When I tile a long part through a short machine, how do I move the board accurately between tiles?

Why tiles miss

The Toolpath Tiling Manager splits the toolpaths correctly, but it cannot move the wood for you. Each tile is output so it cuts in the same area of the machine, which means the board has to slide by exactly the tile length and stay parallel. Any error in that move shows as a step in the cut. The answer is a fence plus registration pins.

The pin and fence method (as published by a machine maker)

In the design

1. Set the job origin to the lower left corner.
2. Draw a rectangle for each tile, the width of the board and one tile long, and stack them along the feed direction with the alignment tools.
3. Draw 1/4 inch circles for dowel pins at the lower left and lower right of each rectangle, kept in the waste area outside the finished part. Position them with the alignment and move tools, not by eye, because the tiling only works if every set of holes is spaced identically.
4. Make a toolpath for the hole sets, cutting 1/4 inch deeper than the material thickness so the holes continue into the spoilboard.
5. Create the real toolpaths for the whole part as normal, then open the Tiling Manager, choose Feed-through in X or Y, and set the tile size to match your rectangles.

When saving

• Save the registration hole toolpaths with Output Tiled Toolpaths unchecked. If they are tiled, the tool cannot reach the next set of holes because they lie outside tile 1.
• Save the part toolpaths with Output Tiled Toolpaths checked. You get one file per tile.

At the machine

1. Fix a fence to the spoilboard, parallel to the feed axis. The tutorial checks it by jogging a V-bit tip along both ends.
2. Zero X and Y at the board corner. Cut the registration holes, then run tile 1.
3. Unclamp, slide the board along the fence, and drop dowel pins through the next set of holes into the holes already in the spoilboard.
4. Clamp outside the cutting area, support the overhanging end, and run tile 2. Repeat.

Overlap

The official documentation says overlap matters most for Individual Tiles cut from separate pieces, where it should be at least the tool radius for shaped bits such as V-bits. For feed-through on one board it is mainly a margin for setup error.

Pro tips

• Pull a pin if it sits in the path of the next toolpath.
• Z is re-zeroed after each bit change, not after each slide, as long as the board stays flat on the same spoilboard.
• Machine smallest tile first puts the leftover short tile at the beginning instead of the end.