Calibrating a NuArc integrator... Sandy King?

Discussion in 'Contact Printing' started by SusanV, Feb 9, 2007.

  1. SusanV

    SusanV Member

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    I've read on one of the forums somewhere.. maybe here, a post from
    Sandy King describing how he calibrated his NuArc exposure unit so
    that one "unit" equaled 1 second. I've been trying to do the same,
    but am having a hard time getting it to work. My unit has an "eye"
    mounted on top of the brackets that hold the lamp in place. The
    eye is in a cylindrical black housing that can be tilted at different
    angles. It also has a disk mounted over the eye... this disk can be
    rotated, and as it's rotated, the eye is totally exposed, then gradually
    the eye is blocked more and more by black paint on the back of the
    disk. I assume this is for adjusting the sensitivity of the eye, and
    therefore, the value of one exposure unit.

    I hope Sandy sees this thread because it's all his fault I've opened
    up this particular can of worms! :surprised:)

    Can anyone shed some light (har har) on this little gadget and how
    to adjust it? Sandy just talked about aiming the eye more or less
    toward the lamp, but with my unit, the eye seems aimed at the
    metal brackets above the lamp, and I can't see where it can... "see"
    the lamp at all, no matter how it's adjusted.

    thanks,
    Susan
     
  2. colivet

    colivet Member

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    Susan, I wonder why it is so important to have it match seconds. I ususally print by units just fine. I am a little puzzled there.

    I have not done that but I suppose you could adjust the distance of the UV sensor so that it will count faster or slower according to your needs.
     
  3. Brickbird

    Brickbird Subscriber

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    NuArc calibration

    Susan,

    I have a 26-1K and have been in the dark all day and just noticed your post taking a break. The integrator has a dial that you can turn. If I recall correctly I set mine on the lower number,possibly 2 or 3. I tried to set the dial then turned it on to time it to seconds but it is really not that necessary to have them equal. Just time the units with a watch and write on the front what 100 units is and 200 is etc..You never will have the units stay at the same seconds anyway due to the degredation of the lamp over time. My units are 100=2 min, 200=5min and 300=8 min. Don't worry about having 1000 units=1000 minutes. It ain't gonna happin. Leave the integrator pointing where it was when you took the top off. Hope this helps.

    Tav Walraven
     
  4. Brickbird

    Brickbird Subscriber

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    Correction

    I meant to say that 1000 units will not have to equal 1000 seconds. Sorry for the confusion.
     
  5. SusanV

    SusanV Member

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    Hi all, and thanks for the responses!

    You're right of course, that it isn't absolutely necessary to have each unit = 1 second, but it just seemed to make sense to me to start off with mine that way. I just got it, and am still finding my exposure times for polymer gravure plates. Sandy's original post made it sound like such an easy adjustment, that I thought I'd do it with mine too.

    Another thing... my exposures (there have to be 2 exposures per plate), are going to be in the 30 to 40 second range. What I've found is that the bulb takes that long to come up to full brilliance. That wouldn't be a problem for long exposure times, because the integrator does it's job... but what happens with a shorter exposure time? That's one reason I'm interested in having my "units" well calibrated.

    susan
     
  6. Brickbird

    Brickbird Subscriber

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    Short Times

    Susan....My suggestion would be to find some rubylith material or just use a large piece of mounting board to cover up your polymer and wait for the light to come up to full lumens and then remove it. Start your unit timing from that point. If you are only doing that process for a while then you might want to turn your integrator wheel to a different number to slow the "unit per second" timing. Any printing company that had a NuArc might still have some ruby material laying around. It is a dark red masking material used to block UV light while making plates "in the old days". I sent you a pm with my numbers if you would like to call.

    Tav Walraven
     
  7. SusanV

    SusanV Member

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    Hi Tav, and thanks for the help! I got swamped today after I wrote the posts above, and didn't have time to get back to it. Tonight is busy, too... I"ll be back here tomorrow and and we'll get this thing figured out! Thank you very much for the help... see ya

    Susan
     
  8. sanking

    sanking Member

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    Of course you can make one unit on the NuArc equal whatever length of time you like, but I personally like to calibrate so that one second of time equals one unit of exposure. If nothing else establishing the rough equivalence makes it easier to exchange exposure data with other people.

