Adapting a Prior Optiscan Stage to the Stackshot 3x (Part 1)

Background and Motivation

Earlier in the year, I acquired a Prior Optiscan stage for $350, I later realised I overpaid by a good $100 but it was far too late and the seller was very kind. Not going to bother his day with a returns request. I picked up a junk Prior controller for $50, it was a dud that would not turn on.

Just as I thought my dreams of automating my microscope were shattered, I met someone from a chat group who is an expert tinkerer. He made his own programmable automatic micropipette puller, which was honestly on an entirely different level to my capabilities. We quickly struck up conversations and built a friendship over the common hobby and passion in microscopy. As I was looking around, I saw my Stackshot 3x controller collecting dust and a sudden epiphany hit me — why not just use that? A working Prior Scientific controller would cost a good $500, the joystick alone typically ends at $300. The Stackshot 3x lacks a joystick input, but I am happy to compromise.

Another major issue with my stage is the lack of a microscope stage clip. I purchased a used BH2 clip and sawed it down, then glued it to the stage. This is an incredibly wasteful and bad method, but I just wanted a working system at that point.

Under the Hood

The construction of this stage is incredibly simple, the 12-year-old me would have been able to disassemble and reassemble. This is one of the major advantages of Prior Scientific’s mechanical products, they are simple and robust, and they work flawlessly. I have already showcased the simplicity of Prior’s focusing drive.

The x-axis only translates the slot at the top, which holds a specimen clip. My unit did not come with one and the stage’s specimen clip is impossible to find as a standalone unit, I simply modified a BH2 clip and glued it on, trying my best to have it aligned. The y-axis component can be seen when the stage is flipped over.

A weird DB15, three rows type connector is used. You can faintly see the numbering, which will be different from mine. I only discovered this after looking at the photos. Anyway, this does not matter.

The y-axis component is showcased here. It couples with the bottom plate, being driven by ball bearings. This makes the stage feel incredibly smooth and satisfying, despite its decade-old age.

Despite its simplicity and robust construction, there are also cost-cutting measures being used. A Prior Scientific system will cost $5,000+, this gives you X, Y, and Z-axis automation, and their powerful control box with software. I personally think a lot of the cost falls under research and development. A system as elaborate as this, fully compact and upgradeable is not cheap to develop. Back then, Chinese-made controller systems were not readily available. Nowadays, many companies simply utilise commercial systems as a core and build around them. Less lazy ones scrape the labels off, but that does not do much if the opponent is educated. Right, what is the cost-saving measure here? Well, simply using a couple of tactile switches as limiters, instead of an accurate hall-effect sensor. Quality hall-effect sensors are about $3 each, these switches used in computer mouse are maybe 20 cents.

The main component is revealed, a rather expensive and highly precise Lin Engineering 4109V-51D two-phase stepper motor. This motor is rated for a current of 1.2A and boasts a small stepping angle of 0.9 degrees. Conventional motors are 1.8 degrees in this realm. This motor is priced at around $35 each, fairly expensive compared to a cheap but adequate Chinese model.

Lin Engineering PDF datasheet

The next step is figuring out the pins of that weird DB15 connector.

Pinout of the Prior ES110 stage

As long as you are using an optiscan stage with the DB15 three rows type connector, this diagram should be applicable. Always check yourself with a multimeter.

Making an Adaptor

The construction of the adaptor was supposed to be trivial, however, I hit into some issues and it ended up taking me 3 days. The issue was very simple, one-half of the Stackshot connector was faulty. I took a surplus cable I had and cut it in half, since Stackshot charges $7 for one connector and $10 for a cable, it made more sense to me. I ended up trying out every combination, which was 4!=24, none of them worked.

The shorter adaptor did not function as desired

With the connector removed and colour-coded wired figured out, simply solder the wires according to Stackshot’s pinout diagram. The use of heat-shrink pipes is crucial, it makes the adaptor robust.

Stackshot motor datasheet

Please be aware of the pins being mirrored when you are working with these plugs. The pinout’s perspective is from my point of view, looking into the plug. You cannot do the same thing for two plugs. When they make, the leftmost pins are connected to the rightmost pins from the perspective of the person looking at it. This may seem very trivial, but trust me, I have came across many that screwed components up big time because they forgot about this simple fact and did not bother to check connectivity after prototyping.

I will not show the final product because it was abysmal and sad to look at. I was quite happy with the result but not the cable itself.

Due to the proximity of the stage to the controller, a far shorter cable is warranted. The current cable is long and annoying. I am thinking of making a proper cable with connectors that allow me to connect plugs of different lengths. This will take more time to make but it is better in the long run since I can just make longer cables if my setup changes drastically. In Part 2, I will construct such a cable. As of now, I am still waiting for parts.

Here is a video of demonstrating the system and explaining some of the basic functions.

Here is a short clip, showcasing the system in action.

References

Lin Engineering motor specification: https://www.linengineering.com/products/stepper-motors/hybrid-stepper-motors/4109-series/4109V-51

Stackshot Motor pinout: https://cognisys-inc.com/stackshot-motor-connector.html

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