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Stl part

Stl part

You can get this dialog box pressing the 'Cut Stl part'  link located in the Startup dialog

You can use this if you own a Cnc machine with an added rotary axis. If you press ' Cut Stl Part' link  the following dialog will appear:

A Stl part is a solid described by a triangular meshed surface, supplied by an external Stl file.
The Stl file must follow the rules of the Stl standard, or some problem can arise. The application check the most important rules and show a warning is some problem happened.
Stl files are well known, as this is the standard file format used by 3D Printers.
You can generate and modify Stl files using the supplied devStl Tool application, you can run it from the Startup dialog.
For some regular shape may be you will find more convenient to use a 'TwistRot Part', the cut in this case will be more accurate and faster.

The cut will be performed dividing the part in projected section, one for each rotation.
A projected section is the contour of the shadow of the part on a plan, created by a Collimated light (a Collimated light is light whose rays are parallel).
Then, for each rotation, the hotwire will follow the right side of this path. After every cut, the hot wire goes to the safe position (optional), the foam block is rotated, and a new cut applied.
Of course the hotwire cannot render well concavities along its length. So, if the part includes concavities, we suggest to select well the Rotation axis, to minimize them.
If internal holes are created in the Path, they will be ignored. So, again, take your time to evaluate the best Rotation axis.
If possible try to avoid also up/down movements changes during every single cut, this can affect the quality of the final part.

To load a new Stl file use the 'File - Import a Stl file'  menu, see below the full description of the menu.
In the left side of the dialog you can see the controls to setup your Stl part.
In the middle a 2D preview, showing the computed projected section for the rotation selected by the horizontal cursor.
In the right side the 3D preview of the Stl part.

Now we will explain in deep every single part of the dialog.

Left side: the parameters and commands

Change rotation axis Frame:

When you import a new Stl file, the original Z axis is used as the rotation axis.
You can here select a new rotation axis between X and Y, considering that the applied rotation axis will be the Z axis, as shown in the 3D picture.
You can also select to invert the orientation of the Z axis, if you want a Top/Down inverted cut.
If this is not enough, as you have a Part with a strange angle, press the 'Rotate the Part to set the right rotation angle' button. You will see in  the screen this new window:



You can as first select the axis to use to perform the rotation, and the right View will be displayed in the 3D picture.
Then just press on of the button surrounding the angle step to apply some rotation. Every button will apply a 1 x angle step, 5 x angle step, 15 x angle step.
You can also select to use the Orthogonal view this can help to have a better control over the 3D picture.
Then just press OK to confirm the new settings, or Cancel to ignore them.

Change rotation axis placement Frame:

When you import a new Stl file, the Z will be centered on the Volume Center of the part, considering its max/min X and Y coordinates.
If you need to make more adjustements, just press the 'Move the rotation axis placement' button. You will see in  the screen this new window:



You can as first select the axis to use to perform the movement, and the right View will be displayed in the 3D picture.
Then just press on of the button surrounding the distance step to apply some rotation. Every button will apply a 1 x distance step, 5 x distance step, 15 x distance step.
You can also select to use the Orthogonal view this can help to have a better control over the 3D picture.
Then just press OK to confirm the new settings, or Cancel to ignore them.


Cutting parameters:

You select here:

• the number of Rotations to apply. When possible we suggest to apply an even number, in this way you can then select to cut the Left/Right side in one shot.
  Version 3 includes the possibilty to customize the rotations using the buttons:
  • Reset - Pressing Reset the number of equispaced rotation will be applied
  • Customize Rotations - Pressing this button the  'Customize Rotations' dialog will appear. You can then create manually or in automatic way a number of NOT equispaced rotations, to cut the part in a faster and better way.
  • Customize Twisted Rotation - Pressing this button the  'Customize Twisted Rotations' dialog will appear. You can then create in automatic way a number of NOT equispaced and not costant rotations, to cut the part in a faster and better way twisted parts. Using this feature for each cut the rotation angle will chenge to perform the best possible cut!
• the Profile accuracy. The Profile is the Red bold line displayed in the 2D picture. The higher the accuracy, the longer the computing time.

