Using Boxes.py

Boxes.py is made of a library that is not visible to the user and multiple generators – each having its own set of parameters and creating a drawing for it own type of object. These generators are divided up into different groups to make it easier to find them:

  • Boxes

  • Boxes with flex

  • Trays and Drawer Inserts

  • Shelves

  • Parts and Samples

  • Misc

  • Unstable

The parameters for each generators also come in groups.

Units of meassurement

In general all measurements are in Millimeters (mm). There is no option to change the units of measurement and there is no plan to add such a option.

A second way to define lengths is as multiple of the material thickness which is one of the standard parameters described below. This allows features to retain their proportions even if some parts depend on the material thickness.

The description texts should state the unit of each argument - please open a ticket if the units are missing somewhere.

Default arguments

In the web interface this is the bottom group right before the Render button. These are basically all technical settings that have little to do with the object being rendered but more with the material used and the way the drawing and the material is processed.

The settings are

thickness

The thickness of the material used. This value is used at many places to define the sizes of features like finger joints, hinges, … It is very important to get the value right - especially if there are fingers that need to fit into some holes. Be aware that many materials may differ from their nominal value. You should always measure the thickness for every sheet unless you have a very reliable supply that is known to stick very closely to specifications. For (ply) wood even a 100th of a millimeter makes a notable difference in how stiff the fit is. Harder more brittle materials may be even more picky.

burn

The burn correction aka kerf is the distance the laser has to keep from the edge of the parts. If the laser would cut right on the edge it would cut away the outside perimeter of the part. So the burn value is basically the radius of the laser - or half the width of the laser cut.

The value of the burn parameter depends on your laser cutter, the material cut and the thickness of the material. In addition it depends on whether you want the parts to be over or under sized. Materials that are spongy like wood can be cut oversized (larger burn value) so they can be press fitted with some force and may be assembled without glue. Brittle materials (like Acrylic) need to be cut undersized to leave a gap for the glue.

Note: The way the burn param works is a bit counter intuitive. Bigger burn values make a tighter fit. Smaller values make a looser fit.

Small changes in the burn param can make a notable difference. Typical steps for adjustment are 0.01 or even 0.005mm to choose between different amounts of force needed to press plywood together.

To find the right burn value cut out a rectangle and then meassure how much smaller it is than its nominal size. The burn value should be around half of the difference. To test the fit for several values at once you can use the BurnTest generator in the “Parts and Samples” section.

format

Boxes.py is able to create multiple formats. For most of them it requires ps2edit. Without ps2edit only SVG and postscript (ps) is supported. Otherwise you can also select

  • ai

  • dxf

  • gcode

  • pdf

  • plt

Other formats supported by ps2edit can be added easily. Please open a ticket on GitHub if you need one.

tabs

Tabs are small bridges between the parts and surrounding material that keep the part from falling out. In theory their width should be affected by the burn parameter. But it is more practical to have both independent so you can tune them separately. Most parts and generators support this features but there may be some that don’t.

For plywood values of 0.2 to 0.3mm still allow getting the parts out by hand (Depending on you laser cutter and the exact material). With little more you will need a knife to cut them loose.

inner_corners

How to handle inner corners. Inner corners are an issue as a round tool like a laser or mill cannot create sharp inner corners. There are different options:

  • loop create a loop that fills the corner

  • corner just a simple sharp corner in the path that will leave a radius untouched.

  • backarc naive implementation with inverted arcs connection the straight lines.

See also burn correction details

debug

Most regular users won’t need this option.

It adds some construction lines that are helpful for developing new generators. Only few pieces actually support the parameter. The most notable being finger holes that show the border of the piece they belong to. This helps checking whether the finger holes are placed correctly.

reference

Converting vector graphics is error prone. Many formats have very weird ideas how their internal units translates to real world dimensions. If reference is set to non zero Boxes.py renders a rectangle of the given length. It can be used to check if the drawing is still at the right scale or may give clues on how to scale it back to the right proportions.

Common Parameters and Types

Section parameters

Some generators support an arbitrary number of sections. This can be used for rows or columns of compartments, staggered heights or otherwise dividing some length in multiple sub sections. The standard parameter making use of this are sx, sy and sh (instead of x, y and h).

Most generators will add walls between the comparments, so the total size might be larger depending on the number of compartments (and additional walls).

The sizes of the sections are divided by a colon (:) e.g. 30:25.5:70. Instead of repeating the same value they can be replaced by value*numberofsections e.g. 50*3 meaning the same as 50:50:50. To equally divide a length into several sections overallwidth/numberofsections can be used - e.g. 120/4 being the same as 30:30:30:30. All these formats can be freely mixed.

mounting_holes

Some generators provide the option to create pear shaped mounting holes. To generate the right size holes, the shaft and the head diameter of the mounting screw must be configured. The format is “shaft:head”, both diameters given in mm (e.g 3.5:6.5). If only the shaft diameter is given (e.g. 3.5), a round mounting hole is generated. Setting the mounting hole diameter parameter to 0 disables the creation of mounting holes.

outside

Most messurements are internal sizes. If a generator offers this parameter it will re-calculate the inner sizes to fit walls and outside features within the given dimmensions. This can be a bit surprising for edge types that have protrusions like hinge eyes, handles, feet, etc as those are typically also taken into account. If the dimmensions are not sufficient to accommendate these features the box may not work properly. Most generators do not have checks for such issues (like negative height) and it is left in the responsibility of the user to check if the result still is sane.

For generators offering multiple compartments this will also fit-in the inner walls. It will sum up all sections then subtract the space needed for the walls and then scale all compartments so they will fill the remaining space.

Edge Type parameters

All but the simplest edge types have a number of settings controlling how exactly they should look. Generators are encouraged to offer these settings to the user. In the web interface they are folded up. In the command line interface they are grouped together. Users should be aware that not all settings are practical to change. For now Boxes.py does not allow hiding some settings.

Finger Joint Settings

finger

width of the fingers in multiples of the thickness

space

width of the spaces between fingers in multiples of the thickness

surroundingspaces

minimal amount of space before the first and after the last finger. This is in multiples of regular space between fingers. Reduce this if there are no fingers fitting on short edges.

style

how finger joints should look like. There may be more styles to choose from in the future.

extra_length

Make the outset part of the finger joint longer to allow grinding off burn marks. Note that this may not be great for non 90° joints where the corner is butted against the opposing cutout.

Stackable Edge Settings

For boxes to actually stack they need to be the same width and depth and angle, width and height of the feet need to be the same.

angle

inside angle of the feet.

height

height of the feet

holedistance

distance from finger holes to bottom edge. May be reduced to save height by sacrificing stability of the connection to the bottom of the box.

width

width of the feet

Colors

The generated files uses the following color conventions:

Black

The outer edges of a part

Blue

Inner edges of a part

Red

Comments or help lines that are not ment to be cut or etched

Green

Etchings

Normaly you will cut things in the order: Green, Blue, Black. If other colors are present, the meaning should hopefully be obvious.