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Modifying A Paterson Orbital Processor
Modifying A Paterson Orbital Processor
Dave Miller
Published by Dave miller
23rd September 2008
Default Modifying A Paterson Orbital Processor

The purpose of this article is to show how a Paterson Orbital Processor may be modified to allow its use as a sheet film processor.

This useful item was originally sold as a daylight10x8 print processor, in fact it was marketed as a colour print processor with the capability of accepting a number of smaller prints using the supplied divider pegs if required. I have long used them, in conjunction with the motor-base accessory for developing my 10x8 monochrome prints as it has the footprint of little more than a single tray, but thatís another story.

Whilst no longer made they are available on the second-hand market, although the price has risen recently due to their popularity.




Cover with the filling funnel in the middle





Underside of the lid showing the light trap and flow guides


Examinations of the pictures above will show the two part construction of the light tight lid.

Perhaps before I go any further I should address its perceived advantages and disadvantage over conventional sheet film developing units.
  • It is very easy to load, the hardest part is ensuring that the emulsion is uppermost.
  • Once loaded the process can be completed in daylight.
  • If a motor-base is used you can get on with something else during most of the process.
  • It is very frugal in the use of chemistry.
  • The results are consistent.
  • Itís easy to clean.
  • The only drawback is the limited number of negatives that it can handle at one time.
The internal base is very smooth, whilst this is not a problem for its designed use as an R/C paper processer it does allow a suction effect with a wet negative that we could do without.

This effect can be broken by simple modification to the tray base that will still allow the unit to be used for its original purpose. This can be achieved placing spots of slow drying epoxy adhesive over the base. Small spots placed on a 2cm grid is ideal. These spots settle during curing and leave smooth domes which, when hardened are quite impervious to our chemicals, and particularly kind to the rear of negatives, which do tend to move around a little during processing.




Modified tray base


This stage of modification renders the unit entirely suitable for the processing of single 10x8 negatives in daylight conditions. It allows the water rinses to reach both sides of the negative to remove all traces of fixer so as to ensure that the negative is completely washed. I should add that I use something akin to the Ilford fill and dump washing process.

One can also use this modified tray to process two 5x7 negatives, or four 5x4 negatives if the supplied mushroom separator pegs are used to keep the negatives from riding over each other.

Whilst the level of modification described here will suffice I have taken it one step further to make a processor dedicated to the development of 5x4 negatives.


Extending the spacer pegs


As can be seen above I have replaced the four mushroom pegs with fixed plastic posts that extend up almost to the underside of the tray lids. This prevents any possibility of the negatives overriding the mushroom pegs during the, perhaps over vigorous washing routine I employ.

Although the unit was designed to use a mere 60ml of chemicals I use double this amount to be quite certain of complete coverage when developing prints. Experimentation has shown that this quantity is also quite sufficient for a single sheet of 10x8 film if continuous agitation is employed. However, when developing four 5x4 negatives I have occasionally noticed bromide drag marks appearing adjacent to the posts on thin negatives. I think this is due to the flow of the chemicals around the tray being disrupted, in a regular fashion, around the posts. I have found that it can be overcome in one of two ways. The first is to rock the tray irregularly by hand for the first minute of development, and then put it on the motor base for the remainder of the period. Secondly, and this is the method I now adopt, increase the amount of developer to 200ml.

As with any change of developing method or developer type experimentation is required to establish the best routine and chemical mix for you, this product is no different to others in that respect.
__________________
Regards
Dave
www.davids.org.uk
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  #1  
By BobRob on 11th November 2008, 12:22 AM
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you must be a mind reader dave...I was thinking earlier that I could use an orbital to process 5 x 4...i'm off to ebay to take a look.

bob
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  #2  
By Dave miller on 11th November 2008, 05:41 PM
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Quote:
Originally Posted by geetoo View Post
you must be a mind reader dave...I was thinking earlier that I could use an orbital to process 5 x 4...i'm off to ebay to take a look.

bob
Good luck with the hunt.
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  #3  
By Mike Meal on 24th December 2008, 02:04 PM
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Dave do you think that replacing the mushroom pegs is essential or did you do this to this just to err on the side of caution?
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  #4  
By Dave miller on 24th December 2008, 02:07 PM
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Quote:
Originally Posted by Mike Meal View Post
Dave do you think that replacing the mushroom pegs is essential or did you do this to this just to err on the side of caution?
No, it's not essential, but a 5x4 film sheet can climb over the standard mushroom pegs if the agitation is vigorous.
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  #5  
By Paul Mitchell on 24th December 2008, 02:13 PM
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I put deep grooves in the bottom of my orbital and still use the mushroom pegs without any problem.

Paul
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  #6  
By Dave miller on 24th December 2008, 02:18 PM
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Quote:
Originally Posted by Paul Mitchell View Post
I put deep grooves in the bottom of my orbital and still use the mushroom pegs without any problem.

Paul
Did you use a rotary cutter for the grooving?

I found that to be the case with the pegs; until it wasn't I didn't like the patchy development the resulted from one negative partly covering another.
As I said, with gentle adgitation the mushrooms should be OK.
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  #7  
By Paul Mitchell on 24th December 2008, 03:06 PM
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Quote:
Originally Posted by Dave View Post
Did you use a rotary cutter for the grooving?

I found that to be the case with the pegs; until it wasn't I didn't like the patchy development the resulted from one negative partly covering another.
As I said, with gentle adgitation the mushrooms should be OK.
Dave, I used a Stanley knife and made deep cross hatch scoring across the whole bottom, I then finished off with a quick rub with some wet & dry to get rid of the sharp edges, works a treat. I also agree with you about using more than 80ml, I in actual fact use 150ml and it's fine.
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  #8  
By Mike Meal on 24th December 2008, 04:30 PM
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I was a little concerned about scoring the base and it scratching the negs so I followed Dave's article. The only thing that slightly bothers me now is that the epoxy lumps may lift the neg off too high so I've decided to go for 200ml of chemicals.
Looking forward to using the Orbital though, my old Combi tanks used 1000ml of chemicals so the Orbital gives me other developer options rather than sticking with Rodinal for economy.
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  #9  
By Dave miller on 24th December 2008, 04:42 PM
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Quote:
Originally Posted by Mike Meal View Post
I was a little concerned about scoring the base and it scratching the negs so I followed Dave's article. The only thing that slightly bothers me now is that the epoxy lumps may lift the neg off too high so I've decided to go for 200ml of chemicals.
Looking forward to using the Orbital though, my old Combi tanks used 1000ml of chemicals so the Orbital gives me other developer options rather than sticking with Rodinal for economy.
If you have any doubts try loading it with old negs and plain water and running it with the top off. You can then see where the fluid gets to.
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