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LF_rookie_to_be
19-Feb-2012, 08:21
Could anyone provide some more information on a Thomas vacuum pump? Here are the specifications from the Gardner Denver site:

Model Number: 007CDC19
Product Family / Type: Diaphragm
Operating Mode: Vacuum
Medium: Gas
Vacuum Flow Rate: 0.7 cfm / 18.4 l/min
Vacuum Continuous: 23.0 in.Hg / -780 mbar
Max Intermittent Vacuum: 23.0 in.Hg / -780 mbar
Max Vacuum Restart: 23.0 in.Hg / -780 mbar
Energy Supply: DC
Voltage: 12V
Motor Rating: 22.4 W
Current Drawn: 3.8 A
Motor Type: Permanent Magnet
Motor Protection Class: F
Speed: 2800 rpm
Weight: 2.90 lb / 1.30 kg
Ambient Temperature: min.50 °F / 10 °C
Ambient Temperature: max.104 °F / 40 °C
Stroke: 0.20 in / 4.8 mm

My questions are:
1. Is it perfectly safe to power it using a 12V/60W/5A AC/DC protected converter for halogen/LED lights?
2. Does it look powerful enough to give enough pull for, say, a 30x40" FB double-weight sheet (horizontal projection)?
3. Do the length and bends in the hose affect vacuum pull?

Thanks.
LF_rtb

Erik Larsen
19-Feb-2012, 08:31
I'm not sure about the electrical requirements, but I think you would want a vane pump and not a diaphragm for an easel pump. A diaphragm pump would work for a contact frame to suck glass down but I think the pulsing on an easel would not be ideal. I could be wrong however:)
Regards
Erik

LF_rookie_to_be
19-Feb-2012, 08:38
Erik, do you mean the pull of this type of pump isn't completely constant and continuous for a vertical easel?

Erik Larsen
19-Feb-2012, 08:55
That right, it pulses as the diaphragm moves vs say the continuous suction of say a vacuum cleaner.
Regards
Erik

LF_rookie_to_be
19-Feb-2012, 09:07
Thanks, Erik.

Jim Jones
19-Feb-2012, 09:24
A vacuum chamber can filter out pulsations from the diaphram pump. Kinks in a vacuum line would affect performance, but modest bends won't. The vane type vacuum pumps I once used for 32x40 graphic arts film were much larger, with maybe 1/4 HP motors. They would draw down to about 24 PSI. Requirements for contact printing halftones is much more stringent than holding photo paper in a vertical easel. EVen a lowly vacuum cleaner might work for a well designed easel. You may need a clamp to hold the top of the paper during draw-down.

LF_rookie_to_be
19-Feb-2012, 09:38
Jim, say a 32x45" large, 2" thick easel has two inner compartments connected with a tunnel. The inner vertical third is separate and doesn't have a grid of holes on the top surface. The pump's inlet is on top and connects to the middle of the aforementioned tunnel. Could this design minimize the pulsations from this particular pump?

Erik Larsen
19-Feb-2012, 09:58
If your easel is 2 inches thick, I would just hook up a vacuum cleaner to it. I've done 40x50 inch prints on a peg board easel with a vacuum cleaner without problems except the exhaust port of the vacuum cleaner fills the darkroom with warm air pretty fast. I have a diaphragm pump for my contact frame and it would not hold enough compared to my vacuum cleaner on my set up. If you don't have a vacuum cleaner that would work, a decent vane pump is probably as expensive or more than a quality vacuum cleaner or shop vac. IMO, I just don't think you will be happy with a diaphragm pump. If you already have the pump give it a try, maybe I'm just sucking air:) (pun intended) :)
Regards
Erik

LF_rookie_to_be
19-Feb-2012, 10:08
Erik, the pump is available to me at cca. U$25, but, apparently, it seems even that's too much. I would rather use something a little less noisy and cleaner than a shop vac. What about various water pumps? I've looked into those and some are oil-less and rotary (though more than $25...).

