UnfyOpenSCADLib

LibFile: unfy_fasteners.scad

UnfyOpenSCADLib Copyright Leif Burrow 2026 kc8rwr@unfy.us unforgettability.net

This file is part of UnfyOpenSCADLib.

Unfy_fasteners.scad contains modules for creating bolts, screws, nuts, washers, heatsink inserts and more. These models at the time do not include threads. Their purpose is for subtracting from a model to create holes and countersinks. Realistic models with threads could be added later if there is a use for them.

Fasteners may be generated to size by passing the size as a string. Metric sizes may be passed as “M<number>” such as “M4” or “M3”. It is case insensitie so “m4” or “m3” will work as well. Numbered SAE sizes are represented as “#<number>”, such as “#6” or “#8”. Inch sizes are represented as a decimal number or as a fraction. “1/4” or “0.25” would both represent 1/4”.

Tables are included for looking up dimensions based on these sizes. Shaft diameter of course is the size itself in it’s respective units. Tables also include things like typical diameters and thicknesses of heads for various bolt types, nut, washer and heatset insert dimensions, etc… Most sizes commonly used in 3d-printed projects as well as larger fasteners commonly available in hardware stores are included. If sizes that are outside of the built in tables are requested then the code will attempt to interpolate the missing value.

Functions are included to look up the various dimensions of fasteners by size and type. This way one using this library may allow the end user to choose fastener sizes from the customizer menu. Then the script may adapt, re-sizing or re-positioning things based on the outer dimensions of the requested fastener sizes. Sizes may be looked up as scalars describing just one dimension. Or they may be looked up as a vector which may then be passed to the functions that look up the individual dimensions or the module which renders the part. This way the lookup and/or interpolation need only happen once.

The goal here is to allow the user to create customizable designs where the end user may choose parts that they already have on hand or parts that are easily available. Designers are encouraged to give the end-user plenty of choices. Perfectly valid arguments regarding the merits of measurement systems aside, the best fastener size is the one you already have on hand. The next best is the one your local hardware store sells in bulk rather than the specialty isle.

Provisions are included for distorting horizontal bolt holes, to remove some extra material from the top side. This way when printing via fused filament fabrication plastic which sags down will just cancel this distortion out rather than requiring drilling so the bolt can fit cleanly. The distortion is defined by two special variables, $unf-hdist_y and $unf_hdist_x. These define the extra removed material by height and width respectively, both as a percentage of the shaft diameter.

So far this feature has been developed only for bolt holes and not the other parts. The original intention was to distort every part depending on the angle at which it is rendered. Unfortunately there is no good way to know what angle a part is being rendered in OpenSCAD so it relies on the user telling it. Thus this feature has not been furtner developed.

File Contents

  1. Section: Distorted Shafts
  2. Section: Cap Bolts - unf_cap_*
  3. Section: Countersunk Bolts - unf_csk_*
  4. Section: Hex Head Bolts - unf_hex_*
  5. Section: Heatset Inserts - unf_hst_*
  6. Section: Hex Nut - unf_nut_*
  7. Section: Square Nut - unf_sqr_*
  8. Section: Washer unf_wsh_*
  9. Section: Pillar
  10. Section: Licensing

Function: unf_fnr_type

Synopsis: Fastener Type

Usage:

Description:

Takes a vector describing a fastener and returns a string representing the fastener type.

Arguments:

By Position What it does
in vector describing an unfy_fastener

Function: unf_fnr_size

Synopsis: Fastener Size

Usage:

Description:

Takes a vector describing a fastener or a string representing the fastener size and returns a string representing the fastener size.

Of course this isnt’t doing much when it is passed the string. This is done so that a variable may hold the size string which the user requested before it is expanded into the vector and still work in the same code.

Arguments:

By Position What it does
in vector describing an unfy_fastener or a string representing the size of one.

Function: unf_fnr_diameter

Synopsis: Fastener Clearance Diameter

Usage:

Description:

Takes a vector describing a fastener or a string representing the fastener size and returns the diameter of the widest part in millimeters. Useful for calculating positioning or sizes of parts that will contain the fastener when the end-user is allowed to pick from a variety of sizes of fasteners.

Arguments:

By Position What it does
in vector describing an unfy_fastener or a string representing the size of one.

