Beseler reversing base vs. non-reversing base

Discussion in 'Darkroom Equipment' started by michaelbsc, Jul 30, 2010.

  1. michaelbsc

    michaelbsc Member

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    Hey gang, help me understand something here.

    I've managed to collect a couple of Beseler non-reversing bases as well as a Unicolor reversing base.

    I note that some of the newer Beseler bases reverse using a switch.

    Does anyone happen to know exactly how this switch works? Obviously it's some kind of electrical reversing, not mechanical.

    Being pretty hand with things electronic I could easily install some doo-hicky in one of my nonreversing bases if I knew what it is supposed to do. Does it merely change the phase orientation of the capacitor for the motor so it runs the other way?

    Anyone had their rotating base apart and got a picture or two?

    Thanks,
    Michael
     
  2. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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    You need a reversing motor. My guess is the motor in the non-reversing Beseler base is a hysteresis motor that runs one direction only. If there is a capacitor attached to the motor, or if it runs from a small DC power supply, then it can be reversed.
     
  3. michaelbsc

    michaelbsc Member

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    Adding "Wave Action" to a Unicolor reversing base.

    OK, color me stupid. I dug into the abyss of "the closet" and found that the base in question is not a Beseler at all. It's an Omega Chromega with "Wave action" which is what I was after, the "wave action."

    I've got a Unicolor reversing base and several drums of various types, mostly Beseler. I have used this pretty successfully to do prints that are larger than my trays. As I'm beginning to get very interested in 8x10 film I thought the trick of using the drums for film would be good, but after reading a number of other posts I worried about inadequate developer mixing causing bromide drag.

    Remembering that the closeted base which came with some of the drums had eccentric wheels I thought I would simply make it reverseable too.

    Once I got it out I discovered there's no such luck. As Nicholas guessed it's a shade pole motor, and cannot be reversed without mechanically modifying the armature. Not my cup of tea, and certainly not useful for my purpose.

    So I opened the bottom of the Uniroller (7 screws - piece of cake), and I discovered that the rubber on the drive wheels is nothing more than a large o-ring riding in a grooved plastic wheel. And from the bottom side the o-ring rolls right out of the groove easily.

    Ergo, all I needed to do is introduce a "bump" into the groove to get some "wave action" on the Unicolor, leaving me with a mixing/reversing base. So I cut a couple of small pieces of plastic, shards from a piece of tygon tube, rolled the o-ring out of the groove on one side, shoved in a piece of plastic, rolled the o-ring back in place, and did the same 180 deg out on the other wheel.

    It makes about a 3mm bump on the wheels which sloshes the fluid in the tank. It's not so much motion that the tank becomes unstable on the roller base, but it certainly does increase the mixing action.

    Does it help? I don't know. I've only developed 6 sheets of film this way so far, 4 before the mod and two after, and I've never had a bromide drag problem in that minuscule sample. But I'm going to leave it in place unless some other issue arises.