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 ...





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?

[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 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- 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.