Edge Finder (Indicate Workpiece) Function

User Interface Overview

The controls in the dialog depend on the instrument you select. With a probe or an edge finder, you indicate by touching, so you get buttons for the four edges and a control for which side of the tip touched the wall. With a camera, you indicate by aiming, so those controls are replaced with crosshairs. The rest of the dialog is the same for both.

Since every position comes from the scales, you need to be connected to the adapter to use the function. You can still open the dialog without a connection, but you will see a banner saying that positions can't be captured, and the capture controls stay disabled until the connection returns.

Probe Selector

Using the "Probe" list, you can select the instrument you are indicating with. TouchDRO compensates with the tip diameter stored in the selected profile, so you don't need to type any dimensions at the machine. You will find every instrument from the probe library in the list, with the instrument type and tip diameter under each name.

To set up an instrument that isn't on the list yet, tap "New profile" at the bottom of it. Both that and the edit button beside the list open the profile editor, which the probe profiles page covers in full.

Edge Selector Buttons

The left side of the dialog contains the four edge selection buttons for the Left, Right, Near and Far edges that are used to tell the application which edge is being indicated.

Whether you can arm an edge and wait for the trigger depends on the selected profile. With a profile that has a trigger port assigned, each button has three states. With a profile whose trigger source is set to "None", there is nothing to wait for, so the Scanning state is skipped.

With a trigger port, each button has three states:

• Idle - the button is inactive and the edge has not been indicated
  • Pressing the button will activate the scanning mode for the relevant edge. If any other edge was in the scanning mode, it will return back to the idle state
  • Long-pressing the button will skip the scanning process and will use current spindle position to indicate the edge.
• Scanning - TouchDRO is waiting for electronic edge finder trigger to indicate the edge
  • Pressing the button will deactivate the scanning mode and will return it to the Idle state.
  • When the edge finder input is triggered, TouchDRO will record the position and switch to "Indicated" state. The edge can then be used to set the origin
• Indicated - the edge has been indicated and can be used to set the origin
  • Long-pressing the button will clear the indicated position and return the button to Idle state

Without a trigger port, the Scanning state is omitted. Pressing a button in the Idle state records the current position, the way a long-press does above, and pressing an indicated button clears it again.

External/Internal Buttons

The two "External/Internal" buttons determine whether an internal or external feature is being indicated. Their state sets the direction of tip diameter compensation.

Z Position

Using the "Z Position" row, you can pick up a face along with the edges, in the same operation. The row appears when the selected instrument can measure Z, which means a touch probe. To include Z in the operation, turn on the switch at the end of the row. For a Z-only touch-off with no edges involved, use the separate Set Z Reference function.

You can fill in the value three ways: type it, tap the sync button to take the current Z reading, or tap the arm button so that the next probe touch captures it. In each case TouchDRO applies the setter height or probe offset from the selected profile, and when you press "Set Origin", it sets Z along with the axes that have edges indicated.

Edge Location

The read-only Edge Location text box displays the location of the selected edge/center point in relation to the current absolute origin. The position is displayed for information purposes only and can not be edited directly.

X and Y Origin Selector Buttons

Below the "Edge Location" text box are two rows of three toggle buttons, one row per axis, that provide a way to select the relative location of the origin:

• When one of the edges is indicated, the corresponding button will be activated
• When both edges are indicated, all three buttons will be enabled and the "Center" button will be activated automatically
• Pressing any of the enabled buttons toggles it on and off

Coordinate System Selector

When the "Indicate Workpiece" function is activated, it will default to the Absolute coordinate system. Coordinate system selector radio buttons provide a way to toggle between the Incremental and Absolute coordinate system as needed.

Auto, Add Sub-Datum, and Camera Controls

Auto Button

Using the "Auto" button (also called the "Magic Wand" button) in the center of the edge selection buttons, you can let TouchDRO select the edge for you, based on the direction the axis was moving when the probe triggered.

Note that when auto mode is enabled, the "External/Internal" buttons are disabled.

Add Sub-Datum Button

Using the "Add Sub-Datum" button, you can save the indicated edge or center as a sub-datum coordinate. The button has two modes:

• Short press - adds current point to the sub-datum list, and clears the located edges.
• Long press - adds current point to the sub-datum list, but does not clear the located edges.

Note that TouchDRO saves the located edge or center, with the tip diameter compensated, so the saved point is where the instrument actually touched and not where the spindle was.

