The back and forth rotation is essential, so if you use a lathe, it must have this same type of reversal in the rotation. If you keep going in one direction, you will get uneven development.
My lack of knowledge of lathes , Are there units with reversable motars?
Or are there Stepper Motars that are reversable?
Come on Ron ,jeezz I know you have the answer , you are just playing this out for the rest of the day , this is cruel of you.
I do need the back and forth as well different speeds for different process.
Originally Posted by Photo Engineer
I think you would have to modify the lathe to reverse wouldn't you? If you try that route, think about an inexpensive woodworking lathe for a prototype. You don't need the precision and complexity of a metalworking lathe, in practice you would need only the drive end and rails.
Metalworking lathes use a transmission to reverse, not the motor. A DC motor on ja woodworking lathe can be reversed by switches.
Rather than gearing, use cogs & cogged drive belts except for the engagement of the drum.
The Jobo uses a reversing switch activated by a finger on the drum, it may be simpler to devise a timing device & eliminate the physical switch. Robot marketplace has a variety of belts/cogs, motors etc.
Also check to see if the local high school or university has a robotics club. The only real difference would be application.
I think the easiest part would be the set up of a lathe, hard part in my mind is linking to the drum & reversing it.
You might also try one of the robotics sites to see if there's anyone local that might give you some ideas.
Last edited by John Koehrer; 12-13-2009 at 10:36 AM. Click to view previous post history.
Originally Posted by Bob Carnie
IDK if there are reversable lathes. I've only seen them run in one direction. OTOH, I assume that there are because during tapping for screw threads, you must back the tap off the item you are working on which requires a reversal of direction I would think.
There are reversable stepper motors. I have two. However, mine are rather slow and move in a jerky fashion (steps, naturally). I've never played with the circuit to see what they can really do. So, they might be tunable or you surely could find one that works.
ME is outside - way outside my field. I know what it must produce, but not how to get there. I don't know the equipment well enough.
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Just link one bicycle on each side of the Jobo. Have your 2 assistants pedal, one for left, one fore right.
You in the middle with drums for the cycle's beat ! (tribute to Charlton Heston..) And a stick if they are too slow !
Boom ! Left !
Boom ! Right !
Pre-Wash speed ! Pyro Speed ! Attackkkk !!!!!!
:-) :-) :-)
Originally Posted by Photo Engineer
Both DC and AC motors can be reversed, but AC reversal is much more complex than DC reversal.
Listen Pretty Lith Boy
There has to be one wisenheimer in every group.
This is a really serious matter, I think you should leave this for the folks with brains and go our and look for Jerry.
Originally Posted by Guillaume Zuili
It seems there are two directions here:
1. Simple: A Uniroller-like drum roller with a direct-drive, reversible DC motor, and a couple of current choices to affect motor speed. However, getting controllability or repeatability would probably be difficult. You'd need a motor that ran slow enough for agitation purposes, and you probably don't want the complexity of gears or belts. You'd also need a power supply that had the appropriate current selectors and switches and/or timers.
2. Flexible: A Jobo-like tank rotator, also with a direct-drive motor. But as several folks have pointed out, a stepper motor would be more appropriate. I'm sure there are motors that have a good enough resolution & precision to result in decent, repeatable agitation. Driving the stepper is more complicated (http://en.wikipedia.org/wiki/Stepper_motor), but you get the benefits of higher precision and more torque at lower speeds than regular DC motors, so that would be more appropriate to agitation.
There's a wonderful electronics supply house in Boulder, Colorado, called Sparkfun. They have both a stepper motor (http://www.sparkfun.com/commerce/pro...oducts_id=9238) and a small controller card (http://www.sparkfun.com/commerce/pro...oducts_id=9402). The controller card provides both the right voltage to the motor (from a supply of 7-30VDC, depending on needed torque) and also acts as the gateway to move the motor. The motor controller simplifies the interface to the motor by providing two inputs: one to step the motor, and one to set the direction of the step. For example, if the motor is a 100-step motor, then to turn the tank one full rotation in one second would mean issuing 100 steps at 1/100th of a second interval.
Clearly, that's not something a person would do, so usually one would add a small microcontroller (such as the Arduino, http://www.sparkfun.com/commerce/pro...roducts_id=666) to handle this logic. The Arduino is easily programmable, and it would be fairly simple to write a small program to do agitation at certain rates for certain times. The Arduino has the benefit of having a USB port on it, so its programs could actually be very simple, and take commands from a nearby laptop or other PC if necessary.
The cost of the motor, motor controller, and microcontroller would be about $60.
A caveat: I don't own a Jobo or Uniroller, and have never even used one, nor have I actually built a stepper motor system, so I don't really know what I'm talking about. :-) However, this would be a fun project to work on!
John and others
Keep the ideas coming , I really appreciate this help.
I do have a techno geek/gearhead who was factory trained at Jobo, Durst and Cibachrome- colenta. He is the guy that has kept my machines alive all these years. We are at a stage where they owe me nothing but keeping the tanks and reels in production makes much sense to me.
I am going to give him all and every idea posted here and let him figure out the final product.
Once we have made a prototype and then the 4 devices I wil make available all our schematics, drawings and sources for those of you using Jobos now and still want to keep your tanks in the future and have interest in building your own.