Function: unf_fnr_shaft_diameter

Synopsis: Fastener Shaft Diameter

Usage:

Description:

Takes a vector describing a fastener or a string representing the fastener size and returns the shaft diameter in millimeters.

Arguments:

By Position What it does
in vector describing an unfy_fastener or a string representing the size of one.

Section: Distorted Shafts

Module: unf_shaft

Synopsis: Fastener Shaft

Usage:

Description:

Render a fastener shaft hole, optionally with distortions to account for overhang sagging when 3d-printing.

Figure 2.1.1: various values of unf_hdist_x and unf_hdist_y. (0, 0) or distorted=false would be a perfect circle.

unf\_shaft Figure 2.1.1


Arguments:

By Position What it does
diameter shaft diameter in mm
length length in mm
distorted true/false should this be distorted
body_color color in which to render the shaft if rendered as a positive, color of the cut surfaces if rendering as a negative.
By Name What it does
$unf_hdist_x width of distortion as a percentage of the diameter (0-100)
$unf_hdist_y height of distortion as a percentage of the diameter (0-100)

Module: distortion_test_block

Synopsis: Shaft Distortion Test Block

Usage:

Description:

Render a block with a series of distorted bolt shafts with varying values of unf_hdist_x and unf_hdist_y for choosing the best values to use with a particular setup.

Figure 2.2.1:

distortion\_test\_block Figure 2.2.1


Arguments:

By Position What it does
diameter shaft diameter
depth thickness of the block
steps number of rows, columns
min_spacing minimum spacing between holes
min_dist_x minimum unf_hdist_x to try
max_dist_x maximum unf_hdist_x to try
min_dist_y minimum unf_hdist_y to try
max_dist_y maximum unf_hdist_y to try
body_color color of the block
subtraction_color color of the surfaces cut into the block by the test holes

Section: Cap Bolts - unf_cap_*

The vector representing a cap bolt will consist of, in order:

Function: unf_cap_v

Synopsis: Cap Head Bolt Vector

Usage:

Description:

Retrieve a vector representing the dimensions of a cap-head bolt given the size. Will return the passed parameter if passed a vector. Thus sizes and dimension vectors may be treated interchangably.

Arguments:

By Position What it does
size size as a string or the vector itself

Function: unf_cap_head_diameter

Synopsis: Cap Head Bolt Clearance Diameter

Usage:

Description:

Retrieve the diameter in mm of the head of a cap-head bolt given the size.

Arguments:

By Position What it does
size size as a string or the unf_cap_v() vector itself

Function: unf_cap_head_height

Synopsis: Cap Head Bolt Head Height

Usage:

Description:

Retrieve the height or thickness in mm of the head of a cap-head bolt given the size.

Arguments:

By Position What it does
size size as a string or the unf_cap_v() vector itself

Function: unf_cap_default_length

Synopsis: Cap Head Bolt Default Length

Usage:

Description:

Retrieve a default length for a cap head bolt given it’s size. Probably not very useful in a real design, good for picking a length to demonstrate an example of a unf_cap bolt.

Arguments:

By Position What it does
size size as a string or the unf_cap_v() vector itself

Module: unf_cap

Synopsis: Cap Head Bolt

Usage:

Description:

Render a negative for a shaft and/or head-recess for a cap-head bolt. Note, the cap head is rendered as a simple cylinder with the diameter of the widest part of the actual head. This is because it is meant for being a negative, to recess a bolt and not for printing an actual bolt.

Figure 3.5.1: note - the head_ext area is semi-transparent.

unf\_cap Figure 3.5.1


Arguments:

By Position What it does
size string representing the size or the unf_cap_v() vector.
length length in mm
head_ext length in mm to recess the head beyond just it’s thickness
distorted true/false, should the bolt hole be distorted
body_color color in which to render the bolt if rendered as a positive, color of the cut surfaces if rendering as a negative.
By Name What it does
$unf_hdist_x width of distortion as a percentage of the diameter (0-100)
$unf_hdist_y height of distortion as a percentage of the diameter (0-100)

Section: Countersunk Bolts - unf_csk_*

The vector representing a countersunk bolt will consist of, in order:

Function: unf_csk_v

Synopsis: Counter Sunk Bolt Vector

Usage:

Description:

Retrieve a vector representing the dimensions of a countersunk bolt given the size. Will return the passed parameter if passed a vector. Thus sizes and dimension vectors may be treated interchangably.

