Motorized BTZS tube spinner

[Dave Jeffery]

Has anyone ever designed a motorized BTZS tube spinner that is reversible as I am contemplating building one? Even if you have partially designed one, or given it some thought I would love to hear about any interesting ideas.

Being able to add or remove some tubes quickly and easily will be important. It would be great if it could be durable, light and portable, and run on 12 volts.

My intial idea is to make a bottom rack of rollers that the tubes will be guided into using V shaped guides that rise above the water line in a tray. Designing the racks so the tubes can just be dropped into slots and easily forced into position by the top rack is important. The bottom rack of rollers will have a little spring tension to hold the tubes straight against the drive wheels and reduce any wobble. The top rack will be a motorized rack of rollers that turns the tubes which can be lifted off or pivoted aside on a hinge to make it possible to quickly add or remove tubes. It will be designed to that it would not matter how many tubes were in the racks and I may make it to hold 8 tubes for 4x5 film.

Someone posted a switching curcuit to reverse a rollor base motor and can someone please post the link to that as I can't find it.

It shouldn't take much force to rotate the tubes so this doesn't have to be a heavy duty design IMO. There are lots of cheap off the shelf shafts, gears, pulleys, bearings, motors etc easily available. Some of the small ribbed drive belts and gears are very strong and light. Any parts that can't be purchased will be cast in epoxy fiberglass with foam or woven fiberglass matt.


Any thoughts?

[jack_hui]

Not sure if this helps ...

http://farm5.static.flickr.com/4064/4418588165_4e237746de.jpg

http://farm3.static.flickr.com/2700/4419357002_f637a1c43b.jpg

I didn't make it, someone did ...

[jeroldharter]

Any thoughts?

I'll buy one for 8x10 tubes. I imagine something in which the tubes would be locked in and the apparatus would rotate like a hand cranked wheel through a water bath on the bottom. Otherwise, would need some type of conveyor belt in the water bath. I love the tubes but I just finished working through 70 8x10's, 2 at a time. So some type of machine would be great.

[Dave Jeffery]

Thanks for the post Jack. I want to use the individual tubes for various processing times.

Your post helped me with the design though as initially I thought that friction would be a good enough method to turn the tubes but now I will use a small version of a large electric motor coupler on the end of the tubes since there will be almost no friction and no way for the tubes to bind. The two part coupler mates easily and I may just embed weak magnets in the parts.

The 12V robotics motors are $1 to $2 and long drive belts with 3 pulleys are $5. Once I get further along with the design I will probably go to a robot builders site to get recommendations on specific parts.

I'll keep you posted Jerold as this may be very easy to make.

[Dave Jeffery]

A plastic bearing can be permanently fastened to the capped end of the tube and that can just drop into a round cutout which eliminates the need for rollers. The bearing can be rinsed with water.
The other end has the simple two part plastic coupler on a short shaft with a small belt drive gear on the other end mounted in another plastic bearing. All this can rotate in water.

Hmmm

[Dave Jeffery]

The design is finished.

The side that has the round cutout for the bearing that is mounted on the BTZS tube will be spring loaded so the

tube can just be moved sideways to slip the other end out of the two part coupler.

The removalbe cap with half of the coupler mounted on it will have to have a small key to prevent it from slipping

at all. The length of the tube doesn't have to be perfect as a lot of play can be managed by the coupler.

A belt will drive all the pulleys on all the shafts that have the other half of the couplers on them and it won't

matter if there is a tube in each slot or not. The empty couplers can just spin on the shaft in the bearing.

The belt will run around all the pulleys with a few belt guides and one light belt tensioner. The belt will rise

out of the water where the shaft to the motor is, and the motor will be protected obviously. A disk that slings

water will be mounted on the shaft and all the water will run back into the water bath.

The caps with the couplers can easily sit upright in a support base which will likely be slightly larger tubes

mounted on a plastic base with some drain holes and some spacers under the base to let the water drain.

All the electrical parts are available at the robotics supply places. As the exact speed does not matter for

spinning the tubes by using variable voltage motors this can be run off a car battery at 12v to 13v+, 115v to 12

volt power converters. gell cells, or other voltages that are somewhat close but not exact.

All I need is the curcuit to reverse the motor.

