jobo expert?

[Usagi]

hi,
I got Jobo expert 3010 drum but I have no idea about the required rotation speed.

My current (diy) processor was designed for drums with much smaller diameter. As the diameter of expert drum is so big, it will give a lot less revolutions per minute.
That is about 10rpm

Is that enough? I use rotary processor for E-6, C-41 and BW with D-76 1:1, pyrocat-HD 1:1:100, D-23 as two bath and Emofin.

 

[Dan Henderson]

I am not a Jobo expert - or an owner either since I recently sold mine - but my very basic understanding of physics tells me that the RPM of different diameter drums will be the same at a given speed, will they not? The outside of larger drums will simply move faster.

I never used my Jobo for color processing, but I did find that the recommended higher speed was too fast for processing black and white negatives.

 

[Роберт]

Position P (CPA/CPP ) is 75 RPM. For C41 and E6 normally for the developer position F is used then go to P (Blix, or Bleach and Fix).

 

[Usagi]

that is fast. I cannot figure currently how to get such speed out of the motor I use for rotating the roller wheel axle.

With a some gearing I could get something like 30rpm but that's less than half of designed speed.

 

[Роберт]

Position F is much slower then P. Maybe half in speed. And they are always do turning in reverse.

 

[Neal]

Dear Jukka,

I remember your design. I wonder if attaching larger wheels and allowing the drum to rotate above the water bath would work. It wouldn't be as fast as Jobo recommends, but maybe it would be fast enough.

Neal Wydra

 

[jp80874]

If you search here and the LF Forum you will see that people are having success at several different speeds. Assuming they have reasonable ideas of sucess this may mean that they use different development times. I am not sure. For T Max and HP5 I have used a CPP-2, Rollo Pyro and both 3005 and 3010 drums, 68-69 degrees F for 4-5 years. I increase time if the subject needs more contrast.

John Powers

 

[Usagi]

thanks.

I have to use some sheets to figure out if the speed is fast enough.

Neal, the idea is good. Thank you!

 

[Vaughn]

My 3006 turns at 16 RPM -- seems to work fine.

 

[Tom Kershaw]

I've used 50 r.p.m with my Expert drums.

Tom

 

[Usagi]

My 3006 turns at 16 RPM -- seems to work fine.

That is good to hear.

I did some clocking and found out that my "processor" seems to turn exactly 16 rpm without any modifications.

The traction wheel itself goes 48 rpm.