Mill Standard Drilling Example

Introduction

This topic provides an example of how to create standard hole drillingfeatures for milling jobs in BobCAD-CAM.Standard Mill Hole features areused when drilling holes that are parallel to the Z-axis of the machine.This is the most commonly utilized drilling type in BobCAD-CAM.

This tutorial highlights the following functionality of the BobCAD-CAMsoftware:

  • Using the Mill Hole Wizard to easily define drilling of more thanone hole size (multiple features) in the initial wizard setup
  • Using Hole Groups to drill more than one hole depth within a singlehole feature
  • Controlling the clearance, rapid, and feed planes between holes
  • Using the Machining Strategy to define the types of drilling operationsapplied to the holes

Example File

If you are connected to the Internet, the part file for this example can be downloaded automatically by clicking the following link: Mill Standard Drilling Example 1 BBCD

Once you download and saved the zip file, extract the files on your system in an easy place to remember.You can then open the file to use with this tutorial.All files for the tutorials in this help system available for download can be found by clicking on the following link: http://www.bobcad.com/helpfiles.

In theexample file provided, the job, stock, and machine setup are already defined.

Create a Standard Mill Hole Feature

Set the Drilling Type and Select Geometry

  1. In the CAMTree, right-click MachineSetup and click Mill DrillHole.

  2. In the Mill Hole Wizard, click SelectGeometry.

    The Hole Geometry Selection Manager displays.

  3. Confirm that the default drilling type, Standard Drill, is selected.

For this example, you can select the cylindricalsurface of each hole directly from the model, but to make selection easier,a separate CAD layer contains a copy of only these surfaces.(Note thatthe Point and Arc Usage options do not apply when selecting cylindricalsurfaces.)

Tip: Weare selecting cylindrical surfacesbecause this allows the software toautomatically set our diameter, top of feature, and feature depth.Tolearn about selecting other geometry types, view the Pointand Arc Usage Example.

  1. In the Quick Selection group, of the Home ribbon, clickPick By Layer.

  2. In the Select Layer dialog, click Holes.

    Click OK.



  3. Click OK in the SelectionManager.

    Geometry selection is finished.Notice the hole list displays eachdiameter hole and its parameters.The software automatically createsa separate Mill Hole feature for each hole diameter.The Depth valuefor both of our hole sizes displays as Multiple.This is due to themultiple depths that are achieved in a single feature using hole groups.The hole depths can be modified in the wizard later, as needed.

  4. Click Next>> tobegin defining the parameters for the first hole diameter (feature).

Define the Feature Settings for Hole Groups

The Hole Groups table is an important part of the Feature page in theMill Hole Wizard.Each hole group represents a different hole depth, andthe Hole Groups table allows you to preview, break, regroup, rename, andset the parameters for all hole groups in the feature.ClosedClickClosedhere to expand on the subject of Hole Groups.

 

This section explains Hole Groups and how to define their parameters in the Mill Wizards for all Mill Hole drilling features. This information applies to standard, multiaxis, and cross drilling (Mill Turn).

What is a Hole Group?

A Hole Group can be one or more holes that share three parameters: Diameter, Top of Feature, and Feature Depth. All holes that you select for a feature that share these parameters are automatically placed into a single Hole Group. Read the following section for further hole group requirements for each drilling type.

 

Standard Drilling

The following images show a standard drilling part with holes at three different levels on the model and two hole diameters. The hole groups for this part are shown with the same color.

 

 

Notice the holes that share the same diameter, top of feature, and feature depth have the same color. The software automatically creates the Hole Groups as shown after selecting all of the holes for a single drilling feature.

 

Multiaxis Drilling

In addition to the three shared parameters, multiaxis drilling groups must also share the same tool orientation (tool vector) in order to be grouped.

 

The following images show a multiaxis drilling part with two hole diameters and five different tool orientations. The hole groups for this part are shown with the same color.

 

 

Notice that even though the three larger holes on top have the same diameter, depth, and top of feature, these holes cannot be in a single hole group because they don't share the same tool orientation (tool vector). This is also true for the two sets of smaller holes on the opposing faces, except that they do create two hole groups (shown in blue and green), one for each tool vector.

 

Cross Drilling

Cross drilling hole groups require the same three shared parameters, but the exception here is that the tool orientation/rotation angle does not affect the grouping of holes as it does in multiaxis drilling.

 

The following images show a part with all cross drill style holes at various locations around the model. There are two hole diameters with holes that share the same top of feature and feature depth. The holes groups created from this part are shown with the same color.

 

Why Use Hole Groups?

Hole groups allow you to define more than one depth for drilling within a single feature. A single hole feature can have one or more hole groups so you can optimize the hole features that you create and eliminate the need for extra features. Hole groups also provide more clearance options, or Group Retracts, to handle the rapid movements between hole groups.

