About:

Shiv is a multithreaded G-code generator for 3D printers.

Building:

Dependencies:

• C++11 compiler

Build:

For Unix-like systems:

$ ./build.sh

Note: If you're compiling under Cygwin, remove -fopenmp from $CXXFLAGS in build.sh. Libgomp doesn't seem to work very well under Windows so shiv often ends up running slower with OpenMP enabled.

For Windows (make sure cl is in your %PATH%):

> build.bat

OpenMP is enabled by default for both platforms.

Usage:

Synopsis:

shiv [-hp] [-o output_path] [-c config_path] [-S setting=value]
     [-l layer_height] [-w extrusion_width] [-t tolerance]
     [-s scale_factor] [-d infill_density] [-n shells]
     [-r roof_thickness] [-f floor_thickness] [-b brim_width]
     [-C coarseness] [-x x_translate] [-y y_translate]
     [-z z_chop] binary_stl_file

Flags:

Flag	Description
-h	Show help text
-p	Print configuration
-o output_path	Output gcode path
-c config_path	Configuration file path
-S setting=value	Set setting to value
-l layer_height	Layer height
-w extrusion_width	Constrained extrusion width
-t tolerance	Segment connection tolerance
-s scale_factor	Object scale factor
-d infill_density	Sparse infill density
-n shells	Number of shells
-r roof_thickness	Solid roof thickness
-f floor_thickness	Solid floor thickness
-b brim_width	Brim width
-C coarseness	Output coarseness
-x x_translate	Translate object in the x-axis
-y y_translate	Translate object in the y-axis
-z z_chop	Sink object into build plate

Full settings list:

