DIY Lab Spinner

[sbash]

Inspired by @bevo5 's thread:
https://www.reef2reef.com/threads/magnetic-lab-spinner-thumbs-up.309958/

After not being able quickly find this somewhere where they would ship to me, I started thinking...

This little fan was $2.50 (Canadian, lol), sorry about the lighting. The tank light in the background messed up the exposure...

I stripped it down, removed the bottom, the fan blades and the cage. Then I 3D printed a plat to fit on the drive shaft, and added some double sided tape to grip the sample vial. However (obviously) it spun way too fast!

So, I replaced the power switch with a simple PWM motor controller:

In order to power the PWM module properly, I also had to increase the input voltage by replacing the 2 AA cell battery compartment with a 4 AA cell compartment:

The finished 'product', if you can call it that:

And an action shot:

All in all, the total cost is around $5. Although the PWM module also doubles as power control, I will likely add a power switch so I can just set the PWM and leave it. My finger twitched which increasing the speed and my sample flew everywhere, lol... I would also like to find some square cuvettes (ideally with a smaller opening than the base so the speed can be increased more). Then I can print a spin plate that holds it well for ease of use.

Anyway, this was more of a thought project which ended up being functional so I thought I would share

 

[Tuffyyyyy]

Very cool!

 

[jd371]

Nice job. I looked around and was finding stirrers over $50 and didn't want to spend that much. I found this one and works fine, even has a built in light. The only thing I needed to do is order a smaller stirring bar to fit in the Salifert vials.

https://www.amazon.com/Magnetic-Sti...99266830&sr=8-1&keywords=taylor+magnetic+stir

 

[sbash]

Nice job. I looked around and was finding stirrers over $50 and didn't want to spend that much. I found this one and works fine, even has a built in light. The only thing I needed to do is order a smaller stirring bar to fit in the Salifert vials.

With this design, the plate spins, so there is no fussing with magnets or stir bars (hence the tape to hold the vial, and it is universal); which is what I wanted. If I find some square glass vials, I can eliminate the tape; I need to re-print the plate to fit better on the motor shaft anyway.

Is the stir bar a magnet, or just a small, plastic coated rod? Either way, could you just epoxy coat something that would fit?

I could probably adapt this basic design to be a magnetic stirrer; but the effort would be higher (as this took all of 15 minutes to build). There are also plenty of DIY instructions out there to build such a thing with a computer fan, so it would essentially just be emulating that (at a fraction of the cost).

 

[mcarroll]

Inspired by @bevo5 's thread:
https://www.reef2reef.com/threads/magnetic-lab-spinner-thumbs-up.309958/

After not being able quickly find this somewhere where they would ship to me, I started thinking...

This little fan was $2.50 (Canadian, lol), sorry about the lighting. The tank light in the background messed up the exposure...

I stripped it down, removed the bottom, the fan blades and the cage. Then I 3D printed a plat to fit on the drive shaft, and added some double sided tape to grip the sample vial. However (obviously) it spun way too fast!

So, I replaced the power switch with a simple PWM motor controller:

In order to power the PWM module properly, I also had to increase the input voltage by replacing the 2 AA cell battery compartment with a 4 AA cell compartment:

The finished 'product', if you can call it that:

And an action shot:

All in all, the total cost is around $5. Although the PWM module also doubles as power control, I will likely add a power switch so I can just set the PWM and leave it. My finger twitched which increasing the speed and my sample flew everywhere, lol... I would also like to find some square cuvettes (ideally with a smaller opening than the base so the speed can be increased more). Then I can print a spin plate that holds it well for ease of use.

Anyway, this was more of a thought project which ended up being functional so I thought I would share

Excellent DIY!

I know it's irrelevant to the project, but you know that's overkill x1,000,000 for testing water samples right?

What's something like this used for in a lab, BTW?

 

[sbash]

Great questions!

I know it's irrelevant to the project, but you know that's overkill x1,000,000 for testing water samples, right?

Nope, not any more! This is why I replaced the power switch with the PWM controller module. At full power, I agree and it probably is a million times too much for mixing water samples (it is actually only about 85 times too powerful). However, with the PWM (Pulse Width Modulation) controller module attached to the DC motor, the module literally pulses the motor off an on. The speed is now variable because of the potentiometer (the knob's actual component) in the circuit, which essentially tells the controller how wide the pulse should be. At full speed, it will spin around 10,000 RPM, but now I can dial it down to a nice and casual 120 RPM - maybe a bit faster than that.

What's something like this used for in a lab, BTW?

In my lab, well, mixing samples

In a real lab where science happens on a regular basis, this is a crude form of a centrifuge. Although proper centrifuges do not have a plate for samples like mine (they have a balanced holder for the test vials, cuvettes, plates, etc), I am leveraging the same basic principle (at much lower speeds, thus I am using force instead of friction - the instructions do say 'swirl') to mix the solution. They spin the sample at such a high speed, the fluids in the sample are separated (and conveniently order by density). The best example I can think of off hand is with a blood sample, a centrifuge will separate the blood into blood plasma, white cells and red cells.

 

[mcarroll]

I can dial it down to a nice and casual 120 RPM - maybe a bit faster than that.

How many RPM's is "swirl gently" and how many before it counts as shaking?

Still a cool mod!!!!!

Unfortunately/fortunately, I don't have any problem swirling on my own. But if you can come up with something to auto-dispense the titration drips, I'd sign up to try that in a hurry!!

 

[sbash]

Unfortunately/fortunately, I don't have any problem swirling on my own. But if you can come up with something to auto-dispense the titration drips, I'd sign up to try that in a hurry!!

Haha, touche...

You want a smaller and simpler version of this then:

 

[mcarroll]

Yes! That's it!!

 

[RobertP]

Nice. Next you will be switching to 18650 rechargeable batteries!

 

[MarsRover]

Please wear goggles when you are doing this.......and keep it far away from your tanks.

if that vial breaks free, those chemicals are really bad for your eyes AND marine life.

other that than, cool idea. You can also instead make this into a magnetic stirrer. Put a magnet on that spin table and drop a tiny magnetic dipole (coated in plastic) into the vile.

 

[sbash]

Yes! That's it!!

Hahaha, let me get the stirring table down first; then I will move on to the dispensing.

Nice. Next you will be switching to 18650 rechargeable batteries!

Oh goodness, do not get me started, lol... I do have several, but I also stock alkaline batteries. It all depends how frequently they will need to be changed.

Please wear goggles when you are doing this.......and keep it far away from your tanks.

if that vial breaks free, those chemicals are really bad for your eyes AND marine life.

other that than, cool idea. You can also instead make this into a magnetic stirrer. Put a magnet on that spin table and drop a tiny magnetic dipole (coated in plastic) into the vile.

This is a good safety tip! I am doing this safely and quite far from my tanks, so no need to worry about me or my tanks

That said, the speed is so dramatically low (compared to the fan's full speed), if the vial did break free, it would just make a mess. It actually needs to be quite a slow spin to mix properly. If the speed is too high (see my comment about centrifuges above); then the centripetal force will separate the fluids in the solution.

I do want a magnetic stirrer, for several reason (otherwise, this thread would be about building one, lol). Instead, as mentioned above, I am going to move the plate design to accommodate (literally hold) square sample vials; I just need to take the time to find the right vials. Worse case, I can just use the seachem ones I have; they are not quite what I want, but close enough.

This is really just a proof of concept; there are several things which should be changed/added to make this functional enough for 'daily' use. Right now it is a bit clunky to use. So, I will post up as I evolve this design