Vacuum Easel design

[resurgance]

Hi all,

I came up with a hair brained scheme to build a vacuum easel, after buying a roll of nice curly double weight FB paper.

It seemed like a good idea at the time. It doesn't work.

Please can anyone who has a working easel, preferably a commercial one comment on;
hole size, vacuum pipe size, vacuum pump size (cfm, amps) and if the system has a bleed valve?
General operating principles etc.

I designed the sub channels in a way that all vacuum circuits (there are 4 rows of holes for different paper sizes) are equal in length and fed from a centre point so that the air does not suck more on one side.

The primary problem I believe is that I have a tiny diaphragm pump that doesn't move enough air, and I'm using 6mm pneumatic line instead of the large sizes I am now seeing for commercial units. So not enough air flow.
2mm holes I used, and i suspect that the commercial ones have MANY holes all over the entire surface rather than 'rows' of holes?

I have vacuum solenoid valves so planned to have a footswitch that started timers and pulled down the row of holes at the top of the paper, then 5 seconds later pulled down the middle row, then finally the bottom row so I can hold the line as each one draws down.

Anyway, I should probably just tape the paper down, its just that its so curly and wants to roll up, also I really hate the idea of taking tape off and creating static, fogging the edges from static discharge, creasing the paper etc. Low tack tape still allows the edges to creep up.

The dimensions I use don't help, I want this for Panoramas, so print sizes will be say 1ft x 4ft, 20" x 4ft etc.

Thanks, Stew

[Tin Can]

THis looks like a Drew question.

I have no clue, but my 22x16" NuArc glass topped contact printer uses the OE lab quality vacuum pump pulling through 1/4" plain old air hose. The holes are in a rubber mat, there are 1000's of tiny holes and this thing sucks the glass tight in under 5 seconds to 20 in.-Hg and my hose leaks.

This is not a DIY system. This pump should pull almost 28 in-Hg. Almost like a HVAC standard pump, but oilless and has micron filters.

[resurgance]

Randy my pump pulls down to -85kap which I think is -25inHg? So it must be a cfm thing, or total flow. I don't think the pump has enough flow by a long shot.
Its great to hear that you use standard 1/4 inch line - tell me is that OD or ID?

[resurgance]

This is the pump I am using, but a 240VAC version. Oil-less laboratory style single stage diaphram pump.
http://www.coleparmer.com/Product/Gast_Vacuum_pressure_diaphragm_pump_single_head_1_1_cfm_220_240VAC/EW-07061-22

Now I am beginning to wonder if it is how I have bonded the top to the base, and if the base is porous. And my pump is too small...

Have had a pretty good track record with successful home builds of some pretty cool stuff, but I didn't really think this one through.... There seems to be a tad more to vacuum than I gave it credit for.

[Tin Can]

Randy my pump pulls down to -85kap which I think is -25inHg? So it must be a cfm thing, or total flow. I don't think the pump has enough flow by a long shot.
Its great to hear that you use standard 1/4 inch line - tell me is that OD or ID?

ID and it's crush proof. Gas station air hose. You can drive over it.

[Tin Can]

This is the pump I am using, but a 240VAC version. Oil-less laboratory style single stage diaphram pump.
http://www.coleparmer.com/Product/Gast_Vacuum_pressure_diaphragm_pump_single_head_1_1_cfm_220_240VAC/EW-07061-22

Now I am beginning to wonder if it is how I have bonded the top to the base, and if the base is porous. And my pump is too small...

Have had a pretty good track record with successful home builds of some pretty cool stuff, but I didn't really think this one through.... There seems to be a tad more to vacuum than I gave it credit for.

I agree you must have a big leak.

That pump seems expensive enough...

Have you tried the shop vac?

[resurgance]

I didn't pay that for it of course! Less than its worth but more than not much....

No I have not tried a shop vac, I just thought of a quick test, sellotape over each row of holes, and tried it - its my easel. Gauge only just climbs above nothing.

Hmph. Ok back to the drawing board on the easel. Fortunately this was pretty inexpensive.

[Tin Can]

I love DIY projects.

Sounds like you do too.

The second version of anything is better!

