How fast is your expert?

[swmcl]

I'm wondering if I could get an idea from other users of Expert drums as to the RPM they would estimate during processing please.

I saw a note in another topic where someone used 50rpm on a Jobo 25 series I think it was but I'm not seeing too many references to the Expert drum series.

I assume there is a speed at which you get more oxidization than development at the low end and at the high end you might get suds!

any and all experiences would be helpful here.

The chemistry I would use most times would be PyroCAT in Glycol but I'm not sure if this makes a huge difference.

The reason I ask is because I would like to motorise my drum.

Thank in advance,

Steve

[Drew Wiley]

I found that at the low end Jobo is still too high an RPM for lots of things. That's why
I built my own motor based with a bigger motor and lower gear reduction (which I
still have to photograph for a few people - I'd didn't forget - get it done eventually!)
Aerial oxidation is a real problem, so various developer tweaks have been formulated to help with the problem, or an argon gas tube can be inserted.

[swmcl]

Sorry Drew,

I have no idea what a Jobo processor speed range is. That is part of my reasoning for finding out!

I've heard of the Nitrogen thing I think it was but Argon would be even better I agree.

Cheers,

[Ron Marshall]

I hand roll my 3006 at about 30 RPM.

[sanking]

I'm wondering if I could get an idea from other users of Expert drums as to the RPM they would estimate during processing please.

The chemistry I would use most times would be PyroCAT in Glycol but I'm not sure if this makes a huge difference.

Steve


Steve,

When developing film in a Jobo with any pyro staining developer I would recommend that you set the RPM to the slowest speed possible. Higher speeds tend to produce more oxidation than lower speeds, all other things being equal. Some pyro developers are more likely to give high general stain from oxidation, but all of them give more with high speed RPM than with low speeds.

Sandy King

[Drew Wiley]

My bad - I meant to say argon, but was keeping one eye on that remarkable Chilean
mine rescue thing being televised at the moment.

[IanMazursky]

For Jobo ATL processors, Jobo recommends and i use 50 RPM for the Expert (3000) drum series.
I bet any faster (75 RPM) and the inertia would probably damage the processor with a fully loaded Expert drum.

I also use 50 RPM for the 2800/2500 series of drums and 75RPM for the 1500 series of drums.

[Sirius Glass]

I use "P" [5] with the 3010 drum.

Steve

[Robert Hall]

I use 50 rpm with PMK on my expert drums and 25 rpms on a 3006 with an insert for the 12x20

[Sal Santamaura]

Speed dial settings on the CPA/CPP-2 processors are meaningless unless one knows which motor version is installed.

With the latest motor, a full 1 liter of chemistry and dial setting of "F" mine turns at 46 rpm. For developers that are not susceptible to oxidation, i.e. non-pyro and adequate active chemistry for film area loaded, the range of 45 rpm to 50 rpm is optimum.

[Scotty230358]

I also hand rotate my expert drum and find that I am managing about 30 rpm. IIRC one of the ways to mitigate against oxidation is to increase the volume of part A by 30% or increase the amount of Sodium Sulphite. However it's one or the other not both.

Perhaps Sandy King may be able to confirm this?

[swmcl]

Thanks gents.

I'm making a processor at the moment. The gear ratios I've selected at present are not aimed at 50 rpm so I'm glad I asked the question. I've got the figures of 15 to 25 in my head for some reason.

My motor does 50 rpm flat out so I'll need to change some things.

I'll have such a collection of gears I'll be able to do anything from about 6rpm through 80 which is kinda silly.

A definitive answer in rpm for the oxidation issue might have to come after the gear gets working if no one has it now.

Thanks again.

Steve

[Drew Wiley]

30 rpm? That's interesting, because that's the speed that worked best for me (though
I now prefer tray development).

[Robert Hall]

Where did you get the gears?

What kind of motor are you using?

[Chauncey Walden]

I add the EDTA solution per Gordon's recommendation and have no over oxidation problem with PMK in the Jobo. I use P speed. Lower speeds caused streaking.

[swmcl]

Hi Robert,

I'm not adapting a Jobo. My design is completely new and unrelated to Jobo. I've actually never seen a Jobo apart from pictures and never will I suspect. Jobo went belly-up earlier in the year and I had decided that I needed to build so that I could get parts and keep it running into the future. The project is taking all my waking hours.

I'm not sure talking about any specific parts has much use if not referring to existing Jobo units!

Cheers,

[Bruce Watson]

I'm using a 3010 tank on a CPP-2. When I start, I flip the little reversing toggle out of the way to get continuous rolling in one direction. Then I time it against my darkroom timer. This helps me set the CPP-2's speed very close to 30 rpm.

At processing time I flip the reversing toggle back to get reversing on the drum.

Processing TMY-2 in XTOL, mostly 1:3.