    How to do it? First, unplug the NuArc and then remove all of the screws on the top. Then, carefully lift the top and move it back out of the way. Be careful when doing this to avoid damage to the power cord of the fan.

    You can adjust exposure by two different mechanisms. At the very front of the unit, in the middle, is the light sensor. You can adjust it by moving it up and down so that it sees more or less of the hole that looks down to the bulb, or you can adjust it by opening or closing the filter on the front of the sensor. If you want to adjust to one second of time equal one unit of exposure, first turn on the unit and allow the bulb to warm up for about a minute. Then open (or close) the filter (or adjust the sensor away from or toward the opening to the bulb) until time and units match. There is no point in perfect eqjuivalence so don't obsess too much about perfection in carring out this operation.


    Good luck,

    Sandy King
     
  9. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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    Which model nuArc are you working with?

    I designed the SM2100 and EZ-1 integrators for nuArc and am familiar with some of their lower-end integrators.

    It is customary to initially have the integrator work at 1unit = 1second. The integrator and sensor are designed for optimum performance at this calibration. If the unit is counting too fast the pre-amplifier may be saturating - too much light is getting to the photocell and the integrator can't handle the signal.

    If you set the unit to 1:1 with a new lamp it is easier to monitor the fall off in light output as the lamp ages. When it slows to 1/2 speed it is a good idea to replace the lamp.
     
  10. SusanV

    SusanV Member

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    OK life slowed down enough for me to get back here...

    Hi Sandy, and thanks for the information. The past few days
    I've become pretty familiar with the inside of the Nuarc as I've
    tried to get it adjusted as you'd suggested.

    Nicholas, thanks for checking in on this. I have the 26-1K.
    I'm happy to hear that you are so familiar with these integrators.
    I just got it last week, and have had trouble with the light
    flickering, then going out occasionally. The bulb looked old
    and was quite blackened so I got a new one and installed it
    last night. Then while trying to adjust the sensor early this
    morning, the new light stopped working. ugh. I checked the
    fuses, and one was blown. Tomorrow I have to try to find
    new fuses for it ( I plan to just replace them both). Now I'm
    wondering why the fuse blew, and if this thing really has some
    serious problem. It's on it's own dedicated circuit that's getting
    112 volts (I checked that at the receptacle), and the input
    and output leads on the transformer are set correctly for that
    voltage. I have learned way more about electricity and the inner
    workings of this thing than I really want to know :surprised:) I just want
    to expose my plates and make some nice images.

    So... Sunday I will try to get fuses and hope that fixes the bulb
    situation, then maybe I can get back to calibrating it, and I
    welcome help with that. Maybe the reason I had trouble getting
    a repeatable result before was the old bulb.

    Thanks... please stay tuned while I try to work through this the
    next few days. I appreciate the help!
    Susan
     
  11. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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    The 26-1K isn't one I am all that familiar with. I assume it has the simple 1-channel integrator. Some of the 8-channel units have little plug-in cards that set the detector sensitivity. With age the contacts get cruddy and integrator operation is erratic. I am not sure if the 1K's integrator has plug-ins, if it does, and they are easy to get to, then unplug and plug them a few times, ditto with the cable from the sensor.

    An old bulb is the #1 cause for erratic light output. It should have a white
    coating on the inside of the bulb. If the quartz has melted and distorted then there is something seriously wrong, though it may just be a blocked fan.

    If the new bulb went out after 10-30 seconds (maybe longer) and/or the fuse blew then I would double and triple check you have the right bulb. Just because it matches the old one doesn't mean it is the right one, it is quite possible the old bulb was also the wrong type [the sort of problem that can give endless frustration].

    Don't be afraid to call nuArc. Their support staff is very helpful and will aid you with used equipment. nuArc isn't what it used to be, what with computers doing all the pre-press work, and they are now a part of M&R Print, but I have heard the customer suppor is still the same high quality and 24-7.

    http://www.mrprint.com/en/department.aspx?id=14

    The 26-1K is still in production, so nuArc will be familiar with the unit and will have lots of spare parts available if you need them.