Camera Controls

When you select a camera or microscope profile, the dialog replaces the touch controls with aiming controls. The four edge buttons show crosshair lines instead of a tip approaching a wall, and a center button appears between them in place of the "Auto" button. The "External/Internal" row is hidden, since a crosshair has no tip and no inside or outside, and the "Z Position" row is hidden as well, since a camera doesn't measure Z.

Each edge button shows the crosshair line you need to lay on the edge: the left and right buttons show the vertical line, since you pick up an X edge by putting that line on it, and the near and far buttons show the horizontal one. With the center button, you take the position under the crosshair as the center in both X and Y at once.

Working With the Indicate Workpiece Function

Indicating an Edge With a Manual Edge Finder

Indicating one of the four edges of a workpiece consists of the following steps (using left edge as an example):

1. Bring up the "Indicate Workpiece" function dialog
2. Select the probe profile for the instrument you are using
3. Move the spindle to the left of the workpiece and lower it as needed
4. Move the spindle towards the left edge of the workpiece until the edge finder is triggered
5. Long-press the left edge selector button; once TouchDRO emits a "long" beep, the button will switch to the "indicated" state
6. TouchDRO will automatically activate the "Left" button for the X Axis Origin
7. If desired, tap the "Incremental" radio button to set the incremental origin
8. Press the "Set Origin" button

If desired, the origin for the second axis can be set at the same time by repeating steps 3-5 for the desired edge.

Indicating an Edge With a Touch Probe

The process of indicating the workpiece edge with an electronic touch probe is similar to the process described above and consists of the following steps:

1. Bring up the "Indicate Workpiece" function dialog
2. Select the probe profile for the instrument you are using
3. Move the spindle to the left side of the workpiece
4. Press the left edge selector button; the button will display "scanning" animation
5. Slowly move the axis until the probe touches the left edge and is activated; the edge selector button will change to the "Indicated" state
6. TouchDRO will automatically activate the "Left" button for the X Axis Origin
7. If desired, tap the "Incremental" radio button to set the incremental origin
8. Press the "Set Origin" button

Analogous process can be used to find any of the other three edges as needed.

Finding the Centerline of a Workpiece

On a traditional DRO console this is the "1/2" function, also called the "half" or "centerline" function: you indicate one edge, then the other, and the readout splits the distance. In TouchDRO you do the same thing in this dialog, and TouchDRO activates the "Center" button for you once both edges are indicated.

1. Bring up the "Indicate Workpiece" function dialog
2. The tip diameter is irrelevant for a centerline, because the compensation cancels between the two edges; any instrument selection will do
3. Move the spindle to the left side of the workpiece
4. Indicate the left edge:
   1. If using an electronic edge finder:
      1. Press the left edge selector button; the button will display "scanning" animation
      2. Slowly move the axis until the probe touches the left edge and is activated; the edge selector button will change to the "Indicated" state
   2. If using a manual edge finder:
      1. Move the edge finder towards the left edge of the part until the edge finder is triggered
      2. Long-press the left edge selector button
5. Repeat steps 3 and 4 for the right edge of the workpiece
6. TouchDRO will automatically activate the "Center" button for the X Axis Origin
7. If desired, tap the "Incremental" radio button to set the incremental origin
8. Press the "Set Origin" button

Finding the Center of a Hole

To find the center of a hole, you do the same half-the-distance operation on both axes. This works on a bore, a boss, or any feature you can touch from opposite sides.

1. Bring up the "Indicate Workpiece" function dialog
2. The tip diameter is irrelevant for a hole center, because the compensation cancels between the two edges; any instrument selection will do
3. Move the spindle to the approximate center of the hole
4. Indicate the left edge:
   1. If using an electronic edge finder:
      1. Press the left edge selector button; the button will display "scanning" animation
      2. Slowly move the axis until the probe touches the left edge and is activated; the edge selector button will change to the "Indicated" state
   2. If using a manual edge finder:
      1. Move the edge finder towards the left edge of the part until the edge finder is triggered
      2. Long-press the left edge selector button
5. Repeat steps 3 and 4 for the right edge of the workpiece
6. TouchDRO will automatically activate the "Center" button for the X Axis Origin
7. Repeat steps 3 through 5 for the Y axis
8. TouchDRO will automatically activate the "Center" button for the Y Axis Origin
9. If desired, tap the "Incremental" radio button to set the incremental origin
10. Press the "Set Origin" button

Working With a Camera or a Microscope

With a camera, a USB microscope, or a dedicated centering microscope, you indicate a feature by aiming at it instead of touching it. On a manual mill this is usually the quickest way to pick up a feature, since you don't need to arm anything or creep up on the edge. You bring the crosshair onto the feature and tap a button.

