Ok I really like the site it's really informative. One thing I dont understand though is how you do the core profiling. Is there a specific tool you need for it? and how is it done?
I would really appreciate some help on this.
Welcome to the site Andrew!
You do need a special tool for core profiling - a router. By using a router along with a jig you can profile your skis relatively easily.
Alright thanks
its actually pretty simple to make the jig it just takes a little time
just make the surface on which you profile on is very, very flat
You mean the surface that the wood core goes on?
yup
are any of you still using the thickness planer method of core profiling? I wondered if the taper to 0" was a problem...
above "Guest" was me.
i still use the thickness planer as my profiling method. the planing to 0" is a a little problem because the wood starts to blow out, but i tend to cut away a lot of the tip and tail sections for the tipspacers anyway so it doesn't matter too much.
big Kam and Kelvin have a good idea of combining both the planer and router methods to profile the cores. first use the planer to take off the majority of the wood. it's much faster and less wear on the router. then you set up your router jig and finish off the core to get cleaner tip/tail profiles.
That makes sense. To be honest I was trying to avoid building the profiling jig because I am so excited to get a pair in the press that I didn't want to spend the time on the jig.
I now know that it will be a necessary tool and will endeavor to build one asap.
Any revisions on the original plans for the router profiling jig?
Thanks for all of your feed back on this subject. Plotting this project has been the highlight of my summer.
nothing to kill summer time like ski building.
no updates on my part for the router profiling jig. it's pretty simple and works really well. i'm going to build a new one pretty soon, but for the base of the jig I'll use a bunch of 2x3's glued together and then put it into my planer. hopefully this will create a super sturdy and flat surface for the blank wood core.
i would spend some time and make your router jig carefully, however. if everything's cut accurately and works properly then profiling will be less of a pain.
hi guys,
do you think it is possible to use a planner like this?
http://www.evendi.de/jsp/eVendi2004/product_info.jsp?p=58008
i got only this one and i dont have the money to buy a new one...
thanks.
karsten
i'm sure you can profile a core with that. it may take a lot more time but it should do the job. i've heard of some snowboard companies using handheld planers (back in the old days) to profile their cores. and i remember some kid profiled his cores with a hammer and chisel. so if they can do it you can do it. just go slow with the planer and take a lot of measurements.
A belt sander would be better for hand tools.
so is there anyone that has actually used a vacuum pump to press the skis? if so where do you find the bags to seal it with and what kinda pump did you use?
i haven't used a vacuum setup to make skis yet, but have been using it for various other things like sidewalls and mold construction. I'm liking the vacuum more and more as I use it and am going to use it for skis soon.
I'm using a vacuum generator and bag from https://www.qualityvak.com/index.html and it is the venturi type. Electric ones work just as well and are nice if you don't own a big air compressor. I have a 2hp compressor and it is not really up to the task.
Here is a site that describes how to build one:
http://www.joewoodworker.com/veneering/welcome.htm
I've got a giant bag that fits the mold and everything, but I wouldn't recommend that since its a pain to wrestle the mold into the bag. A better way is to get vacuum film and seal it to the top of your mold. You can get the vacuum film, breather material and other stuff from http://www.fiberlay.com/
-kelvin
Vaccum is a very common pressing system in working with composites. It is standard in aircraft industrie and as my experience with compsoites comes from building aircrafts it was naturally to use it for my first ski.
As i use a relatively small mold (1900x200mm) i put it into a vaccum bag. The pump i use is a laboratory model from KNF (810) :
http://www.knf.co.uk/products/index.htm
(It is the one on the lowest picture.)
In my opinion vaccum is the simplest an safest way to create a relatively high pressure (-0,8bar means 8000kg/m2 pressure!).
thanks guys so does any one have any pics? so the bag would go over the bottom ski shaper and the mold?
Here is a pic of a quick test that I did. The entire mold goes into the bag. You don't need a top mold for a vacuum press
another pic of vacuum pressing the sidewalls.
-kelvin
I use vacuum as well, we have a pump in the lab ans it is seldom used.
This is serial production...
A friend of mine made two pairs of skis without using neither the vacuum pressing nor the press.
He has used several clamps. I had the feeling it could be possible, but I have easy acces to the pump, so I never pushed the clamp thing further. I have to aks more details.
This is a good option if somebody does not have a compressor, a pump or if he does not want to spend time and money to build a press.
so where do you get those big bags? plus is it kinda hard to get it into the bag when it is all being epoxyed togeather? i have seen it done with just with like half a bag and taped to the top of the mold would this work better or worse? thanks guys for all your help!!!!
I think that most here have seen the page on graf about using a refrigerator compressor to use vacuum bagging, though it's a little spare on the details.
I found this page which has slightly more detail. But an old Scientific American Amateur Scientist article shows how to turn a refrigerator compressor into a vacuum pump that'll generate and hold a pressure of about 1-2 mmHg, or basically -1 atm relative. So that's 20% better than just using the compressor alone and getting -0.8 atm with very little effort/expense. But maybe it's not really worth it, just throwing this out there.
(warning ramble: SciAm used to be so cool in the 60's when this article was published. Telling you how to make things like a 2Mev linear particle accelerator, a nuclear magnetic resonance spectrometer, or how to measure the temperture in a cow's stomach. Now it sucks, which is sad. Ok, ramble done.)
davide - Is that cardboard in your pic? Are you using it as a breather fabric or just above the breather fabric?
