Notebook

Hinges in Scad4J¶

I am about to design a model RC plane. In order to attach the control surfaces to the body I am planning to use some hinges.

Fortunatly there is a 'Parametric Hinge' written by 'Rohin Gosling' that can be used in OpenSCAD. In this Blog I will check out how we can use this in Scad4J.

Setup¶

In [9]:

%classpath config resolver maven-public https://software.pschatzmann.ch/repository/maven-public/
%classpath add mvn ch.pschatzmann:scad4j:0.0.1-SNAPSHOT

In [10]:

import ch.pschatzmann.scad4j._
import ch.pschatzmann.scad4j.d1._

import java.io.File
import java.net.URL

Out[10]:

import ch.pschatzmann.scad4j._
import ch.pschatzmann.scad4j.d1._
import java.io.File
import java.net.URL

By default we display the models in 3D. We can change this behaviour by calling SCAD.setDisplay3D(false). This way we display simple images that are also also visible if the Workspace is published.

In [11]:

SCAD.setFormatter(new ch.pschatzmann.scad4j.format.OpenSCADFormatter())
SCAD.setDisplay3D(false)
var model = new SCAD()

Out[11]:

scad4j V0.1

Load the first Hinge¶

Fortunatly the library is not only on Thingiverse, but also on Github.

So we can load it with the help of a simple URL.

In [12]:

var url = new URL("https://raw.githubusercontent.com/rohingosling/OpenSCAD/master/Parametric+Butt+Hinge/Model/Regular/parametric_butt_hinge_3.6.scad")
var hinge = model.scad(url)

hinge.display

Compiling design (CSG Products normalization)...
Normalized CSG tree has 91 elements

Out[12]:

Supported Parameters¶

From the source file we see that we can define the following parameters

scad

/* [Assembly Options] */

enable_male_leaf             = 1;     // [ 0:No, 1:Yes ]
enable_female_leaf           = 1;     // [ 0:No, 1:Yes ]
enable_fillet                = 1;     // [ 0:No, 1:Yes ]
// Turn this off to omit the hinge pin from the female leaf.
enable_pin                   = 1;     // [ 0:No, 1:Yes ]
// Turn this off to set a custom pin diameter. Auto pin size is equal to the leaf gauge.
enable_auto_pin_size         = 1;     // [ 0:No, 1:Yes ]
enable_pin_shaft_counterbore = 0;     // [ 0:No, 1:Yes ]
enable_fasteners             = 1;     // [ 0:No, 1:Yes ]
knuckle_gusset_type          = 0;     // [ 0:None, 1:Linear, 2:Circular, 3:Parabolic ]
// From +180 degrees fully closed, to -90 degrees fully opened. Default = 0 (ie. Opened flat).
throw_angle                  = 0.0;   // [ -90 : 5 : 180 ]
// Rotates the model 180 degrees about the z-axis.
flip_model                   = 0;     // [ 0:No, 1:Yes ]
// Recommended value is 64 or greater.
resolution                   = 128;
component_color              = "Silver";

/* [Hinge Parameters] */

hinge_width                           = 65.0;
leaf_height                           = 60.0;
// Leaf and knuckle thickness. Values greater than 3mm recommended.
leaf_gauge                            = 5.0;
// Recomended values between 0.3 and 4.0. Better quality below 3.0, tough to loosen.
component_clearance                   = 0.4;
knuckle_count                         = 7;               // [3:2:31]
// Manual pin diameter setting. Only has effect, if "Enable Auto Pin Size" is set to "No".
pin_diameter                          = 3.0;
parametric_pin_diameter               = ( enable_auto_pin_size == 1 ) ? leaf_gauge : pin_diameter;

/* [Pin Shaft Parameters] */

top_pin_shaft_counterbore_diameter    = 6.5;
top_pin_shaft_counterbore_depth       = 2.5;
top_pin_shaft_counterbore_shape       = 0;            // [ 0:Circular, 1:Square, 2:Hexagonal ]
bottom_pin_shaft_counterbore_diameter = 6.0;
bottom_pin_shaft_counterbore_depth    = 2.5;
bottom_pin_shaft_counterbore_shape    = 2;            // [ 0:Circular, 1:Square, 2:Hexagonal ]

/* [Fastener Parameters] */

// For countersunk, the chamfer angle may be adjusted using the other parameters.
fstener_head_type                = 0;   // [ 0:Counterbored, 1:Countersunk ]
counter_sink_depth               = 2.5;
fastener_thread_diameter         = 3.5;
// Add 0.5mm to 1.0mm to the fastener head diameter, to allow for head clearance. 
fastener_head_diameter           = 7.0;
fastener_count                   = 6;   // [3:32]
fastener_column_count            = 2;   // [1,2]
// Distance from the edge of the head diameter, to the edges of the leaves.
fastener_margin                  = 3;

Using Parameters for the Hinge¶

We pass our parameters to the hinge library:

In [13]:

var hingeParameters = model.parameters()
hingeParameters.add("hinge_width","10")
hingeParameters.add("leaf_height","100")

var hinge20 = model.scad(url, hingeParameters)

hinge20.display

Compiling design (CSG Products normalization)...
Normalized CSG tree has 147 elements

Out[13]:

Moving the Hinge¶

For my purpuse it is important that we can place the hinge correctly. So we test if the translate and rotate functionality is working as expected

In [14]:

var hingeTest = hinge20.copy()
    .translate().values(10,10,10)
    .rotate().values(0,0,90)
    .obj

hingeTest.display

ERROR: Parser error in file "/tmp/tmp-7384019220159570659.scad", line 88: syntax error

Can't parse file '/tmp/tmp-7384019220159570659.scad'!

Exited with error code 1

Out[14]:

null

Oops - this did not work becuase the system tries to use the whole source code as a scad object. This will not work because the scad files consists of parameters and multiple modules.

So we need to indicate the entry point on which we can apply the operations.

In the source code with find


// -------------------------------------+---------------------------------------+---------------------------------------+---------------------------------------
// Module:      Main
// Module Type: Model
//
// Description:
//
// - Program entry point.
//
// -------------------------------------+---------------------------------------+---------------------------------------+---------------------------------------

main();

module main ()

So the call of main(); is the entry point which will trigger the display of the object. We define this to the our hinge object

In [15]:

hingeTest.setEntryPoint("main();")

hingeTest.display

Compiling design (CSG Products normalization)...
Normalized CSG tree has 147 elements

Out[15]:

And I am happy now because I was getting the exptected result!

In [ ]: