Changing reversal interval of Uniroller base

[Dirk Rösler]

I have disabled the reversal on my Uniroller base for 4x5 processing with the 3010 Expert drum, but lately I have issues with 8x10 in the 3005 Expert drum where occasionally some areas areas are undeveloped or uncleared. Always seems to happen at a similar position so I want to get the base to reverse direction again automatically.

Has anyone found a solution to increase the interval using the mechanical switching setup that is in there or is the only way to insert something electronic (and if so what exactly would accomplish this)? Would prefer the mechanical path for simplicity, but if no other resolution will do the electronics... thanks.

[Chuck Pere]

The easy way is to turn the drum by hand every so often(30 sec?). Hey you are watching it anyway to make sure it doesn't fall off the base. I did it electronically by using an oscillator made from a 555 timer IC. I used a 9 vdc battery and put a small circuit board into the base. If I did it over I would use a small wall plug power supply as my battery has gone dead at the wrong time. You could also use a repeating relay if you can find one anywhere. If I recall correctly the oscillator controls a relay that takes the place of the old mechanical switch. I adjusted the timing so that the drum turns two times before repeating.

[BradS]

Dirk,

you might try changing the amount of chemistry used. A small change in the volume of liquid in the drum may have a relatively large effect in the fluid flow dynamics inside the drum. In theory, any small disturbance should do the trick...picking up the drum and physically re-orienting it on the roller base every minute or so ought to work too.

I really like Chuck's solution too but am probably too lazy to actually do more than think about implementing it.

[Vaughn]

Dirk -- I disabled my Unicolor also. I am noticing some uneven development, also, with the 3005...to the point if I have large areas of even tonality, I will tray develop. I have started to lift the drum and rotate it every minute, but have not tested it with any negs with areas of even tonality to see if it helps.

I use to have drastic problems with uneven clearing on the back side of the negs. I was using Kodak Rapid Fix with hardener. The problem went away when I switched to Ilford Rapid Fix without hardener.

Vaughn

[Dirk Rösler]

Thanks guys. I would like to automate this for the sake of consistency and also to leave the drum unattended (I have it hit a wall on either side if it starts walking; also this is not so bad when it reverses, only unidirectional it becomes a problem).

Re. amount of chemistry I am using 500 ml which I thought is a good amount. Not too much, not too little. I am using Rodinal 1+50 with great results with Acros. Do you think I should reduce or increase that? It is already quite heavy for the motor I thought.

I have not tried the pre-rinse yet, perhaps that also helps but I think liquid simply consistently not reaching some areas in the long tube is the real issue there.

Yes, ideally there would be some rocking, perhaps by introducing some unevenness on the rubber wheels. Or I can ask Hiroshi Sugimoto for his solution:

"I myself have done my share of inventing tools for realizing various art projects. My studio is more of a workshop Often they just don't sell the tools I need for the job: like a "simultaneous vertical-horizontal agitator” to prevent uneven film developing for my Seascape negatives... " http://www.sugimotohiroshi.com/colors.html

I will look into the relay setup, have to visit an electronics store and ask for help.

[Jan Pedersen]

Until i started reversing the 3005 and 3010 drums manually i had similar problems with both uneven developement and not clearing the back in the fix. I use a Beseler base and now reverse every other minute when developing time exceed 10 minutes and every minute when developing time is less than 10 minutes and when fixing. Reversing the drum resolved all problems. I also add liquids while drums are rotating just to eliminate the posibility of uneven development when drum is standing upright.

[Dirk Rösler]

Hello Jan, this confirms my suspicion. I also add liquids while rotating.

[BradS]

...I also add liquids while rotating.


How do you do that? I know it is easy on a Jobo lift...but, on a simple motor base? Do you have a special curved funnel or something? Please share...:)

[Vaughn]

How do you do that? I know it is easy on a Jobo lift...but, on a simple motor base? Do you have a special curved funnel or something? Please share...:)

I add chemicals while the drum rotates (I thought that was SOP). I bought a short piece of plastic tubing from the hardware store that fits over the end of the funnel. Since the tubing is sold on a reel, it already has a curve to it. I use a piece that is fairly thick-walled as it keeps its curve.

A small amount seems to always spill out while one is filling the drum...one tries to fill as quickly as possible. But add it too fast and the fluid backs up a bit -- an 8x10 tray catches it easily enough.

Vaughn

[BradS]

Hmm, Thanks Vaughn. I'll have to try that. I've always just set the drum on the counter, tiped it a little away from vertical and poured the chems in - slowly (yup, they spill out all over the counter if you pour too fast this way too).

[Jan Pedersen]

I use a funel i bought at a NAPA auto store, it has a piece of clear soft plastic tube attached. Works well.

[David Karp]

How do you keep the tube from popping out while you are filling? I seem to have a problem with this (with one of those funnels from the auto parts store). I have been cooking up some solutions, but have not tried any yet.

[Vaughn]

Hmm, Thanks Vaughn. I'll have to try that. I've always just set the drum on the counter, tiped it a little away from vertical and poured the chems in - slowly (yup, they spill out all over the counter if you pour too fast this way too).

Brad, if the tubing does not already have the curve to it, you might try putting the piece into boiling water, then remove it and let it cool in the shape you want it to be. I have not tried this, but who knows? It might even work!

Vaughn

PS...I only lose perhaps 5ml of developer (out of the 1000ml I use)...more with fix and water as I am not as careful with those.

[Jan Pedersen]

David, Is it possible that your tube is to long and therefore to difficult to keep steady?
I don't remmeber if i cut mine shorter but i think i did. it is about 5" long. I hold it partly by the tube to bend it a bit and then let my pinky touch the rotating drum to keep the tube steady inside the drum. As Vaughn have said, a little fluid is coming out but i keep the filling end of the tube above the sink so no big deal.