    The 26-1K is a reliable and popular unit that has been around for 30 years [I first saw one in '79, when I was designing their instant-start power supply] and there shouldn't be any great problem getting it humming along.
     
  12. SusanV

    SusanV Member

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    Here's what I've found out today. Both of the little "barrel" fuses mounted
    in the case of the Nuarc were the wrong type. One is supposed to be a 5
    amp, 250v, but instead it was an 8 amp 250v. The other was supposed to
    be a 20 amp., 250v "slo blo", and it was a fast acting fuse instead. it's the
    one that blew. I guess a "slo blo" or "time delay" fuse allows for some short
    spikes of current flow at start-up, and the fast acting fuse... acts fast :smile:.
    Maybe?

    So those things are now corrected.

    The new lamp is the correct one, I double checked that. it works great now
    that I changed the fuse that was blown.

    I finally got it adjusted so that one unit = about 1 second when the
    lamp is fully illuminated. (Very helpful when discussing the process with
    others, and troubleshooting any problems I or someone else might have)


    Nicholas... per your suggestion I checked all the connectors, and slid them
    off and on a few times to make sure they were making good contact. There
    was a lot of fine dust on and in this unit, but the little connectors are all
    covered with plastic protectors, which is a help. While doing that though...,
    I also found TWO ground wires that were barely connected... just hanging
    there with the nut (that's supposed to hold them tight...), all the way out
    to the end of the bolt, about to fall off! Glad I found that. I also have
    noticed another green wire that's not connected to ground... just has a piece
    of electrical tape wrapped around the end of it. Will be checking into that
    some more tomorrow.

    Hopefully I'll also be making some gravures :smile:

    thanks for the help, I really appreciate it. Hopefully I'm all set now
    ::: crossing fingers::::

    Susan
     
  13. rtuttle

    rtuttle Member

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    Susan:
    I don't have a lot of experience with this unit but I do have tons of experience using Nuarks fliptops and contact units. That little light probe in the back should have a phillips head screw in the middle. If you loosen it up ever so slightly you can turn it so the aperature changes. If the time is too slow open it, and vice versa. There is no harm in doing this as that is it's function. Nuark equipment is functional and sometimes clumsy. They also have a long history of changing suppliers for things like daughter boards and not telling everybody in their employ. You should be able to do what your looking to with it though.
     
  14. SusanV

    SusanV Member

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    thanks... it's workin like a charm, now!

    susan
     
  15. sanking

    sanking Member

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    I am curious to know if the light integrator on your 26-1k gives consistent results if you make exposures one after the other? A freind who uses a 26-1k told me that he can not get repeteable results with his unit unless he always alllows it for the same period of time before making the exposure. This seems to defeat the idea of the integrator, but in discussions with someone at NuArc very recently one of the technicians there suggested that the problem might be that the light sensor of the integrator reads visible light, not UV. I thought this was odd, but as I said, it did come from one of the technicians at NuArc.

    Before acquiring my Amergraph ULF-28, which gives beautiful consistenty with multple prints, I also used a NuArc 26-1k for kallitype and pt/pd printing. I recall having some problem with consistency, but at the time attributed it to coating and humidity conditions.

    Sandy King
     
  16. RobertP

    RobertP Subscriber

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    Amergraph ULF-28....Got it on my wish list. But I find my 26 1K integrator to be pretty accurate. I always turn it on for 200 units before I start printing then I allow plenty of time before I try to restart. Restrike isn't the best with these but very seldom do I print past 1000 units. But I'm all for cutting down on the work prints when doing ULF pt/pd prints
     
  17. Peter Cane

    Peter Cane Member

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    Nicholas:

    Thanks for your comments on the Nuarc-I've been loking for one in the Maryland area for awhile-just missed one being tossed out in DE by two days!! (light table with it too) What a shame. Anyway, I use the fstop timing method in my darkroom and love it. I have a tape that reads out stops and third stops since I can't use one of your timers with my D2. Can the Nuarc be set up with your fstop timer?

    Thanks

    Peter