[AJ Edmondson]

I fabricated one years ago using a small Hurst high-torque motor (reversible)... put a 1/2" aluminum rod in a lathe and drilled out a 3/4" depth hole to fit the 1/4" shaft for the motor. I attached eccentrics to the ends of the shaft so I get side-to-side agitation as well as rotation (I used a Hurst 12 RPM but you can buy different speeds). In use now for more years than I can recall.

[Joanna Carter]

The design is finished.
Well, since you are a photographer, you do realise we are expecting pictures of the finished article? :D :p

[jeroldharter]

I wish I were handy. I watched my daughter take her shabby diorama (aided by my engineering expertise) into school alongside other kids with their dioramas with 3 story buildings, water features, etc.

I would love to see what you come up with. But now you have me thinking. You might have cost me hours of time, several futile trips to the hardware store, and several evenings surfing the net trying to invent something that won't work.

I do like the idea of something like this waterwheel in the attachment. The tubes could fit in the slots on the wheel and bungees could hold the tubes in place. A wheel that could take 6 tubes would be best for me because my Inglis washer holds 6 sheets. The lower part could dip into a water bath as the wheel turns, either with a motor or even a hand crank. It could probably fit in a 16x20 deep tray for 8x10 tubes. Speaking of Inglis, I bet he could make a manual one out of acrylic.

Then I would have to figure out how to dothe stop and fix for 6 8x10 tubes at once...

[domaz]

You can use an H-Bridge like this (http://www.sparkfun.com/commerce/product_info.php?products_id=9479) to reverse electrical motors. You probably need some diodes and other simple components as well- I can try to dig out a circuit if you want. To actually tell the H-Bridge when to reverse use a microprocessor like an Arduino (http://www.sparkfun.com/commerce/product_info.php?products_id=666)- these are easily programmed from any computer with a USB port and the code is in C- so easy to write. I wrote a program to reverse a motor once and it was literally about 10 lines of code. The micro controls the timing of when to reverse the motor and can also do things like check and display temperature of your water bath if you want to extend this project a bit.

[Jack Dahlgren]

I second the use of arduino as an easy to use microcontroller. With a few lines of code you can have this thing turn the motor one way and then another. I'm sure you could probably find a PID routine to control a heater for the water as well.

I'm working on setting one up as a processing timer.

[Daniel Stone]

what about adapting something like the hot-dog rollers that are in gas-station food courts?

simple stainless steel rollers all geared together, you could just set it into a tray of water say 1" deep.

-Dan

[Kirk Keyes]

MMMmmmmmm - hot dogs while you develop film!!!!

[domaz]

what about adapting something like the hot-dog rollers that are in gas-station food courts?

simple stainless steel rollers all geared together, you could just set it into a tray of water say 1" deep.

-Dan

Nice idea but I've never seen those things turn very fast. Also might have electrical bits that would end up in the water if you submersed it..

[Dave Jeffery]

Well, since you are a photographer, you do realise we are expecting pictures of the finished article?


I'll be happy to but after looking for parts today it will take some time to get things together.

-------------------

"I fabricated one years ago using a small Hurst high-torque motor (reversible)..."

Thanks Joel I'll look into the Hurst motors and 1/4" SS shaft is plenty strong. I will probably go with two motors now for 8 rollers. Thanks!

-----------------------

"You can use an H-Bridge like this......."

Thanks Domaz! I'll need some time to look into those controllers further.

----------

"I second the use of arduino as an easy to use microcontroller. With a few lines of code you can have this thing turn the motor one way and then another. I'm sure you could probably find a PID routine to control a heater for the water as well.

I'm working on setting one up as a processing timer."

Sounds like this is what I will end up using.

---------------------
"what about adapting something like the hot-dog rollers that are in gas-station food courts?"

My initial idea was to turn the tubes with sets of rollers similar to that but now the design is exactly like the hot dog cart rollers turn, only each roller (BTZS tube) will easily be removable.

Think of one side of the hot dog cart having individual supports for each roller (for each tube). Each of these supports have spring pressure normally holding them at a perfectly verticle position. The BTZS tube rotates in the bearing that is mounted on the tube, and that bearing sits in a round hole in the spring tensioned support. The supports can be pulled back against the spring pressure about an inch and a half giving the other end of the tube enough clearance to slide out of a slightly larger tube at the other end.

