Here at Hackaday we love all kinds of builds, and we celebrate anytime anyone puts parts together into something else. And while we love the quick and dirty builds, there’s just something about the fit and finish of this four-axis SMD stencil printer that really pushes our buttons.
This build comes to us from [Phillip], who like many surface-mount users was sick of the various tape-and-PCB methods that are commonly used to align the solder stencil with the PCB traces. His solution is this fully adjustable stencil holder made from aluminum extrusions joined by 3D-printed parts. The flip-up frame of the device has a pair of clamps for securely holding the stainless steel stencil. Springs on the clamp guide rods provide some preload to keep the stencil taut as well as protection from overtensioning.
The stencil can move in the X-, Y-, and Z-axes to line up with a PCB held with 3D-printed standoffs on a bed below the top frame. The bed itself rotates slightly to overcome any skew in alignment of the PCB. [Phillip] was aghast at the price of an off-the-shelf slew-ring bearing for that axis, but luckily was able to print up some parts and just use simple roller bearing to do the same thing for a fraction of the cost. The frame is shown in use below; the moment when the pads line up perfectly through the stencil holds is oddly satisfying.
This puts us in mind of a recent, similar stencil printer we covered. That one was far simpler, but either one of these beats the expedient alignment methods hands down.
An equivalent 4 axis manual stencil printer with frame support, up to 400x400mm from china and all metal costs about 250€. I have one.
Nevertheless, that is agreat open source option.
We need Alex from Stickvise to come up with the absolute minimum functional solution to PCB stencil holding. This build is amazing but there has to be something between scrap PCBs and the International Space Station.
Stencil8 would qualify in my mind as absolute minimum as well as being very functional. Plus, as I recently found you can use the stencil8 base plate as a tooling plate for other jigs/fixtures.
I created a low cost stencil alignment jig for small batch prototyping. Basically it is a 3D printed/laser-cut jig and procedure in KiKit to generate 3D printed alignment piece. See more at https://github.com/yaqwsx/KiKit/blob/master/doc/stencil.md
How about something like this:
https://youtu.be/HVxvKYdUOOY
I created special stencil alignment parts in my eagle library. It is a hole with a cream area on top of it. I put this part in two corners of the pcb. In one pcb I solder pins in these holes. This pcb becomes my alignment aid.
Started a bill of materials based off scaling from the parts and images and a bit of guesswork here:
https://docs.google.com/spreadsheets/d/1A7Fg_CgfPcbLEn5Zp_6HpfGlA350f67ehTiDADjn61A/edit?usp=sharing
Going to try and order parts soon. Will update with changes as I go.