How does Merge Toolpaths work in VCarve Pro & Aspire, and when should I use Merge By Part?

Overview

Merge Toolpaths combines two or more toolpaths that use the same tool (for example pocketing and profiling) into a single optimized toolpath. Instead of running Toolpath A fully and then starting Toolpath B, the merged result is ordered to cut more efficiently, which reduces rapid move distance and machining time. It is available in both VCarve Pro and Aspire.

Key requirement: All toolpaths being merged must use the same tool. Toolpaths using different tools cannot be merged together.

How to Merge

1. Create all the toolpaths you want to merge (using the same tool)
2. Make all target toolpaths visible (check their checkboxes in the Toolpath List). The merge tool always tries to merge ALL visible toolpaths, so hide any you do not want merged
3. Click Merge Visible Toolpaths in the Toolpaths menu. This opens the Create Merged Toolpath form
4. The toolpaths to be merged appear in the box marked "Toolpaths to be merged"
5. Set the ordering options (see below)
6. Enter a name for the merged toolpath
7. Click Merge Toolpaths

The original toolpaths are not modified. The merge creates a new toolpath, and the originals remain for reference or recalculation. If you edit an original toolpath, merge again so the merged toolpath reflects the change.

Ordering Options

The form has several ordering checkboxes. When the toolpaths are merged, each ordering strategy that you ticked is calculated and the quickest result is chosen.

Merge By Part Option

This is the most important option and the most misunderstood.

Without Merge By Part: The merge optimizes the whole toolpath. Example: pocket all circles first across the entire sheet, then profile all squares. All pockets are done before any profile cuts.

With Merge By Part: The merge also groups related geometry to cut together. Example: pocket the circles inside Square 1, then profile Square 1, move to Square 2, pocket Square 2's circles, profile Square 2, and so on.

The critical use case: When your toolpaths have a required order (for example pocket before profile, so the part doesn't fall out), Merge By Part keeps that order for each part. Without it, you might profile some parts before their pockets are cut.

Merge By Part respects the order of toolpaths in the Toolpath List and the order of contours within each toolpath, as far as it can. If contours of two different toolpaths lie within the same part, the contour of the first toolpath is cut before the contour of the second. Reordering the toolpaths in the list (for example A, B, C versus B, C, A) changes the merged result.

Practical Example

Production sign run: You have 12 identical badges on a sheet, each needing a pocket (letter recess) and a profile cutout.

• Without Merge By Part: All 12 pockets might be cut first, then all 12 profiles. The last badge to be profiled has been sitting loose for a while.
• With Merge By Part: Pocket Badge 1, profile Badge 1 (secured before moving on), pocket Badge 2, profile Badge 2, and so on. Each badge is fully processed before moving to the next, which is safer for holding parts.

Feeds and Speeds

If the toolpaths being merged have different feeds and speeds (even with the same tool, you might have set different feeds for different operations), the merge automatically changes the feeds and speeds for the different parts of the merged toolpath. Check that your post-processor supports multiple feed rates in a single file.