Hi, I'm really new to this ski building thing and have been trying to gather information before I attempt to build my own skis. I have looked around this forum and have noticed that almost everyone uses a peunamic press like the one shown in the "how to build your own ride" section. This press seems like quite an undertaking for someone like me, with limited skills, and I was wondering if their are any other press designs that work well. I have looked into vaccum presses but they are a bit expensive so I was thinking about a press that consisted of a top and bottom mold held together with heavy-duty ratchet tie-downs. Does anyone have any experience with this type of press? Does it produce durable skis?
Also on a side note, is the only function of a press to bend the skis into the right shape?
Any help would be appreciated.
Thanks
alternatives to a peunamic press
Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp
Re: alternatives to a peunamic press
Google "build your own vacuum pump" for a cheap and reliable pump made out of fridge components or go to joewoodworker.com for a pump that cost less than 300.00 complete. A good vacuum set up works great at a fraction of the cost and effort of a press. The vacuum will easily form the skis over the mold and you can see shat you are doing and contain the whole mess in a plastic bag!! The purpose of the pressure is to uniformly distribute and press out the excess glue as well as form the ski over the mold. If you are using room temperature marine epoxies the pressure of the vacuum is more than adequate. I would take a lot of clamps to equal the pressure of a vacuum or air powered press but there is at least one person who has a clamp press and another who is building a hybrid press using a bicycle pump and clamps.uni412 wrote: I have looked into vaccum presses but they are a bit expensive
Tony
Thanks for your advice. I'm now leaning towards a vacuum press and have been looking at my options online. On fibreglast.com I found one for $100 that connects to an air compressor and pulls 27" Hg.
The link is:
http://www.fibreglast.com/showproducts- ... nt-19.html
This seems alot cheaper than average. Is it to good to be true?
The link is:
http://www.fibreglast.com/showproducts- ... nt-19.html
This seems alot cheaper than average. Is it to good to be true?
That is just the vacuum generator. You will need a vacuum switch and solenoid to maintain the vacuum. It'll also require a good size air compressor. I have one and my 2hp compressor is a little too small. You could run it continuosly, but then you'll need a really big compressor.
If you already have a compressor that's up to the task, then it is a good way to go.
-kelvin
If you already have a compressor that's up to the task, then it is a good way to go.
-kelvin
Thanks for your help. I'm new to this and have a lot of questions.
First, I have a 5 HP 13 gallon air compressor that produces 6.2 CFM at 45 psi and 5.9 CFM at 90 psi. Will this be strong enough for continuess use?
Also, this might be a dumb question but, if the vacuum bag was completely sealed, would you have to keep the pump running? I don't really know much about how these vacuums work and was just wondering.
First, I have a 5 HP 13 gallon air compressor that produces 6.2 CFM at 45 psi and 5.9 CFM at 90 psi. Will this be strong enough for continuess use?
Also, this might be a dumb question but, if the vacuum bag was completely sealed, would you have to keep the pump running? I don't really know much about how these vacuums work and was just wondering.
If you use the air powered vacuum generator then there is already a hole in the bag unless you use the vacuum valve and solenoid that Kelvin suggested. It is very difficult to find and stop the little vacuum leaks that you get so the pump tends to run almost continously anyway. Another nice option with the Vacuum system is the ability to infuse the resin, this lets you lay up the ski dry and then you put the vacuum on and suck the mixed resin into the layup. I watched a large windmill blade being infused yesterday and it definitely reasonable for ski construction. I'll keep you posted on my testing on a sample layup soon.uni412 wrote:Also, this might be a dumb question but, if the vacuum bag was completely sealed, would you have to keep the pump running? I don't really know much about how these vacuums work and was just wondering.
Tony
As tony said, it is very difficult to get a perfect seal.
Here is a link on how to build a vacuum system.
http://www.joewoodworker.com/veneering/v2-about.htm
I have one from these guys:
https://www.qualityvak.com/venturi.html#vm
-kelvin
Here is a link on how to build a vacuum system.
http://www.joewoodworker.com/veneering/v2-about.htm
I have one from these guys:
https://www.qualityvak.com/venturi.html#vm
-kelvin
I have the press from Joe wood worker, and am able to pull ~20” HG at 4500 ft above sea level. I might be able pull a bit more if I put hose clamps on some of my connections. They also use a vacuum reservoir (4 ea. 16” of 3-4” PVC pipe w/end capes) to keep the system from running too much. My compressor is a 5 hp 20 gal tank and seems to do a nice job. I just need to get it out of the room so I can find the leaks easier.
