Time-O-Lite runs 1 sec. long.

Discussion in 'Darkroom Equipment' started by Worker 11811, Jul 18, 2012.

  1. Worker 11811

    Worker 11811 Member

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    I have a Time-O-Lite Master (M-59) that runs one second too long no matter what time you set it for.

    If you set it for 5 seconds it runs for 6. If you set it for 30 seconds, it runs for 31. If you set it for 60 seconds, it runs for 61.
    If you carefully set the pointer at zero seconds, just before it trips off, it runs for one second.

    I've taken the back off, dusted it out and put a drop of oil on the shaft but it still behaves the same way.

    It's a pain in the ass to always set the dial for one second less than you really want. Does anybody have any ideas or solutions?
     
  2. ic-racer

    ic-racer Member

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    I'd reposition the pointer on the shaft clockwise one second. I think there are one or two screws affixing the pointer to the shaft.
     
  3. Worker 11811

    Worker 11811 Member

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    What manner of fastener holds the pointer to the shaft? I can't quite tell.

    I couldn't find an Allen key that fits. Neither does a screwdriver seem to fit, flat-bladed or Phillips.
    I'm sure it's not a Torx. None of my Torx bits fit, either.

    Could it be a Bristol spline? Many small screws in cinema projectors are Bristol splines.
    Unfortunately, I don't have a set of Bristol keys any more.

    I hope the heads haven't been cammed out by the previous owner. (i.e. Using an Allen key to tighten a Bristol screw would certainly risk stripping out the heads.)

    Given the cost of buying a set of Bristol keys, I might be better off buying a new timer from somebody on Ebay.
     
  4. ic-racer

    ic-racer Member

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    It should be some SAE size, as I believe these were USA made. If no SAE wrench fits it could easily be stripped. My experience with tiny screw excractors is that they break off in the hole then you have an even more difficult problem.
    What I'd do is drill the screw out and re-tap the new hole for a larger grub screw.

    Perhaps a common problem:
     
  5. Whiteymorange

    Whiteymorange Member

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    How about the old "set it one unit short of what you want" solution? It saves a lot of fidgeting since it seems to be consistant in it's weirdness.
     
  6. Mike Wilde

    Mike Wilde Member

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    You can get used to it. One of my analysers is a bridge balancing timer. So once calibrated, you meter for where you want the first non white, and press the button, and get a bang on exposure, with no indication of how many seconds it was. It works great of negatives needing the same paper grade, and is a bit trickier to work with when changing paper contrast. I will miss it when one of the tubes in it finally burn out.
     
  7. Worker 11811

    Worker 11811 Member

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    1) I have been looking closer and doing some research. The screws are Bristol splines. It looks like somebody tried to use an Allen key on them. They are partially stripped but, if I can find the correct tool, I MIGHT be able to get them out. If and when I get them out, I'll replace them.

    2) I have been adjusting my times by one second. I'm in "Clean and Fix Mode" in my darkroom, right now, getting ready to do some printing. I want to see if I can get the thing to work the way it's supposed to. I have a GraLab timer if I need to use it but I'd prefer a repeating timer. Besides, I usually use the GraLab to time print development.

    3) I am thinking that resetting the pointer is the thing to do.
    As I have been watching the timer run, I have noticed how it works... Or, more to the point, how it works wrong: When the button is pressed and the motor starts to run, the pointer stays still for a second before it starts to move. This makes me think that the pointer needs to be taken off to solve the problem.

    There is spring tension that causes the timer shaft to wind clockwise when the motor isn't running. Moving the set pointer, causes the spring tension to wind the time pointer against the stop on the set pointer. There is a clutch that engages when the motor runs, causing the timing shaft and pointer to turn counter-clockwise.

    It seems to me that there is a delay between the time when the motor starts to run and when the pointer starts to move. I am guessing that the clutch is slipping for a second.

    My theory is that whoever took that pointer off last, the one who stripped the screws, turned the shaft too much and over tensioned the spring. The motor and clutch are slipping because of the extra torque needed to move the pointer. Removing the time pointer, unwinding the tension and resetting it might solve the problem.

    Up till now, I have been compensating by one second but I just want to make the thing work right. If I can't get it to work the way I want, I'll just switch to the GraLab until I can get another Time-O-Lite from Ebay or some place.
     
  8. Leigh B

    Leigh B Member

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    It's probably a Bristol key. These were very popular during WWII and for decades thereafter, used for high-reliability applications.

    The recess looks like an Allen hex on casual examination, but with a magnifying glass you'll see that there are lobes or scallops.

    You can buy individual wrenches and small sets from McMaster-Carr at www.mcmaster.com
    They're not expensive, and McM only charges actual shipping costs; no minimum order.

    - Leigh
     
    Last edited by a moderator: Jul 19, 2012
  9. George Nova Scotia

    George Nova Scotia Subscriber

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    On Time-o-Lite Model m-72 They are indeed bristol spline an xcelite 99-65 fits nicely. set screws are #6 NC 32tpi 1/8".
     
  10. Bill Burk

    Bill Burk Subscriber

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    I found a flat-head screwdriver 0.775" width fit the set-screw nicely and I was able to loosen the two screws on the red pointer easily.

    Of course the tension relaxed and the virtual pointer moved past 60.

    I chased the pointer while it was clicking and got it to indicate exactly what I get by trial and error.

    I set the rear set-screw of the red pointer firmly but without cinching. It's behind the black main dial most of the time so it would be a bear to adjust in motion.

    But the side set-screw is easy to adjust while the timer is clicking. I hit the time switch and loosen the side set-screw and move the red dial a second or two closer or farther from where it should be, then tightened it on-the-fly just enough to hold in place.

    Then I got a stopwatch and timed.

    You want the red dial to click off when it is pointing at about the one-second mark.

    That's the secret.

    Expect that first second to be consumed by the startup. Expect about 1.5 seconds before the first click. But you will get the time you set on the dial.

    You can't get less than 2 seconds anyway.
     
  11. Worker 11811

    Worker 11811 Member

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    I was thinking along the lines of what you suggest.

    I haven't found the right tool yet. Most of the places in town don't have it. Out of about a dozen places I either visited or phoned, only one guy even knew what a Bristol wrench is. Then he quickly said, "Nope, don't have it."

    Probably going to just break down and order the damn thing.
     
  12. Bill Burk

    Bill Burk Subscriber

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    Have you tried precision flat-head screwdrivers? That's all I used.
     
  13. Worker 11811

    Worker 11811 Member

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    I haven't because it looks like the screw head is partially stripped from somebody else trying to use an Allen key. I'll need to use the correct tool to get the screws out then replace them with new ones.
     
  14. Bill Burk

    Bill Burk Subscriber

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    At first, I thought that too, but when I got in there, the flathead did the trick and they weren't very tight.

    Maybe they just "look" that way, and because an Allen key doesn't fit at all might add to the illusion.

    I don't remember if I had tried before. I've had the thing long enough that I would have.