Processing Overstructures

In this document we will explain step by step of how to process properly an Overstructure object in MillBox.

Importing your part

During the import window, you must select 'Overstructure' or 'Bridge or Denture over Bar' depending on your MillBox interface. These objects will appear to you like below:

Preparing your file for Milling

Margin / Prep Line

After the import, we must check if the object has a good defined margin line (shown in pink) all around the cavity where the bar will be allocated, like image below:

The margin / prep line is really important for processing Overstructures properly. MillBox will identify the best axis to mill out this cavity using this line as reference. All of the internal undercuts will be optimized when the margin line is presented because during the milling of those internal areas MillBox will use the cavity axis as orientation, as we can compare between the images below:

With Margin Line

Without Margin Line

If the margin line was not created during the import procedure, we must manually create it by using the following tool in MillBox.

If the user tries to calculate an Overstructure without a margin line defined, MillBox will show the following message at the moment the user selects the "Start Mill" button. This message will inform the user that one or more Overstructures have no margin lines and it may be necessary to designate it, it will also show the user the icon of the tool needed to draw the margin line

Drilling Axes / Screw Channels

For every Cylinder / Hole that we have in the object we must check if the drilling axes (Green Lines) are detected as shown below:

This curve determines where the drilling operation starts and stops. It should always be at the very top of the access channel and extend to the bottom of the hole.

If some of the drilling axes is not detected automatically, we can use the "Cylinder / Drilling Axis Detection" tool to identify those cylinders / holes.

User can select between detecting the cylinder by clicking in a single point of the cylinder or by clicking on three sides of the cylinder. In many cases the single point detection is sufficient, but for angled screw-channels, we suggest to use 3 point detection.

Red Caps

The red caps are created to prevent the tool from entering the screw access channel during Roughing and Finishing operations as these operations are meant for surface finishing and not drilling. These caps / temporary surfaces are automatically turned off in the strategy for the drilling operations to allow precise machining of the holes. These caps should exist at the top and bottom of the access channel only.

To check if the Red Caps are detected in your object, make sure that they are set as Visible in your Visual Layers (or by using Ctrl+R key combo):

If there are one or more Red Caps missing from a screw channel, we must detect them using the tool shown below and by clicking inside of the screw channel:

Milling Options

Like explained, with the margin line present, MillBox will mill the internal cavity using the best insertion axis, but there could still be some undercuts present within the cavity, so there are two options to remove those undercuts that user can use.

On the strategy side, there could be an option to mill the internal undercuts for Overstructures, this options could be visible or invisible depending on your Strategy configuration - check with your dealer for more details.

If the object has internal undercuts, we suggest to mark this option at the Milling Options presented during calculation:

User can also paint the undercut areas that he wants to remove by using the Milling Zone Designation tool and choosing "Undercut 3+2 Manual with 1.0 mm" as operation to make sure the undercuts will be removed.

Configuration

If a ConstructionInfo (exocad) or a PTS (3Shape) file is presented at the same folder and has the same name as your STL file, MillBox will read those files and import the margin from it, if present.

If the object has no ConstructionInfo or PTS files, there is an option inside the General Configuration (March 31, 2020 update and later) that can be toggled on and allows MillBox to identify / detect margin lines on Overstructures during the import process.

If this option is enabled, this means MillBox will try to create this margin curve during the import procedure, but the import time of the Overstructure object will take longer as a result.

If this option is disabled, MillBox will detect the curve unless if there is ConstructionInfo or PTS files to assist in placing this information. The import time is reduced in comparison, but the user must draw the margin line using the tool shown above.