diff --git a/attachments.scad b/attachments.scad index 47d409c..23f54d7 100644 --- a/attachments.scad +++ b/attachments.scad @@ -2278,6 +2278,14 @@ module corner_profile(corners=CORNERS_ALL, except=[], r, d, convexity=10) { // * Rotates this part so it's anchor direction vector exactly opposes the parent's anchor direction vector. // * Rotates this part so it's anchor spin matches the parent's anchor spin. // . +// This module is also responsible for handing coloring of objects with {{recolor()}} and {{color_this()}}, and +// it is responsible for processing tags and determining whether the object should +// display or not in the current context. The determination to display the attachable object +// occurs in this module, which means that an object which does not display (e.g. a "remove" tagged object +// inside {{diff()}} cannot have internal {{tag()}} calls that change its tags and cause submodel +// portions to display: the entire child simply does not run. + + // For a step-by-step explanation of attachments, see the [Attachments Tutorial](Tutorial-Attachments). // // Arguments: diff --git a/gears.scad b/gears.scad index 4b50d9e..eab8a1b 100644 --- a/gears.scad +++ b/gears.scad @@ -72,6 +72,7 @@ function _inherit_gear_thickness(thickness) = // this section provides the minimal information needed for gear making. If you want more information about the // details of gears, consult the references below, which are the ones that we consulted when writing the library code. // - Tec Science +// * [Involute Gears](https://www.tec-science.com/mechanical-power-transmission/involute-gear/geometry-of-involute-gears/) // * [Gear engagement](https://www.tec-science.com/mechanical-power-transmission/involute-gear/meshing-line-action-contact-pitch-circle-law/) // * [Gears meshing with racks](https://www.tec-science.com/mechanical-power-transmission/involute-gear/rack-meshing/) // * [Gear undercutting](https://www.tec-science.com/mechanical-power-transmission/involute-gear/undercut/) @@ -211,7 +212,7 @@ function _inherit_gear_thickness(thickness) = // be automatically incorporated. (Consider the situation where one gear mates with multiple other gears.) With modest // profile shifts, you can probably ignore this adjustment, but with more extreme profile shifts, it may be important. // You can compute the shortening parameter using {{gear_shorten()}}. Note that the actual shortening distance is obtained -// by scaling the shortening fator by the gear's module. +// by scaling the shortening factor by the gear's module. // Figure(2D,Big,NoAxes,VPT=[55.8861,-4.31463,8.09832],VPR=[0,0,0],VPD=325.228): With large profile shifts the teeth need to be shortened or they don't have clearance in the valleys of the teeth in the meshing gear. // teeth1=25; // teeth2=19; @@ -1692,7 +1693,7 @@ function rack2d( tthick = trans_pitch/PI * (PI/2 + 2*profile_shift * tan(PA)) - backlash, l = teeth * trans_pitch, ax = ang_adj_to_opp(trans_pa, adendum), - dx = ang_adj_to_opp(trans_pa, dedendum), + dx = dedendum*tan(trans_pa), poff = tthick/2 - backlash, tooth = [ [-trans_pitch/2, -dedendum], @@ -2365,7 +2366,7 @@ function worm_gear( assert(is_finite(gear_spin)) let( helical = asin(worm_starts * circ_pitch / PI / worm_diam), - pr = pitch_radius(circ_pitch, teeth, helical), + pr = pitch_radius(circ_pitch, teeth,helical), hob_rad = worm_diam / 2 + crowning, thickness = worm_gear_thickness(circ_pitch=circ_pitch, teeth=teeth, worm_diam=worm_diam, worm_arc=worm_arc, crowning=crowning, clearance=clearance), tooth_profile = _gear_tooth_profile( @@ -2567,7 +2568,7 @@ function _gear_tooth_profile( rrad = _root_radius(circ_pitch, teeth, clearance, helical=helical, profile_shift=profile_shift, internal=internal), srad = max(rrad,brad), - tthick = circ_pitch/PI / cos(helical) * (PI/2 + 2*profile_shift * tan(pressure_angle)) - backlash, + tthick = circ_pitch/PI / cos(helical) * (PI/2 + 2*profile_shift * tan(pressure_angle)) + (internal?backlash:-backlash), tang = tthick / prad / 2 * 180 / PI, // Generate a lookup table for the involute curve angles, by radius @@ -2662,9 +2663,11 @@ function _gear_tooth_profile( ? [last(line1), isect_pt, line2[0]] : [line2[0], isect_pt, line1[0]], rounded_tooth_half = deduplicate([ - if (!internal) each arc(n=8, r=round_r, corner=rcorner), + if (!internal && round_r>0) each arc(n=8, r=round_r, corner=rcorner), + if (!internal && round_r<=0) isect_pt, each tooth_half_raw, - if (internal) each arc(n=8, r=round_r, corner=rcorner), + if (internal && round_r>0) each arc(n=8, r=round_r, corner=rcorner), + if (internal && round_r<=0) isect, ]), // Strip "jaggies" if found. @@ -3163,7 +3166,10 @@ function worm_gear_thickness(circ_pitch, teeth, worm_diam, worm_arc=60, crowning // distance between the rack's pitch line and the gear's center. If you set internal1 or internal2 to true then the // specified gear is a ring gear; the returned distance is still the distance between the centers of the gears. Note that // for a regular gear and ring gear to be compatible the ring gear must have more teeth and at least as much profile shift -// as the regular gear. +// as the regular gear. +// . +// The backlash parameter computes the distance offset that produces a total backlash of `2*backlash` in the +// two gear mesh system. This is equivalent to giving the same backlash argument to both gears. // Arguments: // teeth1 = Total number of teeth in the first gear. If given 0, we assume this is a rack or worm. // teeth2 = Total number of teeth in the second gear. If given 0, we assume this is a rack or worm. @@ -3177,7 +3183,7 @@ function worm_gear_thickness(circ_pitch, teeth, worm_diam, worm_arc=60, crowning // internal1 = first gear is an internal (ring) gear. Default: false // internal2 = second gear is an internal (ring) gear. Default: false // pressure_angle = The pressure angle of the gear. -// backlash = Add extra space to produce the specified backlash +// backlash = Add extra space to produce a total of 2*backlash between the two gears. // Example(2D,NoAxes): Spur gears (with automatic profile shifting on both) // circ_pitch=5; teeth1=7; teeth2=24; // d = gear_dist(circ_pitch=circ_pitch, teeth1, teeth2); @@ -3248,7 +3254,7 @@ function gear_dist( pa_eff = _working_pressure_angle(teeth1,profile_shift1,teeth2,profile_shift2,pressure_angle,helical), pa_transv = atan(tan(pressure_angle)/cos(helical)) ) - mod*(teeth1+teeth2)*cos(pa_transv)/cos(pa_eff)/cos(helical)/2 + backlash*cos(helical)/2/tan(pressure_angle); + mod*(teeth1+teeth2)*cos(pa_transv)/cos(pa_eff)/cos(helical)/2 + backlash*cos(helical)/tan(pressure_angle); function _invol(a) = tan(a) - a*PI/180;