Tray Rocker Project

[Beevo]

Having more than enough spare time on my hands I designed and built a device to gently rock a photographic tray...

Action Video:

 

[koraks]

Hah, neat! Good job, I like it.

 

[Nige]

I've been thinking of doing something similar... cause some lith developer/paper combos I've been using take 15mins to develop, which is a long time to rock a tray!

 

[fdonadio]

Not really wanting to be nitpicky, but already being…

Is there a way to improve the noise? Sounds loud, although I know smartphones amplify everything when it’s a little bit too silent for them…

 

[koraks]

Is there a way to improve the noise?

I think if you put the device on some kind of foam/rubber mat, the noise is a whole lot less loud. It seems to be amplified by the worktop it's one. In the construction itself, it might be possible to mount the motor to the frame with some kind of bearing/coupling that doesn't transfer the vibrations as well as directly bolting it onto the frame.

 

[fdonadio]

I think if you put the device on some kind of foam/rubber mat, the noise is a whole lot less loud.

Sounds good. I don’t have any space for a home darkroom at the time, but I would certainly be interested in some of these.

 

[Beevo]

I think if you put the device on some kind of foam/rubber mat, the noise is a whole lot less loud. It seems to be amplified by the worktop it's one. In the construction itself, it might be possible to mount the motor to the frame with some kind of bearing/coupling that doesn't transfer the vibrations as well as directly bolting it onto the frame.

If I find it annoying enough I will add an isolator to the stepper. The base already has a soft rubber layer. The mic on the phone makes it sound much louder than it is. The remaining issue is the driver is, at best, half stepping

 

[mshchem]

Neat! First "automatic" processing machines were huge rocking machines. Great for fixing, toning etc.

Keep perfecting! Good project.

 

[MattKing]

Well done!
Now you can perfect it by increasing randomness of the agitation by getting it to alternate - lift and return one near corner, then lift and return the other near corner .
It is absolutely hypnotic to watch that video!

 

[Bill Burk]

Well done!
Now you can perfect it by increasing randomness of the agitation by getting it to alternate - lift and return one near corner, then lift and return the other near corner .
It is absolutely hypnotic to watch that video!

Came here to say the same: agitation needs to be more turbulent, rocking one side will lead to uneven results.

Make two

 

[MattKing]

Came here to say the same: agitation needs to be more turbulent, rocking one side will lead to uneven results.

Make two

Or put the lifting rods on some sort of eccentric wheel.

 

[Neal]

Nice!

 

[reddesert]

Or put the lifting rods on some sort of eccentric wheel.

I think you could print the lifting-rod structure, which is now two symmetric arms that are aligned with the rotation axis, as a slightly more complex structure with the arms offset from the rotation axis in different directions. This is a little hard to describe in words, but imagine that the rotation axis of the lifting rod thing is the center of a clock. Try placing the base of the arms offset to the edge of the clock, say one base at 1 o'clock and one base at 5 o'clock (or 7 o'clock if you need symmetry), but the arms both stick out in the same direction, to the right. As it rotates, I think the high end would transfer from one arm to the other, allowing the tray to rock side to side.