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stepper motor / PC control of emulsion making

Photo Engineer said:
Although the pump information I give will work well for all of my emulsions, this is due to design....
PE
Click to expand...

Yes.

This is clear.

Are there unique advantages of certain pump speed profiles over their substitue profiles?
 
Ray;

I'm not sure what you mean by substitute profiles. I don't think I used that terminology. A pump has only one profile but may have 3 ranges due to tubing selection. This is basically the inner diameter of the tubing. On some pumps you need 3 heads for the tubing types and on others one head fits all 3 sizes of tubing. The pump shown in the picture in one of the earlier posts is the latter type.

PE
 
Circles

Photo Engineer said:
Ray;

I'm not sure what you mean by substitute profiles. I don't think I used that terminology. A pump has only one profile but may have 3 ranges due to tubing selection. This is basically the inner diameter of the tubing.
PE
Click to expand...

Sorry, I was grasping for words to express a concept.

I did not mean the pump's profile, I meant the "profile" of addition rates in the formulation.

Once you have a formula giving you the results you desire, you have certain pump/flow/ramp details that are essential to creation of the crystal shapes, their size and their size distribution, dopant position et cetra.

My use of the word profile was ment to include addition rates in 4 dimentions (the additional dimention being time) rather than a single fixed rate.

My question was based on the assumption that one wanted to change
pump rates (that is, the complete program) for some reason.

Are their limits as to what can be done at different speeds?

In its simplist form my question relates to problems of changing scale;
but I was wondering if there were other considerations I have overlooked.

Perhaps there arn't any, but if so, then why not always use rapid additions?
Certainly, crystal construction may be more "accurate" if it proceeds slower....

Answering my own question, I would have to say the wide variety of pump speeds exist because they are in fact necessary...

unless they are only used for research.

I am not completely awake yet;
please excuse me if I am talking in circles.

Ray
 
Ray;

Addition rate is usually a + bt + ct^2 .... etc., and the polynomial is adjusted based on growth rate of the outer surface of a given volume, so as to get even growth. It differs with each crystal shape and size.

Absolute addition rate also controls speed and contrast as stated in a number of textbooks and as has already been discussed here. I need not go into that again here.

PE
 

Ray;

You asked the questions above about addition rates. Yes, the reasons for using a variety of addition rates are well known, so I didn't answer.

PE
 
Yes, But.

Photo Engineer said:
Ray;

You asked the questions above about addition rates. Yes, the reasons for using a variety of addition rates are well known, so I didn't answer.

PE
Click to expand...

Yes, but.

My question stems from someting you wrote:

"...what I am forced to do is re-engineer every single emulsion I know to perform at small scale...."

and was made in the hope of learning more about the limtations of down-scaling and scale changes in general.

I am not aware of any detailed discussion of this problem.

IIRC, you have indicated elsewhere that you have had some, perhaps extensive, professional experience in this area. So I thought to ask.

I can refer to the work of Sheppard, Carroll and Duffin for their mathematical treatments of SJ methodology but not for a discussion of scale related problems.

Perhaps my question was poorly formulated?

In any case, I am more than happy to withdraw the question.


Ray
 
Your question was misunderstood and is now clarified.

Ok, years ago, they could not get good contrast because of poor sulfur sensitization methods (active gelatin was used), and so they used varied addition rates as part of the process of varying contrast, but at the expense of varying speed. In fact, if you look at many formulas from 100 years ago or 75 years ago addition times are not specified or it is stated that silver nitrate is dumped over the side. A person adjusted dump rate to get the desired contrast, and "dead grains" required silver rich coatings.

I can take an intermediate point in this and devise varying contrasts by adjusting addition rates upwards (to fit my pump speeds) and by decreasing finish (sulfur treatment) to get the speed and contrast index that I want. This puts me in the scale range (100 ml - 1000 ml) I want, and the flow range I want (as seen on the chart above). However many complex T-grain formulas require specific addition rates to grow the edges and scaling this is not a simple task.

PE
 
As I have the attention span of a gnat, and certainly do not add the silver solution evenly, I came up with a little device to drip it in for me. I've got a little flexible silicon tubing (from an RC plane's fuel line) attached to a pipette, and then the other end to a plastic bottle cap, with the bottle turned upside down and the bottom cut out (ala buret). Iv'e got the bottle attached to a ring stand and the pipette, whose only use is to neck down the flow of the tubing (.1ml pipette), which goes to the kettle. I raise the plastic bottle to various heights based on the flow I want. (naturally, it slows during the make, but I'm still an amateur)

Now- after reading all of the issues ya'll have with the current pumps available, could you put this set up on a vertical screw so that it could be raised and lowered to increase or decrease flow? You could calibrate the "pump" based on various levels of head vs. pipette size, and since you'll know how much fluid you place in the jar, and also the rate it's coming out, a computer should be able to raise the jar (plastic bottle in my case) to keep the head level - and therefore the flow, constant (or quadratic if needed). Now, you may want a valve on the bottom of your jar so that the start of your flow is more instantaneous, ie. PC raises the head to the appropriate level, then the valve opens. By the time the liquid exits the pipette, the liquid has had time to accelerate to it's needed flow. When the valve shuts off, the flow should stop relatively instantaneously, as the pipette will not allow air into the tubing and therefore the liquid will stay put.

Got the Idea off of a time warp episode where they used a similar set up to meter and take pictures of water drops. I can get mine to do about a drop a second, which i figure is about 3 mL per minute. I think you could get it to go slower, if you imersed the end of the pipette into solution, since the surface tension of the water forces it to make drops instead of disperse into solution, I have not played with it enough to figure this out, and my plastic bottle doesn't have 1 ml Graduations on it. My pipette does, so if I can make this system ramp down to .1Ml per minute, as stated in PE's prior post, I'll post up how I did it. Of course, building circuitry to control this is so far beyond me, I doubt I'll ever attempt it.
 