On the other end of the tube, the cap end, there will be a little over and inch of extra tubing. This will have two - 1/4 inch slots cut on exact opposite sides of the tube from the end of the tube back about 1" so when the tube slides into the slightly larger pipe a 1/4 inch pin slides into the slots. This pin that is slid into the slots will turn the BTZS tube. Haing long slots in the tube will allow for various tube lengths to all work. There will be no spring pressure pushing against the end of the tube once it is in place.

The slightly larger tube with the pin that the BTZS tube slides into will be mounted on a 1/4" Stainless steel shaft that runs through the support on the other side. This side will be like the hot dog stand design with a solid long support with all the shafts going through it mounted in bearings or bushings. The other side of the 1/4" shaft will have small ribbed belt pulleys mounted on it. A long belt will run across the all the pulleys to a motor. The belts will move a little water around and protecting the eletrical parts is important.

I will probably use two motors to turn 4 tubes each though as there will be less stress on the small belts when all the rollers start turning and it may make the timing easier as well.

---------------------------
"I do like the idea of something like this waterwheel in the attachment. The tubes could fit in the slots on the wheel and bungees could hold the tubes in place."


Jerold -For a system for 8x10 tubes you would just have to beef up the sizes of the shafts and motors etc., and I hope my description above helps you visualize the design a little better.

Thanks all!!!

[Dave Jeffery]

Domaz or Jack,

Is this the board and the code that I need?

http://www.arduino.cc/playground/Main/DCMotorControl

[Dave Jeffery]

This motor controller was recommended in a post at the Robot Shop Community Forums and it works with the Arduino.

http://www.robotshop.ca/pololu-high-current-motor-driver.html

[Jack Dahlgren]

This motor controller was recommended in a post at the Robot Shop Community Forums and it works with the Arduino.

http://www.robotshop.ca/pololu-high-current-motor-driver.html

That is exactly the sort of thing you need. I'd skip that circuit that you posted in favor of something like this which has terminals to connect to etc. etc. unless you want to solder a bunch of things together.

Then just write a bit of code for the arduino to control it.

[Dave Jeffery]

Thanks so much Jack! You and Domaz have made the controller curcuit very easy to find and put together.

There were a lot of kits to make the controller board but with all the robotics around they are getting very common and ready made for different applications. There are the light duty ones for toy size robots as well as the more robust ones for large robots.

I still have not decided exactly which motors to run but once I do someone at the Robot Shop site can probably point me to the code for the Arduino. The code to reverse the motor(s) at a certian time interval is very basic compared to the all the various coding used for the robots.

Lots of H-bridge controller videos are on YouTube as well.

Thanks again!

[Jack Dahlgren]

It should not be too difficult to write something that will reverse the motor gently to minimize strain on the system. This is where having a micro-controller is preferable to a simple reversing switch.

[AJ Edmondson]

With the Hurst high-torque motors a pause or "interrupt" causes them to reverse. These are (or were) available in various rpm versions but the speed was a function of the gearbox and thus not variable. To give you an idea of what Hurst meant by "high-torque" I bought two, one for the BZTS tubes and a second to drive the front standard of an Elwood 8x10 Enlarger. If you have ever seen one of these beasts you know that the bellows, standard, lens-board and lens add up to a significant amount of mass and the Hurst motors are still going strong after twenty years or so!

[salihonba]

I made it about 6 years ago, in plastic gears and a small motor,
http://lh6.ggpht.com/_gvRcWa2LHhg/S5zy8wYu_kI/AAAAAAAAFcs/hpK-Rnkv1lI/s800/P0000708.JPG
But I want it stay in the tub, so a smaller type was developed,
http://lh6.ggpht.com/_gvRcWa2LHhg/S5zzCqJLrQI/AAAAAAAAFc0/rupxhNmxQZo/s800/P0000711.JPG
very good for individual tube time control
I wrote to Phil Davis about this type, he said he would rather keep things simple........
Since I found that negative presented well with no reverse rolling, so I did not try to reverse during the developing...

[Daniel Stone]

that's pretty nifty!

-Dan

[jeroldharter]

That looks great and simple!


Could you not put the larger one in a bigger tray?
Do you have a problem with the tubes floating up off the gears if used with a water tempering bath?
How do you deal with the gears attached to the tubes making them "tippy" when upright?
Could you do that for 8x10 tubes (3)?
If so, what would you charge for these?

[Dave Jeffery]

"With the Hurst high-torque motors a pause or "interrupt" causes them to reverse."

