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Thickness Fixes (+ 3.0 default) #93

Merged
merged 14 commits into from
Nov 27, 2020
Merged

Thickness Fixes (+ 3.0 default) #93

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773f4df
Lock flap dimensions to die-cut specs
dmadison Sep 16, 2020
e87928c
Fix side bolt positions
dmadison Sep 16, 2020
ee7e685
Limit vertical inset to bolt head diameter
dmadison Sep 17, 2020
ceb3664
Account for flap width in spool calculations
dmadison Sep 16, 2020
8172e21
Reduce default thickness to 3.0
dmadison Sep 17, 2020
a68fc98
Increase flap width slop
dmadison Sep 18, 2020
2ba8388
Merge branch 'master' into thickness
dmadison Sep 25, 2020
f82e43c
Add clearance to front and side tab connections
dmadison Sep 27, 2020
088bca6
Add clearance to spool strut tabs
dmadison Oct 5, 2020
06f9358
Refactor spool strut tabs as strut num joints
dmadison Oct 5, 2020
57e65ff
Add clearance to spool joints
dmadison Oct 5, 2020
5707087
Add clearance to connector pieces
dmadison Oct 5, 2020
8f5534d
Update model kerf value from Ponoko
dmadison Oct 5, 2020
63fcb01
Add depth clearance to connector brackets
dmadison Oct 7, 2020
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4 changes: 4 additions & 0 deletions 3d/flap_dimensions.scad
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Original file line number Diff line number Diff line change
Expand Up @@ -19,5 +19,9 @@ flap_height = 43;
flap_thickness = 30 / 1000 * 25.4; // 30 mil
flap_corner_radius = 3.1; // 2.88-3.48mm (used just for display)

flap_notch_height_auto = false;
flap_notch_height_default = 15;
flap_notch_depth = 3.2;
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flap_pin_width = 1.4;

93 changes: 51 additions & 42 deletions 3d/splitflap.scad
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Original file line number Diff line number Diff line change
Expand Up @@ -67,13 +67,13 @@ spool_horizontal_explosion = lookup(spool_explosion, [
]);


// Kerf based off http://blog.ponoko.com/2011/07/12/figuring-out-kerf-for-precision-parts/
// It's better to underestimate (looser fit) than overestimate (no fit)
kerf_width = 0.19 - 0.02;
// Ponoko kerf values are 0.2 mm for MDF and acrylic (all thicknesses)
// Remember: it's better to underestimate (looser fit) than overestimate (no fit)
kerf_width = 0.2 - 0.02;

// MDF, .125in nominal
// http://www.ponoko.com/make-and-sell/show-material/64-mdf-natural
thickness = 3.2;
// MDF, .120in nominal
// https://www.ponoko.com/materials/mdf-fiberboard
thickness = 3.0;

eps=.01;

Expand All @@ -90,10 +90,12 @@ assembly_color4 = [.204, .161, .114]; //"34291D";
flap_rendered_angle = 90;

// Amount of slop of the flap side to side between the 2 spools
flap_width_slop = 0.1;
flap_width_slop = 0.5;

// Amount of slop for the spool assembly side-to-side inside the enclosure
spool_width_slop = 1;
spool_tab_clearance = 0.10;
spool_joint_clearance = 0.10;


num_flaps = 40;
Expand All @@ -114,13 +116,13 @@ outer_exclusion_radius = flap_pitch_radius + flap_height + 2;

front_forward_offset = flap_pitch_radius + flap_thickness/2;

flap_notch = sqrt(spool_outer_radius*spool_outer_radius - flap_pitch_radius*flap_pitch_radius);
flap_notch_depth = 3;
flap_notch_height = (flap_notch_height_auto == true) ? sqrt(spool_outer_radius*spool_outer_radius - flap_pitch_radius*flap_pitch_radius) : flap_notch_height_default;

spool_width = flap_width - flap_notch_depth*2 + flap_width_slop + thickness*2; // spool width, outside face (spool to spool)
spool_width_clearance = max(spool_width, flap_width + flap_width_slop); // width clearance for the spool, either for the spool itself or the flaps

spool_width = flap_width - flap_notch_depth*2 + flap_width_slop + thickness*2;
legacyAssert(spool_width >= flap_width, "Flap is wider than spool!");
spool_strut_tabs = 3;
//legacyAssert(spool_width >= flap_width, "Flap is wider than spool!");
spool_strut_num_joints = 3;
spool_strut_tab_width=8;
spool_strut_tab_width_narrow=6;
spool_strut_tab_outset=8;
Expand All @@ -141,7 +143,7 @@ motor_slop_radius = 3;


