vacuum easel design that doesn't require masks for smaller paper. How's it work?

[vinny]

http://www.ttind.com/vacuumoverview.html
I came across this in my search for designs.

[Dan Henderson]

Vinny: thanks for pointing me to that video on vacuum easel construction. I emailed the guy last night and by this morning he had sent me a copy of the video. Seems pretty straightforward once the proper perforated steel is located.
Dan

[Jim Michael]

If it's a factor on a horizontal easel you could turn off outer regions when not needed by a valve. Use a manifold to divide the the airflow proportionally by region, then turn off those regions not being used. Looks like Grainger has a good selection of perf steel.

[Jim Jones]

Some of us have built vacuum easels. I drilled small holes in Masonite on a half inch grid, although others have used pegboard. Internal bracing kept the Masonite from compressing inward due to the vacuum. Guides along two sides permitted precise placement of the photo paper. An ordinary vacuum cleaner provided the suction. A steel top would have been nice for using magnetic guides, but would have been more difficult and expensive to work with.

[vinny]

Some of us have built vacuum easels. I drilled small holes in Masonite on a half inch grid, although others have used pegboard. Internal bracing kept the Masonite from compressing inward due to the vacuum. Guides along two sides permitted precise placement of the photo paper. An ordinary vacuum cleaner provided the suction. A steel top would have been nice for using magnetic guides, but would have been more difficult and expensive to work with.

Valves, possibly but I doubt it.
Jim, i'm asking about the design in the link I provided. A regular box full of holes isn't going to hold paper flat unless they're all covered.

[Erik Larsen]

That unit in the link you gave looks pretty slick. I can't quite wrap my head around how it works though. I wish I could see a bigger picture of the surface and figure out how it can hold a vacuum on small prints with the rest of the easel unmasked? It looks very simple but my simple mind can't figure it out.
Erik

[Jim Jones]

Valves, possibly but I doubt it.
Jim, i'm asking about the design in the link I provided. A regular box full of holes isn't going to hold paper flat unless they're all covered.

True, but the holes outside the image area are easy to cover with a paper frame that also shows where to place the photo paper.

[vinny]

True, but the holes outside the image area are easy to cover with a paper frame that also shows where to place the photo paper.

right, I think we all get that. Still doesn't answer my question though.

[Donald Miller]

I believe that if you have a vacuum pump with sufficient CFM that there is no need for a manifold or valves. The size of holes and calculations for CFM required would be a rather straightforward.

[polyglot]

I'm with Donald. Big enough pump solves the problem; you need lots of CFM but not a lot of pressure; a scroll-blower would be perfect.