Hi in there. first I'd like to thank you for your site and wish you a very good year from france.I'm half french and finnish skier and wood carpenter and I wanted to ask you if a vacuum bag and vacuum pump from the retailer roarockit.com would be suitable and enough powerful to give shape to a telemark ski.
best regards
samuli
Yes, it is card board used as breath fabric.
I have also this special fabric, but most of the time I use cardboard. Actually I have the feeling now that the breath fabric allow a better pressure distribution. And it is possible to use the breath fabric several time if it is protected from the epoxy with a plastic sheet.
I have pressed four sets of skis using a vacuum pump. It accually works, but it took me 3 pairs to accually get a ski that I could use. I get my vacuum pump from United Rentals. Just ask them for a the vacuum pump off of a concrete coring machine. You can get the bags at www.fibreglast.com, It is also a good site to buy fiberglass and epoxy.
Don't know if you folks have seen this.
http://www.joewoodworker.com/veneering/welcome.htm
I plan to build the V2 venturi pump soon. They have a kit with all of the parts except the PVC pipe and end caps. The price is right and all available in one place.
My parts came in for my vacuum press Friday and I was able to put it together Saturday. It hasnt snowed in a week or two so staying home and working on this was a good thing. Im using the Project V2 set up with my 20 gal compressor that I already have. It took me a couple of hours to prep everything, and another hour to assemble. I still have to get a couple of end caps and make it a four chambered vacuum reservoir.
I was able to draw 20 in. HG easily at 4500 ft above sea level. It would go to 21 in HG with a bit of time. Thats .7 bar or ~10.29 PSI. As near as I can tell I have no leaks and was able to hold the vacuum for over an hour.
Ill be running some shake down tests this week on a couple of small projects, and get used to bagging my layups.
Hafte
I've got myself a vacuum press setup that is rated at 28inHg (~.95 bar) and the next thing I want to do is purchase a heating blanket.
Will a vacuum press setup create sufficient pressure to properly press a set of skis. I know 13-14psi over a large area adds up to a decent force, but how would this compare to a firehose press with 45-60psi of air in it?
Now that I've got the vacuum press setup I'm faced with a major problem: how am I going to run the leads from the thermocouple from inside the bag to outside the bag? As far as I can tell, Michaels does not offer a blanket with a single setpoint. Perhaps I'll have to contact them about that.
Judging from this picture:
The entry point of the power cable and thermocouple lead produces a bump on the heating blanket. Will this telegraph through to my skis, or should I order a longer length so that this section is beyond the workpiece. Or would an aluminim sheet like the Leangs used be advisable.
Thanks for any info you can offer
My heat blanket has lots of wires running through it. The first time I used it I got lots of ripples in the topsheet of my skis. However, these ripples don't seem to really affect the ski function, and I have skiied 10 days on that first heated pair (the better rockets). Lately though, I have been putting a sheet of thin plastic between the heat blanket and ski, and it seems to help a lot. There are still ripples, but they are really small. Next I am going to try some aluminum sheet, and i think that should solve the problem.
I would bet that with your heat blanket, if you used an aluminum or steel sheet, you wouldn't have any problems with it.
One more thing about running leads from inside to outside the bag. I bet you could just lay the blanket on top of the vacuum bag.
The bumps are only on one side. We have a couple layers of 1/8" hardboard over the ribs of our mold. I made a cutout in one layer to accommadate the bumps and then laid a sheet of aluminum over the blanket. The bumps face down in the cutout. Here is a pic: Not the best picture, but I think you get the idea.
You can get vacuum tape and bag material and rather than putting your whole mold in a bag, you would tape down tha bagging material to the top of your mold.
You can buy single setpoint controllers from www.omega.com
-kelvin
Thanks for the input, guys.
Michaels does offer a termostatically controlled blanket that functions at a single temperature. I'm sure it will produce more error than a PID setup would, though I'm confident that as long as it is within 10deg of the setpoint I should be fine.
I'll check out the vacuum bag/tape idea. Setting up the PID controller along with the SSR is about the only way I'll managed to get school credit for this project.
i also have a belt sander. do you really think its better?
I used a simple hand planer (not eletric powered) to profile the core. But i used some preshaped wood strips (5x20mm and 5x40mm) i glued together in one layer at tip and tail and two layers in the middle. So i only had to shape tip and tail sections and a smooth transition from 10 to 5mm strength. Together with the Airex C70.75 foam shovel (3mm) it was pretty simple and fast (2h per core).
I'm getting ready to make my tool for profiling using my thickness planer.
I was wondering if anyone has had issue with the part charttering/moving around on the bed of the tool.
The grabber screw tips to hold the part is a good idea. I was also trying to come up with a way to use the vacume to hold the part, but I don't like the idea of running the hose through the planer.
Seems the rollers in the paner would keep the part form moving too much. Is this the case?
Thanks
I screw the cores down at the tips (from the top) and then in the middle (from the underneath). Additionally, I use clamps. I will profile half of the core, then move the clamps and profile the other half. I have had really good luck with this method.
try using a hot glue gun.
If you leave your core a little longer on both ends, you could clamp or even screw it down, cutting off the excess later.