[resurgance]

Yup! My last one was making a box for a 50" x 90ft Classic FB roll, I came up with what I like to think of as a good design! Next one after the easel is to come up with some method of automating a panorama print roller for a sort of wallpaper tray. So I do not have to do it manually while selenium toning, washing etc. Kind of like;
https://www.fotoimpex.de/shopen/darkroom/deville-bobinoir-paper-winder-127-meter.html
Seems like a good idea.
I thought I could use an encoder and counter to motorise it :)
It may not happen yet....

[Tin Can]

Sounds great. Why not! This stuff keeps me out of trouble.

Maybe...I had a big DIY revelation last night and this one may take 20 years, which I doubt I have. So I need to write it down, sell it, start it and maybe never see it.

So it goes

[Jim C.]

Dpn't have a vacuum easel yet, mine is a work in progress tucked into a corner, but I think that your pump isn't pulling enough CFM's at 1.1
to overcome leaks in the easel. I have built a vac forming machine and it uses a 5 CFM HVAC pump that "stores"
the vacuum in two 11 gallon reservoir tanks. Tests when I was building it without the reservoir tanks took a minute or so
for it to grab a plastic garbage bag and seal the platen using just the 5 CFM pump.
The vacuum form press platen is made of aluminum and MDF with less than a 1/16 gap between the Al and MDF
the gap or channels are important with a low CFM pump since that gap has to be "emptied" before you get any vacuum at your drilled holes.

What material your is easel made of, and how big are your channels that feed the holes ?

[resurgance]

A 20year DIY? woah! now we're talking! Well Sir I wish you all the best - my mind is currently boggling!

Jim I agree, from what I can tell after reading a document about CNC vac tables, a 4x8ft table needs 6-7hp of vac. And now I am a little more versed on the type of vac - a shop vac moves a lot of air but uses more horsepower and doesn't draw down as much, a positive displacement pump draws down nice, but is expensive and doesn't move quite as much air etc...

I understand what you mean about the cavity in back being drawn down first. I had routed channels for each row of holes, the channels are fed from the centre, and were done with a round nose bit of 8mm diameter, so they have what I would have thought as enough cross sectional area at the time.
The easel I made from a dense but light material that actually could be a real contender for a porous top layer, as it leaks like a sieve! It is a 1" thick sign board I can't think of the official name for it, but its dense, not like foam core, and heavyish, but not like MDF.

I'm abandoning this now I think in favour of a new concept;
http://makezine.com/projects/make-41-tinkering-toys/shopbot-desktop-universal-vacuum-hold-down-system/

This looks like the ticket! The consideration for me will be weight - I have a Devere 5108, so I plan to take the baseboard off, and mount my vac easel in place - however the chassis is prone to sagging with too much weight which is totally undesirable obviously for print sharpness, as it will sag towards the unsupported side. I can't lock it in place as I need to be able to drop it when making wide pano's even with a 240mm lens and 4x10" neg.

I have found a pump 'locally' (well, same island as me) that hopefully stays within my budget (has lots of watchers...) and also bought a 2kw shop vac internal blower/vac unit.

So I think I have officially come up with hairbrained scheme #4587:v2

[Tin Can]

Just to clarify the 20 year DIY is not photo related.

I like your new plan and I can see myself doing the same for pano. I have a FOTAR 10x10 and a wider vac top would be nice. Please keep us updated.

I think you have it now.

[Jim Jones]

Long ago I made a vacuum easel for 11x14 paper from a thin hardboard top plate with small holes on a 1/2" grid. Internal bracing kept it from being drawn towards the rigid bottom plate. An ordinary house vacuum provided enough suction for any paper I used. After loosing it in a darkroom fire, I bought a more convenient Speed-EZ-EL.

[Bill Burk]

I've got a ByChrome vacuum easel with its pump.

A shop vac is good comparison. You want to move a lot of air so the paper holds flat even though a lot of air is leaking.

Your vacuum pump is not the right type of pump for the purpose. It's designed to move a small amount of air to achieve a greater amount of suction.

Yours is designed to work with glass and a rubber mat that seals against the glass. That is a different kind of project, but since you have it now you should look into making very large contact prints... that's what your pump is good for.

[Jim C.]

