DIY jobo base (work in progress, input welcome)

[Colin Graham]

This is a rock-tumbler style motor base I've been tinkering around with for the past few months. Getting the motor and driver sized right was a little tricky for an electronic illiterate like me, but this last version seems to work well with a 12v DC car seat motor (http://www.amazon.com/gp/product/B005IR1NBA/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1) and a 10A speed controller board (http://www.amazon.com/gp/product/B00HTZ5OS2/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1). (More details through the link on the video page.)


https://vimeo.com/164843384

The motor had a right angle lead screw attached to it that I wanted to drive the drum shaft. The drive was a weird mix of helical and worm, even the lead screw itself was a strange size, so I ended up hacking off the whole transfer case and using a chain drive. You can see the vestigial worm drive shaft sticking out past the chain sprocket.

Anyway, not sure how much the frequent reversing of the motor will hurt the driver or motor itself over time, but it's working well so far. Now that I have the drive ratio, torque, dB, and a nice broad range of available speeds worked out, I might try a programmable version of this to automate it a bit more. The motor specs list a 25A stall current, but only draws about 1.5A no load. I haven't hooked a multimeter up to it to check the current draw during the switch reversal (mine's MIA), but I'm only using it in the 30 RPM range at light loads. Those higher speeds in the video test were mostly to test the stability of the drum on the rollers. The thing can really fly, almost 120 RPM with a liter of solution at full speed! But I only dared to go halfway on this clip.

Anyway, it would be great if any of the electronically-inclined folks here could point out any potential problems with my setup or suggest a good compliment of motor controller/logic board for this motor. Also, how bad do you think I'm stressing the components switching directions so often?

Thanks in advance for any input.

[David Karp]

I know nothing about electricity and motors, but your creation seems awesome.

[Richard Wasserman]

I unfortunately can't help with any of your questions, but I will be following this with great interest. Looks very nicely done!

[koh303]

Cool project.

Watch your fingers on that exposed drive chain and gears.

Reversing is good for your film, consider adding that into your automation.

[Jordan]

I've been waiting for people to start making these. Please continue and I would happily purchase one as I'm sure many others would as well. Well done.

[koh303]

I've been waiting for people to start making these. Please continue and I would happily purchase one as I'm sure many others would as well. Well done.

Not to detract from this very nice work, Beseller unicolor motorized bases have been around for decades and sell for next to noting.

[Colin Graham]

Thanks for the comments.

Koh303, that's funny, but I guess you're right. It does look a bit menacing with the whirling chain. I've stalled this by actually sticking my finger into the chain drive at the sprocket. It doesn't even pinch, so it's harmless. About the reversing, that's pretty much the point of this project. It's already got a manual rocker switch that allows for changing directions, as the video clip demonstrates. The next step is replacing the manual controller board with a motor driver that will handle the stall current, then I can automate the reversing cycles so I don't have to flip the switch manually. Actually, that's about the only thing I want to program, it's nice to be able to control the speed in real time.

This (https://www.pololu.com/product/2507) is the driver I think I need. But they're fairly pricy compared to what I've got into this, and coupled with an arduino is total overkill for what I want this to do. It would be perfect if I could manually vary the rotation speed with one potentiometer, the manually vary a motor-reversing delay cycle with another, but not sure if such a thing exists.

[Jordan]

The Beseller motor bases work indeed, but honestly they aren't great and especially with larger drums. They're slow and fairly unsteady. This is much much nicer and has speed adjustments.

[Colin Graham]

I agree with both sides about the Beseler motor bases. They're certainly adequate, but there were absolutely none to be found anywhere when I first started on this project. On the other hand they do seem loud and rather limited, and the videos I've seen of them in action inspired me to just make my own instead of waiting for one to pop up for sale.