Arguments:

By Position What it does
size size as a string or the vector itself

Function: unf_csk_head_diameter

Synopsis: Countersunk Head Clearance Diameter

Usage:

Description:

Retrieve the diameter in mm of the head of a countersunk bolt given the size.

Arguments:

By Position What it does
size size as a string or the unf_csk_v() vector itself

Function: unf_csk_head_height

Synopsis: Countersunk Head Height

Usage:

Description:

Retrieve the height or thickness in mm of the head of a countersunk bolt given the size.

Arguments:

By Position What it does
size size as a string or the unf_cap_v() vector itself

Function: unf_csk_default_length

Synopsis: Countersunk Bolt Default Length

Usage:

Description:

Retrieve a default length for a countersunk bolt given it’s size. Probably not very useful in a real design, good for picking a length to demonstrate an example of a unf_csk bolt.

Arguments:

By Position What it does
size size as a string or the unf_cap_v() vector itself

Module: unf_csk

Synopsis: Countersunk Bolt

Usage:

Description:

Render a negative for a shaft and/or head-recess for a cap-head bolt. Note, the cap head is rendered as a simple cylinder with the diameter of the widest part of the actual head. This is because it is meant for being a negative, to recess a bolt and not for printing an actual bolt.

Figure 4.5.1: note - the head_ext area is semi-transparent.

unf\_csk Figure 4.5.1



Arguments:

By Position What it does
size string representing the size or the unf_cap_v() vector.
length length in mm
head_ext length in mm to recess the head beyond just it’s thickness
distorted true/false, should the bolt hole be distorted
body_color color in which to render the bolt if rendered as a positive, color of the cut surfaces if rendering as a negative.
By Name What it does
$unf_hdist_x width of distortion as a percentage of the diameter (0-100)
$unf_hdist_y height of distortion as a percentage of the diameter (0-100)

Section: Hex Head Bolts - unf_hex_*

The vector representing a hex head bolt will consist of, in order:

Function: unf_hex_v

Synopsis: Hex Head Bolt Vector

Usage:

Description:

Retrieve a vector representing the dimensions of a hex-head bolt given the size. Will return the passed parameter if passed a vector. Thus sizes and dimension vectors may be treated interchangably.

Arguments:

By Position What it does
size size as a string or the vector itself

Function: unf_hex_head_diameter

Synopsis: Hex Head Bolt Clearance Diameter

Usage:

Description:

Retrieve the diameter in mm of the head of a hex-head bolt given the size.

Arguments:

By Position What it does
size size as a string or the unf_hex_v() vector itself

Function: unf_hex_head_height

Synopsis: Hex Head Height

Usage:

Description:

Retrieve the height or thickness in mm of the head of a hex-head bolt given the size.

Arguments:

By Position What it does
size size as a string or the unf_hex_v() vector itself

Function: unf_hex_default_length

Synopsis: Hex Head Bolt Default Length

Usage:

Description:

Retrieve a default length for a hex head bolt given it’s size. Probably not very useful in a real design, good for picking a length to demonstrate an example of a unf_hrx bolt.

Arguments:

By Position What it does
size size as a string or the unf_hex_v() vector itself

Module: unf_hex

Synopsis: Hex Head Bolt

Usage:

Description:

Render a negative for a shaft and/or head-recess for a hex-head bolt.

Figure 5.5.1: note - the head_ext area is semi-transparent.

unf\_hex Figure 5.5.1



Arguments:

By Position What it does
size string representing the size or the unf_hex_v() vector.
length length in mm
head_ext length in mm to recess the head beyond just it’s thickness
distorted true/false, should the bolt hole be distorted
body_color color in which to render the bolt if rendered as a positive, color of the cut surfaces if rendering as a negative.
By Name What it does
$unf_hdist_x width of distortion as a percentage of the diameter (0-100)
$unf_hdist_y height of distortion as a percentage of the diameter (0-100)

Section: Heatset Inserts - unf_hst_*

The vector representing a heatset insert will contain, in order:

note - these are pilot hole dimensions, not dimensions of the actual insert

Function: unf_hst_v

Synopsis: Heatset Insert Vector

Usage:

Description:

Retrieve a vector representing the dimensions of a heatset insert given the size. Will return the passed parameter if passed a vector. Thus sizes and dimension vectors may be treated interchangably.