Default cutting settings Frame:

Here you can apply important refinements to the cut:

• The Cutout offset will remove the specified size from the Bottom and Top sides. This size is measured along the vertical line (Z axes of the 3D preview)
• The Min axis distance lets you to specify a minimal safe-uncut band from the rotation axis, for the Upper and Lower sides.
• Safe points Offset and Angle: after every cutting, before to apply the next rotation angle, the hot wire will move to these optional safe points. Setting a 0.0 offset no movement will be applied to that side. Checking the 'Edit Safe Points on 2D Preview' checkbox you can then see and drag 2 blue squares in the 2D preview to graphically set the Safe points.
• Apply a min distance for the full axis length (it can be negative) from the rotation axis by the "Apply min. axis dist. full len.:" option.

Verify Stl when importing: checking this option, when you import a STL file it will be verified. If the application finds some problem you will advised, so you have the possiblity to fix them. You can for example use DevStl Tools to fix them, see the Startup dialog to run it. Enabling this option will perform longer processing time during the import job.

Command Buttons:

• Apply  - Apply actual settings 
• Cut(/Mill) - A small Menu will start where you can select if you want to start the  'Cut Stacked part' dialog, where you can select the type of cut and Create the right cutting GCode as a Stacked Part (you can then add more Parts), or simply go directly to cut it as a single part by a Lathe ('Cut by Lathe' dialog) or by a Rotating Table ('Cut by Rotating Table'  dialog).
  If you are running devFoam 3DM, you can also see a menu item to go directly to create the milling GCode for this single part, the 'Mill Stl Part'  dialog will start
• OK - If are modifying a part from the  'Cut Stacked part' dialog, you can confirm the new settings and go back to the 'Cut Stacked part' dialog using the OK button
• Cancel - If are modifying a part from the  'Cut Stacked part' dialog, you can cancel the new settings and go back to the 'Cut Stacked part' dialog using the Cancel button
• Close  - Exit this Window 

Middle side: the 2D preview

I think the better thing is to explain what you can see here by colour and line type. Consider also that you can turn on-off some components by the '2D Preview' menu.

• Red bold curve: this draws the cutting line (Profile) referred to the Actual rotation. You can change the Active rotation using the horizontal slider. Only the right side of the projected section will be cut for each rotation.
• Grey dotted curve: this draws the full projected section of the Actual rotation.
• Green lines: these draw the Paths to Safe points.
• Blue dotted line: the Rotation axis.
• Light yellow zones with no contour: the Regions drawing the applied Min axis distances.
• Light pink zones with no contour: the Regions drawing the cutout offsets.

Pressing the 'Fit to screen' button you will maximize the drawing to the 2D preview window size.

Right side: the 3D preview

You can see here the 3D Preview of the Stl part. Consider also that you can customize it by the '3D Preview' menu.
The transparent cyan plan can be rotated by the horizontal slider placed at the bottom side of the 2D preview. This define the plan where the shadow will be projected, just imagine the plan all behind the part, to receive the full shadow.
Here is displayed attached to the Rotation axis, as we think is more intuitive.
The optional grid can be customized by the '3D Preview' menu.
You can make measurements on the 3D preview selecting the Orthogonal view and some predefined Top-Side-Front view.

The menu

Using the supplied menu you can control all the advanced settings.

File menu:

• Import a Stl file...: Import an existent Stl file
• Open: Open an existent Stl part
• Save: Save the actual Stl part
• Save as...: Save the actual Stl part with a new file name

2D Preview menu:

• Show Cut out zones: show/hide the cut out zones, rendered as light pink regions
• Show Min Axis zones: show/hide the Min axis distance zones, rendered as light yellow regions  

3D Preview menu:

• Select Part colour: you can change the part colour
• Grid settings and Background colour: you can change the background colour and grid settings
• Show original STL file: show the solid as the Original Stl part, ignoring the cut result. 
• Show real final part: show the solid as close as possible as the shape it will get after the cut. If the cutting paths have some concavities (up/down movements change), this preview can differ from the final part. But this is a bad condition, if possible avoid it.
• Apply Smoothing: Apply smoothing to the part surface. The process time can be longer when enabled.

I suggest also to take a look at this page, to better understand some important concepts of devFoam: DevFoam FAQ and important concepts