// Width measured from the outside of the walls
enclosure_wall_to_wall_width = thickness + spool_width_slop/2 + spool_width + spool_width_slop/2 + max(28byj48_mount_bracket_height + m4_button_head_length, 4 + 28byj48_mount_bracket_height - spool_width_slop/2) + thickness;
enclosure_wall_to_wall_width = thickness + spool_width_slop/2 + spool_width_clearance + spool_width_slop/2 + max(28byj48_mount_bracket_height + m4_button_head_length, 4 + 28byj48_mount_bracket_height - spool_width_slop/2) + thickness;

// Width of the front panel
enclosure_width = enclosure_wall_to_wall_width + 28byj48_chassis_height + 28byj48_chassis_height_slop - thickness - 28byj48_mount_bracket_height;
Expand All @@ -151,10 +153,10 @@ front_window_overhang = 3;
front_window_upper = front_window_upper_base - front_window_overhang;
front_window_lower = sqrt(outer_exclusion_radius*outer_exclusion_radius - front_forward_offset*front_forward_offset);
front_window_slop = 0;
front_window_width = spool_width_slop + spool_width + front_window_slop;
front_window_width = spool_width_slop + spool_width_clearance + front_window_slop;
front_window_right_inset = thickness - front_window_slop/2;
enclosure_vertical_margin = 10; // gap between top/bottom of flaps and top/bottom of enclosure
enclosure_vertical_inset = thickness*1.5; // distance from top of sides to top of the top piece
enclosure_vertical_inset = max(thickness*1.5, m4_nut_width_corners_padded/2); // distance from top of sides to top of the top piece
enclosure_height_upper = exclusion_radius + enclosure_vertical_margin + thickness + enclosure_vertical_inset;
enclosure_height_lower = flap_pitch_radius + flap_height + enclosure_vertical_margin + thickness + enclosure_vertical_inset;
enclosure_height = enclosure_height_upper + enclosure_height_lower;
Expand All @@ -165,6 +167,8 @@ enclosure_length = front_forward_offset + 28byj48_mount_center_offset + m4_hole_


// Enclosure tabs: front/back
enclosure_tab_clearance = 0.10;

num_front_tabs = 2;
front_tab_width = (enclosure_wall_to_wall_width - 2*thickness) / (num_front_tabs*2 - 1);

Expand All @@ -187,6 +191,8 @@ connector_bracket_length_inner = side_tab_width * 2 - m4_button_head_diameter/2;
connector_bracket_thickness = captive_nut_inset - thickness - 0.2;
connector_bracket_width = enclosure_width - enclosure_wall_to_wall_width + thickness*2 + connector_bracket_thickness*2;
connector_bracket_overlap = 4;
connector_bracket_clearance = 0.10;
connector_bracket_depth_clearance = 0.20;


mounting_hole_inset = m4_button_head_diameter/2 + 2;
Expand All @@ -208,7 +214,7 @@ echo(front_window_height=front_window_lower+front_window_upper);
echo(front_forward_offset=front_forward_offset);
echo(flap_exclusion_radius=exclusion_radius);
echo(flap_hole_radius=flap_hole_radius);
echo(flap_notch=flap_notch);
echo(flap_notch_height=flap_notch_height);


module standard_m4_bolt(nut_distance=-1) {
Expand Down Expand Up @@ -248,7 +254,7 @@ module m4_captive_nut(bolt_length=m4_bolt_length) {

// ##### Struts for bracing spool #####
module spool_strut_tab_hole(narrow) {
square([thickness, narrow ? spool_strut_tab_width_narrow : spool_strut_tab_width], center=true);
square([thickness + spool_tab_clearance, narrow ? spool_strut_tab_width_narrow + spool_tab_clearance : spool_strut_tab_width + spool_tab_clearance], center=true);
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Hmmm, I wonder if it would make sense to define the clearance values not on a per-part basis, but as 2 high level parameters, something like:

  • thickness_clearance
  • cut_clearance

Since cuts should be consistent and much lower variability than thickness, it seems like it would make sense to use a smaller clearance value for cut-to-cut joints (where dimensions are entirely controlled by cuts) compared to cut-to-thickness joints (where dimensions rely on inherent material thickness and therefore need a larger tolerance to ensure fit).

