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 closly to specifications. For (ply) wood even a 100th of a milimeter 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.

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 dimmensions. 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.

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 interfacce 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.