This was inexpensive and easy to make. The only reason I'm in this over $40 is I tried several different motors, drive components and boards. The only reason it took more than a few hours to make is because I enjoy tinkering with DIY stuff. In fact I just replaced the chain and sprockets with a timing belt and pulleys, so now it's nice and quiet. But for now, I'm not going to try to automate the reverse cycles, it's just not worth the added complexity or extra expense. It's no hardship to just flip the rocker switch as needed. It's a pretty nice break from sitting in the dark shuffling film in trays.

[Drew Wiley]

It's kinda late in the game for any advice that I have. Ideally you want a gearmotor that translates the energy into a much lower RPM with higher torque, so you
could potentially drive bigger drum and solution volumes without bogging down. High RPM's are not really desirable in photographic processes. Lowering the speed electronically to 30 RPM helps, but its better to select a gearmotor and control which brackets the right correct mix/max working speed. I realize this is a fun project for you, and you should be commended for it. But if you want to do something more serious, get ahold of a Grainger catalog where you can peruse all kinds of combinations (their website is a poor substitute). Having reversibility is a nice feature, but not essential. But it needs to do this gently, not suddenly. A true linear rocking feature is more useful, esp when working with minimum solution volumes. I've always considered real Jobos motors to be underpowered and too fast. Allegedly the new ones have a bit more clout. Just make sure everything is moisture and corrosion resistant.

[Colin Graham]

I did need a relatively high RPM motor, as the step from the roller shaft to the drum is 1:9. I tried a dc reduction gearmotor on the first version, carefully sized to move the drum at the speed I wanted, but it was really loud and grating.

https://vimeo.com/233585429

The brushed motor I'm using now isn't using it's full torque at the current I'm feeding it, but it's plenty strong for the expert drum at full capacity. I'm probably shortening its life by under-powering it, but they were inexpensive so I just bought two in case I burn one up experimenting. I wanted to use the motor's worm drive since the speed from that was the RPM I wanted, but couldn't the find any matching stock drive components to transfer the drive to the drum roller shaft. I might vary the drive pulley sizes a little to bring the max speed down into the useful range. BTW, that high speed in the clip was just a test- I moved the shafts pretty close together to reduce load, and thought it might have made the drum unstable. The chain sprockets are actually reversed in the video clip- the small one is supposed to be on the motor shaft, so the speeds in the video are much faster than the working setup.

That's an excellent point about the abrupt stop...that would be a nice side benefit of a programmable reverse cycle, you could set the motor to slowly brake before changing directions. Many thanks for the input.

Oops, forgot to mention- Loc-Line (http://www.mcmaster.com/#loc-line-coolant-hose/=vljcr9) is a great hose to use for getting the solution to the drum when spinning. It holds it shape really well and is easily adaptable to funnels. The 1/4" is a bit small, takes 20-25 seconds to drain a liter of solution through it with the mating 1/4" supply valve. 1/2" would probably work better.

[WayneStevenson]

You can use a double pole double throw relay to switch the polarity. And a repeating timer relay to set your reversal intervals.

[Colin Graham]

Thanks Wayne. I saw a ready made relay board (http://www.mcmelectronics.com/product/CEBEK-I-27-/28-4745) a while back that seem to be sort of like what you mention, but I couldn't tell from the PDF if they are repeating, or set up for a single event, or if they will need a separate motor controller, etc... Does 'returns to idle circuit' mean you have to manually reactivate for for each cycle? I can't tell if it's possible to loop it. I really just need to spend the time to research this properly before I go any further with it.

Anyway, the law of diminishing returns definitely applies here- not sure how much research or money I want to put into this to avoid flipping a switch manually. The more I use this, the less of an issue it is.

[Colin Graham]

A few things I forgot to mention earlier. I'm not interested in building more of these or selling them, it has too many unknowns. Also, the video from the original post was moved to Vimeo (https://vimeo.com/user36765036/videos)- sorry about the dead air.

[Joan Aguer Poch]

Some time ago I built a base for Jobo drums, this circuit you need it

http://fadisel.es/cebek-electronica/temporizadores/temporizador-ciclico-12v-cebek-i-10_r_283_202.aspx

can regulate the rotation time very well, and is launched automatically at the time that the women running (no need to control anything else)

Sorry for the bad ingles

[Colin Graham]

Thanks for the link. But can the 'rest cycle' be configured to allow polarity reversal to the motor so it will switch directions? I'd always assumed I would need a double-pole relay for that.