Resurgance,
CNC vacuum tables are a different beast from a vacuum table that needs to hold work down
against a spinning tool bit hogging out material, compared to a sheet of paper.
Besides a shop vac motor roaring away in a darkroom would make the experience miserable
and kick up dust too ! Granted the shop vac could be moved outside the darkroom, but then you'll
have to deal with plumbing it.

Set your vacuum system up as it is now and start the pump, lay a sheet of plastic
over the surface where you've drilled holes and wait till it pulls down.
Listen for leaks with a mechanics stethoscope, a length of tubing held up to your ear is a simple one,
slowly scan all over, vacuum leaks are very difficult to trace.

I suggest that rather rather tossing what you have already made you make some minor modifications,
since the material your using is porous, seal it, if it's wood based a few coats of thinned lacquer or shellac
would work, if it's a plastic material then choose another that isn't porous, it sounds like you're
using Sintra a foamed PVC sheet. Which is a poor choice since the material tends to warp over
time if not stored properly, especially if your easel is going to be 4 ft wide.
Make the holes smaller, if you have to, you didn't mention what diameter they were.

[resurgance]

Randy I'm really intrigued!

Bill contact prints are amazing; it wasn't that long ago I saw one in person, that was done in the early 1900s - I was a bit taken back by the detail recorded. It was only small, I can imagine that a ULF contact would be a thing to behold. The largest format I have is 8x10, but I do have a friend up North who is has a 20x24" camera, and is thinking about making an enlarger for it! apparently he already has a lens. Imagine a 3x enlargement from a 20x24 neg??

Jim I am lucky here, as my darkroom is a self contained shed outside, so the vac can easily run outside with minimal effort. I am very careful with dust, my mancave is positively pressured by twice filtered air, I have a small radiant heater under all of my lenses (if I was a purist I wouldn't store these in my darkroom, but it is how it is for now) And I am able to use glassed negative carriers with only an airbrush compressor and have no need to retouch. I had wondered about having the top surface of the vac easel as unsealed mdf - anything wood and unsealed usually magically generates dust. Maybe I use that plastic product and then will have to deal with static. On a side note, I wonder if its OK to use plexus to reduce static on easel, and have no chemical reaction with toning?
I'll do that with the plastic, although like you said it has already started to warp, as I made the mistake of leaning it up against a wall.... And also I may have internal leaks, so am sitting on the fence about doing something with this or re-doing the easel. Its not wood based, and I used a solvent to bond the top sheet to the bottom, so I cant take it apart to reseal it anyway. I had drilled 2mm holes in rows, with holes 20mm or so apart, and in rows along top and bottom edge of where paper sits, and also in the middle, with a few auxiliary rows to cover a few paper sizes, but same width to match the roll size.

Probably the main cause of leaks will be the perimeter, so I could first try sorting this out? Then when I get me shop vac motor I could try this again with the high cfm pump, taking a large line into easel and splitting up into smaller diameter lines at the last minute. I designed it so that there will be no holes open to air, so maybe I could try with my existing pump as it is if the leaks were only on the perimeter and able to be sealed up? Hmmmm.. got me thinking now....

[charleymeyer]

Hi, I have a By Chrome vacuum easel that came from a commercial lab that closed in the 90's. It's max size is 20x24" and has an enclosed vacuum cleaner motor connected with a shop vac hose. I'll get some photos up later as it resides in my basement. One needs a high volume vac like a shop vac rather than a laboratory high vacuum pump.

Charley

[Jim C.]

Resurgance,

Sounds to me that since the top is solvent glued that can be a huge source of leaks around the perimeter if the
top and bottom sheets aren't dead smooth which Sintra isn't since it has a slight matte sheen to it.

Re reading your first post the easel you're planning is as big as my vacuum form platen, so it may be
that you'll need a higher CFM. In anycase, use what you have as a prototype for proof of concept,
sounds like you're close to getting it, check it the way I described in #16,
I would reduce the size of the holes, 2 mm seems awfully large, and reduce the depth and width of your feed channels
8mm wide X ? depth is still a lot of volume. The less air the pump has to evacuate in the plenum the more vacuum
will be at the holes. Use silicone window caulking to seal off the perimeter of the plenum.
As an example my vacuum form machine platen which is 24 X 36" has .30" holes ( .76mm ) spaced an inch apart
the plenum gap is approx 1/16 of an inch, i used wire cloth as a spacer, it pulled pretty well but not enough to form plastic
using just the pump alone, but if were an darkroom easel easel it'll probably do fine.

