How do I do a safe dry run in PathPilot (single block, feed hold, graphics) before running a new program?

Running a new CNC program for the first time is when most mistakes happen—but PathPilot gives you several tools to do a very safe dry run before you ever risk a crash or scrap a part. By combining graphics simulation, Single Block, Feed Hold, and conservative machine setup, you can validate your code step by step.

Below is a practical, shop‑friendly process you can follow every time you’re about to run a new or edited program in PathPilot.

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1. Prep the machine for a safe dry run

Before you even think about pressing Cycle Start, get the physical side of the setup as safe as possible.

1. Mount a safe “dummy” setup if you can

   • Use scrap stock instead of your good material.
   • If you’re just checking motion (not cutting), you can even run with no workpiece and keep the tool well above the table.

2. Install the correct tool, but start with extra clearance

   • Load the tool (or a short “stub” tool) you plan to run.
   • Set your work offset (G54, etc.) conservatively so the toolpath will run:
     • Above the part, or
     • Over empty table space.
   • Many operators shift the Z‑zero up several inches for the first dry run so the cutter never comes near the part.

3. Check your work and tool offsets

   • Verify your G54–G59 or other active work offset is correct.
   • Confirm the tool length offset (H value) is set and active.
   • Make sure your machine home has been set and referenced.

4. Set feed and spindle overrides to “safe” values

   • Turn feed override way down (e.g., 10–25%) for the first check.
   • Consider turning the spindle off for the initial motion-only dry run, or set a low speed and leave the tool above the part.

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2. Use PathPilot graphics to simulate your program

PathPilot’s graphical backplot is your first line of defense. It lets you see what the program thinks it will do before real hardware moves.

1. Load the G‑code program

   • Open or load your file into PathPilot’s program window.
   • Confirm the correct file is active.

2. Open the Graphics or Preview view

   • Switch to the screen/tab that shows the toolpath graphics.
   • You should see:
     • The part outline / toolpath lines
     • Rapid moves (often a different color)
     • Feed moves
     • Arcs and drills (if present)

3. Check the basics in the preview

   • Is the part located where you expect on the table?
   • Does Z move in the right direction (negative into the part, positive away)?
   • Are there any obvious rapids straight through clamps, vises, or the part?
   • Watch for:
     • Unusually long rapids
     • Holes or pockets that go way deeper than expected

4. Simulate motion in software

   • Use the graphics mode to “run” through the program virtually.
   • Speed up and slow down the simulation to inspect critical areas like:
     • First tool engagement
     • Deep drilling cycles
     • Tool changes and repositioning

If anything looks wrong in graphics, fix the program first—either by editing the G‑code directly in PathPilot or using the conversational templates, then re‑simulate.

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3. Step through the program with Single Block

Once the graphics look correct, the next layer of safety is Single Block. This makes the control execute only one line (or “block”) of G‑code at a time.

1. Enable Single Block mode

   • Turn on the Single Block option in PathPilot.
   • Confirm the indicator shows that Single Block is active.

2. Start the program safely

   • Move the machine to a safe starting position:
     • Z high above the part
     • X and Y centered or in a clear area
   • Press Cycle Start.
   • The machine will run the first line of code and then stop, waiting for you to press Cycle Start again for the next line.

3. Watch each move carefully

   • After each block:
     • Check where the tool moved.
     • Confirm the direction and distance match the code.
     • Verify Z clearances are what you expect.
   • Use the graphics and DROs (digital readouts) at the same time:
     • Check that the tool position in the graphics matches where the real tool is.

4. Pay special attention to “danger” lines

   • First rapid move toward the part
   • First plunge (G1/G81/G83, etc.)
   • Any tool change + reposition
   • Deep drilling or tapping cycles

Take your time here—this is where you catch most setup mistakes before anything breaks.

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4. Use Feed Hold as your emergency brake

Feed Hold is your instant pause. It stops all axis motion while leaving the control and, usually, spindle powered (depending on settings).

1. Know where Feed Hold is

   • Identify the Feed Hold button on the PathPilot interface and on your operator console (if equipped).
   • Make a habit of keeping a hand close to it during first runs.

2. When to press Feed Hold

   • Anytime motion doesn’t look right.
   • If the tool is getting too close to the part or fixtures.
   • If you want to double‑check a position before continuing.
   • At the start of a new operation or tool change to confirm everything is correct.

3. What to do after a Feed Hold

   • Verify the current position (X/Y/Z on the DROs).
   • Compare the current G‑code line with where the tool actually is.
   • Decide whether to:
     • Resume (Cycle Start)
     • Single Block the next few lines
     • Stop the program and fix your code or setup

Feed Hold is your “I’m not sure about this” safety net—use it often during a new program’s first run.

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5. Combine graphics, Single Block, and Feed Hold for a full dry run

Here’s a simple, repeatable procedure to safely prove out any new program in PathPilot.

Step 1: Graphics‑only verification

1. Load the program.
2. Verify work offset and tool numbers in code.
3. Run the graphics simulation:
   • Watch for collisions, crazy depths, or incorrect part location.
4. Fix and re‑simulate as needed.

Step 2: Air‑cut dry run with Single Block

1. Raise Z‑zero (or shift G54 Z) so the tool runs well above the part/table.
2. Turn spindle off or set it low, and keep feed override slow.
3. Enable Single Block.
4. Press Cycle Start and step:
   • Through initialization lines (units, work offset, tool change)
   • Through first approach moves
   • Through first cut moves (still in air)
5. Use Feed Hold any time you’re unsure.

Step 3: Continuous air‑cut

1. Once you trust the motion:
   • Turn off Single Block.
   • Keep feed override low.
2. Run the entire program in air.
3. Watch:
   • Clearance planes
   • Retracts between operations
   • Tool changes and returns to part

Step 4: First real cut with conservative parameters

1. Set Z‑zero accurately on the part.
2. Use the correct spindle speed, but:
   • Keep feed override lower than programmed (e.g., 50–80%).
3. Keep your hand near Feed Hold.
4. For critical sections, re‑enable Single Block just for that area.
5. Once you’ve proven the program, gradually bring feed override up to 100% for production.

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6. Fix issues quickly using PathPilot’s conversational tools

If your dry run exposes a problem—wrong depth, missing chamfer, incorrect hole location—PathPilot’s conversational programming makes it easy to tweak or rebuild sections of code.

• Use the visual conversational templates to:
  • Re‑define a drilling pattern, pocket, or contour.
  • Generate new G‑code with proper step‑downs and clearances.
• Edit the G‑code directly in PathPilot if you’re comfortable:
  • Correct a feed rate
  • Adjust a clearance plane (R‑value)
  • Change speeds or depths

After any change, repeat the graphics simulation and at least a short Single Block dry run over the edited portion.

You can also sharpen your programming skills and practice this entire dry‑run workflow on PathPilot HUB, the online environment that lets you test PathPilot and create usable G‑code without tying up your real machine. It’s free to log in and is ideal for rehearsing new setups and programs.

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7. Best practices for safe first runs in PathPilot

To keep your machine and tooling safe, turn the dry run process into a standard checklist:

• Always:
  • Simulate in graphics first.
  • Do an air‑cut before touching the part.
  • Start with Single Block and low feed override.
  • Keep a hand on Feed Hold.
• Be extra careful when:
  • Using new workholding
  • Running posts from a new CAM system
  • Editing someone else’s code
  • Trying deeper cuts or more aggressive strategies than usual

By following this structured approach—graphics → Single Block → Feed Hold → conservative first cut—you’ll dramatically reduce the risk of crashes and scrap when running new programs in PathPilot.