How do I set up and execute a two-sided (double-sided) machining job in VCarve Pro & Aspire with accurate registration?

Overview

Two-sided (double-sided) machining lets you cut both sides of a piece of material in one project file. The software manages the mirror transformation so the top and bottom designs align when the material is flipped. It is used for signs with features on both faces, 3D reliefs from both sides, and thick carved pieces where single-sided depth is not enough.

Setting Up a Two-Sided Job

1. Open the Job Setup form (File > New, or Edit > Job Size and Position for an existing job)
2. Set material dimensions (width, height, thickness)
3. Select the Double Sided job type
4. Under Flip Direction Between Sides, choose horizontal or vertical flipping:

• Horizontal: you turn the board over like a page (left edge becomes right edge).
• Vertical: you turn the board end over end (top edge becomes bottom edge).
• The software uses this choice to manage the alignment of the geometry for each side, so it must match how you will physically flip the material.

5. Set Z Zero Position:

• Material Surface: Z zero is the top surface of the material on each side.
• Machine Bed: Z zero is the bed or table of the machine.
• Zero off same side (option): Z zero references the same physical location whether or not the material is flipped.

6. Click OK

Working in a Two-Sided File

• Top/Bottom toggle: Icons on the View toolbar above the 2D view switch the active side.
• All drawing and toolpath creation applies to the active side.
• To see components from both sides together, use Multi Sided View in the 3D view.
• When you switch sides, the software shows the mirrored view as it would appear from the other face.
• Components can be created independently per side, or copied or moved to the opposite side with the right-click option.

Z-Zero Settings

This is the most critical and confusing setting in two-sided work.

Material Surface:

• Z zero for Side 1 is the top of the material when it is face-up.
• Z zero for Side 2 is the top of the material after flipping (the original bottom).
• Set each side's Z zero at the machine.
• Best for decorative work and 3D carvings that do not need to meet in the middle.

Machine Bed:

• Both sides reference the spoilboard surface as Z0.
• Z depths are absolute, not relative to the material surface.
• Useful for through-cuts where features on both sides must meet.
• Requires a flat, consistently surfaced spoilboard.

Registration: The Most Critical Part

Registration is how you make sure the material goes back in the same position and orientation after flipping. If registration fails, top and bottom do not align.

Method 1: Dowel pins (most reliable)

1. Add two registration hole vectors (for example 0.25" circles) as a mirrored pair about the flip axis: the same distance either side of the job center line you flip around. For a horizontal flip that line is the vertical center line, so both holes sit at the same Y and equal distances left and right of center. Holes placed directly on that center line also work.
2. Set them up as part of the Side 1 toolpaths and drill them first, through the material and into the spoilboard, before machining anything else.
3. Insert snug dowel pins into the spoilboard holes.
4. Machine the rest of Side 1 with the material sitting over the pins.
5. Flip the material and drop it back over the pins. Because the holes are mirror images about the flip axis, they land back on the pins.
6. Machine Side 2.

Keeping the board from going back rotated 180 degrees: with a mirrored pair, a board turned the wrong way can still fit both pins. Mark one edge of the stock (for example with a pencil arrow) and always keep that mark toward the same side of the machine. Do not move the holes off the mirrored positions to solve this, because that breaks the alignment.

Tips:

• Dowels must be a snug fit. Pre-made dowels are often undersized, so test fit.
• Position the holes as far apart as practical. Further apart gives more accurate angular alignment.

Method 2: Center datum with a jig

1. Set the job origin at the center of the material.
2. Machine a jig, or screw scrap wood fences to the spoilboard, to make a snug pocket the size of the material.
3. Place the material in the jig and machine Side 1.
4. Flip the material and drop it back in the jig. The center stays centered.
5. Machine Side 2.

The jig method removes the need for precise edge measurement, and slight size variation in the material does not cause misalignment because the jig positions from the center. The disadvantage is that the jig must be rebuilt for each material size and thickness.

Critical machine requirement:

For two-sided work to align, the machine gantry must be truly square to the Y axis, and the Z axis must be perpendicular to the spoilboard. Any existing misalignment doubles on the second side. Square the machine before attempting two-sided jobs.

Saving Toolpaths

Side 1 and Side 2 toolpaths are saved as separate files:

• Enable Add side to toolpath name before saving. This adds the side name to each saved toolpath name so you cannot confuse them at the machine.
• Save all Side 1 toolpaths first.
• Switch to Side 2 and save all Side 2 toolpaths.
• At the machine: run the Side 1 file, flip the material, run the Side 2 file.

Common Mistakes

• Wrong flip direction set in Job Setup: the software mirrors the wrong axis and the Side 2 design is offset. Match exactly how the physical flip will happen.
• Registration holes that are not mirrored about the flip axis: the holes will not drop back over the pins after the flip.
• Drilling the registration holes after the other side 1 work, or not at all: the pins must exist before the flip.
• Changing XY zero between sides: never reset XY zero between sides. Set it once and leave it.
• Material not square to the machine: tiny squareness errors double on the second side.
• Z-zero setting mismatch: if the software is set to Machine Bed Z but you zero off the material surface at the machine, cut depths are wrong. Match the settings exactly.
• Using a finished-size piece of material: if it is slightly undersized or out of square, registration becomes unreliable. Start with oversized material and trim afterward.