Don't not sure about Plexus but looking it up it seems to be wax based, if it doesn't transfer to the paper I would guess it's fine for toning.

[resurgance]

Thanks Charley,

Jim yeah there are leaks galore. I will check with plastic sheet next few days (work gets in the way of recreation!) channels are 8mm deep too.

I just found out that positive displacement vacuum and I think vacuum pressure in general is related to the weight/mass of the thing I'm trying to suck down! So now I'm not sure if the bleeder board CNC method is suitable for FB paper. I have worked at a local wood CNC place as a contractor, and today rang my contact there and he has invited me to try a piece of paper on his vacuum table that sucks down MDF for machining. This will be an interesting experiment.... The plot thickens....

[charleymeyer]

Hi, I have a By Chrome vacuum easel that came from a commercial lab that closed in the 90's. It's max size is 20x24" and has an enclosed vacuum cleaner motor connected with a shop vac hose. I'll get some photos up later as it resides in my basement. One needs a high volume vac like a shop vac rather than a laboratory high vacuum pump.

Charley

Hi Bill, I'm in Mountain View and was just in Pacifica day before yesterday... Interesting that there are two ByChromes so close. I've some photos:

151314

151315

151316

[charleymeyer]

OK, posted a bit prematurely, the vacuum is noisy, the holes are approximately 1/16" and spaced 3/8" apart horizontally, adjacent rows are offset and 5/16" above or below. Holes near the edge of the paper are filled. There are hangers on the back of the easel to mount it vertically on a wall.

[John Jarosz]

I'm confused. Is this a vacuum frame to hold paper for enlargement or a vacuum frame to sandwich a negative against paper for a contact print? I have made both but before I post anything I want to make sure it's the right design.

[charleymeyer]

This is a vacuum easel for holding paper flat for enlarging or copying, not contact printing - that would be a vacuum frame.

[resurgance]

Thanks Charley, thats really helpful!
The holes in my easel are not that much bigger. So it seems that mine may work yet, but only once I get the high flow pump.
Although the base would be a lot different. I think I'm going to make mkII as the base I made has already started to bow, and I figure If i'm going to go to all this hassle I want a perfectly parallel table to my negative stage!!!
I have a motor coming that from what I understand should be similar to the insides of a ByChrome setup, essentially a shop-vac housed in a nice metal enclosure?

Greg I will let you know how the bleeder board method goes, it seems like this method may possibly be dependant on the weight of what one is trying to suck down, lets find out! Great enlargers the Devere's! I built an LED light source for mine modelled from the Modern Enlarger Lamps model 3 - it works very very well.

John, 8x20 seems like a really good format! contact prints??

[John Jarosz]

My vacuum easel is essentially what was the film stage of a 20x24 Argyle copy camera. The film laid on the a plastic ground glass perforated with holes. The hole sizes and pitch were similar to the examples posted here by others. I replaced the plastic groundglass with a steel sheet. I drilled with a zillion holes to replicate the original pattern. The vacuum pump is a miniature version of a shop vac. It has about a 1"diameter hose with a spring inside to prevent collapse from the pump to the easel. This type of easel requires a high airflow.

One thing I notice using this easel is that double weight FB paper develops a curl at the edges and the vacuum easel is not strong enough to overcome this. I have worked to remove the curl by reverse curling the paper on a counter edge. This is tricky to avoid creases in the paper but it can be done. It does take a significant amount of time to get each sheet flat enough to permit the easel to 'grab' it at the edges. RC paper (or film) does not have the curl at the edges and works perfectly right out of the box.

For really curled paper I have resorted to using the flexible magnetic material used for signs and refrigerator magnets in strips . So of course with this method the image can't extend to the edges of the papers. Single weight paper would solve the issue but SW is long gone.

The pumps that work like shop vacs require a certain amount of airflow to cool the motor. Blocking off all the holes in the easel may slightly increase the vacuum but cause the motor to overheat. You need to strike a balance.