[Joan Aguer Poch]

If they act in a time of two relay circuits
then wiring the inputs on the back, one of the other circuit,
motor varies the rotation.
Here now is very late, but tomorrow a small fare scheme and the public

[Joan Aguer Poch]

131077

He was right, I had to change the original relay for a double

Here is a small outline.
The resistor is to smooth the starting month.

[Joan Aguer Poch]

131079
131080
some pictures

[Colin Graham]

Oh ok, that makes sense. Very cool. Good to know swapping relays is an option. Many thanks for the drawing and the pictures.

I do like that relay board- dual potentiometers and it appears to be rather straightforward to hook up some external pots to it as well. I did have one other question though- do you know if there is a brief delay between the motor reversing in this type of circuit so there isn't a lot of current draw on the motor? The motor I have is rated for 25 amps at stall current, and was worried an immediate switch in motor direction might fry this type of circuit. It only draws about 1.5 amps at typical load though. Or is that what the resistor is for in your drawing- by 'starting month' do you mean start-up current?

Thanks again for the help.

[DrTang]

what would really be cool..was if there was some cheapish and easy to build circuit with parts from radio shack.. that I could put together and easily insert into the wiring of a Beseler Motor Base - that would change rotation .. if I had to sit there and manually flip a switch.. that would even be way better than picking up the tube..dumping half the chemicals onto the kitchen table and starting t up again

ideally..one could adjust the timing and have it slow down a bit before stopping and changing direction.. as well as ramping up to speed when starting



so..all you McGyvers out there.. chop-chop...the very very small world of home processing sheet film users await

[Joan Aguer Poch]

Oh ok, that makes sense. Very cool. Good to know swapping relays is an option. Many thanks for the drawing and the pictures.

I do like that relay board- dual potentiometers and it appears to be rather straightforward to hook up some external pots to it as well. I did have one other question though- do you know if there is a brief delay between the motor reversing in this type of circuit so there isn't a lot of current draw on the motor? The motor I have is rated for 25 amps at stall current, and was worried an immediate switch in motor direction might fry this type of circuit. It only draws about 1.5 amps at typical load though. Or is that what the resistor is for in your drawing- by 'starting month' do you mean start-up current?

Thanks again for the help.

Many amps 25 amps.
Although everything is reduced to a more powerful relay

[Jac@stafford.net]

what would really be cool..was if there was some cheapish and easy to build circuit with parts from radio shack.. that I could put together and easily insert into the wiring of a Beseler Motor Base - that would change rotation .. if I had to sit there and manually flip a switch [...]

Regarding the reverse - At the moment I have a Beseler Motor Base model #8921 open. The model #8922 'Pro' version is the same but with a reversing switch. In fact this body has the hole cut-out for the reversing switch; it is merely covered by the product label.

There is plenty of room inside this for the extra components. All that's in there now is dead-simple AC 120 motor, a couple wires and a cooling fan attached to the motor axle. No electronics.

If we can find the reversing specs, I will try them with this and the other three different motor bases I have.
.

[DrTang]

Regarding the reverse - At the moment I have a Beseler Motor Base model #8921 open. The model #8922 'Pro' version is the same but with a reversing switch. In fact this body has the hole cut-out for the reversing switch; it is merely covered by the product label.

There is plenty of room inside this for the extra components. All that's in there now is dead-simple AC 120 motor, a couple wires and a cooling fan attached to the motor axle. No electronics.

If we can find the reversing specs, I will try them with this and the other three different motor bases I have.
.

I have a Beseler non reversing.. and a unicolor (I think) that is reversing..apart and in a box.. and if I would have been paying attention in H.S. Electronics class..maybe I could figure out how to transfer the right parts on over.. but alas I was not paying attention