So far I have used it to make a couple skateboards and 8’ and 10’6” surfboards. Probably the biggest things I’ll ever bag. I was using 1 lb/cu ft EPS foam rock table and had to keep the vacuum around 10-11” HG so the foam would not collapse.
Anyway for ~$160.00 US the Joe woodworker unit and a compressor are pretty worth while, and easy to put together. It should see plenty of use here as we progress into actually building skis in the next few weeks.
I bought my bagging supplies from www.fiberglasssupply.com . I have the 36” tube bag and sealing tape for the ends. They also have stuff to do infusion systems, but the ability to create mistakes that way seems a bit high/costly for me.
Hafte
So far I have used it to make a couple skateboards and 8’ and 10’6” surfboards. Probably the biggest things I’ll ever bag. I was using 1 lb/cu ft EPS foam rock table and had to keep the vacuum around 10-11” HG so the foam would not collapse.
Anyway for ~$160.00 US the Joe woodworker unit and a compressor are pretty worth while, and easy to put together. It should see plenty of use here as we progress into actually building skis in the next few weeks.
I bought my bagging supplies from www.fiberglasssupply.com . I have the 36” tube bag and sealing tape for the ends. They also have stuff to do infusion systems, but the ability to create mistakes that way seems a bit high/costly for me.
Hafte
A good source for buying cheap and high quality vacuum pumps is ebay - i bought mine for about 30 $. This is definetly the cheapest way to get a good press!
I'm using this type of pump:
http://www.knf.com/oemini.htm
I'm using this type of pump:
http://www.knf.com/oemini.htm
uni412--
Most people that use pnuematic or hydraulic presses use them because they can product more pressure. However, the reason why they usually want more pressure is due to the design and materials they choose and the resulting need for better pressure control.
You can build a very light and tough pair of skis simply using formblocks and a manual clamping system. The one caveat is that you really need to know your materials and have very precise mold and parts.
In production runs, the search for higher and better control of pressure tends to be reflected in very expensive platten presses (either pnuematic or hydraulic---hint, even the home builder can build a press that is equal to what manufacturers use at a fraction of the cost). This is usually because of a combination of faster cycle time but also greater pressures to deal with some materials that litterally need to be fused together through high pressure and tempurature to either get a good fit or a good bond and sometime both! Some materials behave differently at different pressures and tempuratures.
A good craftsman should be able to build a superior ski using simple wood formblocks, clean molds and a simple cramp system. But, you would not want to do that if you want to turn out a single unit every 15 minutes, 24 hours a day, 7 days a week!!!!!!!
Most people that use pnuematic or hydraulic presses use them because they can product more pressure. However, the reason why they usually want more pressure is due to the design and materials they choose and the resulting need for better pressure control.
You can build a very light and tough pair of skis simply using formblocks and a manual clamping system. The one caveat is that you really need to know your materials and have very precise mold and parts.
In production runs, the search for higher and better control of pressure tends to be reflected in very expensive platten presses (either pnuematic or hydraulic---hint, even the home builder can build a press that is equal to what manufacturers use at a fraction of the cost). This is usually because of a combination of faster cycle time but also greater pressures to deal with some materials that litterally need to be fused together through high pressure and tempurature to either get a good fit or a good bond and sometime both! Some materials behave differently at different pressures and tempuratures.
A good craftsman should be able to build a superior ski using simple wood formblocks, clean molds and a simple cramp system. But, you would not want to do that if you want to turn out a single unit every 15 minutes, 24 hours a day, 7 days a week!!!!!!!
but.. suppose you had your vacuum setup inside oh lets say a 16" pipe, and pressurized that to 30-some pounds. Now you have 2 bar pressure. (or is it 3.. math is my weak point)
Best of both worlds? Thats some darn good pressure - and that could be a cheaper, easier to build compromise solution over a pneumatic press. It would be conceivable to use one large compressor with a splitter for the venturi side and the pressure side. The pressure side won't require much airflow
Gosh golly gee whiz - I just gave myself an idea!! lol
Best of both worlds? Thats some darn good pressure - and that could be a cheaper, easier to build compromise solution over a pneumatic press. It would be conceivable to use one large compressor with a splitter for the venturi side and the pressure side. The pressure side won't require much airflow
Gosh golly gee whiz - I just gave myself an idea!! lol
I used to be a lifeguard, but some blue kid got me fired.