Modifying Hole Groups - Feature Settings

The following information explains the use of hole groups in the Feature page of all Mill Hole Wizards.

Using the Hole Groups Table

The Hole Groups section of the Feature settings provides a table for editing Hole Groups and their parameters. You can set the Top of Feature and Feature Depth by typing the values or selecting geometry. You can also break hole groups into separate groups and then regroup them as needed, for example, to modify the rapid movement between holes.

 

Important: All of the values that display in the Hole Groups table (except Number) can be editing by clicking that item in the table and typing the new value or name. The buttons next to the Hole Groups table are used with the Hole Groups that are selected in the table. When you click a Hole Group in the table, a preview of the holes displays inside the dialog box to help you visualize the parameters for that group.

 

Hole Groups
 
Number Name Top of Feature Feature Depth
1 Group 1 -1.0000 1.0000
2 Group 2 -0.5000 1.5000
3 Group 3 0.0000 2.0000
       
     
    Break Hole Group  
       
    Regroup Hole  
       
    Pick Top  
       
    Pick Bottom  
               

 

Number

Each hole group is given a number as a reference to the group in the table. This number is automatically created and cannot be edited.

 

Name

Hole groups are automatically named in sequential order with the format of name and number (Group 1). Click the name of any hole group in the table to make it available for editing. Type the new name to create a custom name for the group.

 

Top of Feature

The Top of Feature is the top of the hole as an incremental value from the Machine Setup or machining origin location. Click the Top of Feature value in the table to make it available for editing. Type the new value to set the top of feature for the hole group. After selecting a group in the list, you can use the Pick Top button to set the value using geometry selection.

 

Important: For multiaxis drilling, the Top of Feature is in reference to the selected geometry, not the machining origin. For cross drilling, the Top of Feature is a radial distance from the center of the part (or the Z-axis of the machining origin for Mill Turn jobs).

 

 

Feature Depth

The Feature Depth is the depth of the hole as a positive incremental value from the Top of Feature. You can click the value in the table to make it available for editing. Type the new value to set the Feature Depth. You can also use the Pick Bottom button to set the value using geometry selection (after selecting a group in the list). Be sure to properly set the Top of Feature before selecting the Feature Depth.

 

Tip: For cross drilling (Mill Turn), the Top of Feature and Feature Depth values are calculated as a radial distance from the rotation axis/machining origin. Selecting cylindrical surfaces allows the software to properly calculate both of these values. When using any other geometry type, if the hole extends past the center of the part, you may need to manually type the appropriate Top of Feature and/or Feature Depth value instead of using Pick Top or Pick Bottom.

 

 

Counterbore Depth

The Counterbore Depth is the depth of the larger hole for counterbore holes. This is a positive incremental value from the Top of Feature. Click the Counterbore Depth value in the table to make it available for editing. After selecting a group in the list, you can use the Pick Counterbore Depth button to set the value using geometry selection.

 

 

Break Hole Group

The Break Hole Group button breaks the selected Hole Groups into separate single-hole groups. This can only be used when there is more than one hole in the group. Each resulting hole group contains a single hole and the naming follows that of the original group in the format: previous group name, period, new group number (Group 1.1, Group 1.2).

 

Regroup Holes

The Regroup Holes button takes all selected Hole Groups from the list and makes a single hole group. The naming of the new group follows that of the hole group with the lowest number.

 

Important: In order to regroup holes, the groups that you select must share the same Top of Feature and Feature Depth. Edit these values in the table to be the same for all holes that you want to regroup before clicking Regroup Holes. Note that for multiaxis drilling, holes must also share the same tool orientation or direction vector in order to be grouped.

 

Pick Top

The Pick Top button is used to set the Top of Feature value by selecting geometry such as a point, snap point, or surface edge. Select a Hole Group in the list before clicking Pick Top, or if you don't select a group, you can set the Top of Feature for all groups.

 

 

Pick Bottom

The Pick Bottom button is used to set the Feature Depth value by selecting geometry such as a point, snap point, or surface edge. Select a Hole Group in the list before clicking Pick Bottom, or if you don't select a group, you can set the Feature Depth for all groups.

 

 

Pick Counterbore Bottom

The Pick Counterbore Bottom button is used to set the Counterbore Depth value by selecting geometry such as a point, snap point, or surface edge. Select a Hole Group in the list before clicking Pick Counterbore Bottom, or if you don't select a group, you can set the Counterbore Depth for all groups.

 

Previewing the Hole Groups

To make it easier to visualize the parameters you are defining, when you click a group in the Hole Groups table, a preview displays inside the dialog box. The preview displays each hole, the machine setup (machining origin), the feature preview (top, bottom, and diameter), and the workpiece if you have selected one for the job.