Yes, my 8x20 negs are contact printed both in silver gelatin and Carbon Transfer. Wonderful format.

[resurgance]

Thanks John, interesting to hear about the DW FB, I was just going to ask Charley about that very thing!
I pretty much only use the Ilford Classic FB Glossy DW paper, so I was hoping to figure out a design to hold this down, otherwise I am thinking that I may as well use magnets from the outset?
Well It'll be a week or so before I can get some paper into the CNC shop to try on the bleeder board system, but based on what has been said I have my doubts....

[bob carnie]

If the film is bigger than the paper then it would work for contact printing.

This would be a great easel for most alternative process where single exposure is needed.


This is a vacuum easel for holding paper flat for enlarging or copying, not contact printing - that would be a vacuum frame.

[John Jarosz]

I believe using the vacuum plus the magnets so the center of large prints are kept flat will give you more repeatable results. `

[resurgance]

John I have not used FB paper from a roll before, do you think it will be prone to bowing up in the middle in protest to being help down at each edge? The natural curve of it is quite tight, its a 90ft roll, I have not printed anything yet on it, have too many balls in the air right now.... Diameter is around 8" so it has a tightish curve on her.

[John Jarosz]

I've got no first hand experience with silver gelatin paper in rolls. So I can't say.

[Drew Wiley]

With many papers you not only need an appropriate hole pattern for vacuum itself, but some kind of perimeter rim or blade system to hold the paper edges down.
Otherwise, curl on sides or corners might defeat the vacuum. Adjustable blades are obviously nice for composition purposes.

[resurgance]

Hi Drew, ok. I guess in some ways that makes the design easier if I know I am going to take care of the edges independantly.
I have 2 saunders easels, they are fantastic, I would love to have one the same that did 4ft wide prints! I'll have to come up with a cunning scheme to make sure the blades that I use end up being true, and my print does not resemble a parallelogram...

[Drew Wiley]

It can be done. But doing it right can end up costing a few hundred bucks extra and will obviously add some weight. Look into linear motion rails and matching locking carriages. Blades can be attached to carriers via mounting holes. This is the best way, though not the cheapest.

[Daniel Stone]

Resurgance,
I am in the design stages of making my own, custom easel that would employ custom-cut(via laser, from CAD drawings) "overlay masks" for specific print sizes/crop ratios. This would completely eliminate the need to worry about non-square masking blades in the traditional two and four-blade easels(ala Saunders).

I don't know if it would be commercially viable, or solely for my own purposes, but it would use magnetic force to hold down the "mask", sufficient force to eliminate any paper curl, but light enough to allow easy lifting of the mask(which would be hinged) when the exposure is done.

I would also have a contact/proofing glass overlay, so the base would not need to be removed from the table, just a simple change of what is being used, a mask, or the contact proofing glass. Masks could be stored in a flat file, or in a box, or vertically in a "file" configuration.

It's a slow-go process, as I'm working with limited time, and the prototyping stage can be expensive as well ;)

Just thought I'd share. No photos at this specific time, but perhaps using magnets could be an option for you, instead of vacuum force?

-Dan

[Drew Wiley]

Some papers can have an aggressive enough curl that magnets might not be sufficient. Vac can be way more powerful; in fact, a small vac pump is enough. I like to have my actual print borders showing, with a "reveal" between this and the mat window itself if possible.

[John Jarosz]

I like to have my actual print borders showing, with a "reveal" between this and the mat window itself if possible.

I do too. And while it's tempting to use a precut paper print size making an essentially 'borderless' print I think you'll find tiny white flecks on the edges of those prints where the emulsion has come off the paper during washing or handling. I can't display a print like that. So a final trim is almost always necessary.

[resurgance]

Drew and John I agree, I always have a 5mm or so 'reveal' with crisp edges between image on print and matt board - looks real sharp.

Daniel Easel sounds great - I think I am swaying toward what Drew is saying about having vacuum as well. Now that I am pretty certain I will be planning on having magnetic perimeter blades for holding and masking the vacuum part will become a lot easier, especially since for this particular easel I will only really be doing 2, maybe 3 different sizes. I am now feeling like I am closer to almost coming up with an actual hair brained scheme.

