62-71mm dimensions. They have the same core profile and triax fg in them. The topsheets are a mix of a few woods that my dad spliced together. They look pretty cool. I need to look into doing the waxless base fish scales like a few people have done on here in the past. I saw the GO AT bases karmav builds and I know somebody else was doing this with a router a few years back (ra?).



In preparation for building my skis I sand blasted some edges today. That turned out to be a lot of work as the sand blaster was tricky to operate. I am not sure what was going on there but they do look good. No rust.



cores:


A sneak preview of what is going to be the topsheet on my next pair of skis:

[falls]

awesome. glad to see you back at it !

[skidesmond]

Nice skis including the cross country skis and the Kingswood veneer is awesome!