I just wondered if any of you guys working toward a PC controled system have thought about a setup like that - It seems to no have some of the problems ya'll have with other types of pumps. Wasn't askign a question at all, just sharing an idea.

So if it does work, yeah - I'll post how I did it, and approximate capabilities.
 
PC control will be very expensive and difficult. BTDT.

You need control mechanisms and high end equipment to carry out the on/off and rate stuff. I am doing it manually.

PE
 
totalamuteur - interesting setup, but the system I'm using seems a lot simpler and easier. I've got a peristaltic pump and have it disperse the solutions directly into the kettle.

(I've probably posted this info earlier in this thread, but here's another one for sale http://cgi.ebay.com/ISCO-WIZ-Pump-D...ViewItemQQptZBI_Pumps?_trksid=p3286.m20.l1116 If anyone is interested in buying this one, check with the seller and make sure the yellowish tubing clips that go over the metal rollers have little levers on the clips - sometimes they break off and then you can't tighten the tubing against the roller)

I can adjust flow rates from 0.1 to over 10 mls per minute, and if I wanted to, it can be hooked up to a serial port on a computer and let the computer send start and stop commands to it. So if you want PC control (with no feedback, of course) here's a pretty simple way to do it, and you don't have to build it.
 

Yes.
That was one of the first methods that was suggested to me by a fellow student at the time. I appeared to be having trouble blowing glass and someone told me what they would do... (TIP: For extreamly fine control, use a looooong tube and raise the height by small fixed increments!) I listened politely and then continued working glass; I still use those glass items to this very day!

While basicially a sound method [tube + variable fall distances], I did not like needing to clean out the leftovers in the tubes, nor trouble with retention issues... but on a small scale, w/ good flow, that should not be much of an issue; Generally I prefer not to use plastic however...

I also have peristaltic pumps and a pumped injection syringe system, both capable of very fine controll, but the syringe method "hiccups" once every cycle; very tiny hiccups, but very real never the less. Of all the methods, the syringes have the coolest sound effects... but are also the largest, the heaviest, most cumbersome and are also the most fragile and difficult to clean!

Ray
 
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The earliest method of addition at Kodak involved the use of graded tips to control flow rate. These came in sets of tips of different sizes in little velvet boxes and were the treasured posession of every emulsion maker, and handed down over the years to their replacements.

Woe betide a person who broke a tip. A new one had to be extruded that matched the broken tip. I learned how to make this type of tip in a glassblowing class in graduate school. I never used them at Kodak though.

I posted a picture here somewhere of a Kodak making setup that used this type of tip.

PE
 

Boy you can say that again!

In 18 years, I have not broken a single one.
Thermometers- now that is a different story

I was holding one a bit to gently and Mother of God, it slipped out and into the kettle... had it been an alcohol thermometer, I might have just seen how it would turn out, but being Hg, I just turned on the lights and started all over.

Photo Engineer said:
I posted a picture here somewhere of a Kodak making setup that used this type of tip.
PE
Click to expand...

Can any one shed some light on how one searches for images on APUG?
If this is a bona-fide Kodak set-up I would love to see it!

Ray
 
Ray - when you say hiccups - what do you mean? Your syringe pump stops? Is it something you think is specific to your syringe pump?
 
totalamateur said:
and then the other end to a plastic bottle cap, with the bottle turned upside down and the bottom cut out (ala buret).
Click to expand...

What about using a large (30, or 60, or 100 ml) disposable plastic syringe with the plunger removed? That way, you will have volume gradations printed on the side of the syringe and you can gauge the flow of the liquid ot of your "burette".
 
Kirk Keyes said:
Ray - when you say hiccups - what do you mean? Your syringe pump stops? Is it something you think is specific to your syringe pump?
Click to expand...

I doubt it is specfic... I think they all suffer this problem to greater or lesser degree.

Someone somewhere might have invented a more pefect device but the "hiccup" comes IIRC, at the point where a "withdrawn" plunger becomes "depressed"... psychological puns intended.

Pretty hard to eliminate the last tell tale signs completly, I would imagine.
It is really only a very very tiny amount, but nevertheless, it is not perfectly continous.

Ray
 
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We never had any problems with syringe pumps at EK, but then with our budget, IDK how pricey they were compared to yours Ray.

PE
 
Photo Engineer said:
We never had any problems with syringe pumps at EK, but then with our budget, IDK how pricey they were compared to yours Ray.

PE
Click to expand...

I was sort of expecting you would say that!

Like I said, someone might have made a better system and if anyone had the means AND the will power, it would have been Kodak.

I stress however, my hiccup is very small and momentary....

Just to be sure we are ccompasring Mac to Fuji apples
and not apples and oranges,
is the device you describe
delivering unlimited continous flow using 2 syringes per reactant,
or a was it single syringe having a limited, maximum capacity?

Ray
 
It could deliver continuous fixed or ramped flows, and had a source "jar" size that was based on scalability. It could be unlimited, but then would be unscalable and there were provisions in the software and hardware for an unlimited supply.

There were 2 syringes with separate computer controlled flows, Salt and Silver, and the salt could be varied to control vAg. They were called AgS and XS respectively in the software and hardware monitoring panels. Pumped delivery systems were the same in all regards but were Aga, Agb, Agc and Xa, Xb and Xc etc... denoting pumped delivery and the following letters referred either to source jars (several could be used of varying concentration) or could refer to ILD (In Line Dilution) systems which could take one silver and deliver a varying concentration to the kettle using an ILD system.

There, more than you ever wanted to know. I doubt if anyone could engineer that at home.

PE
 
It is only when you tell me more than I want to know, that I really begin to learn!

Ray
 
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