Vacuum Easel Vibration Troubles

[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. (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

 

[Claire Senft]

No problem

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

 

[Peter De Smidt]

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.

 

[David A. Goldfarb]

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.

 

[Peter De Smidt]

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

 

[Donald Miller]

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.

 

[Charles Webb]

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.

 

[Peter De Smidt]

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.

 

[edz]

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.

 

[Steve Roberts]

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

 

[Bruce Osgood]

Build Your Own ?

............ 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!) ..............
Steve

Steve, this has been a long time rolling around in the back of my brain. I would think you considered Peg Board as the flat surface because it is pre-drilled but you must have rejected it for some reason. Am I right? If so, what was that reason?

 

[Claire Senft]

No vibration

The easel I am using is not particularly refined..no vacuum control to reall speak of for different paper size..thank God for creating duct tape...I think it was on the fourth day. It is heavy though. It have a heavy layer of felt glued to the backside at the factory. I have not weighed the easel but it must be approaching 25 pounds.

 

[glbeas]

Peter you should probably try just covering the unused area of the vacuum bed with sheets of paper to allow for a full vacuum buildup. That will pull all surfaces in tight and the vibration should stop.

 

[Peter De Smidt]

Hi Gary. I'm sorry that I wasn't clear. I had the vibration when the all the holes of the easel were covered by a large piece of thick paper. So far, I've changed the fitting going into the easel to minimze air leaks at that point, and I've switched to a heavy flexible plastic vacuum hose. This one isn't ribbed. It's made out of a thick rubberly plastic that dampens vibration well. With these changes there is much less vibration. When it's on and covered with paper, I can still feel vibration by resting my palm on the paper, but it's much less. It's about the same amount of vibration that my color head has when the fans are running. It's small enough that I'll try making some prints and seeing if I notice any problems.

Thanks for all of the suggestions.
Peter
www.desmidt.net

 

[Steve Roberts]

Steve, this has been a long time rolling around in the back of my brain. I would think you considered Peg Board as the flat surface because it is pre-drilled but you must have rejected it for some reason. Am I right? If so, what was that reason?

Hi Bruce,
I must admit that I hadn't considered peg board, probably because I don't remember having seen any for years. If we're talking about the same product (hardboard with about 3/16th inch holes) I'd have been concerned about the board flexing inwards at the middle when under vacuum (perhaps some supports would have sorted that) and also the relatively large size of the holes. I went for smaller ones (in 1/8th inch thick ally) because a) they wouldn't get in the way of viewing as much as larger ones and b) the picture of the vacuum easel that someone showed me had little holes. Even my ally sheet has a central support "just in case". Perhaps larger holes would have allowed me to use a vacuum cleaner with less suck (and hence less noise).
I'm trying to convince myself that the uncovered holes are useful in hoovering up any airborne dust that would otherwise settle, but perhaps they are just sucking in more dust from outside the darkroom!
Best wishes,
Steve

 

[Clueless]

Whom else has vac easel solutions and problems? How do you rate the "suck" power for comparison purposes?

 

[Phillip P. Dimor]

You might want to invest in a neoprene or similar pad underneath the easel.
www.sciplus.com has plenty, larger ones with adhesive on the bottom even.

Rigid PVC won't help the vibration, i've always used a rubber hose that is similar to what one uses with a vacuum cleaner.

You could find a vacuum/pressure guage and possibly install it in the easel or inline with the vacuum hose. The vacuum is usually specified as Hg/in. My Sandmar/Olec vacuum frame pulls 15" Hg.

I've made a vacuum easel by cutting a hollow door in half and duct-taping the open end. Drilled many tiny holes in a pattern and hooked a tube up to it. It worked fine for me. I'm sure the door wasn't perfectly flat but my prints were sharp enough that I didn't care.

If you are printing 11x14's on your 20x24 vac. easel, you should place the 11x14 in the center and find scrap prints or pieces of paper to block off the surrounding holes in the easel. It makes for better suction..

The vacuum is usually rated in terms of Hg/in. My Sandmar/Olec vacuum frame pulls 15 to 18 Hg/in. The higher the number, the greater the compression/pull..
Anyone feel free to correct me on any of that..