top-cable-guide.py

import queryabolt
import cadquery as cq

# This is to protect the camera cable from the sharp edges of the top of the
# extrusion and guide it on the right path towards the Pi.

class Workplane(queryabolt.WorkplaneMixin, cq.Workplane):
    pass

press_fit = 0
tight_fit = 0.1
fit = 0.2

# Chamfer
c = 0.5

# Thickness. Not load-bearing by any means.
t = 2.4

v_slot_hold_h = 5

v_slot_d = 20
v_slot_slot_w = 6
v_slot_d_fit = v_slot_d + press_fit
v_slot_bolt = "M4"

# We need to move it past the housing to avoid getting it tangled in fingers.
worm_bearing_holder_l = 27  
housing_l = 42.1382         # both generated by `gearbox.scad`
slider_t = 4                # minimal v-slot wall thickness
knob_d = 42                 # semi-arbirtrary, based on clearance

housing_with_knob_l = housing_l - worm_bearing_holder_l / 2 + knob_d / 2 + fit

w = v_slot_d_fit + 2 * t
l = housing_with_knob_l + w + (slider_t - t)
guide_h = w / 4
rail_h = guide_h * 1.75

t_h = v_slot_hold_h + t + rail_h


def guide():
    guide_w = w / 8

    # Make the v-slot mount, fillet edges ribbon will pass through.
    vslotMount = cq.Workplane().box(w, w, v_slot_hold_h + t)
    vslotMount = vslotMount.faces("-Z").shell(-t, kind = "intersection")
    vslotMount = vslotMount.faces(">>Y").workplane().rect(w, v_slot_hold_h + t).extrude(l - w)
    # vslotMount = vslotMount.edges("#Y and >Z").fillet(1)

    # Make the top guide.
    vslotMount.faces("+Z").workplane(centerOption="CenterOfBoundBox").tag("top")
    vslotMount = vslotMount.workplaneFromTagged("top").rect(w, l).extrude(guide_h)
    vslotMount = vslotMount.edges(">Z and |X").fillet(guide_h * 0.75)
    vslotMount = vslotMount.workplaneFromTagged("top").pushPoints([(-(w - guide_w) / 2, 0), ((w - guide_w) / 2, 0)]).rect(guide_w, l).extrude(rail_h)
    vslotMount = vslotMount.edges(">Z").fillet(1)

    # And clearance for the rack. In the non v-slot portion, it can be used to route 
    # illumination wiring.
    vslotMount = vslotMount.faces("<Y").workplane().center(0, -v_slot_hold_h / 2 - t).rect(v_slot_slot_w, v_slot_hold_h).cutThruAll()

    e_o = -l / 2 + w
    e_d = housing_l
    # To facilitate illumination routing here, make a hole allowing the cable to join
    # the camera cable.
    p_d = 4
    vslotMount = vslotMount.faces(">Z").workplane(centerOption="CenterOfBoundBox").move(0,  e_o + p_d / 2).rect(v_slot_slot_w, p_d).cutThruAll()

    # For optional zip ties.
    vslotMount = (vslotMount.faces(">X").workplane(centerOption="CenterOfBoundBox")
                  .pushPoints([(e_o + e_d / 2, 0), (e_o + e_d * 3/4, 0), (-l / 2 + w / 2, 0)])
                  .slot2D(3, 1.5, 0).cutThruAll()
    )

    return vslotMount

# If you find the cable slipping out of the guide, the zip tie slots, or the clip are for you:
def clip(fit = 0):
    clip = cq.Workplane("XZ")
    w_fit = (w + fit) / 2
    h = t_h + fit
    clip_t = t * 3 / 4
    pts = [
        (w_fit - clip_t, 0),
        (w_fit - clip_t, -clip_t),
        (w_fit, -clip_t),
        (w_fit + t, 0),
        (w_fit + t, h + t),
        (0, h + t),
        (0, h),
        (w_fit, h),
        (w_fit, 0),
        (w_fit - clip_t, -0),
    ]
    return clip.polyline(pts).mirrorY().extrude(t)
    
show_object(guide(), {"name":"top-cable-guide"})
show_object(clip(fit).translate((0, 0, -(v_slot_hold_h + t + tight_fit) / 2)), {"name":"top-cable-clip"})