It is easiest to print bolts vertically standing on their heads but
tensile strength is then maximally impacted by layer adhesion.  Printing at
a significant angle from vertical can achieve much better tensile strength
but requires support or cutting the bolt to create a flat surface to lay on
the print bed to print horizontally.  There are many cases where cutting
the bolt is not a good option and for those cases I've found it fussy to
generate support in a slicer that contacts the bolt precisely as I want to
allow for clean easy support removal.

Here's an OpenSCAD script for creating bolts to be printed at an angle
with integrated support that I've found helpful for rapidly knocking out a
variety of fasteners with good tensile strength that take trivial clean up
effort to be ready for use.  It uses BOSL2/screws.scad to create bolts.
It's quite basic with little polish and can require tweaking of a few
parameters to get best results but still I've found it very useful and
think others might too.  The technique I used to generate the support could
readily be adapted to a wide range of other objects.

If anyone knows of better approaches to printing bolts or generating
support I would love to hear about it.

include <BOSL2/std.scad>
include <BOSL2/screws.scad>

$fn= $preview ? 12 : 256;
eps = 0.001;

// set trimscale sufficiently large to shave enough of the threads to
eliminate or minimize producing isolated blobs when sliced that don't print
well
// set ulength=0 for no chamfer to threaded shaft
// use x0_fudge to adjust where print_bolt() support starts on x axis
// use z_fudge to adjust z height of print_bolt()
module setenv_bolt(name, head="hex", drive="none",
ulength=undef, nut_threads=2.5, nut_diameter=0,
tolerance="6g", trimscale=1.0, slop=0.06,
zrot, x0_fudge=0, z_fudge=0,
support_thickness, support_gap = 0.15, support_ears_d, support_ears_z
= 0.2)
{
spec = screw_info(name);
$name = name;
$head = head;
$drive = drive;
$p = struct_val(spec, "pitch");
$l = struct_val(spec, "length");
$d = struct_val(spec, "diameter");
$nh = $pnut_threads+1.5;
$nd = nut_diameter ? nut_diameter : $d1.2+4.0;

 $nut_spec = struct_set(spec, [
     "length", $nh+2*eps,
     "thread_len", $nh+2*eps
     ]);

 $tolerance = tolerance;
 $trimscale = trimscale;
 $ul = is_undef(ulength) ? $p*0.5 : ulength; // should also add in

amount tolerance spec undersizes threaded minor radius
$tl = $l - $ul;
$bolt_spec = struct_set(screw_info(name, head=head, drive=drive), [
"thread_len", $tl
]);
echo($bolt_spec = $bolt_spec);

 $hs = struct_val($bolt_spec, "head_size", $d);
 $hh = struct_val($bolt_spec, "head_height", 0);

 $slop = slop;   // $slop is parameter of BOSL2 screw_hole()

 // align hex head to rest on a flat when rotated about Y axis for

printing as headsize is across flats
// may want default angles for drive types too
auto_zrot = ($head=="hex") ? 90 : 60;
$bolt_zrot = is_undef(zrot) ? auto_zrot : zrot;

 $x0_fudge = x0_fudge;
 $z_fudge = z_fudge;
 $support_thickness = is_undef(support_thickness) ? 0.9+0.1*$d:

support_thickness;
$support_gap = support_gap;
$support_ears_d = is_undef(support_ears_d) ? 3+$d : support_ears_d;
$support_ears_z = support_ears_z;

 children();

}

module bolt() {
zrot($bolt_zrot) screw(spec=$bolt_spec, tolerance=$tolerance,
orient=DOWN, anchor=TOP);
}

module shank_chamfer_mask(od, c) {
difference() {
zcyl(h=c, d=od+10eps, anchor=TOP);
up(eps) zcyl(h=c+2eps, d=od-2*c, chamfer1=-c, anchor=TOP);
}
}

