r""" Roll spindle (+-90 deg) at the sting root, for the six-component balance (cad/six_component_balance). Layout along the sting axis (x, inches from the BMC; the housing does not roll, everything inside it does): 16.45 front cap retains the front bearing outer ring 16.65 front bearing 6907 35 x 55 x 10 mm deep-groove, sealed 17.0-20.0 sting flats in the spindle's D-D bore; 2x 1/4-20 bolts at x = 17.75 / 19.25 (top clearance + c'bore, bottom tapped) reached through the housing's top windows at roll 0 19.66 rear bearing 6907 (bearing span 3.0 in), preloaded by a KM7 (M35x1.5) locknut inside the rear cap 20.50 wire exit the sting wire bore turns radially out through the spindle, into the adapter window 20.80-22.80 NMRV030 50:1 worm gearbox (purchased; self-locking), hollow 14 mm output keyed onto the spindle; NEMA 23 on its input, pointing +y (sideways) 23.30 spindle end 6 mm diametric magnet on axis -> AS5048A absolute encoder on a bracket All drive parts sit more than 21 in from the BMC, outside the pitch-sector cheek band (16.4..20.7 in), so pitch rotation never sweeps them into the cheeks; the motor points sideways so it stays off the floor at +20 deg pitch. Purchased parts (gearbox, motor, bearings, locknut) are modelled as envelopes - check the vendor drawings. Run (from this folder): ..\..\.venv\Scripts\python build_roll_spindle_cad.py """ import math import sys from pathlib import Path import cadquery as cq HERE = Path(__file__).resolve().parent sys.path.insert(0, str(HERE.parent / "aluminum_balance")) sys.path.insert(0, str(HERE.parent / "six_component_balance")) sys.path.insert(0, str(HERE.parent)) from build_balance_cad import box # noqa: E402 import build_6c_balance_cad as K # noqa: E402 IN = 25.4 MM = 1 / 25.4 # bearings 6907: 35 x 55 x 10 mm B_ID, B_OD, B_W = 35 * MM, 55 * MM, 10 * MM LIP = 0.04 # cap pilot lip that clamps each bearing outer ring X_BF0 = 16.65 # front bearing front face X_BR1 = X_BF0 + 3.0 + B_W # rear bearing rear face (span 3.0 in centre-centre) X_BR0 = X_BR1 - B_W HOUS_HALF = 1.45 # housing 2.90 x 2.90 square CAP_T = 0.20 REAR_CAP_BORE = 2.10 # clears the KM7 locknut (52 mm = 2.047 in), lip still bears on the outer ring X_HOUS0, X_HOUS1 = X_BF0 - LIP, X_BR1 + LIP # housing body X_CAPF0 = X_HOUS0 - CAP_T X_CAPR1 = X_HOUS1 + CAP_T SHOULDER_D = 1.50 # spindle body between bearings HOUSING_INNER_D = 1.70 ADAPTER = (X_CAPR1, X_CAPR1 + 0.55) GBX = (ADAPTER[1] + 0.05, ADAPTER[1] + 2.05) # NMRV030 envelope along x GBX_HALF = 1.25 GBX_CD = 30 * MM # worm centre distance (input axis below the output) DRIVE_D = 14 * MM X_END = GBX[1] + 0.50 X_WIRE = ADAPTER[0] + 0.25 STING_BOLTS = (17.75, 19.25) FOLLOWERS = (17.3, 19.4) # cam-follower studs, both side faces: kept over the clearance bore STUD_DEPTH = 0.45 # (wall there is 0.60 thick; deeper would break into the bore) def cyl(d, x0, x1, y=0.0, z=0.0): return cq.Workplane("YZ").center(y, z).circle(d / 2).extrude(x1 - x0).translate((x0, 0, 0)) def ring(od, idd, x0, x1): return cyl(od, x0, x1).cut(cyl(idd, x0 - 0.01, x1 + 0.01)) # ================================================================== spindle (4140, rotates with the sting) def make_spindle(): x_nose = X_CAPF0 s = cyl(1.30, x_nose, X_BF0) # nose through the front cap s = s.union(cyl(B_ID, X_BF0, X_BF0 + B_W)) # front bearing seat s = s.union(cyl(SHOULDER_D, X_BF0 + B_W, X_BR0)) # body / bearing shoulders s = s.union(cyl(B_ID, X_BR0, X_BR1)) # rear bearing seat s = s.union(cyl(B_ID - 0.02, X_BR1, X_BR1 + 0.38)) # M35x1.5 thread for the KM7 locknut s = s.union(cyl(1.0, X_BR1 + 0.38, ADAPTER[1] + 0.02)) # wire-exit neck s = s.union(cyl(DRIVE_D, ADAPTER[1] + 0.02, GBX[1] + 0.05)) # 14 mm keyed drive shaft through the gearbox s = s.union(cyl(0.50, GBX[1] + 0.05, X_END)) # encoder end # sting bore: round ahead of the flats, D-D over the flats (x 17..20) r_st = K.STING_D / 2 + 0.0025 x_flat0, x_sting_end = 20.0 - 3.0, 20.0 s = s.cut(cyl(2 * r_st, x_nose - 0.01, x_flat0)) dd = cyl(2 * r_st, x_flat0, x_sting_end + 0.01).intersect(box(x_flat0 - 0.1, x_sting_end + 0.1, -1, 1, -0.3525, 0.3525)) s = s.cut(dd) # wire path: axial 0.30 bore from the sting end to the exit neck, radial exits up and down s = s.cut(cyl(0.30, x_sting_end - 0.01, X_WIRE + 0.15)) s = s.cut(cq.Workplane("XY").center(X_WIRE, 0).circle(0.125).extrude(2, both=True)) # sting bolts: top clearance + c'bore, bottom tapped 1/4-20 for xb in STING_BOLTS: s = s.cut(cq.Workplane("XY").center(xb, 0).circle(0.1405).extrude(1.0)) s = s.cut(cq.Workplane("XY").center(xb, 0).circle(0.21).extrude(0.3).translate((0, 0, SHOULDER_D / 2 - 0.28))) s = s.cut(cq.Workplane("XY").center(xb, 0).circle(0.1005).extrude(-1.0)) # 5 mm key on the drive shaft, 6 x 2.5 mm magnet pocket on the end s = s.cut(box(ADAPTER[1] + 0.15, GBX[1] - 0.10, -2.5 * MM, 2.5 * MM, DRIVE_D / 2 - 3 * MM, 1)) s = s.cut(cyl(6 * MM, X_END - 2.5 * MM, X_END + 0.01)) return s # ================================================================== fixed parts def make_housing(): h = box(X_HOUS0, X_HOUS1, -HOUS_HALF, HOUS_HALF, -HOUS_HALF, HOUS_HALF) h = h.cut(cyl(B_OD + 0.0005, X_HOUS0 - 0.01, X_BF0 + B_W)) # front bearing bore (+ cap lip) h = h.cut(cyl(B_OD + 0.0005, X_BR0, X_HOUS1 + 0.01)) # rear bearing bore (+ cap lip) h = h.cut(cyl(HOUSING_INNER_D, X_HOUS0, X_HOUS1)) # clearance bore / outer-ring shoulders for xb in STING_BOLTS: # top access windows for the sting bolts h = h.cut(cq.Workplane("XY").center(xb, 0).circle(0.30).extrude(2)) for xf in FOLLOWERS: # 3/8-24 cam-follower studs, both sides h = h.cut(cq.Workplane("XZ").center(xf, 0).circle(0.166).extrude(STUD_DEPTH).translate((0, HOUS_HALF + 0.01, 0))) h = h.cut(cq.Workplane("XZ").center(xf, 0).circle(0.166).extrude(-STUD_DEPTH).translate((0, -HOUS_HALF - 0.01, 0))) for x in (X_HOUS0 + 0.35, X_HOUS1 - 0.35): # 1/4-20 mounting holes, both sides, z = +-1.0 for z in (-1.0, 1.0): h = h.cut(cq.Workplane("XZ").center(x, z).circle(0.1005).extrude(0.6).translate((0, HOUS_HALF + 0.01, 0))) h = h.cut(cq.Workplane("XZ").center(x, z).circle(0.1005).extrude(-0.6).translate((0, -HOUS_HALF - 0.01, 0))) for x in (X_HOUS0, X_HOUS1): # #8-32 cap screws, 4 per end for y, z in ((1.15, 1.15), (-1.15, 1.15), (1.15, -1.15), (-1.15, -1.15)): d0 = x if x == X_HOUS0 else x - 0.5 h = h.cut(cyl(0.136, d0, d0 + 0.5, y, z)) return h def make_cap(front=True): """End cap with a pilot lip that enters the bearing bore and clamps