Figure 4 also shows an end
view of an alternative method for
constructing the support rail, with
no milling required. Replace the
notched section with two pieces of
1/16” x 1/2” aluminum. Clamp
everything together with the center
section offset to create a cavity for
the PCB edge, then drill and tap as
described previously. It may be
necessary to add a thin shim
between two of the sections in
order for a 1/16” thick board to
Once the support rails are
complete, they can be attached to
Refer to Figure 5 for dimensions of the side supports.
I used aluminum, but any sturdy material will do. The
exact dimensions aren’t critical, but the piece must be
thick enough to fully countersink a 1/4” flat head screw. I
applied a few self-adhesive rubber furniture feet to each
support to keep the jig from sliding around. The foam
backer plate can be made from any thin sturdy material (I
used 1/8” aluminum sheet; see Figure 6).
Depending on the material thickness, the threaded
studs on the toggle clamps may need to be adjusted so
that they clamp snugly but without excessive force. A
piece of 1” thick foam rubber should be sized to fit
loosely through the jig frame, approximately 5” x 9. 75”. I
used inexpensive polyurethane foam — available in sheets
from a local craft store — and bonded it to the plate with
3M Super 77 spray adhesive.
■ FIGURE 3. Installing
the extrusion connector.
The design of the board support rail can vary
depending on the type of equipment you have available
to fabricate it. The key feature, of course, is the small
cutout where the PCB will fit. The width of this notch
depends on the thickness of the circuit boards you will be
using, but 1/16” (0.063”) is the most common size.
An important design point for me was making the
depth of the notch as shallow as possible, since I often
work with boards that have components mounted almost
to the very edge. I have access to a milling machine, so I
chose to fabricate each support rail from two sections of
1/8” x 1/2” aluminum sandwiched together (see Figure 4).
The notched component ended up being two
identical pieces butted end-to-end, as this made the
machining easier. To attach the sections, clamp them
together and drill a number of pilot holes (I used six; four
would be sufficient). Separate the sections, then
countersink the holes in the notched piece(s) and thread
the other holes for #6-32 thread.
■ FIGURE 4. Board support rail detail.