Drew I used linear bearings for my home made LED light source on my Devere 5108; Super cool things - I guess you are more talking about rails like on a rotocutter? But same principle; I like that idea! I think the sides would be easy, I am pressed for space as I only have 1200mm wide for the baseboard, so I need to be careful to not take up too much space (to maximize print size and make good use of 50" roll); whatever I come up with for blades will be more than likely 10mm wide, or just shy of 1/2" in imperial speak - and that will be easy to keep parallel as I have benches either side of my enlarger, and the print will pretty much go cabinet to cabinet. The top and bottom of the print is where the important bit is, and I am confident I can come up with a simple registration thing, like a bit of alloy or marks etc, then measure to the bottom. If they are made from angle or small square section alloy they will keep straight then I suppose I only need to look after the bottom of the print?

[Drew Wiley]

I've got a bunch of plans in my desk right now, but am basically burnt out on machinery projects. Gotta finish a fence soon then start up on the house remodel again. Just a few more months and I'll be retired anyway, and hopefully have time to have my cake and eat it too. The big precision vac easel I have on my 14ft
tall 8x10 additive color enlarger is dedicated to that unit, and is way way too heavy to put on anything else. It has an interesting system of pins which move along four slotted tracks with measurement marks, then accept masking blades put on separately afterwards, registered to these pins. It works nicely but is slow to use. But I still need to make a bladed 30x40 easel for the backup L184 color unit I recently installed and refurbished. Otherwise, I do have various 20x24 vac easels which have cannibalized the masking blade system from Saunders pro easels, which can easily be moved from enlarger to enlarger. No time to color print this summer anyway, or any darkroom time for that matter, except for loading and developing film. I got tied up for awhile during rainy weather machining
several pin registered neg carriers just in case I need something more intensive to tie me up during retirement like dye transfer printing, which I've acquired all
the necessary supplies for, and have already learned how to do separation negs etc. But first I've got a lot of ordinary RA4 printing to catch up on, if anything I do in the darkroom can be called ordinary. There will be a lot of registered masking tweaks involved in these too. Then a mountain of drymounting to catch up on. Good thing I enjoy this kind of activity.

[resurgance]

Ha! So its universal then? I have only just recently discovered this phenomena that is projects far outweighing time or enthusiasm. I sometimes think of John Travolta in movie 'Phenomenon' where he can't sleep for months and does all sorts in the wee small hours.... Doesn't end so well for his character though.
I have young kids and am self employed, still have maybe 20 years if I'm lucky before I get to the big R.
And I have know for some time that I can't have my cake and eat it too... I guess it would be bad form to resign myself to the fact; I like your optimism for the possibility of being able to!

[Tin Can]

A lot of maniacs here. I am retired and nobody to comfort. Good & bad. :)

I am certain many projects have kept me alive. I need tasks even if it's tilting at windmills. Today I hope to finish my bike so I can get it out of the studio and get back to building a camera. I try to DIY everything. Made an adjustment to my studio/darkroom exhaust system today to pull air off the ceiling when it's not sucking sink fumes. A pipe dream.

[resurgance]

Well I am not sure what I am up to, I have a lot of different hobbies and interests, but am also really engaged at work; Lately I have been thinking I may have a bit of an issue at jumping at things. These things I am genuinely interested in, but I am a bit swamped! Also my enthusiasm is waning a tad due to the constant stream of *things* to do.
One thing is for certain going out with a camera and what follows in the darkroom is quite relaxing, and even though I am not shooting much at the moment, I always have ideas in my head for where I am going to go when I do get time.
For some strange reason I just bought 3 fordson super majors for dirt cheap, with the idea of making one good one. I should have walked away.
Then there is the chicken house which I am welding up a 316 SS sub frame for, to combat the red mite, a pergola to keep my significant other happy, an archway into our 'orchard' if you can call it that, my vacuum easel, a roller system for processing ong panoramas, an irrigation system (I do electrical automation so its a bit over the top), my 'observatory' (also over the top, I control it from inside my house), RC plane, and a myriad of other bits and bobs that caught my magpie like fancy...

Therapy session anyone?

Randy what sort of bike are you building?

