Working with Guides

A lot of machining work is done to a line rather than to a point: the two walls of a slot, the four sides of a pocket, the shoulder a cut must not cross. A common way to mark a slot on a DRO is to define two coordinates, one for each wall, and then machine to each in turn. This works, but it's awkward: each stored coordinate carries both axes, so activating one also disturbs the readout for the axis you weren't working. TouchDRO has guides for this specific case. A guide is a vertical or horizontal line on the Graphical View display that marks a single coordinate, and machining to it comes down to driving one axis readout to zero.

Under the hood, a guide is a one-axis sub-datum. It is stored in the current workspace, appears in the sub-datum list under the name "Guide", and activating it works just like activating a sub-datum: the relevant axis readout switches to showing the distance to the guide, and deactivating the guide returns the readout to its previous state. The concepts behind sub-datums are covered in the "Sub-Datums and Workspaces" guide.

TouchDRO graphical view with two vertical guides; the active guide and its row in the sub-datum list are highlighted
Fig. 1: Two vertical guides in the graphical view; the active guide and its list row are highlighted

Creating Guides

To create a guide at an arbitrary position, long-press an empty area of the projection view. This opens the "Add Guide Line" dialog, where you can select the orientation of the guide, vertical or horizontal, and enter its position:

Fig. 2: Add Guide Line Dialog
Fig. 2: Add Guide Line Dialog

To create a guide that passes through an existing sub-datum, long-press the sub-datum in the projection view and choose "Add Horizontal Guide Here" or "Add Vertical Guide Here" from the "Sub-Datum Commands" dialog. The guide lands exactly on the stored coordinate, so this is the accurate way to work an edge that is already marked by a point.

Fig. 3: Add Guide Commands in the Sub-Datum Commands Dialog
Fig. 3: Add Guide Commands in the Sub-Datum Commands Dialog

Activating and Deactivating Guides

To activate a guide, tap it in the projection view. The guide's line is drawn brighter and thicker, and the relevant axis readout switches to showing the distance to the guide, so machining to the boundary means driving that readout to zero. If another guide or sub-datum was active, it is deactivated first; only one can be active at a time.

To deactivate a guide, tap it again. The axis readout returns to its previous state.

Deleting Guides

To delete a guide, long-press it in the projection view and confirm the deletion. Since guides appear in the sub-datum list, a guide can also be deleted from the list, the same way as any other sub-datum.

Fig. 4: Delete Guide Confirmation
Fig. 4: Delete Guide Confirmation

Guides on a Lathe

On a lathe, the projection view shows the Z/X plane, and guides take on lathe meanings: a vertical guide marks a Z position, such as the face of a shoulder, and a horizontal guide marks a diameter. Turning to a shoulder with a guide active works the same way as milling to one: feed until the readout reaches zero.

Modal Functions

Three of the mode toggle buttons on the graphical view work off guide activation. The buttons themselves are icon-only and are described, along with the rest of the toggles, in the "Graphical View Display" guide; this section covers what each mode does during guide work.

Guide Snap

Guide snap, toggled with the button marked with a magnet pointing at a line, selects guides for you. When the mode is on, TouchDRO watches the direction of travel and activates the guide the cutter is heading toward, so the readout is always counting down to the next boundary. Reversing the feed direction switches the selection to the guide behind you. Guide snap is available in TouchDRO Plus.

Automatic Proximity Warning

When the automatic proximity warning mode, toggled with the speaker button, is on, activating a guide arms the near-zero warning for the guide's axis, targeted at the guide. As the cutter approaches the boundary, the warning starts beeping, and the beeps turn into a solid tone near zero. The warning behaves identically to the one in the "Axis Details" dialog, and deactivating the guide disarms it.

Automatic Cutter Radius Compensation

When this mode, toggled with the button marked with an end mill approaching a line, is on and a cutter is selected via the "Cutter Radius Compensation" function, activating a guide recalculates the tool offset direction so that the readout shows the position of the edge of the cutter closest to the guide. The readout then reads zero when the edge of the cutter, rather than its center, is on the boundary.

This mode is only available when the machine type is set to "Vertical Mill" or "Horizontal Mill" in the TouchDRO application preferences.

How To Use Guides

Cutting a Slot on a Mill

Goal: cut a horizontal slot that is 0.75 in wide using a 1/4 in cutter; slot depth is irrelevant for the purposes of this example.

  1. Select a cutter:
    1. Open the "Cutter Radius Compensation" dialog
    2. Enter 0.25 into the "Tool Diameter" field
    3. Select inches, if needed
    4. Set the tool position to the center
    5. Press "Set Radius Compensation"
  2. Move the cutter to the centerline of the desired slot location
  3. Switch to the graphical view; if your tablet is in vertical orientation, this step is not necessary
  4. Add two horizontal guides, one on each side of the centerline:
    1. Long-press an empty area of the projection view to open the "Add Guide Line" dialog
    2. Enter "++0.75/2" (or "++0.375") into the "Position" field, select the "Horizontal" orientation, and press "Add Guide"
    3. Open the "Add Guide Line" dialog again, enter "--0.75/2" (or "--0.375"), and press "Add Guide"
  5. Turn on the automatic cutter radius compensation mode
  6. Tap the top guide and move the table until the axis readout shows 0.0
  7. Make one or more cuts as needed to achieve the desired depth
  8. Tap the bottom guide and repeat the previous two steps
  9. Remove the material in the middle

Cutting a Rectangular Pocket on a Mill

Goal: cut a square pocket that measures 1.5 in by 1.5 in.

  1. Select a cutter, as in step 1 above
  2. Move the cutter to one corner of the desired pocket
  3. Switch to the graphical view, unless your tablet is in vertical orientation
  4. Add two horizontal guides: one at the current position, using the two-arrow sync button, and one 1.5 in away, using "++1.5" or "--1.5", depending on which way the pocket runs
  5. Add two vertical guides the same way
  6. Turn on the automatic cutter radius compensation and automatic proximity warning modes
  7. Tap the cutter circle and select the offset direction that places the cutter inside the pocket
  8. Activate the vertical guide on the far side of the pocket
  9. Plunge the end mill and cut toward the activated guide. When you get to within 0.1 in, the proximity warning starts beeping; as you keep moving, the beeps turn into a solid tone. At that point, the edge of the cutter is within 0.005 in of the pocket wall
  10. Activate the next guide and mill toward it; stop when the beeps turn into a solid tone
  11. Repeat the previous step for the remaining two guides
  12. Mill away the material in the middle
  13. Repeat the last four steps as many times as needed to achieve the desired depth
  14. For the cleanup pass, keep moving toward each guide until the solid tone stops and the readout shows 0.0; this pass produces a clean sidewall