Arguments:

By Position What it does
size size as a string or the vector itself

Function: unf_hst_diameter

Synopsis: Heatset Insert Diameter

Usage:

Description:

Retrieve the diameter in mm of the hole for a heatset insert given the size.

Arguments:

By Position What it does
size size as a string or the unf_hst_v() vector itself

Function: unf_hst_height

Synopsis: Heatset Insert Height

Usage:

Description:

Retrieve the length in mm of the hole for a heatset insert given the size.

Arguments:

By Position What it does
size size as a string or the unf_hst_v() vector itself

Module: unf_hst

Synopsis: Heatset Insert

Usage:

Description:

Render a negative for a heatset-insert hole.

Figure 6.4.1: note - the head_ext, extra_room and bolt shaft areas are semi-transparent.

unf\_hst Figure 6.4.1


Arguments:

By Position What it does
size string representing the size or the unf_cap_v() vector.
opening_taper_percent enlarge the opening with a taper for ease of insertion.
length Heatset inserts for the same bolt size do come in a variety of lenghts. Fortunately, because when using them one is melting into the plastic it is not necessary to be 100% accurate. For this field use one of small, medium or large to get holes for smaller to larger heatset inserts respectively.
head_ext length in mm to recess the head beyond just it’s thickness
extra_room Continue the hole, at the inserts outer dimension a bit farther into the part. This creates a space for molten plastic to flow to when inserting the insert.
bolt_hole_depth Extend the hole at the width of the bolt, not the width of the insert beyond the insert to make room for the bolt to pass through the insert and deeper into the hole.
body_color color in which to render the insert if rendered as a positive, color of the cut surfaces if rendering as a negative.

Section: Hex Nut - unf_nut_*

The vector representing a hex nut will contain, in order:

Function: unf_nut_v

Synopsis: hex-nut vector

Usage:

Description:

Retrieve a vector representing the dimensions of a hex-nut bolt given the size. Will return the passed parameter if passed a vector. Thus sizes and dimension vectors may be treated interchangably.

Arguments:

By Position What it does
size size as a string or the vector itself

Function: unf_nut_diameter

Synopsis: Hex Nut Clearance Diameter

Usage:

Description:

Takes a fastener size or a hex nut vector and returns the clearance diameter

Function: unf_nut_height

Synopsis: Hex Nut Height

Usage:

Description:

Retrieve the height (thickness) of a typical hex nut given the bolt size.

Arguments:

By Position What it does
size size as a string or the unf_nut_v() vector itself

Module: unf_nut

Synopsis: Hex Nut

Usage:

Description:

Render a negative for a hex nut hole.

Figure 7.4.1: note - the ext area is semi-transparent.

unf\_nut Figure 7.4.1



Arguments:

By Position What it does
size string representing the size or the unf_nut_v() vector.
ext length in mm to recess the nut beyond just it’s thickness
body_color color in which to render the nut if rendered as a positive, color of the cut surfaces if rendering as a negative.

Section: Square Nut - unf_sqr_*

The vector representing a square nut shall contain, in order:

Function: unf_sqr_v

Synopsis: Square Nut Vector

Usage:

Description:

Retrieve a vector representing the dimensions of a square nut given the size. Will return the passed parameter if passed a vector. Thus sizes and dimension vectors may be treated interchangably.

Arguments:

By Position What it does
size size as a string or the vector itself

Function: unf_sqr_length

Synopsis: Square Nut Side Length

Usage:

Description:

Retrieve the length of a side of a square nut.

Arguments:

By Position What it does
size size as a string or the unf_cap_v() vector itself

Function: unf_sqr_height

Synopsis: Square Nut Height / Thickness

Usage:

Description:

Retrieve the thickness of a square nut, it’s height when lying flat.

Arguments:

By Position What it does
size size as a string or the unf_cap_v() vector itself

Module: unf_sqr

Synopsis: Square Nut

Usage:

Description:

Render a negative for a square shaped nut

Figure 8.4.1: note - the ext area is semi-transparent.

unf\_sqr Figure 8.4.1



Arguments:

By Position What it does
size string representing the size or the unf_sqr_v() vector.
length length in mm
ext Extra height added to the negative for recessing the nut.
body_color color in which to render the nut if rendered as a positive, color of the cut surfaces if rendering as a negative.

