Need some info on vacuum pumps please(for use in a Vacuum frame)

[John Jarosz]

You have a good combination there. I have the same pump. They are expensive at retail.

For silver you can run it at full vacuum. If you get into alt processes you may need to regulate the vacuum to avoid dessicating the sensitized material.

Keep the big frame, you need it eventually.

john

[Ron McElroy]

hey guys!

thanks for all the info so far, I guess its been my stroke of luck this evening !

literally "just" after I posted this thread, I happened to find a Nuarc vacuum frame on my local LA craigslist(one I didn't notice during my daily searches the past 3wks straight ). Well, I was kind of taken back, the stated outside dimensions in the listing was 26"x30", so it was much bigger than I'll ever need, so I'm still on the lookout for a smaller unit(16x20 or smaller)

-Dan

Great little frame you found. I used on just like it to compose film in the old days of prepress. While I'm sure that some vacuum frames were built smaller than yours, it will be a rare find. That is a small frame from the prepress world.

[nolindan]

If you get into alt processes you may need to regulate the vacuum to avoid dessicating the sensitized material.

Good point.

With porous paper the need for running at maximum vacuum is less as any trapped air can escape by bleeding through the paper. This isn't the case if you are contacting two pieces of film or film and a plate.

[Drew Wiley]

Nicholas, thank you for the clarification. Please forgive me if I'm one of those "overkill"
types, but I personally tend to find once I get specialized equipment I either jerryrig it
or find new uses for it later which involve more complicated processes. Refurbishing old
graphics equipment was fun for awhile, while I had time for it. I got a wonderful pin
registered 30x40-plus vac easel off a huge process camera and rigged it with masking
blades etc., and have made a number of other easels, including register types.

[aaron_mcfarlin]

Can someone tell me if it has to be a "GAST" brand rotary vane pump? Or would one of the inexpensive rotary vane pump available on ebay and amazon for $65 also work fine?
I couldn't figure out if there is a something different about them other than quality?
And what horse power do i need for a 20x24 frame?
I'm thinking to build myself something similar to what Dennis Ramos is selling (portable vacuum frame). Looks like he pairs his with one of these cheaper pumps.

https://www.ebay.com/itm/133796300366

[Tin Can]

I have a Gast, it is a Dry Vane rotary pump with filters for dust

The one you are examining is oil bath and spits oil mist everywhere, it is made and sold for Air Conditioning for a car or outside home AC box

If I had to use that nasty device again, I would put it OUTSIDE and run a vacuum hose into Dark Room

It will contaminate your enlarger, all prints, films, etc and may be impossible to clean said DR

[Kiwi7475]

Can someone tell me if it has to be a "GAST" brand rotary vane pump? Or would one of the inexpensive rotary vane pump available on ebay and amazon for $65 also work fine?
I couldn't figure out if there is a something different about them other than quality?
And what horse power do i need for a 20x24 frame?
I'm thinking to build myself something similar to what Dennis Ramos is selling (portable vacuum frame). Looks like he pairs his with one of these cheaper pumps.

https://www.ebay.com/itm/133796300366

I have a cheap one like what you’re showing and it works but boy it is messy. It leaks oil (they all do) so it’s sitting on a tray and I need to refill every time. I don’t use it often so I can put up with it but if you’re serious about this don’t get these oily mess cheapos.

[Drew Wiley]

No decent pump leaks oil. Millions are small high quality vac pumps are in use in food industry mass-production lines, the tech and pharmaceutical industries, and other applications requiring total cleanliness. I don't know how they're distributed at this time, but who makes em; but an ordinary outlet like Grainger might stock something small enough at reasonable cost, meaning at least a hundred bucks apiece. I have all I the options I need. Avoid Chinese made Amazonish knockoffs like the plague.

It's pretty easy to adapt handheld little household vacs if you bring the hose through the wall to isolate noise and output air, as well as improvise an basic bleeder valve to significantly lower the vac draw. If you want to talk full-lab high end variable-power true HEPA vac systems that's also an option; but there goes your next dream lens budget!

[Erik Larsen]

This is a good deal and will work fine for your frame. It is an oilless diaphragm pump. Nuarc used this exact pump on some of their plate burners with integrated vac frame. You can use one of those cheap ones but as others have noted you must get an oil mist filter for the exhaust because it emits a mist that you don’t want in your darkroom. The filter cost about as much as the pump!
https://www.ebay.com/itm/16363226945...UaAnlMEALw_wcB

[Drew Wiley]

Diaphragm pumps have a distinct disadvantage. Their peristaltic action actually jiggles things. This might not be a significant problem in a vacuum frame tightly compressed together for sake of contact exposure; but it you plan to use the same pump for a vacuum easel via enlarger projection, it can affect sharpness. That can be noticed under a grain magnifier when the pump action is on. (Been there, done that; learned the hard way.)