This part of the model involves both, so it would change to something like:

Suggested change
square([thickness + spool_tab_clearance, narrow ? spool_strut_tab_width_narrow + spool_tab_clearance : spool_strut_tab_width + spool_tab_clearance], center=true);
square([thickness + thickness_clearance, narrow ? spool_strut_tab_width_narrow + cut_clearance : spool_strut_tab_width + cut_clearance], center=true);

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Maybe, but the variability for both is wide enough that I'm not sure making the distinction would be beneficial. Both the kerf and the thickness are precise but not accurate, so assuming that the initial values are correct the tolerances should be roughly the same for both. The bigger overarching problem is that the design relies on friction-fit parts which necessitate accurate manufacturing.

}
module spool_strut_tab_holes(narrow=false) {
for (i=[0:3]) {
Expand All @@ -259,7 +265,7 @@ module spool_strut_tab_holes(narrow=false) {
}
}
module spool_strut() {
joint_tab_width = spool_strut_inner_length / spool_strut_tabs;
joint_tab_width = spool_strut_inner_length / spool_strut_num_joints;
linear_extrude(thickness, center=true) {
union() {
translate([0, -spool_strut_tab_width_narrow / 2]) {
Expand All @@ -272,15 +278,15 @@ module spool_strut() {
difference() {
square([spool_strut_inner_length, spool_strut_width]);

// subtract out tabs
// subtract out joints
union() {
for (i = [0:2:spool_strut_tabs-1]) {
translate([i*joint_tab_width, -eps])
square([joint_tab_width, thickness+eps]);
for (i = [0:2:spool_strut_num_joints-1]) {
translate([i*joint_tab_width - spool_joint_clearance/2, -eps])
square([joint_tab_width + spool_joint_clearance, thickness + spool_joint_clearance/2 + eps]);
}
for (i = [1:2:spool_strut_tabs-1]) {
translate([i*joint_tab_width, spool_strut_width - thickness])
square([joint_tab_width, thickness+eps]);
for (i = [1:2:spool_strut_num_joints-1]) {
translate([i*joint_tab_width, spool_strut_width - thickness - spool_joint_clearance/2])
square([joint_tab_width, thickness + spool_joint_clearance + eps]);
}
}
}
Expand Down Expand Up @@ -354,9 +360,9 @@ module flap_2d() {
}
}
translate([-eps, flap_pin_width])
square([eps + flap_notch_depth, flap_notch]);
square([eps + flap_notch_depth, flap_notch_height]);
translate([flap_width - flap_notch_depth, flap_pin_width])
square([eps + flap_notch_depth, flap_notch]);
square([eps + flap_notch_depth, flap_notch_height]);
}
}

Expand Down Expand Up @@ -412,7 +418,7 @@ module motor_shaft() {
module front_tabs_negative() {
for (i = [0 : num_front_tabs-1]) {
translate([thickness + (i*2+0.5) * front_tab_width, 0, 0])
square([front_tab_width, thickness], center=true);
square([front_tab_width + enclosure_tab_clearance, thickness + enclosure_tab_clearance], center=true);
}
for (i = [0 : num_front_tabs-2]) {
translate([thickness + (i*2+1.5) * front_tab_width, 0, 0])
Expand All @@ -427,11 +433,11 @@ module connector_bracket() {
translate([connector_bracket_thickness, -eps]) {
square([connector_bracket_width - connector_bracket_thickness*2, connector_bracket_length_outer - connector_bracket_length_inner + eps]);
}
translate([connector_bracket_thickness, -eps]) {
square([thickness, connector_bracket_length_outer - connector_bracket_overlap + eps]);
translate([connector_bracket_thickness - connector_bracket_clearance/2, -eps]) {
square([thickness + connector_bracket_clearance, connector_bracket_length_outer - connector_bracket_overlap + connector_bracket_depth_clearance + eps]);
}
translate([connector_bracket_width - connector_bracket_thickness - thickness, -eps]) {
square([thickness, connector_bracket_length_outer - connector_bracket_overlap + eps]);
translate([connector_bracket_width - connector_bracket_thickness - thickness - connector_bracket_clearance/2, -eps]) {
square([thickness + connector_bracket_clearance, connector_bracket_length_outer - connector_bracket_overlap + connector_bracket_depth_clearance + eps]);
}
}
}
Expand Down Expand Up @@ -484,8 +490,8 @@ module motor_mount() {
module side_tabs_negative(hole_sizes=[], extend_last_tab=false) {
for (i = [0 : len(hole_sizes)]) {
length = (extend_last_tab && i == len(hole_sizes)) ? side_tab_width * side_tab_width_fraction + eps : side_tab_width * side_tab_width_fraction;
translate([-thickness / 2, thickness + (i*2) * side_tab_width + side_tab_width * (1 - side_tab_width_fraction)/2, 0])
square([thickness, length]);
translate([0, thickness + (i*2) * side_tab_width + side_tab_width * (1 - side_tab_width_fraction)/2 + length/2, 0])
square([thickness + enclosure_tab_clearance, length + enclosure_tab_clearance], center=true);
}
for (i = [0 : len(hole_sizes) - 1]) {
hole_size = hole_sizes[i];
Expand All @@ -508,8 +514,8 @@ module backstop_bolt_slot(radius) {

