I had a need for a shaker to gently agitate specimens in cleaning solution, but I figured that I just needed a very small, compact device, and decided to try building something before I went out and bought something. The end product worked so well that I have no plans to buy a lab shaker at this point.
The solution I ended up taking solves a few problems at once: how to gently agitate the specimen, and how to keep the specimen fully submerged despite its tendency to float.
Here is the solution:
It uses the focus stacking controller that I built, just with a new mode added that does nothing but turn the motor back and forth, like a washing machine on the agitation cycle.
Since I use hot water + soap solution, there is steam involved that condenses on everything inside the container. To prevent the motor from getting wet, I placed a rubber o-ring between the motor and lid, and used nylon spacers where the screws are, between the motor and lid, to give the o-ring room. I smeared plumber's grease between the shaft and motor to prevent moisture from seeping into the stepper motor body. Finally, I put some vent holes in the lid for steam to escape through.
The specimen is put in a wire mesh tea ball, fully submerged, and the motor attaches to the tea ball using a coupling and some brass wire.
The focus stacking controller needed no hardware changes, just a small addition to the software.
Since I had all of these parts already, cost was $0 and the whole thing probably took 45 minutes to assemble, including writing the code. This doesn't include the prior cost of the parts of course, or the time already invested in building the stacking controller.
Maybe this will inspire someone to a similar end... it's not pretty, but it seems to do the job quite nicely.
A home-made "shaker" for cleaning specimens in soa
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A home-made "shaker" for cleaning specimens in soa
Last edited by Rylee Isitt on Thu Nov 06, 2014 2:11 am, edited 1 time in total.
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TheLostVertex,
I just made it user-configurable, rather than hard-coding numbers into the software. The UI lets you set the number of steps it turns before it reverses, and the RPM at which it turns.
All three of my motors max out at somewhere around 200 RPM before they start stalling, which is pretty slow but plenty fast for cleaning, I would think. If you've ever watched your wash machine spin back and forth during the agitation cycle, it seems to be a similar speed.
It might be tricky to test experimentally... I'll probably just use whatever seems to work well enough and leave it at that.
I just made it user-configurable, rather than hard-coding numbers into the software. The UI lets you set the number of steps it turns before it reverses, and the RPM at which it turns.
All three of my motors max out at somewhere around 200 RPM before they start stalling, which is pretty slow but plenty fast for cleaning, I would think. If you've ever watched your wash machine spin back and forth during the agitation cycle, it seems to be a similar speed.
It might be tricky to test experimentally... I'll probably just use whatever seems to work well enough and leave it at that.
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- Joined: Fri Apr 13, 2012 3:54 pm
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Hi Keith,
Here's a video: https://www.youtube.com/watch?v=n3y3IZ1ZMIA
It's not a particularly good video but hopefully it does the job!
Here's a video: https://www.youtube.com/watch?v=n3y3IZ1ZMIA
It's not a particularly good video but hopefully it does the job!
Thanks Rylee!
This makes it very clear how often you reverse rotation and how fast you spin the specimen. Very helpful indeed! I have a box full of stepper motors that I purchased on Ebay and several "spare" controller chips that were left over from the construction of my own bug stepping apparatus. Making something similar will be a great winter project. We got 2" of snow last night...
Keith
This makes it very clear how often you reverse rotation and how fast you spin the specimen. Very helpful indeed! I have a box full of stepper motors that I purchased on Ebay and several "spare" controller chips that were left over from the construction of my own bug stepping apparatus. Making something similar will be a great winter project. We got 2" of snow last night...
Keith