I'll look into those as I think I've decided to build a hot dog tube processor that will spin one or two Jobo drums as well. No sense using seperate tubes for the same development times so a combination of drums and tubes would be best. I looked at the Hurst motors and really like the quality so thanks for the heads up as that is probably what I will use now.

Is there a cheap timer and relay that can be used to interrupt the curcuit? The Arduino controller is probably over kill if this interrupt feature is still built into the motor's controller.

Thanks Joel
--------------------------------

Nice processor Salihonba! I will probably use pulleys and belts since they are so cheap and I don't have to be exact on the hole spacing as I'll be using a hand drill to make this. Spinning a couple of drums will probably require a beefier system as well.

------------------

Jerold,

Now that I have decided to make the processor stronger there is no reason it couldn't be made wider and spin 8x10 tubes. A unit could be made that is adjustable and could process 4x5, 5x7, 8x10 tubes and / or drums of the same length. Unfortunatley this is not something that I will be able to make quickly. A decent craftsman should be able to look at this information or Salihonbas and be able to make one for you. Lots of parts on the Robot Shop website.
If you need I could do some simple sketches and post them. The exact design of the spring loaded tube release has not been finished yet. I may switch to letting gravity hold the tubes in place.

One could imagine that universal end caps could be created that could be epoxy fiberglassed onto any length of tube or drum. If this were to become a product standard 2 and 4 roller spinning ends could be made and people could just order how may roller ends they would like and add more capacity as needed. Various belt lengths and some length adjustment space at the motor base would make a somewhat universal design possible. Just adjust the width of the unit for different film sizes.


I aslo like the idea of making a drum that has a chemical resistant big plastic ball valve with a removeable custom handle to drain it. One would just slide a flat flange on the drum into a receptacle that would make a light tight connection and just open the ball valve to drain the drum quickly. Obviously the tank that catches the developer would have to be light tight as well but large schedule 40 pipe would work. Shut the ball valve and flip the drum, valve upright, into a similar light trap for the top of the drum to add the stop bath. Once the drums were loaded in the dark everything else would be possible in daylight.

What other features would be nice to have?

Thanks all!!!!

[salihonba]

That looks great and simple!


Could you not put the larger one in a bigger tray?

Yes I did, and it worked fine
Do you have a problem with the tubes floating up off the gears if used with a water tempering bath?
Carefully control water level in tub then it makes no problem
How do you deal with the gears attached to the tubes making them "tippy" when upright?
oh, I made a pile of bigger tubes for resting.
Could you do that for 8x10 tubes (3)?
donno, never try that, I shoot 4x5
If so, what would you charge for these?
try do that yourself, it is quite easy, and I should try rubber belt for new version.

[younghoon Kil]

I made it about 6 years ago, in plastic gears and a small motor,
http://lh6.ggpht.com/_gvRcWa2LHhg/S5zy8wYu_kI/AAAAAAAAFcs/hpK-Rnkv1lI/s800/P0000708.JPG
But I want it stay in the tub, so a smaller type was developed,
http://lh6.ggpht.com/_gvRcWa2LHhg/S5zzCqJLrQI/AAAAAAAAFc0/rupxhNmxQZo/s800/P0000711.JPG
very good for individual tube time control
I wrote to Phil Davis about this type, he said he would rather keep things simple........
Since I found that negative presented well with no reverse rolling, so I did not try to reverse during the developing...

This may be late, but could you tell me what materials were used to make these tubes? I want to make it too. :eek:

[Roger Thoms]

This may be late, but could you tell me what materials were used to make these tubes? I want to make it too. :eek:

Those tubes are manufactured and sold through “The View Camera Store”, although they show out of stock right now. Here a link to a thread on 5x8 development, see post #9 for an example of 5x7 tubes I made from electrical pvc and AB’s plumbing fittings. You can make tubes for 4x5 the same way. https://www.largeformatphotography.info/forum/showthread.php?102469-5-x-8-Developing-Tank&p=1032416&viewfull=1#post1032416

Roger

[bmikiten]

The whole point of the water bath was to provide not only some modicum of temperature control but also the random motion that allows for the even development. When Phil and I were developing the BTZS tubes, the entire point was to NOT do what Jobo was doing and to avoid motorizing it. Just an FYI.

[Roger Thoms]

Good point on the water bath, that’s how I’ve always used the BTZS tubes. It’s really hard to beat the water bath for even development.

Roger

[younghoon Kil]

Thank you all for your responses! :)