Setting	Default value	Description
layer_height	0.2	Layer height.
tolerance	0.001	Segment connection tolerance. Large values can be used to close holes in broken models.
scale_constant	1000000.0	Clipper uses integers, so we need to scale floating point values. Precision is 1/scale_constant units. Coordinates in the range ±4.6e+18/scale_constant are accepted.
coarseness	0.01	Approximate output coarseness. Useful for simplifying high polygon count meshes.
extrusion_width	0.45	Constrained extrusion width. Should generally be set to a value equal to or slightly larger than the nozzle diameter.
xy_scale_factor	1.003	The object is scaled by this ratio in the x and y axes to compensate for shrinkage. Around 1.003 works for PLA. ABS should be somewhere between 1.004 and 1.009.
z_scale_factor	1.0	The object is scaled by this ratio in the z axis to compensate for shrinkage. Should probably be left at 1 unless a high temperature heated chamber is used.
x_center	0.0	X coordinate to center the object on.
y_center	0.0	Y coordinate to center the object on.
packing_density	0.75	Controls how tightly packed the extrusions are. 0 means just touching and 1 means fully packed.
edge_packing_density	0.5	Controls how much extra negative offset is applied to the outer perimeter to compensate for reduced packing density of its constrained edge. Automatically set to 1 when outside_first is true or shells is less than 2.
shell_clip	0.15	Length to clip off the ends of shells in units of extrusion_width.
extra_offset	0.0	Offset the object by this distance in the xy plane.
infill_density	0.2	Sparse infill density.
infill_pattern	grid	Sparse infill pattern. Legal values are grid, triangle, triangle2, and rectilinear.
solid_infill_angle	45.0	Solid infill angle in degrees.
sparse_infill_angle	45.0	Sparse infill angle in degrees.
shells	2	Number of loops/perimeters/shells (whatever you want to call them).
roof_thickness	0.8	Solid surface thickness when looking upwards.
floor_thickness	0.8	Solid surface thickness when looking downwards.
min_shell_contact	0.0	Minimum contact patch through roof and floor layers in units of extrusion_width. Small values will reduce print time compared to larger values, but may produce weaker parts.
solid_fill_expansion	1.0	Distance to expand solid infill, in units of extrusion_width.
material_diameter	1.75	Diameter of material.
flow_multiplier	1.0	Flow rate adjustment to compensate for incorrect E-steps or E-step variation between material types.
feed_rate	50.0	Base feed rate. Feed rates below are actual speeds (in units/s) if set to a positive value, or a multiple of feed_rate (or other if specified) if set to a negative value. In other words, 40 is 40 units/s, but -0.5 is feed_rate * 0.5 units/s.
perimeter_feed_rate	-0.5	Outer shell feed rate.
loop_feed_rate	-0.7	Inner shell(s) feed rate.
infill_feed_rate	None	Sets both solid_infill_feed_rate and sparse_infill_feed_rate.
solid_infill_feed_rate	-1.0	Solid infill feed rate.
sparse_infill_feed_rate	-1.0	Sparse infill feed rate.
support_feed_rate	-1.0	Support structure feed rate.
iron_feed_rate	-1.0	Top surface ironing feed rate. A negative value means a multiple of solid_infill_feed_rate.
travel_feed_rate	120.0	Travel feed rate.
first_layer_mult	0.5	First layer feed rates (except travel) are multiplied by this value.
coast_len	0.0	Length to coast (move with the extruder turned off) at the end of a shell. This can reduce start/end blobs if set correctly, but will cause gaps if set too high.
wipe_len	0.0	Length to wipe the nozzle after retracting.
retract_len	1.0	Retraction length.
retract_speed	20.0	Retraction speed.
restart_speed	-1.0	Restart speed. A negative value means a multiple of retract_speed.
retract_threshold	30.0	Unconditional retraction threshold.
solid_infill_retract_threshold	5.0	Retraction threshold when doing solid infill in units of extrusion_width.
retract_after_shells	false	Retract unconditionally after printing the last shell.
extra_restart_len	0.0	Extra material length on restart.
sparse_restart_max_dist	0.0	Travel distance required to reach sparse_restart_max_vol when doing non-retracted travel moves during sparse infill.
sparse_restart_max_vol	0.0	Maximum extra restart volume for the above case.
z_hop	0.0	Raise the z axis by this amount after retracting when traveling.
z_hop_angle	15.0	Ascent angle for z-hop.
only_hop_between_islands	false	If z_hop > 0, only do a z-hop move when traveling between islands.
cool_layer	2	Turn on part cooling at this layer (numbered from zero). Set to -1 to disable cooling.
start_gcode	None	Prepend this G-code to beginning of the output file.
end_gcode	None	Append this G-code to the end of the output file.
cool_on_gcode	M106 S{cool_value}	G-code to turn on cooling.
cool_off_gcode	M107	G-code to turn off cooling.
cool_min	127.0	Minimum cool value.
cool_max	255.0	Maximum cool value.
cool_min_time	60.0	If layer time >= cool_min_time, the cool_min value will be used.
cool_max_time	10.0	If layer time <= cool_max_time, the cool_max value will be used.
cool_off_time	0.0	If layer time >= cool_off_time, cooling will be turned off. Set to zero to disable this feature.
edge_overlap	0.5	Allowable edge path overlap in units of extrusion_width.
comb	true	Avoid crossing boundaries. Automatically disabled if z_hop > 0 and only_hop_between_islands is false.
strict_shell_order	false	Always do insets in order within an island.
align_seams	true	Align seams to the lower left corner. The nearest point is picked instead if this is false.
align_interior_seams	true	Align interior seams to the lower left corner if align_seams is also true. If false, only exterior seams are aligned.
simplify_insets	true	Do simplify_path() operation on all insets (only the initial outline is simplified if this is false)
fill_inset_gaps	true	Fill gaps between shells.
no_solid	false	If true, only generate solid fill on the very top and bottom of the model.
anchor	false	Clip and anchor inset paths.
outside_first	false	Prefer exterior shells.
iron_top_surface	false	Run the nozzle over exposed top surfaces a second time.
separate_z_travel	false	Generate a separate z travel move instead of moving all axes together.
preserve_layer_offset	false	Preserve layer offset when placing the object on the build plate. Useful for certain multi-part prints.
combine_all	false	Orients all outlines counter-clockwise. This can be used to fix certain broken models, but it also fills holes.
poly_fill_type	non_zero	Poly fill type for union. Sometimes even_odd is useful for broken models with self-intersections and/or incorrect normals.
inset_join_type	miter	Join type for negative offsets. Legal values are miter, square, and round. square tends to retain tiny details better, but miter produces simpler (smaller) gcode.
outset_join_type	miter	Join type for positive offsets. Legal values are miter, square, and round.
offset_miter_limit	2.0	Sets ClipperOffset.MiterLimit. See the ClipperLib documentation for details.
offset_arc_tolerance	5.0	Sets ClipperOffset.ArcTolerance. See the ClipperLib documentation for details.
fill_threshold	0.25	Infill and inset gap fill is removed when it would be narrower than extrusion_width * fill_threshold.
infill_smooth_threshold	2.0	Solid infill lines are converted to a smooth curve when the region being filled is narrower than extrusion_width * infill_smooth_threshold.
min_sparse_infill_len	1.0	Minimum length for sparse infill lines.
infill_overlap	0.05	Overlap between infill and shells in units of extrusion_width.
iron_flow_multiplier	0.1	Flow adjustment (relative to normal flow) for top surface ironing.
iron_density	2.0	Density of passes for top surface ironing.
generate_support	false	Generate support structure.
support_everywhere	true	False means only touching build plate.
solid_support_base	true	Make supports solid at layer 0.
connect_support_lines	false	Connect support lines together. Makes the support structure more robust, but harder to remove.
expand_support_interface	true	Expand support interface by the distance between support lines.
support_angle	70.0	Angle threshold for support.
support_margin	0.6	Horizontal spacing between support and model, in units of edge_width.
support_vert_margin	1	Vertical spacing between support and model, in layers.
interface_roof_layers	3	Number of support interface layers when looking upwards.
interface_floor_layers	0	Number of support interface layers when looking downwards.
support_xy_expansion	2.0	Expand support map by this amount. Larger values will generate more support material, but the supports will be stronger.
support_density	0.2	Support structure density.
interface_density	0.7	Support interface density.
support_flow_mult	0.75	Flow rate is multiplied by this value for the support structure. Smaller values will generate a weaker support structure, but it will be easier to remove. The default works well for PLA, but should be increased for materials that have trouble bridging (like PETG).
min_layer_time	8.0	Minimum layer time.
min_feed_rate	10.0	Minimum feed rate.
brim_width	0.0	Brim width.
brim_adhesion_factor	0.5	How stuck to the object the brim is. 0 is just touching and 1 is packed as tightly as normal shells.
raft_xy_expansion	5.0	Expand raft beyond the model by this amount.
raft_base_layer_height	0.3	Layer height for the first layer of the raft.
raft_base_layer_width	0.6	Extrusion width for the first layer of the raft.
raft_base_layer_density	0.5	Fill density for the first layer of the raft.
raft_vert_margin	1.0	Vertical gap between the model and raft, in units of layer_height.
raft_interface_flow_mult	0.75	Flow rate is multiplied by this value for the raft interface layers.
raft_interface_layers	1	Number of solid interface layers.
material_density	0.00125	Material density in arbitrary_mass_unit / input_output_unit^3. The default is approximately correct for PLA and millimeter input/output units.
material_cost	0.01499	Material cost in arbitrary_currency / arbitrary_mass_unit. The arbitrary mass unit must be the same as used in material_density.
gcode_variable	None	Set a variable that can be expanded within a G-code string option (see "G-code variables" below).
v	None	Alias for gcode_variable.
at_layer	None	Print a string to the output file at the beginning of a given layer (numbered from zero).