 

 

View Controls

The Hole Groups preview uses the standard mouse controls for altering the viewing position of the preview.

    • You can Rotate the view by dragging with the left mouse button in the preview window. (You can also drag with the middle mouse button.)

    • You can Pan the view by holding down Ctrl (on the keyboard) and dragging with the middle mouse button.

    • You can Zoom in or out using the scroll wheel (rolling the middle mouse button forward or backward).

 

Viewing the Workpiece

The Hole Groups preview may or may not display the part, based on whether or not you have selected a workpiece for the job. Workpiece selection is the first step of using the Stock Wizard, or it can be assigned (or removed) using the Workpiece item in the CAM Tree.

Selecting Multiple Hole Groups

The Hole Groups table allows for multiple selections using standard controls as follows.

 

Important: You can click anywhere in the row of a group to select that group in the list. When you click any value other than the number, it becomes available for editing. When adding or removing selections using modifier keys (Ctrl or Shift), select a group by clicking its row under the Number column.

 

  • Click anywhere in the row of a group to select that group.

  • Hold down the Ctrl key and click any group to add it to or remove it from the selection.

  • After selecting one group, hold the Shift key and click another group to select all groups in between the first and second selections.

  • Tip - when you have multiple groups selected in the table, you can click any other group to select it and clear the other selections.

Hole Groups - Operation Settings

When you go to the Parameters page for any drilling operation in the Mill Hole Wizards, the Hole Groups section displays the name of each Hole Group in the feature. You then select the group name before setting the effective depth, overall depth, and cycle type settings, such as pecking, for each group.

 

 

  1. For now, we are using the default MaterialApproach settings.

The Diameteris already properly set from the selected geometry.

The Parametersare also already properly set for this example.

  1. Under Hole Groups, clickanywhere in the row of Group 1to select it.

Because the group is now selected, the holegroups preview displays inside the dialog box.

To change the viewing orientation of thepreview, drag the left or middle mouse button to rotate.To pan the preview,press and hold the Ctrl key, anddrag the middle mouse button.To zoom in or out, roll the middle mousebutton forward or backward.

  1. In the Hole Groups table, click the name Group1, and type Low.

This hole group is on the lowest level ofthe part, and our custom naming is more descriptive than Group 1.Renaminghole groups is a great way to stay organized when there are many holegroups.

Tip: To edita hole group name, top of feature, or feature depth, click the value (orname) directly in the Hole Groups table.Type the new value or name toupdate it.After editing any value, you can press Tab to move to the nextparameter in the list, or press Enter to finish.

  1. Under Hole Groups, clickthe name Group 2.

  1. Type Mid to rename Group2.

  2. Click the name Group 3,and type High.



    We don't make any other changes to the hole groups at this time.Rememberthat we selected cylindrical surfaces so the parameters for the holegroups are automatically set.

  3. Click Next>>.

Define the Machining Strategy

  1. Under Default Strategy,click the Hole machining strategy.

    This assigns one center drill operation and one drill operation tothe Current Operations list.

  2. On the lower left, click Applyto All Features.

    The software automatically creates one feature for each hole diameteras seen in the tree on the left.The second feature now uses the sameMachining Strategy as the first.

  3. Click Next>> three timesto go to the center drill tool data.(No changes are needed for the Machine Sequence orPosting settings.)

Define the Tool Data and Operation Parameters

  1. Notice the SystemTool check box is selected.For this example, we use the automaticallyselected system tool information, but be sure to update the tool data,machining data, and feeds and speeds as needed when creating yourown programs.

  2. Click Next>>.

    Again, we use the default operation parameters, but notice there areno hole groups listed.For center drill and chamfer operations, theparameters defined here are shared across all hole groups.All otheroperation types allow you to define the parameters for each hole groupseparately.

  3. Click Next>>.

    We use System Tool information again for the drill operation, becausethe software automatically loads a tool with the correct diameterfrom the Tool Library.All of the parameters stored with the toolare automatically set in the wizard.

  4. Click Next>>.

  5. Notice the Hole Groups list.Click Low to select it.

    Under Cycle Type, click Peck.

  6. Click the group name Mid,and then select Peck.

Set the Highgroup to Peck using the same process.

Important: Besure to select a hole group before changing any operation parameters,and make sure to set the parameters as needed for all hole groups.

  1. Click Next>>.

Define the Second Feature and Compute the Toolpath

  1. In the HoleGroups table, repeat the process of selecting the group toview the preview, and then rename each group to Low,Mid, and Highbased on its level on the model.

    Again, the hole groups parameters are automatically set because weselected cylindrical surfaces.

