Building a Curved Form - for Inside the Bag

Illustrated advice on constructing lamination forms for use in vacuum pressing. June 24, 2002

by Ed Ferri

Ed Ferri is the founder of Quality VAKuum Products, Inc. and has more than fifteen years experience working with vacuum applications. QVP specializes in vacuum pressing and clamping equipment for the woodworking and plastics industries. For more information visit the QVP website at www.qualityvak.com or call 800-547-5484.

1. The form for inside the bag has to be strong enough to withstand 1800 lbs./sq.ft. of pressure. The ribs should be made with 3/4" thick plywood, MDF, etc. Make the form 2" to 3" wider and longer than the finished piece.

2. Make the first rib, then use it as a vacuum template to make the others. This method is fast and accurate.

3. The ribs should be solid and not have cutouts to make the form lighter. Place the ribs 3" on center when using a 3/8" bending ply for the top surface or 6" on center when using a 3/4" thick top.

4. Drill a hole in the rib, outline both sides with VAK Tape to make it a vacuum template. We have drilled a hole in our table top and connected a vacuum line to the underside of the table. Place the vacuum rib over the vacuum hole and the work piece on top of the jig. Turn on the vacuum and everything is held to the table top with up to 1800 lbs/sq.ft. of strong holding force.

5. Template rout the ribs using the ALL-in-ONE vacuum pressing and clamping system even while the system is maintaining the vacuum pressure in the bag. The work piece is held to the template, which is held to the table using vacuum.

6. The base can be made from 1/4 plywood or thicker. Cut a slot in the base for better evacuation. Use a right angle vacuum jig to hold the ribs while screwing in place.

7. The press will apply 1800 lbs/sq.ft. of pressure, so the ends must be braced or they will collapse.

8. Nail the top pieces to the form.

Tip
Sand or round the edges so that the bag does not see any sharp edges. Always test a new form by putting it in the bag under full pressure. If you hear a creaking sound, that is a warning itís about to break.

To square the sides, slide the workpiece down the side, clamp and run it through the table saw, trimming part of the form if necessary. Just make sure you donít hit any screws or nails in the form.

Ed Ferri is the founder of Quality VAKuum Products, Inc. and has more than fifteen years experience working with vacuum applications. QVP specializes in vacuum pressing and clamping equipment for the woodworking and plastics industries. For more information visit the QVP website at www.qualityvak.com or call 800-547-5484.