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NopSCADlib
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Fixed belt gap positioning and added ability to rotae it.

This commit is contained in:
Chris Palmer 2020-08-22 11:16:56 +01:00
parent 4cdab218d9
commit b6d25048bc
4 changed files with 13 additions and 8 deletions
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5
readme.md
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@ -209,6 +209,7 @@ Only models 2D paths, so not core XY!
To make the back of the belt run against a smooth pulley on the outside of the loop specify a negative pitch radius.
By default the path is a closed loop but a gap length and position can be specified to make open loops.
To draw the gap its XY position is specified by ```gap_pos```. ```gap_pos.z``` can be used to specify a rotation if the gap is not at the bottom of the loop.
Individual teeth are not drawn, instead they are represented by a lighter colour.
@ -237,7 +238,7 @@ Individual teeth are not drawn, instead they are represented by a lighter colour
### Modules
| Module | Description |
|:--- |:--- |
| ```belt(type, points, gap = 0, gap_pt = undef, belt_colour = grey(20)``` | Draw a belt path given a set of points and pitch radii where the pulleys are. Closed loop unless a gap is specified |
| ```belt(type, points, gap = 0, gap_pos = undef, belt_colour = grey(20)``` | Draw a belt path given a set of points and pitch radii where the pulleys are. Closed loop unless a gap is specified |
![belts](tests/png/belts.png)
@ -245,7 +246,7 @@ Individual teeth are not drawn, instead they are represented by a lighter colour
| Qty | Module call | BOM entry |
| ---:|:--- |:---|
| 1 | ```belt(GT2x6, [ ... ])``` | Belt GT2 x 6mm x 128mm |
| 1 | ```belt(GT2x6, [ ... ], 80, [0, 0.314])``` | Belt GT2 x 6mm x 696mm |
| 1 | ```belt(GT2x6, [ ... ], 80, [0, 0])``` | Belt GT2 x 6mm x 696mm |
| 1 | ```belt(T2p5x6, [ ... ])``` | Belt T2.5 x 6mm x 130mm |
| 1 | ```belt(T5x10, [ ... ])``` | Belt T5 x 10mm x 130mm |
| 1 | ```belt(T5x6, [ ... ])``` | Belt T5 x 6mm x 130mm |

2
tests/belts.scad
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@ -60,7 +60,7 @@ module belt_test() {
[p4.x, p4.y, pulley_pr(GT2x20ob_pulley)]
];
belt = GT2x6;
belt(belt, path, 80, [0, belt_pitch_height(belt) - belt_thickness(belt) / 2]);
belt(belt, path, 80, [0, 0]);
translate([-25, 0])
layout([for(b = belts) belt_width(b)], 10)

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tests/png/belts.png
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14
vitamins/belt.scad
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@ -24,11 +24,13 @@
//! To make the back of the belt run against a smooth pulley on the outside of the loop specify a negative pitch radius.
//!
//! By default the path is a closed loop but a gap length and position can be specified to make open loops.
//! To draw the gap its XY position is specified by ```gap_pos```. ```gap_pos.z``` can be used to specify a rotation if the gap is not at the bottom of the loop.
//!
//! Individual teeth are not drawn, instead they are represented by a lighter colour.
//
include <../utils/core/core.scad>
use <../utils/rounded_polygon.scad>
use <../utils/maths.scad>
function belt_pitch(type) = type[1]; //! Pitch in mm
function belt_width(type) = type[2]; //! Width in mm
@ -43,12 +45,12 @@ function no_point(str) = chr([for(c = str) if(c == ".") ord("p") else ord(c)]);
// We model the belt path at the pitch radius of the pulleys and the pitch line of the belt to get an accurate length.
// The belt is then drawn by offseting each side from the pitch line.
//
module belt(type, points, gap = 0, gap_pt = undef, belt_colour = grey(20), tooth_colour = grey(50)) { //! Draw a belt path given a set of points and pitch radii where the pulleys are. Closed loop unless a gap is specified
module belt(type, points, gap = 0, gap_pos = undef, belt_colour = grey(20), tooth_colour = grey(50)) { //! Draw a belt path given a set of points and pitch radii where the pulleys are. Closed loop unless a gap is specified
width = belt_width(type);
pitch = belt_pitch(type);
thickness = belt_thickness(type);
part = str(type[0],pitch);
vitamin(str("belt(", no_point(part), "x", width, ", ", points, arg(gap, 0), arg(gap_pt, undef), "): Belt ", part," x ", width, "mm x ", length, "mm"));
vitamin(str("belt(", no_point(part), "x", width, ", ", points, arg(gap, 0), arg(gap_pos, undef), "): Belt ", part," x ", width, "mm x ", length, "mm"));
len = len(points);
@ -62,8 +64,10 @@ module belt(type, points, gap = 0, gap_pt = undef, belt_colour = grey(20), tooth
th = belt_tooth_height(type);
module gap()
if(gap)
translate(gap_pt + [0, -ph + thickness / 2])
square([gap, thickness + eps], center = true);
translate([gap_pos.x, gap_pos.y])
rotate(is_undef(gap_pos.z) ? 0 : gap_pos.z)
translate([0, ph - thickness / 2])
square([gap, thickness + eps], center = true);
color(belt_colour)
linear_extrude(width, center = true)
@ -71,8 +75,8 @@ module belt(type, points, gap = 0, gap_pt = undef, belt_colour = grey(20), tooth
offset(-ph + thickness ) shape();
offset(-ph + th) shape();
gap();
}
color(tooth_colour)
linear_extrude(width, center = true)
difference() {