Replies

1. 
   migraine | Feb 26, 2005 04:37am | #1

   I have/had one as you mentioned, until I moved up here to Washington.  I will be making another one in the near future.

   Here's what I did:

   I built a steel frame table and  for a 5x9 press.  The pump and "surge" tank were mounted underneath.  I also used a electric vacuum pump from Gast with a vacuum controller from Quality Vak(I highly recommend this controller).   The surge tank was a old well bladder tank that was gutted and sealed back up(free).  The valves were plain old ball valves purchased from Home Depot 

   I used a sheet of mdf on  the top and then I Attached a 1/4" thick plate of aluminum($400) to the top.  Grooves were cut into the luminum about 3/32"+/- deep into the top about 2" from the edges and a grid pattern about ever 6".  I used a worm-drive Skill saw with a regular, cheap carbide blade.   The intake hole for the top was centered on the grid pattern about 4" in from one corner.

   The frame was made out of 1" square steel tubing with 1/16" walls.  They were mitered and welded.  Any gaps/leaks were fixed with JB Weld.  I applied a 1/2"x 3/4" neoprene foam seal on the bottom of the frame.  The bag was made from a "soft hand" vinyl that is opaque, but still see-through.  The bag had 24" high vinyl sides built into it.  I attached the bag to the outside of the steel frame with 1/8"x 3/4" double sided tape.  Once the bag was taped to the frame, I used a small strip of aluminum  to seal the vinyl bag to the frame.  Just plain old self tapping screws were used to attached the aluminum strips to the steel frame

   The raising mechanism was 4 ropes and pulleys attached at the ceiling.  When I need the press, I just dropped it down.  I left it hanging in the air when not in use.  It was not hard to raise and lower and alot easier to access when pressing large curved parts.  When the press wasn't needed, I used the table for assembly

   I also have an extra vacuum pump if you are interested.

2. 
   Jamie_Buxton | Feb 26, 2005 05:32am | #2

   I built a top-loader for a specific job: veneering some panels about 7' by 7'.   It worked well, but took so much room to store that I eventually junked it.  Vacuum bags are so much easier to store!  My version was similar to migraine's, but maybe a little simpler.

   I made a torsion-box table.   I loosely covered it with two layers of 10-mil sheet vinyl, which was the bottom of my vacuum enclosure.   One layer would have held vacuum, but the material is only 54" wide.  Two layers allowed me to seam sheets together without having a step at the seam.   If your press is narrower, you don't have to play with this issue.

   (The vinyl is sheet vinyl which I got at a plastics store for something like $4 a running yard.   I've since noticed it at fabric stores, too.  I think they make slip covers with it.  This was the one time I've used 10 mil stuff.   For regular vacuum bags, I use 20 mil.)

   I made a frame for the top with 2x4s standing on edge, gussetted at the corners with plywood.  I jointed the botton faces of the frame before I put it together.   I flipped the frame upside down and draped it with another double-layer sheet of vinyl.   This sheet wants to be loose, not taut, so that it can conform to the workpiece in the press.   As it draped down over the outside of the frame, I just taped it to the frame.   Then, along the 2x4s, I applied foam weatherstriping to the sheet vinyl.  This weatherstriping is the seal between the top and bottom sheets of vinyl.   You can get this tape at your local home center.  It is closed-cell foam, so air doesn't leak through it.  IIRC, it was 3/4" wide by 1/4" thick.

   I punched a hole through the top vinyl sheet and glued in a vinyl tube of the correct diameter to fit my pump's nipple.   I used a small drill bit to perforate the tube inside the press.   I don't bother with kerfs in the press's platen.  I just drape that tube around the workpiece a bit.   Air molecules are darn small, and will leak through small openings.  That is, they'll get sucked to the vacuum pump without the kerfs.

   To close this press, I used lots of bar clamps -- roughly one every 8" around the perimeter.   That turns out to be a lots bar clamps, but fortunately they don't have to apply a lot of force.  They just need to snug the frame down to the table.  That is, they can be lightweight and inexpensive.  However, getting them all on the press takes some time, so I used urea-formaldehyde glue for its long open time.

   Like I said at the top, this press worked just fine.  It was just too big to store easily.

    

3. 
   user-5880422 | Feb 26, 2005 08:19am | #3

   just got a catalog from vacupress, they had some detail shots of their table and how it seals. I'm not advocating just copying it, but you will get some ideas by looking at how they did it.