Has anyone tried to slow down the rotation speed of Beseler or Unicolor motors by using a rhiastat (spelling)? Any ideas on the effects of development times, or eveness/uneveness of developing negatives? Any thoughts on the ultimate developing RPM? What about damage to the motor?
Just what ifing...
dee
I actually think you could slow these drums down by about 1/2 and still get nice even development, but I don't see that there is anything to be gained. The ones I have worked with already have a fairly slow RPM compared to Jobo, for example.
With Jobo, however, it is a good idea to slow down the RPM, especially when developing film in Pyro developers such as PMK, Rollo Pyro and Pyrocat-HD. If the drum rotates to rapidly with these developers you can get a lot of general stain from aerial oxidation.
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Sandy,
Have you used the Unicolor drums sucessfully with PMK and Pyrocat-Hd without using an EDTA additive?
Thanks
I have used Pyrocat-HD to good end with both Unicolor and Beseler drums. I don't use PMK any more with rotary processing because in the past I experienced a number of problems with it in this kind of application.
A pre-soak of about five minutes is recommended for all Pyro developers with rotary processsing. And, if there is any question about your water quality it would not hurt to make the pre-soak water slightly alkaline by adding about 1/2 of a teaspoon per liter of sodium carbonate.
For discussion and information about carbon transfer please visit the carbon group at groups.io
[url]https://groups.io/g/carbon
I have used Pyrocat HD with a Jobo 2500 tank on a Unicolor base for just a few sheets of 4X5 and a couple rolls of 120 with no problems. I'd been wondering about a way to make the Unicolor base rotate more turns in each direction, not so much to slow them down. My Unicolor turns slower than my Jobo turned. For some reason I thought an additional rotation would be desirable.
Sandy, I ran my rotary without any presoak and the film seemed fine, but as I said I've only done this a few times using the rotary base, 1:1:100 dilution and lots of working solution (1 liter for two HP5 120s in a 2500 tank, rotary). Can you tell me the reason for the pre-soak? Have I just been lucky so far?
My other Pyrocat HD experiences have been inversion agitition with no pre soak with promising results so far. Thanks in advance.
The pre-soak is more important with sheet film than roll. If you don't pre-soak sheet film there is the possibility of uneven staining on the back of the fillm that may cause a problem in printing. If you are getting good results with roll film withoute the pre-soak just keep doing what you are doing.
I actually prefer the inversion agitation method in tanks for roll film . This allows me to use minimal agitation procedures which with this developer can produce extreme adjacency effects and extremely high acutance.
For discussion and information about carbon transfer please visit the carbon group at groups.io
[url]https://groups.io/g/carbon
I'd been wondering about a way to make the Unicolor base rotate more turns in each direction, not so much to slow them down. My Unicolor turns slower than my Jobo turned. For some reason I thought an additional rotation would be desirable.
I modified my Unicolor 352 to control the time it runs before switching. With a large Expert drum I wasn't getting even a complete turn. But this involves building some electronics and AC wiring. Basically just uses a 555 timer and relay. You can also look for a Repeating relay ( I think that's the name) and figure out how to install this. Sort of expensive when I looked. I set my base to turn 2 revolutions before switching like a real Jobo does. I have a crude circuit diagram if anyone wants it.
I'm reviving this question since this thread went off into other topics immediately.Originally Posted by d.s.
Does anyone have any answers to any of the above questions?
Thanks
Yes, it's very easy to do. Do not use a rheostat/incandescent light dimmer, this will potentially ruin the motor and will make noise. You can get a motor speed controller for almost the same price. I have one with a power cord and a built-in receptacle for a standard plug (plug it in the wall, plug the tool into the speed control), I use it on my hobby lathe and whatever other tools need speed control, but it will work on a motor base as well. Mine is 7A (850W), far more powerful than you need for a Beseler motor base, if you want a cheap source go to your local big box hardware store and buy a ceiling fan speed control. It should be rated at 300-400W, which is ample for the Beseler (I don't have one in front of me so I can't tell you the power draw, but it should be well under 100W).
It doesn't work very well on tools that already have an electronic speed control built-in, such as a variable-speed Dremel tool. But the Beseler is a glorified record player, it will work fine.
I second the fan speed controller suggested by Jody_S.
One note: Take care when you get to the slowest of speeds. Depending upon several variables, you might reduce power enough to slow rotation, but when the tank reverses, there might not be enough energy for the turn around. The result is that you might stall the rotation on reversal. Not a huge problem to solve, just be aware of it.
Bill
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