Another Vacuum bag question

[Mark Singer]

I bought a small bag yesterday and the sales man said to make the grooved board that goes inside. He said the hose should go about 6" into the edge of the board and will draw air through the pores in the MDF or ply....is that correct? It seems very strange

[Chris Barton]

Hey Mark,

When I made my platten board for my vacuum system I cut groves on both sides of the board approximately 1/4" deep and then at the edge of the board I drilled a hole just larger than the hose about 6" deep at the intersection of two of the groves. The where the hoe and groves met I drilled a 1/16" hole that intersected both the groves and the hose hole. I will run down and take a picture of it so you can see because I realize it is almost impossible to describe...

[tod evans]

mark, i found nylon window screen is a very effective way to help evacuate the bag. if i`m doing stuff that has sharp corners an old piece of carpet makes a good pad to protect the bag. tod

[Thomas Prondzinski]

Mark

My lower platen is made of melamine(glue won't stick as well) I cut a grid pattern about an 1\8 deep about 6 inches sguare,at the intersection of two of the lines about 2 inches from the edge i instlled a plastic grommet supplied by the maker of my press so when something is put in the bag and the vaccum line is hooked up the nipple of the line will go through the bag and into the grommet so it can't get plugged. can post pics if needed.


Tom

[Chris Barton]

Mark,

Here are a couple of pictures that should help; the first picture shows my platten board which has rounded edges on all sides and the same saw kerf pattern about 1/4" deep on both sides. The second picture is a close up of where the vacuum hose inserts into the side of this board where a saw kerf is on both sides. In the picture "A" is the hole for the vacuum hose, "B" is the samller intersecting hole that goes completely through the board and through hole A, and "C" is the saw kerfs. Does this make any sense?

And PS: what the sales guy told you was bunk...

[Charlie Plesums]

... and will draw air through the pores in the MDF or ply....is that correct? It seems very strange
Back in the days when I was looking at a CNC, I was surprised to learn that the work was held to the table by a vacuum sucked through a sheet of MDF. At most, the hard surface of the MDF was removed by the CNC router, but the vacuum through the MDF was ample to hold the work in place, even when attacked by a fast moving, high power, high speed cutter.

The other half of the story was that the CNC machine, while expensive, wasn't out of the question, but the 15 hp vacuum pump (or larger) to use as a hold-down (not included with the CNC) ruled out that idea, from a noise, power, and cost perspective.

Bottom line, the salesman might not be crazy, but that is not the way it is usually done in vacuum veneering.

Charlie

[Mark Singer]

Again you answered my questions.... thanks I really appreciate SMC just on this one item the members have saved me hundreds of dollars on stuff I didn't really need... We help each other!