Replies

1. 
   gulfstar | Aug 21, 2024 04:03pm | #1

   No, it will not apply enough pressure to compress the glue joint, perfect vacuum will apply 14,7 psi, that makes 30 psi since from both sides, you need at least 100, idealy 250 psi

2. 
   ebourg | Aug 22, 2024 11:36am | #2

   Hmmm, so gluing two 12"x12" boards together would give 12X12X14.7 lbs clamping force, or a bit over 2100 lbs total... not enough? (250 psi would give 12x12x250 = 36000 lbs.. !!)

1. 
   gulfstar | Aug 22, 2024 05:42pm | #5

   Your calculation is correct, so take the 144 square inches and transpose it as 3/4 inches edge glue joint, that would make a 16 ft long glue joint, if you apply 14,7 psi, and each bar clamp develops 2000 lbs then all you need is two clamps, for 36,000 lbs, 18 so one every foot or so.

1. 
   ebourg | Aug 22, 2024 08:06pm | #6

   Got you, I was not thinking of edge gluing but review of the original post would indicate that is the case. For sure if he/she is gluing up a panel then clamps would be the obvious way to go.

3. 
   rclark5 | Aug 22, 2024 12:15pm | #3

   I read it as edge-joining the two pieces of wood, in which case, vacuum bagging would be a lot of work, and apply much less force than standard bar clamps.
   If you are face joining, then vacuum bagging would be the way to go.

1. 
   john_c2 | Aug 22, 2024 02:53pm | #4

   What he said.

   The major issue with edge joining two wide boards is getting them to line up. It usually requires perpendicular clamps, cauls, mallet blows, and finagling. I don't see how you do that while it's inside a vacuum bag.

   You're looking for a solution to a problem that doesn't exist. Just clamp the two panels together.

4. 
   doctom | Aug 22, 2024 11:02pm | #7

   SinceI had referenced veneer glue up in my question I assumed that everyone would know that I was asking about glueing two boards together, face to face, to make a thicker panel.
   I thank you for your replies, but what is the consensus for glueing two flat, well planed boards face to face?

5. 
   _mj_ | Aug 23, 2024 06:04am | #8

   A vac bag is a good choice for your face glueup. Epoxy is a good choice to keep the panels flat. Putting water between 2 panels you want to stay flat is a bad idea.

   (I read your post as an edge-glueup too.)