A camera also lets you pick up features that a stylus can't touch. For example, a scribed line, a center punch mark, a cast or flame-cut edge, the corner of a thin part, or a chipped tooth doesn't give a probe a clean wall to trigger against, but all of them are plainly visible under magnification.

In addition, you can mount the camera on its own bracket beside the spindle and leave it there for the whole job, so picking up a position doesn't cost you a tool change. TouchDRO uses the X and Y offsets in the probe profile to bring the reading back onto the spindle axis, so the accuracy you get depends on those two numbers, and it is worth measuring them carefully once.

For anything you can see the whole of and judge the middle of by eye, such as a hole, a boss, a punch mark, or the intersection of two scribed lines, use the center button. Line the crosshair up on the feature, tap the button, and both axes take that position as the center. To set the origin there, press "Set Origin"; to record it as a point instead, press "Add Sub-Datum". Tapping the center button a second time releases the capture.

To pick up an edge, aim the crosshair line at it and tap the button for that edge, the way an instrument with no trigger port works. Tapping an indicated button again clears it. From there the origin selector rows behave as they do with any other instrument: two opposed edges enable Left, Center and Right for that axis, with Center chosen automatically.

Measuring a Part That Has No Drawing

When you copy a worn part, reverse engineer a mating component, or fit a repair, you need to take the dimensions off the part itself. If you write them down on a notepad, they tend to get transposed, and a part measured over several sittings tends to end up with several slightly different reference points.

Using the "Add Sub-Datum" button, you can record the whole part in one coordinate system instead. Set the absolute origin once, against a corner or a face you can find again, then work through the features:

1. Indicate the feature as described above, using one edge for a face, two for a center, or the camera's center button for anything you can aim at
2. Long-press "Add Sub-Datum" to save the point and keep the located edges, or short-press it to save the point and clear them for the next feature
3. Rename the point in the sub-datum list while you still remember which feature it was

For features you can simply jog to, you don't need this function at all: position the spindle and tap the add button at the bottom of the sub-datum panel to save the current position as a point.

A camera is especially useful for this kind of work, since a part that has no drawing usually has no clean machined edges either, and the features that matter are as likely to be scribed, punched, or cast as milled.

Once you have worked through the part, every hole center, edge, and boss center is stored in the workspace. You can then export the workspace as a DXF drawing and take it into CAD, where you can draw against the points instead of retyping a column of numbers.

Note that this records where the features are, but doesn't measure them. To get the distance between two of them, the center and diameter of a bore from three points on its wall, or the angle an edge runs off square, switch the app into measurement mode and use the measuring functions. Those keep an inspection log of what you measured as well, which the sub-datum list does not.

Notes

Origin location selection buttons can be toggled on and off when they are enabled, so it's possible to turn all three buttons off. In such a case TouchDRO will not change the origin for that axis.

This dialog can be used to verify touch probe alignment. This can be done as follows:

1. Set the dialog up for a reliable manual edge finder by selecting its probe profile
2. Indicate the left edge (for example) using that edge finder as described in the "Indicating an Edge With a Manual Edge Finder" section above
3. Write down the value shown in the "Edge Location" text box
4. Long-press the Left Edge selector button to clear the indicated position
5. Orient the touch probe so the cable is facing away from you (at 12 o'clock position)
6. Set the dialog up for the touch probe by selecting its probe profile
7. Indicate the same edge using the electronic touch probe as described in the "Indicating an Edge With A Touch Probe"
8. Note the new Edge Location value
9. Rotate the probe 90 degrees
10. Repeat steps 7 and 8, rotate the probe by 90 degrees
11. Repeat steps 7 and 8 again, rotate the probe by 90 degrees
12. Repeat steps 7 and 8

At this point you will have five numbers - the position found by the edge finder and four positions found by rotating the probe. Ideally, all five numbers should be close to identical. If the positions differ by more than an acceptable tolerance, you will need to adjust and calibrate the probe to achieve better accuracy.