Driving the Plunger (part 3)

This is part 3 out of 3 in the series (see part 1 or 2).

Well, if after reading previous posts you were curious as to how it all looks, wait no more. Below is a quick video showing its usage. And yes, it was a minimum effort video so sound is not there.

First is the mounting method. Just place syringe around the plunger and rotate to fix in place. If you used another syringe before this, you might need to move the plunger ahead until it makes contact. In the video, you can see that I reverse it a bit and then I move it forward just to illustrate this point.

After dealing with the initial paste surge, you get to control the syringe using either the button in the top-left corner or the foot pedal. As I use a foot pedal, you won't directly see my presses, but you'll notice the LCD flashes.

As you can see in the video, this thing actually works. However, it's not without its issues. The most noticeable one is speed and drooping. Every push creates pressure and, no matter how many pull-back tricks I've tried, it will not squirt paste fast and without excess. Each profile was essentially a balancing act between how much paste I push and how quickly.

Firmware development for this was actually quite easy and really depended on two programming exercises I already had made from before: OLED and rotary button. The rest of the firmware was just reading the button status and pushing text to an OLED. You can check how I did it on GitHub but I will probably also make a separate post on each.

Would I use it? Well, maybe. While it actually does what I intended to do, the whole process is just too slow. I can do non-paste soldering much faster. Also, different paste will react differently and will need adjustments.

It's not great for regular work but it's actually quite okay if you need repeatable solder paste dispensing for special components.

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