Replies

1. 
   migraine | Dec 09, 2003 10:46am | #1

   I have been pressing for 10-12 years and I have found a system that works for me and it really doesn't cost that much more than what I have just seen in the link you have referenced.   I'm not sure that it is worth the money unless you plan to use it on small projects 

   The controller that I used is the from the same company .  Here is a link to QualityVak.  http://qualityvak.com/electric.html#es  it also has a setting for using it as a vacuum hold down.  The controller is the square black box.  Everything else you can buy/make yourself.  If you know what you are doing, the contoller is not that elaborate.  There is a guy on Ebay that been selling quite a few vacuum switches over the lkaast years or so.  They usually go for around $35.00.  But then you would need to wire everything up yourself.  They also self a venturi model, but I'm not sold on that type of system, especially when doing alot of forming with 2'X4'x8' molds

   The controller runs about $275 itself and is worth the money.  You will also need a larger check valve that goes on the end intake port of the pump to prevent air from returning back in to your vacuumed bag.  Some 1/2"-3/4" clear tubing or nylon braided clear tubing and a few ball cock valves work.  You have two options for a bag.  One is to make a bag out of clear vinyl and glue the edges together and leave the ends open to put parts and cauls in and out of the bag.  The ends can easily be sealed off with two sticks and a few spring clamps.  Another way is to make a steel frame and attach a "five sided bag" ( 2ends, 2sides and top).  Then the frame is sealed to the table top with a neoprene or foam seal.  This is my preferred method.

   The vinyl that I have mentioned  can be what we call "patio vinyl" and is available at many plastic and uphostry supply stores.  The vinyl is easilly welded with a vinyl adhesive.  So a narrow strip can be made into a large bag if needed.  Go with medium grade thicknes.  If I remember correctly, it's about 10 mil.  The 30 mill is too ridgid and you really don't need it.  Vacuum works the opposite of pressure.  It self seals itsel.  If you get a hole in it, just temporarily put a piece of vinyl tape on the leak and fix it later.  To give you an idea of the life span of my last vinyl membrane that I build it 9-10 years ago. It's still in used.  It does have a few holes and is starting to leak at some of the seams alittle.  It just means that the pump doesn't turn off as often.  The frame measures 5'wide x 9'long x 2'high.  The vinly is slightly opaque and is a little softer(its called a "softer hand")  than patio vinly, but about the same cost when you buy it by the roll. You should also invest in a "surge tank" or also called a  "resevoir tank".  This will help draw down your initial vacuum on your parts alot fast.  It also helps keep the pump from cycling on and off.  You can also buy new pumps from Graingers.  I am only familiar with Gast rotary vane pumps and I also recommend you stick with oiless models.  And, the bigger the better, especially if you plan on using this for business/production.

   I have been recently checking on ebay and I have been seeing some rotary vane pumps going for around $100 dollars

   Make or buying the press is less than half the battle.  The other part is learning to control warping, glue types and making molds accurate enough and strong enough so the don't implode.  That can really ruin your day and alot of expensive plywood/veneer.

   Let me know if you have more questions.

2. 
   Scrit | Dec 09, 2003 02:05pm | #2

   If you are in the USA the best low-cost site I know of is Joe Woodworker and the site includes build your own instructions and how to veneer pages as well as being a source for supplies. In the UK the nearest would be Bagpress who will sell you all the stuff you need to build your own press

   Oh yes, read the Joe Woodworker site advice about vacuum pumps on eBay - could save ypou from being had!

   
   

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   Edited 12/9/2003 12:43:17 PM ET by Scrit