Developing on a motorised roller base

[swmcl]

Hello again to all you good people,

Today I am asking about a specific situation.

Equipment: one uni-directional motor base, one expert drum.

If one were to lift front of the drum off the roller base every 30 secs or maybe minute into a more upright position and then set it down again - so that it is rolling in the same direction - would this eliminate any patchy development issues ?

The reason I ask is that I am contemplating building a roller base. My design at present assumes the drum is placed on the rollers in one orientation. As I'm contemplating an in water design it will be a messy situation to have to reverse the drum every now and then. I also want to build in a barrier to stop the drum wandering on the rollers. That barrier will be closer to the drum at the bottom than at the top.

The Jobo expert drums allow the tempering water into the drums from the bottom so when they are lifted tempering water flows out the bottom and your chemicals come out the other end !! One can get a little fright at all the fluid sloshing around. Ooops stop that fluid coming from the bottom .. No! Don't tilt it that way! The chemicals come out that end!

I think - I have not seen - the Jobo processing centre has an intermittent tilt to wash the chemicals back and forward during the process...?

I believe other ways to stop any streaky development would be to increase the amount of chemicals and to slow down the speed of rotation allowing less laminar flow.

Would a reversing motor eliminate the problem or would it still be advantageous to periodically tilt the drum during processing?

Maybe I should have egg shaped rollers !! Or just the one at the bottom of the drum ..

Your thoughts are most welcome.

Cheers,

[nolindan]

I use a reversing base made by Unicolor. No issues with splodgy or streaking development.

All the cases of streaking I have heard about were from people with non-reversing roller bases.

It shouldn't be that hard to reverse the motor periodically by using a 555 timer and and a relay. The Unicolor base uses a paddle on a gear to hit a reversing switch.

[swmcl]

Hi Nicholas,

Thanks for your reply, that's one vote for a reversing action alone without any lifting of the drum.

I should have mentioned I do have - at enormous expense - a Beseler reversing base. The expense was in the shipping to Aust and also in that I needed to buy a step-down transformer from 230Vac to 115Vac. The total for a Beseler base for me has been around 300 US dollars.

There are other issues for me also. I have and will continue to use Pyrocat glycol HD as my developer mainly with FP4. This requires a slow rotational speed. One could hook up a variac but this will result in motor burnout if on eis not careful. Motors are designed to run at a certain voltage anything less and there can be problems. The speed of my Beseler with a Unicolor 8x10 drum is aound 42 rpm. With the Jobo 3006 it is less perhaps 25rpm.

Furthermore, if one were to get the temp regulation sorted out one might be tempted to do E6 processing. Here in my part of the world I can send undeveloped sheets across Australia for processing at $9 a sheet or do it at the local cowboys lab for $15 per sheet. This is 4x5 costings!

I've totalled the costs of building a water immersed roller bath at somewhere around $600 - $700 which is quite a bit less than what it would cost me to get a good Jobo kit shipped here. The advantage is that my parts will never wear out and should do the job as accurately as any commercial processor (because I'm looking at industrial controllers) albeit with a bit of manual handling.

Unfortunately, I can't afford to take chances in the dev stage because of the costs before I take the photo be they the materials or the costs in getting to location. Perhaps I should just do studio work in the city ...

What I'm trying to do here is estimate my best/worst scenario for the processor. If I can sort out the rotational issue once and for all I'd be very grateful. For me to build in a reversing action is more expense than if I just have a plain unidirectional setup.

Anyone else want to have a punt on whether lifting the drum periodically will be the equivalent of having a reversing roller ?

Cheers,

Steve

[Vaughn]

I have taken to lifting and reversing the drum a few times -- seems to have helped with some unevenness if skies. I use the 3005.

[swmcl]

Hi Vaughn,

My guess as I've been thinking over the past few days is that I reckon the lifting in itself would be very good for mixing things up a bit inside the drum - even more effect than the reversing. However, both the manual lifting and turning the drum around and just leaving the drum alone on a reversing base are probably both significantly better than just leaving the drum to rotate in one direction only.

Unfortunately, the more manual intervention way wins. The problem is that this is my worst case scenario because of the barrier that stops the drum falling off.

Thanks again,

Steve

[Vaughn]

Yeah -- I have to put something to keep the drum from walking off, too.

I go one min in one direction, the change the direction every two minutes. But if there is a lot of sky (rare in my photos), I am tempted to tray develop.

[Bryan Lemasters]

I happened upon what might be the best solution to the uneven development problem a few years ago, and is something that Steve might want to consider incorporating into his roller base. Among some darkroom equipment that I purchased used a few years back was a Chromega reversing roller base. The difference between the Chromega and others is that the Chromega base has slightly eccentric drive rollers that are indexed 180 degrees apart so that as the drum rolls it also rocks back and forth slightly. Just gotta be careful when using long drums because the aforementioned "walking" combined with mild sloshing of developer tended to cause the drum to tip off the base more easily.

[swmcl]

Thanks Bryan and Vaughn,

Given that I'm finding it really hard to obtain drive wheels of a good diameter of any sort I shall not be thinking of an eccentric variety !!

I (and my wife and kids) only need one eccentric around here !

Rgds,

[venchka]

I have 1 Uniroller reversing base that ceased reversing several developing cycles ago and one Beseler unidirectional base. I use either a Jobo 2551 or Expert 3010 drum with either. Last night I developed 4 sheets of HP5+ in the 3010 tank with Xtol 1:3 for 10 minutes. I will scan tonight. I'll let you know tomorrow if I had a problem. After about 100 sheets I haven't noticed any problems. No motor reversing. No drum flipping. Even developing as far as I can see. Like this.



And this from the same batch:



I am of the opinion that using dilute developer (Xtol 1:3) for a longer time (10-12 minutes depending on film) avoids any uneveness. The 3010 wiggles and wobbles naturally on the motor base. The Beseler has a leveling foot. I adjust it so that the open end of the drum is just above level. That forces the developer all the way in each cylinder. I really have not had any problems.

[Jim Cole]

I got a tip off of this forum a while back that solved my streaking problem with Jobo Expert Drums and a roller base. I bought a reversing Unicolor base, but using it with the expert drums, it reversed way too quickly considering the large diameter of the drums.

The tip was to open the base, remove the lever that causes the reversing switch to flip, remove the switch and relocate it to the lower outside edge of the housing along the side. The wires reach, so no rewiring is required. All you need is a small file or Dremel to cut out 3 sides of a small rectangle of plastic from the housing that will alow the switch mechanism to fit. When you replace the metal bottom of the base, it holds the switch firmly in place.

Now I manually flip the switch every 30 seconds during development.

Works like a charm!