[Perinski]’s design for a mechanical flux dispenser uses some common hardware and a few 3D printed parts to create a syringe with fine control over just how much of the thick stuff gets deposited. The design is slick, and there’s a full parts list to accompany the printed pieces. [Perinski] even has some useful tips on how to most effectively get flux into 5 mL syringes without making a mess, which is a welcome bit of advice.

There is also a separate companion design for a magnetic syringe cap. Not only does it have an O-ring to keep things sealed and clean, but the tip of the cap has a magnet embedded into it, so that it can be stowed somewhere safe while the dispenser is in use, and doesn’t clutter the workspace.

This is all a very interesting departure from the design of most syringe dispensers for goopy materials, which tend to depend on some kind of pneumatic action. Even so, we’ve also seen that it’s possible to have a compact DIY pneumatic dispenser that doesn’t require a bulky compressor.

If you can’t quite figure out how the ergonomics of [Perinski]’s design are intended to work one-handed, you’re not alone. One holds the syringe in their hand, and turns the large dial in small increments with a thumb to control extrusion. [Perinski] demonstrates it close-up around the 4:50 mark, but if you have a few minutes it is worth watching the entire video, embedded below.

I found an all-printed version of a similar design on Thingiverse some years ago. Probably this one: https://www.thingiverse.com/thing:2755949 But there are a few remixes of it now, and some other designs. Probably not as good as this one, but it’s worked fine for me.

IMHO it should be designed with flux reservuar 3D printed too. I can’t buy syringes because I live in a small town (6000 people) and if I go to drug store and buy syringe soon everyone will be speaking that I’m taking narcotics.

You’ll have a really hard time getting a reliable seal down the bore of the printed part. You could do with printed end caps and a extruded tube (glass, copper, plastic) and glue the ends on if you had to

That does sound like a problem, but all the fluxes and solder pastes that I have bought recently are actually delivered in a syringe, and the problem is that it is a syringe with no plunger.

As a workaround you could go the pharmacy with your pot of goop and ask “Do you have anything that would help me dispense this”. You might even make a useful contact for other useful products if you can get them engaged.

What are the advantages of using a threaded rod vs something like a rack-and-pinion? I wanted to use the latter to avoid wear, but the former seems more precise…

With a fine-pitch screw you have increased resolution (and force) per turn of the wheel. I don’t see how a a rack-and-pinion will give you the same advantage, both mechanically and resolution-wise.

But maybe you had something else in mind for the rack-and-pinion?

I thought maybe I could simplify the design in exchange for some precision, since all pieces can be 3d printed and you also need less pieces (e.g. don’t need extra gears to rotate a threaded nut so the piston itself doesn’t rotate) and probably no need for lubrication. But I think I might be underestimating the amount of backlash and bad stuff I’ll get with a rack-and-pinion… Especially in something like a syringe… :)

Neat, but crying out to be motorised.

It’s the next Video on his Channel: https://www.youtube.com/watch?v=K1Iw4lSAZjE

Really neat design. I especially like how he combined two of these cheap thumb.switches.

Yeah, this is the start to a very nice syringe pump. Those things are really expensive – $1-2k from what I recall. They’re very precise too.

I get 404 pages on Thingiverse at both of those links.

That’s been happening a lot on thingiverse lately. Click on the ‘thing files’ tab and manually download the pieces.

Great design. Love the mini lathe. Thanks for the syringe filling demo. Hate the music (too fast and pressured for me).

I’ve always wondered why not a lot of people polish the 3D prints, even from a high resolution printer. Nice project

This looks similar to all aluminum dispenser I got off Aliexpress a few years ago for solder paste. Fits common sizes paste syringes, can probably swap for flux filled syringe as well.

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