module connector_bracket_side_holes() {
// overlap slot
translate([enclosure_vertical_inset - thickness, -connector_bracket_overlap]) {
square([thickness, connector_bracket_overlap + eps]);
translate([enclosure_vertical_inset - thickness - connector_bracket_clearance/2, -connector_bracket_overlap]) {
square([thickness + connector_bracket_clearance, connector_bracket_overlap + eps]);
}
}

Expand Down Expand Up @@ -792,14 +798,14 @@ module split_flap_3d(letter, include_connector) {

module positioned_left_bolts() {
// Top
translate([enclosure_wall_to_wall_width, front_forward_offset - side_tab_width * 2, enclosure_height_upper - enclosure_vertical_inset - thickness/2]) {
translate([enclosure_wall_to_wall_width, front_forward_offset - (thickness + 1.5 * side_tab_width), enclosure_height_upper - enclosure_vertical_inset - thickness/2]) {
rotate([0, -90, 0]) {
standard_m4_bolt(nut_distance=captive_nut_inset);
}
}

// Bottom
translate([enclosure_wall_to_wall_width, front_forward_offset - side_tab_width * 2, -enclosure_height_lower + enclosure_vertical_inset + thickness/2]) {
translate([enclosure_wall_to_wall_width, front_forward_offset - (thickness + 1.5 * side_tab_width), -enclosure_height_lower + enclosure_vertical_inset + thickness/2]) {
rotate([0, -90, 0]) {
standard_m4_bolt(nut_distance=captive_nut_inset);
}
Expand All @@ -808,14 +814,14 @@ module split_flap_3d(letter, include_connector) {

module positioned_right_bolts() {
// Top
translate([0, front_forward_offset - side_tab_width * 2, enclosure_height_upper - enclosure_vertical_inset - thickness/2]) {
translate([0, front_forward_offset - (thickness + 1.5 * side_tab_width), enclosure_height_upper - enclosure_vertical_inset - thickness/2]) {
rotate([0, 90, 0]) {
standard_m4_bolt(nut_distance=captive_nut_inset);
}
}

// Bottom
translate([0, front_forward_offset - side_tab_width * 2, -enclosure_height_lower + enclosure_vertical_inset + thickness/2]) {
translate([0, front_forward_offset - (thickness + 1.5 * side_tab_width), -enclosure_height_lower + enclosure_vertical_inset + thickness/2]) {
rotate([0, 90, 0]) {
standard_m4_bolt(nut_distance=captive_nut_inset);
}
Expand Down Expand Up @@ -911,7 +917,8 @@ module split_flap_3d(letter, include_connector) {
}
}

translate([-flap_notch_depth + thickness + flap_width_slop/2, 0, 0]) {
flap_offset = thickness > flap_notch_depth ? -flap_notch_depth + thickness + flap_width_slop/2 : flap_width_slop/2;
translate([flap_offset, 0, 0]) {
// Collapsed flaps on the top
for (i=[0:num_flaps/2 - 1]) {
if (i == 0 || render_flaps == 2) {
Expand Down Expand Up @@ -944,8 +951,10 @@ module split_flap_3d(letter, include_connector) {
}
}
}
}

if(render_spool) {
if(render_spool) {
translate([(spool_width_clearance - spool_width + spool_width_slop) / 2 + thickness, 0, 0]) {
spool_struts();

// motor spool
Expand Down