// bolt tweaked for printing with threads trimmed and end of unthreaded
shank chamfered
module printable_bolt(angle=0, z_shift=0) {
up(z_shift) yrot(angle) intersection() {
if ($ul>0) difference() {
bolt();
up($hh+$l-$tl+eps) shank_chamfer_mask($d, $p0.5);
}
else bolt();
union() {
// head
zcyl(l=$hh+$l-$tl, d=$hs+3, anchor=BOT);
// trimmed shaft
up($hh+$l-$tl-eps)
cuboid([$d-$p$trimscale,$d,$tl+eps],anchor=BOT);
}
}
}

module print_bolt(angle=60) {
bolt_length = $hh + $l;
support_x0 = $x0_fudge + cos(angle) * $hh;
support_x1 = sin(angle) * bolt_length + cos(angle)$d0.50.40;
support_z = cos(angle) * bolt_length - sin(angle)$d0.4;
z_shift = (angle<=90) ? $z_fudge+sin(angle)$hs0.5 :
$z_fudge+max(sin(angle)$hs0.5, sin(angle)$hs0.5-cos(angle$hh),
-cos(angle)bolt_length+sin(angle)$d0.4);
matrix_from_projection = frame_map(x=RIGHT, y=UP);
matrix_to_projection = matrix_inverse(matrix_from_projection);
union() {
// support for the bolt
multmatrix(matrix_from_projection) linear_extrude(height =
$support_thickness, center=true)
difference() {
polygon([[support_x0,0], [support_x1,0],
[support_x1,support_z+z_shift], [support_x0,z_shift]]);
offset(r=$support_gap) projection(cut=true)
multmatrix(matrix_to_projection) printable_bolt(angle, z_shift);
}
// mouse ears for the support
for(x=[$support_ears_d0.5,support_x1-$support_ears_d*0.5+0.25])
right(x) zcyl(h=$support_ears_z, d=$support_ears_d, anchor=BOT);
// the bolt
printable_bolt(angle, z_shift);
}
}

module nut() {
difference() {
zcyl(h=$nh, d=$nd, chamfer=$nh0.075, $fn=6, circum=true,
anchor=BOTTOM);
down (eps) screw_hole($nut_spec, thread=true, counterbore=false,
bevel=true, anchor=BOTTOM); // , l=$nh+2eps
}
}

// use trimscale=0.0 in setenv_bolt() for untrimmed thread
module inspect_bolt() {
linear_extrude(height = 1)
projection(cut=true) xrot(-90) {
printable_bolt();
up($hh + $l - $nh) nut();
}
}

// EXAMPLES
/*
setenv_bolt("M5,6", "hex", trimscale=0.9)
print_bolt();

setenv_bolt("M4x0.8,8", head="button", drive="hex", ulength=0,
trimscale=1.05, z_fudge=-0.75, x0_fudge=0.5)
print_bolt(angle=53.4);

setenv_bolt("M5,6", "hex", trimscale=0.9)
nut();
//  inspect_bolt();
//  printable_bolt();
*/

OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org

It is easiest to print bolts vertically standing on their heads but
tensile strength is then maximally impacted by layer adhesion.  Printing
at a significant angle from vertical can achieve much better tensile
strength but requires support or cutting the bolt to create a flat
surface to lay on the print bed to print horizontally.  There are many
cases where cutting the bolt is not a good option and for those cases
I've found it fussy to generate support in a slicer that contacts the
bolt precisely as I want to allow for clean easy support removal.

Here's an OpenSCAD script for creating bolts to be printed at an angle
with integrated support that I've found helpful for rapidly knocking out
a variety of fasteners with good tensile strength that take trivial
clean up effort to be ready for use.  It uses BOSL2/screws.scad to
create bolts.  It's quite basic with little polish and can require
tweaking of a few parameters to get best results but still I've found it
very useful and think others might too.  The technique I used to
generate the support could readily be adapted to a wide range of other
objects.

