PCB Holder for milling, drilling, etc (Fully Parametric)

This is a pcb holder/vise for securely holding pcbs in the air while working on or machining them.

Multiple of these holders can be arranged to securely stop a pcb from moving sideways. A small bolt can be inserted to clamp down the pcb to hold it in from the top, if needed.
The vise itself can be bolted to a slot plate like those found on the cheap 3018 cnc mills.

The holders can be arranged, rotated, and moved around using a combination of the slots of the slot plate and the slots within the holder itself.

My use case (3018)

I use this holder for clamping down raw circuit boards and the mill them using my 3018 CNC. My 3018 has a slot plate perfectly fitting M8 round/square-head bolts and the slots are spaced 20-25mm apart, so i am using 25mm slots in the holder to be able to reach and clamp at any point on my CNC.

Naming scheme

The naming scheme of the prerendered holders is as follows:

pcbvise_[bpb]_[wpb]_[sl].stl

with the following values:

• bpb: The (metric) bolt diameter for attaching the holder to the slot plate
• wpb: The (metric) bolt diameter for clamping something down in the vise/holder
• sl: The length of the slot for attaching the holder to the slot plate

Parameters

You can change the following parameters safely:

• Diameter of the bolt clamping the work piece (i.e. pcb) to the holder/vise
• Diameter of the bolt attaching the holder to the slot plate
• Length of the slot for positioning the holder on the slot plate
• Clearances (so that bolts and nuts nicely fit into their holes)
• Elephant foot compensation (Warning: this is also used to allow the vise to rotate when using a nut with a square section after the head)

Furthermore, the following parameters are exposed and can be changed but are untested:

• The real diameter of the bolt attaching the holder to the slot plate
• The side-to-side width of the nut attaching the holder to the slot plate
• The thickness of the nut attaching the holder to the slot plate (the pcb will be placed high enough that the mill cannot break by crashing into the nut)
• The minimum width between the nut attaching the holder to the slot place and anything else (i.e. the outer edge and the "tower")
• The thickness of the plate attaching the holder to the slot plate
• The real diameter of the bolt, side-to-side width and thickness of the nut clamping the work piece to the holder
• The amount the work piece bolt overlaps with the work piece (will influence how securely the work piece is clamped down)
• The width of the support surface for the work piece
• The height of the work piece suspended in the air
• The thickness of material the work piece rests when the work piece tries to move side-to-side
• Some radii for visual satisfaction

Notes

This part does requires that you pause the print to insert the nut holding the small bolt pressing the pcb down.
If you don't want this, you can manually change the "Nut Thickness" in the "Attaching Workpiece to Vise" section of the FreeCAD file to 0mm, and make the "Metric Bolt Diameter" a little smaller to cut threads afterwards, however I (strongly) do not recommend this if you plan on using a bolt to clamp something down.