Section: Washer unf_wsh_*

The vector representing a washer will consist of, in order:

Function: unf_wsh_v

Synopsis: Washer Vector

Usage:

Description:

Retrieve a vector representing the dimensions of a washer given the size. Will return the passed parameter if passed a vector. Thus sizes and dimension vectors may be treated interchangably.

Arguments:

By Position What it does
size size as a string or the vector itself

Function: unf_wsh_head_diameter

Synopsis: Washer Clearance Diameter

Usage:

Description:

Retrieve the outer diameter in mm of a washer given the bolt size.

Arguments:

By Position What it does
size size as a string or the unf_wsh_v() vector itself

Function: unf_wsh_head_height

Synopsis: Washer Thickness (height lying flat)

Usage:

Description:

Retrieve the height or thickness in mm of a washer given the bolt size.

Arguments:

By Position What it does
size size as a string or the unf_wsh_v() vector itself

Module: unf_wsh

Synopsis: Washer

Usage:

Description:

Render a negative for a washer. Does not include a bolt hole since it is only meant to be a negative for recessing a vitamin, not an actual printed washer.

Figure 9.4.1: note - the head_ext area is semi-transparent.

unf\_wsh Figure 9.4.1



Arguments:

By Position What it does
size string representing the size or the unf_cap_v() vector.
ext length in mm to recess the washer beyond just it’s thickness
body_color color in which to render the washer if rendered as a positive, color of the cut surfaces if rendering as a negative.

Section: Pillar

Module: unf_pillar_pos

Synopsis: Render the positive part of a fastener pillar

Usage:

Description:

Stil under Construction Calculates the diameter needed for a support piller that will contain a heatset insert or a nut. Then render the positive part of the pillar.

Figure 10.1.1:

unf\_pillar\_pos Figure 10.1.1


Arguments:

By Position What it does
fastener A string representing the type of fastener that will be contained within the pillar. One of “heatset” or “hexnut”. Future support will be added for “squarenut”.
bolt A string representing the bolt size.
heatset_length One of “short, “medium” or “long” used only with a heatset insert.
length length in mm of the pillar
slope slope in degrees leading from bottom to top of the pillar. note - future version will use a bezier curve, likely replacing this argument.
wall Minimum material thickness between heatset or nut insert and the outside of the pillar.
body_color color in which to render the pillar.

Module: unf_pillar_neg

Synopsis: Render the negative part of a fastener pillar

Usage:

Description:

Stil under Construction Render that which should be subtracted from a pillar so that fasteners may be added.

Figure 10.2.1: Heatset Insert

unf\_pillar\_neg Figure 10.2.1


Figure 10.2.2: Hexnut

unf\_pillar\_neg Figure 10.2.2


Arguments:

By Position What it does
fastener A string representing the type of fastener that will be contained within the pillar. One of “heatset” or “hexnut”. Future support will be added for “squarenut”.
bolt A string representing the bolt size.
length length in mm of the pillar
heatset_length One of “short, “medium” or “long” used only with a heatset insert.
wall Minimum material thickness between heatset or nut insert and the outside of the pillar.
ext length in mm to recess the fastener beyond just it’s length
body_color color in which to render if rendered as a positive, color of the cut surfaces if rendering as a negative.

Module: unf_pillar

Synopsis: Render a fastener pillar

Usage:

Description:

Stil under Construction Render a pillar which will contain a heatset insert or nut and a bolt hole.

Figure 10.3.1: Heatset Insert

unf\_pillar Figure 10.3.1


Figure 10.3.2: Hexnut

unf\_pillar Figure 10.3.2


Arguments:

By Position What it does
fastener A string representing the type of fastener that will be contained within the pillar. One of “heatset” or “hexnut”. Future support will be added for “squarenut”.
heatset_length One of “short, “medium” or “long” used only with a heatset insert.
bolt A string representing the bolt size.
length length in mm of the pillar
slope slope in degrees leading from bottom to top of the pillar. note - future version will use a bezier curve, likely replacing this argument.
wall Minimum material thickness between heatset or nut insert and the outside of the pillar.
body_color color in which to render the pillar
subtraction_color color in which to render the cut surfaces of the pillar.

Section: Licensing

UnfyOpenSCADLib is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

UnfyOpenSCADLib is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with UnfyOpenSCADLib. If not, see https://www.gnu.org/licenses/.

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