This DIY Solder Paste dispenser is an easy project to build, so I thought I would share the details a bit with everyone! When possible I like to build my own tools, it makes sense especially when you have most of the parts on hand. There are a lot of tools that are just yak shaving experience, but fortunately this isn’t one of them!
What parts do I need
for the DIY solder paste dispenser not much!
The heart behind this and any commercial unit is the compressor, so I thought I would go ahead and include it but it should be factored in when comparing prices to a commercial ebay solder paste dispenser. In this case I went to the local big box store and got the cheapest, oilless air compressor I could get in the sub $100 dollar range. this turned out to be a lowes Blue Hawk cheapy compressor.
The other key piece to these machines are the solenoid valves which control the airflow. Commercial units use dual process valves with venturi to create a vacuum on the syringe, but I will use 2 valve to mimic this action and come in under the price to boot! I use a lot of these valves in my Aero ponies projects and I really like STCValve as a reliable source! I really recommend the Stainless Steel ones, over the abs ones they are simply bulletproof. Although the ABS ones are a good price, but will require some more maintenance and can’t handle as much pressure! I recommend model numbers (SS) 2S025-1/4H and (ABS) 2P0251/4S both models come with a choice of power options for the actual Solenoid part. Type 1 is the 12VDC, 2 are 24VDC, 3 110VAC and 4 is 220VAC the best choice for a tool like this I think are the 12VDC they require more amperage but nothing a mosfet and heat sink cant handle. In this example I used the 110VAC version as I had a couple on hand at the time of the build!
After that you need a front end kit of syringes and needles I like this one its a great deal for the price! and something to control the valves with, In the example it is a relay board with an at mega on it that acts like an Arduino. This could be an analog for just about any old arduino and controller board for the solenoids (I think a motor driver could work each valve is a stepper pole 
the DIY Solder paste dispenser works by simply pressurizing the syringe with about 30PSI of compressed air. To actually control the amount of paste dispensed I went with a push button method that while when the button is pushed pressurizes the syringe, then depressurized it when the button is released. I used a custom Arduino relay board for this although many other types of controllers could be used from fully discrete to PLCs driving the relays(such of some commercial units).
In the specific case of the DIY Solder Paste Dispenser the process flows like this. the compressor is attached to the “front” panel via standard air compressor hook ups. This makes it really easy to quickly connect/disconnect and use basically anywhere.
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