If anyone knows of better approaches to printing bolts or generating
support I would love to hear about it.

include <BOSL2/std.scad>
include <BOSL2/screws.scad>

$fn= $preview ? 12 : 256;
eps = 0.001;

// set trimscale sufficiently large to shave enough of the threads to
eliminate or minimize producing isolated blobs when sliced that don't
print well
// set ulength=0 for no chamfer to threaded shaft
// use x0_fudge to adjust where print_bolt() support starts on x axis
// use z_fudge to adjust z height of print_bolt()
module setenv_bolt(name, head="hex", drive="none",
    ulength=undef, nut_threads=2.5, nut_diameter=0,
    tolerance="6g", trimscale=1.0, slop=0.06,
    zrot, x0_fudge=0, z_fudge=0,
    support_thickness, support_gap = 0.15, support_ears_d,
support_ears_z = 0.2)
{
    spec = screw_info(name);
    $name = name;
    $head = head;
    $drive = drive;
    $p = struct_val(spec, "pitch");
    $l = struct_val(spec, "length");
    $d = struct_val(spec, "diameter");
    $nh = $pnut_threads+1.5;
    $nd = nut_diameter ? nut_diameter : $d1.2+4.0;

    $nut_spec = struct_set(spec, [
        "length", $nh+2eps,
        "thread_len", $nh+2eps
        ]);

    $tolerance = tolerance;
    $trimscale = trimscale;
    $ul = is_undef(ulength) ? $p*0.5 : ulength; // should also add in
amount tolerance spec undersizes threaded minor radius
    $tl = $l - $ul;
    $bolt_spec = struct_set(screw_info(name, head=head, drive=drive), [
        "thread_len", $tl
        ]);
    echo($bolt_spec = $bolt_spec);

    $hs = struct_val($bolt_spec, "head_size", $d);
    $hh = struct_val($bolt_spec, "head_height", 0);

    $slop = slop;   // $slop is parameter of BOSL2 screw_hole()

    // align hex head to rest on a flat when rotated about Y axis for
printing as headsize is across flats
    // may want default angles for drive types too
    auto_zrot = ($head=="hex") ? 90 : 60;
    $bolt_zrot = is_undef(zrot) ? auto_zrot : zrot;

    $x0_fudge = x0_fudge;
    $z_fudge = z_fudge;
    $support_thickness = is_undef(support_thickness) ? 0.9+0.1*$d:
support_thickness;
    $support_gap = support_gap;
    $support_ears_d = is_undef(support_ears_d) ? 3+$d : support_ears_d;
    $support_ears_z = support_ears_z;

    children();
}

module bolt() {
    zrot($bolt_zrot) screw(spec=$bolt_spec, tolerance=$tolerance,
orient=DOWN, anchor=TOP);
}

module shank_chamfer_mask(od, c) {
    difference() {
        zcyl(h=c, d=od+10eps, anchor=TOP);
        up(eps) zcyl(h=c+2eps, d=od-2*c, chamfer1=-c, anchor=TOP);
        }
}

// bolt tweaked for printing with threads trimmed and end of unthreaded
shank chamfered
module printable_bolt(angle=0, z_shift=0) {
    up(z_shift) yrot(angle) intersection() {
        if ($ul>0) difference() {
            bolt();
            up($hh+$l-$tl+eps) shank_chamfer_mask($d, $p0.5);
            }
        else bolt();
        union() {
            // head
            zcyl(l=$hh+$l-$tl, d=$hs+3, anchor=BOT);
            // trimmed shaft
            up($hh+$l-$tl-eps)
cuboid([$d-$p$trimscale,$d,$tl+eps],anchor=BOT);
            }
        }
}