Erik Larsen
19-Feb-2012, 10:24
Sorry, I'm not sure if a water pump would work and you're right that a vacuum cleaner is noisy for sure. I put mine in closet and ran a hose to the easel. Wish I could be more helpful.
Regards
Erik

Jim Jones
19-Feb-2012, 11:50
Jim, say a 32x45" large, 2" thick easel has two inner compartments connected with a tunnel. The inner vertical third is separate and doesn't have a grid of holes on the top surface. The pump's inlet is on top and connects to the middle of the aforementioned tunnel. Could this design minimize the pulsations from this particular pump?

The inner compartmentation isn't critical with a vacuum cleaner pump. However, the front and back of the easel should be seperated by a number of spacers so the vacuum doesn't distort the front of the easel.

LF_rookie_to_be
19-Feb-2012, 12:08
Could the compartmentation help with a diaphragm pump? I know it isn't the best, but this little pump is the best deal I found so far.

Sevo
19-Feb-2012, 12:19
That right, it pulses as the diaphragm moves vs say the continuous suction of say a vacuum cleaner.


Enough of a buffer space will settle that issue. Membrane pumps are standard wherever a modestly strong vacuum pressure is needed and not much air transport is required - using anything else for an easel would not save money, and nonetheless have more issues and worse results.

LF_rookie_to_be
19-Feb-2012, 12:23
Sevo,

How to create buffer space and what volume is needed for this purpose and size?

Erik Larsen
19-Feb-2012, 12:31
Could the compartmentation help with a diaphragm pump? I know it isn't the best, but this little pump is the best deal I found so far.

Give it a shot, for 25 bucks it isn't going to hurt much if it doesn't work as intended plus you can use it for a contact frame pump if you want. I'm just passing on my experiences with my setup.
Good luck
Erik

Sevo
19-Feb-2012, 15:35
Sevo,

How to create buffer space and what volume is needed for this purpose and size?

I use a empty 100cc gas-washing bottle (from a laboratory glassware shop) with my darkroom easel, as that was cheap and available off the shelf at the place I got the pump from. But even a longer bit of hose would probably do the job.

Drew Wiley
19-Feb-2012, 17:13
It requires very little to draw down even a print this size. More often people make the mistake of having too much pull. Diaphragm pumps pulsate enough to make most easels jitter a little. You can see this under an easel grain magnifier. But don't expect much help from Thomas. They're out of business for all practical purposes unless you're a mfg yourself. Even an ordinary household little vac will pull paper flat, though I
can't recommend this route because you'll be recharging the batteries way too often. Regular home vac cleaners throw a lot of dust around unless you bring the hose in thru the wall and have the unit itself outside.
You'd need a bleeder valve or handle too to reduce pressure. Variable power HEPA vacs are nice but not exactly cheap.

Jim Jones
19-Feb-2012, 17:31
A 32x45" easel 2 inches thick has plenty of volume to even out pulsations from any vacuum pump. It could be considerably thinner and work as well. The old vacuum cleaner I used years ago on a small easel drew maybe 5 PSI vacuum. This would mean over three tons of suction between the front and back of your easel. It sounds like a lot, but with spacers every few inches apart within the easel, there should be no problem. That pressure is exerted merely in trying to draw the front and back of the easel together, and to some extend, drawing the paper down onto the easel. The more powerful pump on almost as large a vacuum table for graphic arts used a 1 quart canning jar to even out any variations and perhaps to catch some dust in a set-up with short hoses.

LF_rookie_to_be
20-Feb-2012, 12:55
I use a empty 100cc gas-washing bottle (from a laboratory glassware shop) with my darkroom easel, as that was cheap and available off the shelf at the place I got the pump from. But even a longer bit of hose would probably do the job.

Sevo, thanks for this bit of advice, I'll try to tame the pulsing with a gas-washing bottle.

Larry Gebhardt
20-Feb-2012, 14:44
The vacuum pump I have for my easel sounds just a vacuum cleaner. It does move too much air in the room, so I don't use it. Someday maybe when I get a longer hose.