the outer ring.""" x0, x1 = (X_CAPF0, X_HOUS0) if front else (X_HOUS1, X_CAPR1) bore = 1.40 if front else REAR_CAP_BORE c = box(x0, x1, -HOUS_HALF, HOUS_HALF, -HOUS_HALF, HOUS_HALF).cut(cyl(bore, x0 - 0.01, x1 + 0.01)) c = c.union(ring(B_OD - 0.001, bore, x1, x1 + LIP) if front else ring(B_OD - 0.001, bore, x0 - LIP, x0)) for y, z in ((1.15, 1.15), (-1.15, 1.15), (1.15, -1.15), (-1.15, -1.15)): c = c.cut(cyl(0.177, x0 - 0.05, x1 + 0.05, y, z)) return c def make_adapter(): """Spacer between the rear cap and the gearbox: locknut clearance, top/bottom wire-exit windows (+-100 deg arc).""" x0, x1 = ADAPTER a = box(x0, x1, -HOUS_HALF, HOUS_HALF, -HOUS_HALF, HOUS_HALF) a = a.cut(cyl(2.20, x0 - 0.01, x1 + 0.01)) a = a.cut(box(X_WIRE - 0.20, X_WIRE + 0.20, -HOUS_HALF - 0.1, HOUS_HALF + 0.1, 0.4, HOUS_HALF + 0.1)) # wire window for y, z in ((1.15, 1.15), (-1.15, 1.15), (1.15, -1.15), (-1.15, -1.15)): a = a.cut(cyl(0.177, x0 - 0.01, x1 + 0.01, y, z)) return a def make_gearbox_envelope(): """NMRV030 50:1 (purchased): body around the output axis, input boss + NEMA 23 flange along +y, input axis below.""" g = box(*GBX, -GBX_HALF, GBX_HALF, -GBX_HALF - 0.3, GBX_HALF) g = g.cut(cyl(DRIVE_D + 0.004, GBX[0] - 0.01, GBX[1] + 0.01)) # hollow output xm = (GBX[0] + GBX[1]) / 2 flange = box(xm - 1.12, xm + 1.12, GBX_HALF, GBX_HALF + 0.45, -GBX_CD - 1.12, -GBX_CD + 1.12) return g.union(flange) def make_motor(): xm = (GBX[0] + GBX[1]) / 2 y0 = GBX_HALF + 0.45 m = box(xm - 1.11, xm + 1.11, y0, y0 + 2.2, -GBX_CD - 1.11, -GBX_CD + 1.11) # NEMA 23, 56 mm body return m.union(cq.Workplane("XZ").center(xm, -GBX_CD).circle(0.30).extrude(-0.4).translate((0, y0 + 2.2, 0))) ENC_T = 0.12 # encoder bracket plate thickness ENC_GAP = 1.5 * MM # magnet face to AS5048A chip (datasheet range ~0.5-2.5 mm) def make_encoder_bracket(): """1/8 in plate bolted flat to the gearbox output face; spindle end passes through; 4x M3 standoffs carry the AS5048A board on axis, ENC_GAP from the magnet face. Gearbox holes: 2 slots fit the vendor's tapped holes.""" x0 = GBX[1] b = box(x0, x0 + ENC_T, -0.75, 0.75, -0.75, 0.75) b = b.cut(cyl(0.60, x0 - 0.01, x0 + ENC_T + 0.01)) # spindle end clearance for z in (-0.58, 0.58): # 2x slots for gearbox screws b = b.cut(cq.Workplane("YZ").center(0, z).slot2D(0.45, 0.22, 0).extrude(ENC_T + 0.02) .translate((x0 - 0.01, 0, 0))) for y, z in ((0.40, 0.30), (-0.40, 0.30), (0.40, -0.30), (-0.40, -0.30)): # 4x M3 tapped (2.5 mm drill) b = b.cut(cyl(2.5 * MM, x0 - 0.01, x0 + ENC_T + 0.01, y, z)) return b def make_encoder_board(): """AS5048A adapter board envelope (~0.9 in square) + 4 standoffs.""" xb = X_END + ENC_GAP brd = box(xb, xb + 1.6 * MM, -0.45, 0.45, -0.45, 0.45) for y, z in ((0.40, 0.30), (-0.40, 0.30), (0.40, -0.30), (-0.40, -0.30)): brd = brd.union(cyl(5 * MM, GBX[1] + ENC_T, xb, y, z)) return brd def make_bearings(): return [ring(B_OD, B_ID, X_BF0, X_BF0 + B_W), ring(B_OD, B_ID, X_BR0, X_BR1)] def make_locknut(): return ring(52 * MM, B_ID - 0.02, X_BR1 + 0.01, X_BR1 + 0.01 + 0.315) # ================================================================== build, check, export def rotating(phi=0.0): parts = {"spindle_4140": make_spindle(), "sting": K.make_sting(), "balance": K.make_balance(), "puck": K.make_puck(), "pod": K.make_pod()} return {k: v.rotate((0, 0, 0), (1, 0, 0), phi) for k, v in parts.items()} def fixed(): f = {"housing_6061": make_housing(), "front_cap_6061": make_cap(True), "rear_cap_6061": make_cap(False), "gearbox_adapter_6061": make_adapter(), "gearbox_NMRV030_envelope": make_gearbox_envelope(), "motor_NEMA23_envelope": make_motor(), "encoder_bracket": make_encoder_bracket(), "encoder_board_AS5048A_envelope": make_encoder_board()} return f def vol(a, b): return a.val().intersect(b.val()).Volume() if __name__ == "__main__": fx = fixed() brg = make_bearings() nut = make_locknut() sp = make_spindle() print(f"spindle: x {X_CAPF0:.2f}..{X_END:.2f} in, bearings centres {X_BF0 + B_W/2:.3f} / {X_BR0 + B_W/2:.3f} " f"(span {X_BR0 - X_BF0:.2f}), drive {GBX[0]:.2f}..{GBX[1]:.2f}, wire exit x {X_WIRE:.2f}") print(f" min radius of drive parts from the BMC: {math.hypot(GBX[0], 0):.2f} in (cheek band ends at 20.7)") # bearing fits: bearing vs spindle seat and housing bore should touch (tiny/zero overlap), nothing else print("CHECKS (in^3; 0 = clear)") for phi in (-90, -45, 0, 45, 90): rot = rotating(phi) w, hits = 0.0, [] for kr, vr in rot.items(): for kf, vf in fx.items(): v = vol(vr, vf) if v > 1e-6: hits.append(f"{kr} x {kf} {v:.4f}") w = max(w, v) print(f" roll {phi:+4d}: rotating parts vs housing/caps/gearbox/motor/encoder max {w:.5f}" + ("".join("\n " + h for h in hits) if hits else "")) print(f" sting x spindle {vol(K.make_sting(), sp):.5f} ; bearings x spindle " f"{max(vol(b, sp) for b in brg):.5f} ; bearings x housing {max(vol(b, fx['housing_6061']) for b in brg):.5f} ; " f"locknut x rear cap {vol(nut, fx['rear_cap_6061']):.5f}") # loads / stresses N = 25.0 x_bf, x_br = X_BF0 + B_W / 2, X_BR0 + B_W / 2 R_r = N * x_bf / (x_br - x_bf) R_f = N + R_r M = N * x_bf Z = math.pi * (B_ID**4 - K.STING_D**4) / (32 * B_ID) print(f"LOADS at N = {N} lbf: front bearing {R_f:.0f} lbf, rear {R_r:.0f} lbf (6907 C ~ 2,700 lbf) ; " f"spindle bending at the front seat {M:.0f} in-lbf -> {M/Z:,.0f} psi (4140 HT yield ~100 ksi)") print(f"ROLL DRIVE: 35 in-lbf / (50 x 0.35) = {35/(50*0.35)*0.113:.2f} N-m at the NEMA 23 ; +-90 deg in 10 s = 150 rpm") exports = {**fx, "spindle_4140": sp, "bearing_6907_envelope": cq.Workplane().add(brg[0].val()), "locknut_KM7_envelope": nut} for n, wp in exports.items(): cq.exporters.export(cq.Workplane().add(wp.val().scale(IN)), str(HERE / f"{n}.step")) print("exported:", ", ".join(exports)) for phi in (0, 90): asm = cq.Assembly(name=f"roll_spindle_phi{phi:+d}") for k, v in rotating(phi).items(): asm.add(cq.Workplane().add(v.val().scale(IN)), name=k, color=cq.Color(*{"spindle_4140": (0.45, 0.45, 0.5), "sting": (0.35, 0.35, 0.35), "balance": (0.75, 0.75, 0.8), "puck": (0.55, 0.6, 0.9), "pod": (0.2, 0.7, 0.4, 0.35)}[k])) for k, v in fx.items(): asm.add(cq.Workplane().add(v.val().scale(IN)), name=k, color=cq.Color(0.85, 0.62, 0.22)) for i, b in enumerate(brg + [nut]): asm.add(cq.Workplane().add(b.val().scale(IN)), name=f"bearing_or_nut_{i}", color=cq.Color(0.2, 0.2, 0.25)) asm.export(str(HERE / f"assembly_roll_spindle_phi{phi:+d}.step")) print(f" assembly_roll_spindle_phi{phi:+d}.step")