module print_bolt(angle=60) {
    bolt_length = $hh + $l;
    support_x0 = $x0_fudge + cos(angle) * $hh;
    support_x1 = sin(angle) * bolt_length + cos(angle)$d0.50.40;
    support_z = cos(angle) * bolt_length - sin(angle)$d0.4;
    z_shift = (angle<=90) ? $z_fudge+sin(angle)$hs0.5 :
$z_fudge+max(sin(angle)$hs0.5, sin(angle)$hs0.5-cos(angle$hh),
-cos(angle)bolt_length+sin(angle)$d*0.4);
    matrix_from_projection = frame_map(x=RIGHT, y=UP);
    matrix_to_projection = matrix_inverse(matrix_from_projection);
    union() {
        // support for the bolt
        multmatrix(matrix_from_projection) linear_extrude(height =
$support_thickness, center=true)
        difference() {
            polygon([[support_x0,0], [support_x1,0],
[support_x1,support_z+z_shift], [support_x0,z_shift]]);
            offset(r=$support_gap) projection(cut=true)
multmatrix(matrix_to_projection) printable_bolt(angle, z_shift);
            }
        // mouse ears for the support

for(x=[$support_ears_d0.5,support_x1-$support_ears_d0.5+0.25])
right(x) zcyl(h=$support_ears_z, d=$support_ears_d, anchor=BOT);
        // the bolt
        printable_bolt(angle, z_shift);
        }
}

module nut() {
    difference() {
        zcyl(h=$nh, d=$nd, chamfer=$nh0.075, $fn=6, circum=true,
anchor=BOTTOM);
        down (eps) screw_hole($nut_spec, thread=true,
counterbore=false, bevel=true, anchor=BOTTOM); // , l=$nh+2eps
    }
}

// use trimscale=0.0 in setenv_bolt() for untrimmed thread
module inspect_bolt() {
    linear_extrude(height = 1)
    projection(cut=true) xrot(-90) {
        printable_bolt();
        up($hh + $l - $nh) nut();
        }
}

// EXAMPLES
/*
setenv_bolt("M5,6", "hex", trimscale=0.9)
    print_bolt();

setenv_bolt("M4x0.8,8", head="button", drive="hex", ulength=0,
trimscale=1.05, z_fudge=-0.75, x0_fudge=0.5)
    print_bolt(angle=53.4);

setenv_bolt("M5,6", "hex", trimscale=0.9)
    nut();
//  inspect_bolt();
//  printable_bolt();
*/

OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org

It is easiest to print bolts vertically standing on their heads but tensile
strength is then maximally impacted by layer adhesion.

Todd Allen via Discuss wrote:

It is easiest to print bolts vertically standing on their heads but tensile
strength is then maximally impacted by layer adhesion.

After printing many bolts I have come to the conclusion that I safe more time buying them than printing them.
Those are standard components, you can have them in any head-shape, thread-size, and color.
If I print a bolt

• I have to use a thread cutting tool to free the print object of slicer artifacts and oozing
• I am at risk that the bolt layers will separate in operation (it breaks or peals apart)
• it takes a lot more time than reaching for my toolbox of bolts

I have personally settled to own a collection of many differnt lengths of M3-bolts [1], soldering in thread [2], default and safety (plastic ring inlay) nuts [3] and screw glue [4].

It is way easier than printing 10 bolts and then figuring out while 3 of them cannot be fastened with a nut.

My OpenSCAD-preview contains bolts. I need to be sure bolts do not overlap and I can access their head with a tool for fasting. But I have come to the personal conclusion that I should stop printing bolts.

Just my two cents,
Marcus

[1] https://www.hornbach.de/p/linsenkopfschraube-m-kreuzschlitz-din-7985-m3x12-mm-edelstahl-a2-100-stueck/6836149/
I even own m3x45 for 3d printed toys with long axles
[2] https://www.amazon.de/ruthex-Gewindeeinsatz-St%C3%BCck-Gewindebuchsen-Kunststoffteile/dp/B08BCRZZS3?ref_=ast_sto_dp&th=1
[3] https://www.hornbach.de/p/sechskant-sicherungsmutter-selbstsichernd-reyher-din-985-m3-galv-verzinkt-100-stueck/10316758/
[4] https://www.hornbach.de/p/loctite-schraubensicherung-243-mittelfest-normal-5-ml/7663487/
Anything that has to sustain vibrations, like childrens toys, needs to be either secured or glued.

OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org

But I have come to the personal conclusion that I should stop printing