Combining vacuum press and pressure chamber?

[pmg]

Hi,

had an interesting idea some nights ago:
How about combining a vacuum press and a pressure chamber to get the same pressure as a normal pneumatic press (but have all the benefits of a vacuum press).

If you plan to pour sidewalls, a pressure chamber is the way to go anyway. You will need about 4 bar pressure. So why not build it big on top of your vacuum press? This would make a total pressure difference of about 5 bar.

Well, with 4 bar pressure you could just skip the whole vacuum press - 4 bar should be more than enough.

So, the final idea of my thought would be: Build a vacuum press which does not work by sucking air out of one side of the vacuum foil, but by increasing pressure on the other side of the foil.

This could be an interesting thought for people who want to pour sidewalls. They should have a pressure chamber anyway - so why not build it as a press right away?

Regards
Philipp

[richie]

Hi,

had an interesting idea some nights ago:
How about combining a vacuum press and a pressure chamber to get the same pressure as a normal pneumatic press (but have all the benefits of a vacuum press).

If you plan to pour sidewalls, a pressure chamber is the way to go anyway. You will need about 4 bar pressure. So why not build it big on top of your vacuum press? This would make a total pressure difference of about 5 bar.

Well, with 4 bar pressure you could just skip the whole vacuum press - 4 bar should be more than enough.

So, the final idea of my thought would be: Build a vacuum press which does not work by sucking air out of one side of the vacuum foil, but by increasing pressure on the other side of the foil.

This could be an interesting thought for people who want to pour sidewalls. They should have a pressure chamber anyway - so why not build it as a press right away?

Regards
Philipp

Basically that is an autoclave I think, or does an autoclave have heater too? you need to still encapsulate the ski or board in a bag when you put it inside the pressure chamber to actually get a pressure differential to squeeze the laminate and layers, if you have a vacuum within the bag first then you get the extra bar of pressure too, which could therefore lessen the actual pressure you need in the chamber to say 3 bar. With a good bag that sealed well you might be able to set the vacuum up first, outside the chamber, so the wrinkles are all out of the bag and the laminates and core and base are all aligned , close off the vacuum seal assuming its nice and non leaky, then pop it all in your pressure chamber. Putting heat on inside will up the pressure too. You might want to search about autoclaves have a look at this one http://www.c6skiing.com/Technology/ACCP+Technology.html , these guys have a nice setup......

[sammer]

You're thinking on this is all wrong!
Pressure on your vacuum bag is directly related to atmospheric pressure, it's atmospheric pressure that's pushing against your bag in all directions.
An autoclave is a pressure chamber but still needs to have a vacuum bag as the pressure in the autoclave is pressing in all directions. You need to have a lessor pressure inside your bag or nothing is going to happen.
If you have 4 bar in your chamber (and you can pull a full vacuum) that's the pressure your going to get on your bag.

If you put all your materials in a bag at ambient air pressure and seal it up then put it in your autoclave at 4bar you'll only get 3 bar pressure on your bag as you have 1 bar pressure in the bag.

Hope this makes sense!


sam

[twizzstyle]

There have been people on here that have done skis in homemade autoclaves. I'm of the opinion that a firehose press is easier to build than an autoclave, but I've never tried to build an autoclave. I've thought about it for years for other projects, but not for skis.

[pmg]

@Sam:

Thanks for the correct calculation, it was quite late last night and a bottle of red wine didn't help having straight thoughts ;)