[Drew Wiley]

We have a cure for chickens around here. They're called foxes and raccoons. Leave a gap in that nice stainless chicken cage, and you'll have one less chore to
interfere with darkroom work.

[resurgance]

Classic! We don't have either of those, but I was shocked to find out shop bought non free range eggs we got the other day poached better than our girls eggs did!
Hmmm.. food for thought....

On topic; Just bought a huge vacuum pump from an auction, really cheap, 3phase 2.2kW, but I have a VFD sitting around that will take care of that with a single phase input.
The shop vac arrives next week, so I have both shop 1800W shop vac and 2.2kW positive displacement vacuum pump to try. This week hopefully I'll get time to try DW FB paper at the CNC place with their bleeder board setup.

If the shop vac doesn't work I'll make a shop vac for my shed, and if the other one doesn't work maybe I'll take up vacuum forming carbon fibre with epoxy.....

[Drew Wiley]

Both devices will be WAY too strong for a vac easel; so yeah, a bleeder valve will be essential. Otherwise, make sure that shop vac doesn't vent into the same room, or you'll have dust everywhere. I'm sitting about ten feet from a vac pump that I like to show off by showing how it sucks air clear through a board and
allow paper to cling. I call it my $2400 paper clip. I sell em, along with serious vacs. No "Shop Vacs" here. We use the snooty term, "dust extractors" - justifies the
far higher price, along with the fact they actually do what they claim! They are the kind of equipment that can be used in an actual clean room.

[resurgance]

Ah Drew, the real McCoy? They sound expensive!

I was not sure about the bleeder valve, I will look into this, I was more meaning a bleeder board? Similar to a CNC suction table, a sacrificial sheet of low density fibre board. I had my doubts that it would work with paper because of the weight, hence the experiment this week at the CNC place.

I will definitely have whatever I use situated outside the darkroom, I have gone to great lengths to ensure the darkroom is dust free! I use an airbrush compressor and glassed carriers, and have zero need for retouching.

The model I have is an Indovac IVS1000 what are your thoughts?

[resurgance]

Ok. Its a rotary vane pump, on the following link its the exact model shown on top right hand image, of the pump with a separate belt driven pump.
http://www.indovacpumps.com/Rotary-Vane-Vacuum-Pumps.html
So its 1000 l.p.m., and either 600 or 710 MM HG, which I guess is either 23.6 or 28 inches of HG.

Something tells me I can't just slow the VFD down to draw less vacuum, so like you suggested, a bleeder is the ticket?

Something also tells me that this is way overkill for a 2ft x 4ft easel? So I have a small diaphram pump, which is too little, a huge rotary vane pump that is too big, and maybe a goldilocks shop vac which may be just right?

[Drew Wiley]

It's zoned or valved for selection of film area. A shop vac is too powerful unless you install a bleeder valve. You also need to isolate them in another room with a
hose through the wall to limit their noise; and they pass a lot of fine dust, so should never be used actually present in a darkroom, equipped with make-believe
HEPA filters or not. Vac pumps per se should be rotary, not peristaltic or diaphragm pumps, which actually shake the easel plane with their pulses. You might not feel these vibrations; but they're visually obvious under a grain magnifier when the pump is running. Too much vac draw can actually pull film or paper into holes or channels enough to "bruise" the material, leaving indentations that often effect development enough to be apparent in a final print. I remember seeing a number of prints with subtle pegboard holes apparent all over open skies or other high key areas. Damien Hirst would have been proud of that, however.

[Drew Wiley]

Now to the question of pump size relative to easel size. It really depends on how well designed the easel is. Heck, I use a basic little cordless vac on my big 30x40 vac easel. Works fine even for long exposures. The only problem is the cost of replacement batteries over the long haul. So now I have a miniature corded vac set
up with remote footswitch triggering, and the hose through the wall. But think I'll just eventually park my smallest Festool Vac beneath the big easel, since it is true
HEPA and quiet, and use for both the easels, room dust, spider control etc.

[Drew Wiley]

"Shop Vacs" probably didn't exist when that thing was made, and if they did, it was never made for them, for exactly the reason I already mentioned. What was
common for graphics use were small line rotary vac pumps. Put a small line on a shop vac and you burn the stupid thing up due to insufficient air flow anyway.