Jim C.
20-Feb-2012, 19:31
Don't know much about lab glassware other than beakers and graduated cylinders but if you go with a gas washing bottle
that's glass make sure it's vacuum rated, the pump your using doesn't seem like it's strong enough to implode the bottle, but better
safe than surprised. If you're creative you could possibly use a rechargeable soda water dispenser, cheap enough to find in thrift stores
sturdy enough to not implode, you'll need to be creative with the plumbing.
Even rotary vane pumps vibrate, I know I have two 5 CFM ones I use for vacuum bagging / vacuum forming the longer
your vacuum line is the less vibrations.

Michael Clark
20-Feb-2012, 21:59
I had an old 73 Ford PU that used coffee can size can to hold its vacuum for the heater controls in the dash,might take a hike to the local junk yard and find a vacuum canister there.

Mike

Rick A
24-Feb-2012, 04:50
I had an old 73 Ford PU that used coffee can size can to hold its vacuum for the heater controls in the dash,might take a hike to the local junk yard and find a vacuum canister there.

Mike

Why not go to the grocery and buy a large can of broth. All you need to do is drill apropriate sized hole in the top, pour out the contents and rinse, then epoxy the correct size tubing to the can. I'm sure that would cost less than what a salvage yard will charge plus you can have it up and running sooner since you don't have to hunt the thing in the wrecking yard.

Jim Jones
24-Feb-2012, 10:27
Consider the math: a 32x45x2 inch vacuum easel has a capacity of several gallons. It would be a large broth can that makes much difference to such an easel.

Sevo
24-Feb-2012, 12:16
Consider the math: a 32x45x2 inch vacuum easel has a capacity of several gallons.

YMMV - one of the most common factory made types hereabouts uses routed channels (in a otherwise solid board), and accordingly has much less capacity.

Besides, you have to account for differences in cross-section - a wide-bodied vessel does have quite a different buffering action than a low cross-section channel network, so it is not entirely a matter of capacity.

Jim Jones
24-Feb-2012, 13:56
YMMV - one of the most common factory made types hereabouts uses routed channels, and accordingly has much less capacity.

Besides, you have to account for differences in cross-section - a wide-bodied vessel does have quite a different buffering action than a low cross-section channel network, so it is not entirely a matter of capacity.

Very true. The OP mentioned a 32x45x2 inch easel in one post. We should know what vacuum easel the OP actually has or will buy or build before offering specific advice. The 32x40 vacuum printing frames I used had very little capacity, and used a quart jar in the vacuum line.

LF_rookie_to_be
25-Feb-2012, 02:35
Jim,

I plan to build an easel with a 33x46" surface, 2,5mm dia. hole every 2 inches, 1 1/2" total thickness. This easel would be used vor horizontal projection as well as on a screenprinting table, and I plan on routing channels between each hole. The latter was advised to me on another forum and has the purpose of keeping the air flow continuous, though I'm not sure if it's really necessary.

Jim Jones
25-Feb-2012, 07:02
For large holes and fairly wide spacing, pegboard may save you much trouble. My only vacuum easel was for 11x14" paper with holes drilled on a 1/2" grid. Drilling and chamfering over 600 small holes was boring (pun intended). Routing channels proved unnecessary. Once the paper is drawn down, there should be little air flow. The big contact printing frames I used had fabric to channel air away from the film, but unlike an open vacuum easel, the frames sealed at the edges.

Rick A
27-Feb-2012, 16:41
Consider the math: a 32x45x2 inch vacuum easel has a capacity of several gallons. It would be a large broth can that makes much difference to such an easel.

How about a used helium cylander. I have a couple that are each the size of a 20lb propane tank and they are easily modified for pressure tanks, I'm sure they would be just as good as vacuum stabilizers.

Sevo
28-Feb-2012, 05:00
Just about everything mentioned will be safe within the levels the average aquarium pump can deliver - and your paper will stand even less, or it will get pitted at the vacuum holes. In real life, the regular clear vinyl hoses collapse first, so that you cannot even build up that much vacuum.

If you have had an attack of tuning frenzy and scaled up all your kit, pump and hoses to high vacuum specs, now is the moment to discover that you could have had better results for less money - and that you now need an automatic pressure control valve to tame your oversized pump...

LF_rookie_to_be
28-Feb-2012, 09:34
At this moment, I just have the pump, but will look into all the mentioned solutions when the easel is finished. Expect more news in two or three weeks.