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  1. #1

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    Vacuum Easel Vibration Troubles

    I have a Bychrome 20x24" vacuum easel that I'd like to use with my horizontal enlarger. Since the vacuum unit sounds like a vacuum cleaner, I'm working with various duct options to minimize noise. Using 25ft of 1.5" inner dia. ribbed hose for sump pumps did not work out, as the
    combo made a noise appropriate for a banshee. (The dog is still recovering from the trauma of the test run.) Plan 2 involves rigid 1.5" inner dia. PVC pipe. One side of the pipe attaches to the vacuum unit, and the other end attaches to a flexible ribbed plastic hose that goes into the easel proper. A test run showed this solution to be much quieter, and the suction was adequate to hold a large piece of construction paper on the easel. I noticed, though, that the easel vibrates when holding the paper, which can't be good for image sharpness. Does anyone have experience with a vacuum easel? Did you have vibration problems? If so, did you find a solution? I noticed that the seal between the hose that goes in the easel and the easel is not air tight, as I can hear a whistling sound from that connection. Perhaps this air leak causes vibration? I'll try to get a better seal and see if that helps, but I'm open to other suggestions. I realize that I could simply tape, tack, or use magnets to hold the paper on a flat surface, but I'd prefer to use the vacuum easel.

    -Peter
    www.desmidt.net

  2. #2

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    No problem

    I have a vacuum easel. Works nicely. Lots of vibration but this is not transmitted by the hose. Lots of noise too.

  3. #3

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    Claire, so when you put a piece of paper on the easel and turn it on, you can't feel any vibration when you put you hand on the paper? I'm not talking about the vibration from the casing of the vacuum unit. The hose discouples the easel from that. In my case, the easel itself vibrates, either from the oscillating suction, or from the air leak where the hose goes into easel.

  4. #4
    David A. Goldfarb's Avatar
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    Try posting on the Azo forum at www.michaelandpaula.com. Michael Smith uses a vacuum easel, and I think he runs the hose through the wall outside the darkroom so the vacuum unit is in a closet or outdoors, so the noise is elsewhere and the possibility of sympathetic vibration from the motor to the enlarging table is eliminated, though that doesn't rule out the possibility of the oscillating suction that you mention. It would be hard to guess what the cause of the vibration is without seeing how it's set up.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
    Photography (not as up to date as the flickr site)--http://www.davidagoldfarb.com/photo
    Academic (Slavic and Comparative Literature)--http://www.davidagoldfarb.com

  5. #5

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    David,

    Thanks for the suggestion. I'll probably give your suggestion a whirl tomorrow if I don't figure the problem out before then.

    Just FYI, there are two types of vacuum easels. The kind I'm having the problem with is simply a box with a metal face that has 1/16th inch holes every inch or so over it's surface. The paper is held over the easel, the foot switch is depressed, and the paper is sucked to the metal surface by the air being drawn into the holes. The suction unit is really a glorified vacuum cleaner that provides high airflow but low suction trough a long flexible hose.

    The second type of vacuum easel, the type the Michael Smith uses I think, is more complex. Basically, it's a frame with a hinged glass top. On the bottom part there are many plastic nubbies that the print rests on. The negative is then placed on top of the paper, and the glass lid is closed. This forms and air tight compartment around the print. The special low air-flow/high pressure vacuum pump then sucks the air out. This pulls the glass down, which in turn squeezes the negative and print together. It's quite a different animal from what I'm talking about here. I do have an easel of this type as well, but it wouldn't work well for what I'm doing. Not only is it large and very heavy, I'd have to project the image through the glass, which I'd like to avoid.

    -Peter
    www.desmidt.net

  6. #6

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    If the easel itself is vibrating as you indicated then the type of vacuum pump that you are using is incapable of pulling a consistant vacuum. The problem is a design problem originating in the type or size of vacuum pump that you are using. There may be an oscillating vacuum/loss of vacuum condition causing the vibration.

    What you are wanting is a high volume and relatively low vacuum pump. I would begin to research this more completely by determining the air volume that you are needing to evacuate. This will require that you measure the total open air opening. This will need to be determined by measuring each hole surface area and then multiplying this by the number of holes that you have. Please be aware that a single weight paper like Azo will probably allow a certain amount of air passage through the paper. From this total open area measurement you will be able to compute the volume based on vacuum that you need to maintain.

    A possible source for vacuum pumps that may be better suited to your application is WW Grainger.

    Good luck.

  7. #7
    Charles Webb's Avatar
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    For what its worth..........
    I have a 16x20 Bichrome, no transmited viberations, and the pump is quiet enough to sit directly under the enlarger. Has excellent vacuum etc. Purchased it used off of Ebay.

  8. #8

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    I bought my Bi-chrome used off Ebay as well. The pump is the original Bi-chrome. I would think that it'd be of the proper type, and it seems to be working properly. The hose that goes into the easel, on the other hand, is obviously not original. It looks like something from a shop vac, and the fit to the easel isn't air-tight. I'm hoping that's the problem. I'm not going to be using single weight paper with this setup. I think that the vacuum might damage it. I just wanted to check that the vibration wasn't inherent to Bi-chrome easels, since I could spend a lot of time trying in vain to eliminate it. Grainger has some useful things, but I think that they only sell to businesses.

  9. #9
    edz
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    Quote Originally Posted by Peter De Smidt
    I have a Bychrome 20x24" vacuum easel that I'd like to use with my horizontal enlarger. Since the vacuum unit sounds like a vacuum cleaner, I'm working with various duct options to minimize noise. Using 25ft of 1.5" inner dia. ribbed hose for sump pumps did not work out, as the
    combo made a noise appropriate for a banshee.
    Noise is the chief problem with vacuum easels---- why I like mine small (where they can use small vacuums that don't make too much noise (I've now taken to experimentation for another project with an electrostatic frame which seems strong enough for horizontal, completely silent, use very little power and so be suited, as a copy holder, even to a library). The larger the easel and the better suited it is to sucking paper--- there are some frame designs that minimized the number of holes to reduce the demand on the vacuum but there just don't get things flat--- the more power they need.
    Large easels tend to draw KWs of power and use 3-phase power so they, in our amateur settings, suck by multiple sematics. These large motors also tend to be less than maintaince free and will as their bearings get worn make a lot of noise and vibrate like crazy--- which increases the damage to the bearings. The bearings tend to be industrial cartridges and so are easy and relatively inexpensive to replace.
    Edward C. Zimmermann
    BSn R&D // http://www.nonmonotonic.net

  10. #10

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    Last weekend I tried the vacuum easel I have just built for the first time. The surface plate is 12" x 10" with 760 1.5mm dia holes on a 1cm grid (I was pretty good at drilling 1.5mm holes by the time I finished!) I have it connected to a vacuum cleaner, but having that it the room with me was pretty noisy, so I bought a long vacuum cleaner hose, drilled a hole in the ceiling and ran it into the loft space. With the cleaner up there I just hear a distant whooshing and get no vibration problems. I experimented with different vacuum sources (fans, car vacuum cleaner, etc.) but found the suck of a decent domestic cleaner to be necessary for the heavier doubleweight papers. Results were excellent and I'm delighted to have done away with the dust problems of the glass cover sheet that I previously used for borderless prints.
    I built the easel so that I can also use it on the horizontal copying stand that I previously made. One minus point is that at this cold time of year I have some heating on in the darkroom but every time I switch on the easel the uncovered holes suck up all my nice warm air and vent it into the loft !
    Steve

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