Vacuum pump for a 16x20 easel

[SadChi]

Hello,

I would like to build a vacuum 16x20 easel. Could you advice what vacuum pump will be enough? Which one can be bought on *bay?
I saw several pumps like item 220467052190 at low prices, are they good?

Thanks.

[PenGun]

I've used fridge compressors, they are free, but I'm not sure they'd have the volume to do the job.

[Robert Hughes]

You may also be able to use a small vacuum cleaner, such as the ones 3M used to make to clean keyboards and electronic components. I have a friend who uses one of these to clear acetate shavings from his LP record cutting lathe.

[Colin Graham]

It's probably not rated for continuous duty like the industrial pumps are, so it might burn up fast. Plus it sounds slow- 'just connect an airline and it pulls vacuum within 2 minutes'..?

I found one like this (http://cgi.ebay.com/Gast-New-Hermes-Vacuum-Pump-Vanguard-DOA-V188-AA_W0QQitemZ200380977288QQcmdZViewItemQQptZBI_Pumps?hash=item2ea7a31088&_trksid=p3286.c0.m14) for not much more. Runs all day without overheating and is instantaneous, even with 12' of air hose and two ports.

[John Jarosz]

The pump shown by item #220467052190 is an air powered venturi pump.. It consumes a huge amount of air and is woefully inefficient.

The item listed by Colin is the way to go. Should be fine for any vacuum frame.

john

[Drew Wiley]

If your exposure are not too long simply use a small vacuum cleaner, even a cordless one. Doesn't take much. Just make sure the filter is really clean. But never
use a peristaltic or diaphragm type pump, which will actually cause misicule surges
at the easel and possibly affect sharpness. And avoid too strong a vacuum unless you have a bleed-off valve. Be certain that there is plenty of internal honeycombing
within the easel itself, so that the top doesn't deflect when vacuum is applied.

[Colin Graham]

Hmmm.. It occurs to me we might be talking about separate things. I was under the impression you were making a vacuum frame for contact printing- I have no experience with easels to hold silver paper flat when enlarging, so the requirements there might be less. Even so, like John says, stay away from the self-contained venturi pumps, they are inefficient. Typically a venturi needs a separate high duty compressor to run it.

[John Jarosz]

Yes, I assumed we were talking about a contact printing vacuum frame. In fact, I have a picture of the one I built.

If you are talking about a vacuum easel for enlarging, then those will require a much bigger pump as you will have orifices that are always open and the pump will need to pump the air rushing thru open orifices while maintaining a negative pressure at the openings that are blocked by the paper.

In any event, here's a photo of my hard rock maple vacuum frame. The seal is surgical latex tubing. The flexible member is clear vinyl from the hardware store. Use single weight glass if you are using a UV lightsource.

[jeroldharter]

Yes, I assumed we were talking about a contact printing vacuum frame. In fact, I have a picture of the one I built.

If you are talking about a vacuum easel for enlarging, then those will require a much bigger pump as you will have orifices that are always open and the pump will need to pump the air rushing thru open orifices while maintaining a negative pressure at the openings that are blocked by the paper.

In any event, here's a photo of my hard rock maple vacuum frame. The seal is surgical latex tubing. The flexible member is clear vinyl from the hardware store. Use single weight glass if you are using a UV lightsource.

That's a beauty.

[wfwhitaker]

I have two Bychrome vacuum easels, a 16x20 and a 20x24. Each came with a vacuum unit that's very similar to a home vacuum cleaner, produces about the same vacuum and produces at least as much noise. I have another large vacuum easel made by Durst which uses a large Gast vacuum pump. I'm not sure why the difference, but the Bychrome easels have larger holes. The pumps with the Bychrome easels appear to move a larger amount of air more slowly while the Gast pump moves a smaller amount of air more quickly. I think of it as low impedence vs. high impedence, but I may not be completely accurate in my analogy. At any rate, there is probably a relationship between the qualities of the pump used and the load to which it is attached (meaning hole size, tube diameter, etc.). For simplicity's sake, if I were to build such an easel, I'd plan on simply using a home vacuum cleaner or a wet-dry vac, possibly with a bleed valve as mentioned to limit the amount of vacuum pulled. Then drill whatever size holes are needed in the easel itself for it to work correctly. There should be no need buy an expensive vacuum pump. If you're making a vacuum frame for contact printing, that may be another story.

[Richard M. Coda]

Question. We have a central vacuum in our house. I don't have an outlet in the darkroom, but there is one in the wall in the hallway outside the darkroom. Could I possibly have a contractor put another outlet "inside" the darkroom and then just fashion an adapter for my Kostiner vacuum easle? Nice thing is it is exhausted to the garage, is quiet and is not so powerful to cause problems.

[John Jarosz]

That's a very cool idea. i think it would work. Anything to get rid of the noise.

I would connect the easel to one of the existing fixtures and test the idea.

John

[Michael Rosenberg]

Try looking for a pump on McMaster Carr web site. You only need to pull -5 to -10 psi, so it would help to have a vacuum guage. Also look for used pumps from companies that resell equipment from biotechs that folded. They advertise on ebay frequently. Look for an oil-less pump, or have a bleed off valve so that when you shut off the pump it does not draw oil back into the frame. You will need to have a moisture filter on the air-intake port of the pump so you do not contaminate the pump with moisture (available on McMaster Carr).

Mike