openscad/threadlib
1
0
Fork 0
mirror of https://github.com/adrianschlatter/threadlib.git synced 2025-01-29 11:02:43 +01:00
Code Issues Projects Releases Wiki Activity

Updated BSPP_external_thread() and BSPP_internal_thread() to design

Browse Source 
with optimum margins (as insensitive to production tolerances as
possible).
This commit is contained in:
Adrian Schlatter 2019-04-03 21:59:33 +02:00
parent 1ac193d068
commit b368ac6fb2
1 changed files with 52 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

90
BSPthread.scad
View File

@ -6,10 +6,9 @@ British Standard Pipe Thread is based on a triangular profile. The angle between
is 55 deg (symmetrical). We use the following nomenclature:
- crest: The "summit" of a thread
- groove: The lowest point in the valley of a thread
- rcrest, rgroove: Radii of crest and groove, respectively
- t = abs(rcrest - rgroove)
- rpitch = mean of rmajor and rminor
- valley: The lowest point in the valley of a thread
- rcrest, rvalley: Radii of crest and groove, respectively
- rpitch = the mean radius of the original triangular profile
The crest and groove are both truncated by t/6. The radii at these flats are called
rmajor and rminor.
@ -32,43 +31,50 @@ use <thread_profile.scad>
phi = 55;
module BSPP_external_thread(pitch=2.309, turns=3, dminor=30.291, higbee_arc=45, fn=120)
module BSPP_external_thread(pitch=2.309, turns=3, dpitch=31.68, higbee_arc=45, fn=120)
{
t = pitch / (2 * tan(phi/2));
rgroove = dminor / 2 - t / 6;
rcrest = rgroove + t;
section_profile = [[0, -pitch / 2], [0, pitch / 2], [+t, 0]];
rmajor = rcrest - t / 6;
intersection() {
rpitchp = dpitch / 2;
P = pitch;
rcrest = rpitchp + 0.21706 * P;
rvalley = rpitchp - 0.42021 * P;
zvalley = 0.03125 * P;
zcrest = 0.13701 * P;
section_profile = [[0, -P / 2 + zvalley], [0, +P / 2 - zvalley],
[rcrest - rvalley, +zcrest],
[rcrest - rvalley, -zcrest]];
straight_thread(
section_profile=section_profile,
higbee_arc=higbee_arc,
r=rvalley,
turns=turns,
pitch=pitch,
fn=fn);
}
module BSPP_internal_thread(pitch=2.309, turns=3, dpitch=31.86, higbee_arc=45, fn=120)
{
rpitchp = dpitch / 2;
P = pitch;
rcrest = rpitchp - 0.19813 * P;
rvalley = rpitchp + 0.42021 * P;
zvalley = 0.03125 * P;
zcrest = 0.13701 * P;
section_profile = [[0, P / 2 - zvalley], [0, -P / 2 + zvalley],
[rcrest - rvalley, -zcrest], [rcrest - rvalley, +zcrest]];
rotate(180) // rotate by half a turn to fit external thread
straight_thread(
section_profile=section_profile,
higbee_arc=higbee_arc,
r=rgroove,
r=rvalley,
turns=turns,
pitch=pitch,
fn=fn);
cylinder(h=turns * pitch, r=rmajor, $fn=fn);
};
}
module BSPP_internal_thread(pitch=2.309, turns=3, dmajor=33.249, higbee_arc=45, fn=120)
{
t = pitch / (2 * tan(phi/2));
rgroove = dmajor / 2 + t / 6;
rcrest = rgroove - t;
section_profile = [[0, +pitch / 2], [0, -pitch / 2], [-t, 0]];
rminor = rcrest + t / 6;
difference() {
rotate(180) // rotate by half a turn to fit external thread
straight_thread(
section_profile=section_profile,
higbee_arc=higbee_arc,
r=rgroove,
turns=turns,
pitch=pitch,
fn=fn);
cylinder(h=turns * pitch, r=rminor, $fn=fn);
};
}
// testing:
@ -78,9 +84,17 @@ intersection() {
translate([-50, 0, -50])
cube(100, 100, 100);
union() {
BSPP_external_thread(pitch=2.309, turns=3, dminor=30.291,
higbee_arc=45, fn=120);
BSPP_internal_thread(pitch=2.309, turns=3, dmajor=33.249,
higbee_arc=45, fn=120);
BSPP_external_thread(pitch=2.309, turns=3, dpitch=31.68,
higbee_arc=20, fn=120);
translate([0, 0, -1.2])
cylinder(h=9, r=31.68/2 - 0.40020 * 2.309);
BSPP_internal_thread(pitch=2.309, turns=3, dpitch=31.86,
higbee_arc=20, fn=120);
translate([0, 0, -0.9])
difference() {
cylinder(h=9, r=20, $fn=120);
translate([0, 0, -0.1])
cylinder(h=10, r=31.86/2 + 0.40020 * 2.309, $fn=120);
};
};
};