G-code variables:

Variables and settings can be expanded within the start_gcode, end_gcode, cool_on_gcode, cool_off_gcode, and at_layer settings by enclosing the variable/setting name in curly braces: {name}. Alternates can be specified by separating multiple names with colons: {var1:var2:var3}. If a variable/setting does not exist, the next alternate will be tried. If none of the alternates exist, it will expand to an empty string and warning will be printed.

Configuration files:

Configuration files are a simple key-value format. Comment lines start with a #. Lines starting with whitespace are interpreted as a continuation of the previous line.

Example:

### Generic printer configuration
x_center=100
y_center=100
extrusion_width=0.4
feed_rate=60
travel_feed_rate=120
first_layer_mult=0.5
cool_on_gcode=M106 S{fan_speed}
cool_off_gcode=M106 S0
start_gcode=
	G21              ; Metric
	G90              ; Absolute positioning
	M82              ; Absolute extruder position
	G28 X0 Y0        ; Home X and Y
	G28 Z0           ; Home Z
	G1 Z20.0 F3300
	M190 S{first_layer_bed_temp:bed_temp} ; Wait for bed to reach temp
	M109 S{first_layer_temp:temp}         ; Wait for hotend to reach temp
	G92 E0
	G1 E20.0 F100    ; Prime extruder
	G92 E0
	G1 E-{retract_len} F{retract_speed} ; Retract
	G92 E0
end_gcode=
	M104 S0          ; Zero temps
	M140 S0
	G28 X0 Y0
	M84              ; Disable steppers
at_layer=1=
	M104 S{temp}     ; Set second layer temp
	M140 S{bed_temp} ; Set second layer bed temp
material_diameter=1.735
retract_len=0.5
retract_speed=20
gcode_variable=first_layer_temp=220
gcode_variable=first_layer_bed_temp=65
gcode_variable=temp=210
gcode_variable=bed_temp=60
gcode_variable=fan_speed=255
cool_layer=2
min_layer_time=10
min_feed_rate=5

Examples:

Slice infile.stl and output gcode to outfile.gcode:

shiv -o outfile.gcode infile.stl

Same as above, but with some options set:

shiv -o outfile.gcode -d 0.5 -n 3 -x 30 -y 30 -S min_layer_time=15 -S gcode_variable=temp=200 infile.stl

Preview slices of infile.stl in gnuplot:

shiv -p infile.stl | gnuplot

Feature wishlist:

• ASCII STL, AMF, OBJ, etc. support (only reads binary STL currently)
• Bridge detection
• Multi-extrusion support