I searched the forum, and even did a bit of Googling. At my work, we are in need of a CNC controlled dispensing solution, since we are current applying water soluble solder mask to hundreds of boards a month. Is anyone aware of tooling that I could fit that would be able to dispense something the consistency of Elmers glue through a large syringe sized nozzle? My initial thought is a syringe with the the plunger controlled by a stepper motor, but I need to be able to buy that off the shelf, since I’m not smart enough to figure out a way to rig it.
As in you want to use the CNC to place the dots? You could probably get a chocolate extruder kit…but I am not sure if that would work to deposit it well.
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I don’t want to deter you from the MPCNC, but depending on your budget and the exact nature of the liquid you might be able to buy one of these CNC glue dispensing machines. I know nothing about them, so I don’t know if they have a fixed glue that can be used with them or not, but it might be another term you could try searching for.
On further searching, here’s a design for a motor actuator for a syringe.
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Dang that glue machine was fancy! How cool was that thing.
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I would look at finding a way of using small dosing pumps for moving the liquid. I use them on my aquarium and you can dispense a very fine amount. If you ran the hose from the dosing pump to the needle, it should work quite well.
I use this one:
https://www.amazon.com/gp/product/B01IUVHB8E/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
That motor seems small enough to be on the Z axis too. You can probably power it by the fan port. I wonder if the laser mode would work well for that (pwm modulation to adjust speed with federate).
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I would mount the pump closer to the reservoir. They have decent ‘lift’ as far as pulling liquid out, but they do much better at pushing the liquid longer distances.
You may consider replacing the 12v motor with a stepper to more easily control how much is dispensed and how quickly.
In my aquarium system, I’m running it for just under 3 seconds at full speed, but you can provide lower voltages to slow it down if needed. It’s been a while since I’ve tested it, but I think it can still push liquids down to ~6v.
Not a direct answer to your question, but I saw a video where someone sprayed the entire circuit board with tinted lacquer, and then used a diode laser module to burn away the lacquer on the solder pads. This was someone creating DIY circuit boards, so I don’t know how well the technique would work in a commercial setting. Alternately could a laser cut a stencil to be used to protect/expose the areas for the solder mask?
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I’ve used one of these Adafruit Peristaltic pump
The motor can be removed and replaced with a stepper.
Mike
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Peristaltic pump is exactly what I was thinking. Couldn’t you just 3d print the parts and operate with a stepper?
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Looks like there are mostly printed designs out there. E.g.
Or this less intricate design
I like that Wes plopped this question in here, and we have 10 responses (going in some pretty good directions, I think). I sometimes take a day or two to check questions on other forums and I never come back to this kind of response.
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I built one of the 3d printed ones. It didn’t work well for me, but I think it was because of the tubing I bought.
If you need something more industrial, there are higher end pumps that are more precise like this one