I am thinking about making a simple vacuum easel for printing. The idea is to make a very slim 1/2" sealed box of required paper size from plastic or aluminium and drill holes over top surface. Then use DC fan like those in PC power supplies to suck air from it. Low-profile fan is mounted flush with surface into appropriate opening either from paper side (requires extra space) or bottom (needs some sort of feet to let air flow out from beneath).

I feel like DC fan can provide enough suction to hold paper flat. Any comments?

-- Leo Bodnar (lbodnar@armstrong.com), May 30, 2001

Answers

I have put very basic drawing at http://www.geocities.com/leobodnar/vacuum_easel.html to illustrate the idea.

-- Leo Bodnar (lbodnar@armstrong.com), May 30, 2001.

nice drawing Leo!

As to the question.. no idea! How do commercial vacuum easel's work? With the motor mounted to the frame I'd be worried about vibrations.

-- Nigel Smith (nlandgl@unite.com.au), May 30, 2001.

At a previous job, we had a vacuum easel for an electrostatic plate maker (basically a big camera for copying blue prints). The board was about 36" x 48". The surface was sheet metal with a grid of 1/8" holes, about 1/2" apart. The actual vacuum was applied via a series of channels in the wood sub-base, but there were only 8 slots in a star pattern. You don't need to suck on the entire surface. The vacuum was supplied by a 1HP vacuum motor attached by a flexible hose. Vacuum motors are designed to work at an extremely high negative pressure and small airflow. I think a little DC fan would burn up quite fast because it's not designed to create a vacuum. A compressor from an old refrigerator would be a better thing to use. Or an old canister vacuum sweeper if you can stand the noise.

-- Dave Mueller (dmueller@bellatlantic.net), May 30, 2001.

Not sure why one would go to the trouble. If you want borderless prints, various schemes have been published using spray adhesive to make a tacky surface on a board. It isn't terribly sticky, so the paper comes right off after the exposure. There was (is?) a Saunders borderless easel that uses slightly sloped adjustable rails to hole the edges of the paper. That would be pretty easy to make, too. Vacuum easels usually have very small holes or narrow slots, as you don't want to distort the surface of the film or paper. A computer fan probably won't generate enough pressure, though a 120VAC 8" version of the same thing might be close. (check surplus electronic outlets) It takes a surprising amount of power to do this, especially if you have any air leaks. That's why it's common to mask the unused area of the easel to keep the suction up. Vibration is almost certain unless you couple the pump/fan with flexible hose. Almost all the big graphic arts cameras used vacuum backs and I remember them as being fairly noisy!

-- Conrad Hoffman (choffman@rpa.net), May 30, 2001.

"Hold the edges", not hole!

-- Conrad Hoffman (choffman@rpa.net), May 30, 2001.

Before we had vacuum easels, I put some double sided tape down on the corners. This was made less sticky by putting a cloth (our shirt sleeves on the side of the tape to hold the paper) on the tape to pick up some of the fine lint that is naturally on your shirt, a few times. This made it less sticky but sticky enough to hold the edges down. If your printing 20x24, a board of wood, 20x24 was used. If your printing 16x20, a 16x20 board was used. This way there was no guessing about placement. It works great. Cheers

-- Scott Walton (scotlynn@shore.net), May 31, 2001.

You would probably be better off selecting a different kind of fan, like a squiral cage or even better a vacuum pump or use the intake on a compressor. These can be found inexpensively from surplus places. Their size means you would need to connect them via a hose to your easel; this would also probably help reduce vibrations.

Propeller-like fans, like the DC fans used in computers, are good at moving relatively large volumes of air against low resistance / pressure differential. They are not very good at creating much of a pressure differential, which is what you want for a vacuum easel.

-- Michael Briggs (MichaelBriggs@earthlink.net), June 01, 2001.