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worm_gear() thickness and slicing fixes. #1272

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Sep 6, 2023
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worm_gear() thickness and slicing fixes. #1272

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37 changes: 22 additions & 15 deletions gears.scad
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Original file line number Diff line number Diff line change
Expand Up @@ -2347,7 +2347,7 @@ module worm(
// left_handed = If true, the gear returned will have a left-handed spiral. Default: false
// ---
// starts = The number of lead starts. Default: 1
// arc = Arc angle of the mated worm gear to envelop. Default: 45º
// arc = Arc angle of the mated worm gear to envelop. Default: `2 * pressure_angle`
// pressure_angle = Controls how straight or bulged the tooth sides are. In degrees. Default: 20
// diam_pitch = The diametral pitch, or number of teeth per inch of pitch diameter. Note that the diametral pitch is a completely different thing than the pitch diameter.
// mod = The metric module/modulus of the gear, or mm of pitch diameter per tooth.
Expand All @@ -2370,8 +2370,8 @@ function enveloping_worm(
d,
left_handed=false,
starts=1,
arc=45,
pressure_angle=20,
arc,
pressure_angle,
gear_spin=0,
rounding=true,
taper=true,
Expand All @@ -2382,15 +2382,18 @@ function enveloping_worm(
spin=0,
orient=UP
) =
let(
circ_pitch = _inherit_gear_pitch("worm_gear()", pitch, circ_pitch, diam_pitch, mod),
pressure_angle = _inherit_gear_pa(pressure_angle),
arc = default(arc, 2*pressure_angle)
)
assert(is_integer(mate_teeth) && mate_teeth>10)
assert(is_finite(d) && d>0)
assert(is_bool(left_handed))
assert(is_integer(starts) && starts>0)
assert(is_finite(arc) && arc>10 && arc<75)
assert(is_finite(pressure_angle) && pressure_angle>0 && pressure_angle<45)
assert(is_finite(arc) && arc>10 && arc<=2*pressure_angle)
assert(is_finite(gear_spin))
let(
circ_pitch = circular_pitch(circ_pitch=circ_pitch, diam_pitch=diam_pitch, pitch=pitch, mod=mod),
hsteps = segs(d/2),
vsteps = hsteps*3,
helical = asin(starts * circ_pitch / PI / d),
Expand Down Expand Up @@ -2468,7 +2471,7 @@ module enveloping_worm(
d,
left_handed=false,
starts=1,
arc=45,
arc,
pressure_angle=20,
gear_spin=0,
rounding=true,
Expand Down Expand Up @@ -2631,16 +2634,17 @@ function worm_gear(
tang = 360 / teeth,
rteeth = quantdn(teeth * gear_arc / 360, 2) / 2 + 0.5,
pr = pitch_radius(circ_pitch, teeth, helical=helical),
oslices = slices * 4,
rows = [
for (data = [[tooth_half1,1], [tooth_half2,-1]])
let (
tooth_half = data[0],
dir = data[1]
)
for (pt = tooth_half) [
for (i = [0:1:slices])
for (i = [0:1:oslices])
let (
u = i / slices,
u = i / oslices,
w_ang = worm_arc * (u - 0.5),
g_ang_delta = w_ang/360 * tang * worm_starts * (left_handed?1:-1),
m = zrot(dir*(rteeth-0.0)*tang, cp=[worm_diam/2+pr,0,0]) *
Expand All @@ -2652,11 +2656,6 @@ function worm_gear(
) apply(m, point3d(pt))
]
],
zs = column(flatten(rows),2),
minz = min(zs),
maxz = max(zs),
zmax = max(abs(minz), abs(maxz))+0.1,
twang = modang(v_theta(rows[0][0]) - v_theta(last(rows[0]))) / (maxz-minz),
midrow = len(rows)/2,
goodcols = [
for (i = idx(rows[0]))
Expand All @@ -2668,8 +2667,16 @@ function worm_gear(
],
dowarn = goodcols[0]==0? 0 : echo("Worm gear tooth arc reduced to fit."),
truncrows = [for (row = rows) [ for (i=goodcols) row[i] ] ],
zs = column(flatten(truncrows),2),
minz = min(zs),
maxz = max(zs),
zmax = max(abs(minz), abs(maxz))+0.05,
twang1 = v_theta(truncrows[0][0]),
twang2 = v_theta(last(truncrows[0])),
twang = modang(twang1 - twang2) / (maxz-minz),
resampled_rows = [for (row = truncrows) resample_path(row, n=slices, closed=false)],
tooth_rows = [
for (row = truncrows) [
for (row = resampled_rows) [
zrot(twang*(zmax-row[0].z), p=[row[0].x, row[0].y, zmax]),
each row,
zrot(twang*(-zmax-last(row).z), p=[last(row).x, last(row).y, -zmax]),
Expand Down