[venchka]

500ml may not be enough for 8x10. I use 400ml to 800ml in a 3010 depending on the number of sheets. I have used 1 liter without any problems. Not sure what might happen with 1 liter long term. 5 min. pre-soak. Funnel and tube from Wal-Mart. Tube length cut about in half. The funnel has an On-Off twist collar. Tube in the mouth. Motor on. Funnel open. Timer on. Dump at 30 secs. to go. Tank back on motor base. Stop water in the funnel. Tube in the tank. Funnel open when timer buzzes. A little hectic. No problems yet.

If I am only loading 1 or 2 sheets, I use the tube next to JOBO label. I tilt the tank in the sink with the label up. Developer goes in the empty bottom side. Tank on base. Timer on. Stop as above.

[Dirk Rösler]

I also use a normal funnel with a piece of garden water hose, just about enough to bend it for a 90 degree intake. Yes, have to pace the flow a bit, but you get used to it soon. Holding with one hand and pouring with the other is no problem.

[aduncanson]

I have been thinking about the original poster's request for how to delay the reversal period of the Uniroller base. Not knowing anything about the guts of the unit, I assume only that there is some sort of micro-switch which limits the travel causing the motor base to reverse. It would seem possible, and entirely consistent with that level of technology, to create a relay logic circuit to count and divide the pulses coming out of the micro-switch.

I have been delaying posting this idea in hopes that somebody smarter with the technology than I, would explain how this could be done. The web page below gives a circuit that looks like it could be adapted for the purpose. Using 8 relays, he seems to be able to divide the pulse rate by 2, 4, 8 or 16.

http://www.retards.org/library/technology/electronics/relay-counter.pdf

Good Luck

[David Karp]

Thanks for the tips. I will try them out. This is one operation where three hands would help. I was thinking about rigging a bent-wire-hanger-holder-contraption to keep the end of the tube in place while I pour the chemicals into the funnel. I still might try that out. If it works, I will report back.

[Vaughn]

aduncanson...The reversing of the motor in done by a bit of metal whacking a switch, which reverses the motor, then the bit of metal goes in the opposite direction and whacks the switch again, reversing the motor again. Pretty basic mechanism. One stops the motor from reversing by bending the bit of metal so it can't whack the switch.

I am sorry if I got a little too technical;)

Vaughn

[Dirk Rösler]

More technical info ;) : Since the switch whacking thingie is on the axle of the motorised roller and even though there is a tricky plastic bit to extend the whack for slightly more than one axle revolution, the challenge is to hit the switch after even longer time than that.

[Chuck Pere]

You probably could wire up the switch to drive a counter. The counter would then control a relay used to switch directions. Would be limited to switching at intervals of the normal rotation time but that shouldn't be a big problem. Just find the count that gives just over two turns.

I use a flexible funnel and fill while the drum is turning. Seems to work OK but you need to go slowly with the fill. Also I use 1000-1500ml and don't have any motor problems.

The base and Expert drum make a nice system. Biggest issue is the old continuous vs. intermittent agitation controversy.

[BradS]

I was thinking about using a bit of string somehow...the idea is that the string would wrap around the drive axle and eventually, pull on the plastic bit that reverses the motor direction...then the string would unwind and wind around the axle in the opposite direction...and so on.

[Dirk Rösler]

Yes, that's not bad. I was thinking if the switch was a push button type and you could make the axle "grow" thicker while it is turning then it would eventually hit the button.

But the string idea is good too. If you could feed two strings around something on the top and bottom of the housing it could still pull up and down the existing switch. :rolleyes:

[Vaughn]

Hey Brad, let's not get too cosmic on us and get into String Theory!

Another big issue is the habit of the drum to walk off the motor base, even tho the drum ain't got legs. Makes for turning the drum 180 degrees a little bit more of a chore. But at least it always waks off in one direction (to the left on mine). I am afraid to try leveling out the motor base, as for now I just have to worry about placing something on one end to keep it from falling off. I'd like to use something with a bearing or wheel or something to reduce the drag of the drum rubbing on what I use to block it (tho I have kept the surface area in contact to a munimum.)

Vaughn

[Dirk Rösler]

I tried the levelling to prevent the walking, but in the end it looked so slanted that I worried about level of fluids so it is back to as it was.

The reversal of rotation will take care of that as well. I did some sheets in the 2840 drum last week with exquisite results and no walking at all...

[David Karp]

Here is an old thread I found discussing this issue with a Beseler base. Perhaps it might be of interest: http://www.largeformatphotography.info/forum/showthread.php?t=25825&page=2&highlight=roller+base+reverse

[Dirk Rösler]

I am on track with a mechanical solution by means of a specially origami folded paper clip sitting on the axle operating the capacitor's flick switch. At the moment the Expert drum makes exactly one full revolution, which might be enough already but it would be nice to get it to do a little more.

[aduncanson]

How about twisting the drive belt into a Moebius strip? :D

[Dirk Rösler]

My ninja paper clip works, not quite as expected but is a working solution. I have bent it in a way that it behaves like the runner on the shaft which reaches the switch. However I have the clip that way that it only just about reaches the switch so it would randomly trigger it or sometimes just pass by. The trick is to give the clip on the shaft some play so it has a different position every time it revolves.

It is not a reliable steady reversal but my observation shows that it reverses a few times a minute. At worst the drum makes one full revolution so this should work.

The first image shows the first version of the clip, the second the installed one in operation.

Off to develop some film...

[ghost]

Man I'm glad I tray develop. :p

But good luck fellas- nice to see the tinkering spirit!