  2. Click Next>>,and notice that the Hole operationtemplate is selected from using Apply to All Features earlier.

  3. In the tree on the left, click the last Parameters item.

  4. Repeat the process as explained earlier toset all hole groups to the Peckcycle type.

  5. On the lower-right, click Compute.

The resulting toolpath is shown next.

After viewing the toolpath, we see one issue.The rapid plane, applied withinhole groups, is going through the steps of the model because the holeson opposite sides of the part are in the same group.The rapid movementbetween hole groups is determinedby the group retracts as seen in the link moves that retract up abovethe part.Next we modify our hole groups to alleviate the issue.

Edit the Feature, Break and Regroup Holes

For reference, the following image shows the current hole groups usingone color for each group.Remember that each hole diameter is a singlefeature and we are working with two features (both are shown in the image).

After breaking and regrouping holes in the following steps, the holegroups are as follows (one color for each hole group).This final groupingallows us to optimize the toolpath for both features.

  1. In the CAMTree, right-click the first feature name, Feature Mill Hole - 0.3750, and click Edit.

Click the GroupRetracts button under MaterialApproach.

The group retracts handle the rapid movementbetween hole groups, and theyare currently set to a plane in Z with a height of 0.6250.This distanceis in reference to the machine setup (machining origin) location, whichis at the top of the part.

Close the GroupRetracts dialog box.

Next we modify our hole groups so the groupretracts are used when moving from one step (level) of the model to thenext.

  1. Under Hole Groups, clickanywhere in the row of the Lowgroup to select the group and display the preview.



  2. With the Low group selected, click BreakHole Group.

    The group is separated into four single-hole groups (Low.1 throughLow.4).

  3. Click anywhere in the row of group Low.1to select it.

Press and hold the Ctrlkey, and click Low.2 to add itto the current selection.

We can see that Low.2 is on the oppositeside of the part so we don't want to regroup these holes.

Tip: You multi-selectitems in the Hole Groups list using the Shift and/or Ctrl keys.Hold Ctrl and click a group to add itto or remove it from the current selection.Hold Shiftand click a group to select all groups between the first and second selections.

Hold the Ctrlkey and select group Low.2 toremove it from the selection.(Click the row of Low.2 in the Number column.)

Press Ctrland click Low.4 to add itto the selection.

We can see that Low.1 and Low.4 are on thesame side of the part, so these are the two holes we want to regroup.

  1. With both Low.1 andLow.4 selected, click Regroup Holes.

Click the new group Low.1 to confirm thenew grouping.

  1. There are only two holes left on the lower level, so click Low.2, then hold Ctrland click Low.3.

Click RegroupHoles to create a new Low.2 group.

  1. Repeat this process of breaking and regrouping holes for themiddle level (group Mid) so that each group only contains the holesthat are on the same side of the part.

There is no need to break the High hole group.

Breakinggroup Mid results in the following groups.

Mid.1

Mid.2

Mid.3

Mid.4

Groups Mid.1and Mid.4 are regrouped to createa new group, Mid.1.

Groups Mid.2and Mid.3 are regrouped to createa new group, Mid.2.

To update the changes for this feature, clickCompute.

Edit the Second Feature, Break and Regroup Holes

Now we break and regroup the holes for the second feature.Again, theprocess here is to use the Ctrl key to add and remove selections whileviewing the hole groups preview, and then regrouping the holes as needed.In this section we use the Shift modifier to select multiple list items.

  1. Right-click the second feature name, Feature Mill Hole - 0.1250,and click Edit.

  2. Under HoleGroups, click anywhere in the row of group Lowto select it.

    Press and hold Ctrl,and select group Mid.

    With Lowand Mid selected, click Break Hole Group.

  3. Select group Low.1 andobserve the hole groups preview.

    Hold Ctrland select Low.2.

    Group Low.2 is on the opposite side fromLow.1 and we want to regroup holes that are on the same side of the part.

    Hold Ctrland click Low.2 to remove it fromthe selection.

    Group Low.3 is also on the opposite sideof the part.

    Hold Ctrland click Low.4 to add it to theselection.

    We hold Ctrland select all the low level holes that are on the same side of the part:Low.5 and Low.8.

  4. With Low.1, Low.4,Low.5, and Low.8selected, click Regroup Holes.

    Click the new Low.1 group to display thepreview.



  5. Click group Low.2.

    Press and hold the Shiftkey, and click group Low.7.

    Notice that all groups from Low.2 throughLow.7 are selected.



    Click RegroupHoles.

  6. Repeat this process to regroup the mid-level holes using thesame process.(Group Mid is regrouped into Mid.1and Mid.2 as shown next.)



  7. Click Compute to updatethe toolpath.



    The result of breaking the hole groups isan efficient toolpath for our example part that uses a minimal rapid planewithin groups and only retracts above the part to move from one groupto the next (group retracts).

This concludes the tutorial.