How do I set up a 3D carving in Aspire: standalone vs. dish/recess, material setup, and the most important settings to get right?

Overview

A common entry point into 3D is carving an imported STL or clipart model. There are two main approaches: standalone 3D carving (the model sits directly in the material, with the background machined away or left at the surface) and dish carving (the model is recessed into a dish in the material surface). Choosing the approach and setting up Material Setup correctly is a critical part of 3D work.

Two Approaches: Standalone vs. Dish

Standalone 3D Carving

The model is carved directly into the material. The machine cuts down from the material surface into the model shape.

Workflow:

1. Import or place your model.
2. In Material Setup, position the model within the material (for example Gap Above Model of 0 or a small amount).
3. Choose a machining boundary, such as a boundary vector around the model, for the toolpaths.
4. Calculate 3D Roughing (if needed) and 3D Finishing toolpaths.

Best for: deep carvings, full-depth reliefs, and signs where the background is the material surface.

Dish Carving

A shallow dish is machined into the material, and the 3D model sits inside it, recessed below the material surface.

Benefits:

• It can reduce machining time, because roughing only has to clear the shallow dish rather than a large surrounding area.
• It reduces material waste.
• The flat material surface acts as a natural border around the carving.
• It suits plaques and signs where the carving sits in a recessed panel.

Workflow:

1. Draw the dish outline (circle, rectangle or custom shape).
2. Create a dome from it with a Round shape.
3. Set the dome's Combine Mode to Subtract, and leave Base Height at 0. The dome's height is subtracted from the surface, so the dish is as deep as the dome is tall. Do not also give the dome a negative Base Height: subtracting a shape that has been lowered below zero adds to the surface instead of cutting into it.
4. Place your 3D model inside the dish and use Base Height (or Level Base Height) to set where it sits in the recess.
5. Check the result in the 3D view, then calculate toolpaths. Roughing removes the dish material, and finishing follows the full model-and-dish surface.

Test the dish on a scrap piece first.

Best for: plaques, decorative inset panels, projects where machining time matters, and designs where the flat surrounding material should remain as the border.

Material Setup: A Critical Step

The Material Setup form controls where the 3D model sits within the physical material block. If this is wrong, the router either cuts too deep or does not reach the full model depth. A summary is also shown on the Toolpaths tab.

Key settings:

• Gap Above Model: the distance between the top of your model and the top surface of the material. It is often 0 for surface carvings.
• Gap Below Model: the distance between the bottom of the model and the bottom surface of the material. Leave enough material below the model so you do not cut through the bottom of the board.
• Model Thickness: reports the thickness of your composite model, built from all the currently visible components.
• Thickness (of the material): the model must be thinner than the material. You can position the model within the material block with either gap, or double-click one of the three lines next to the slider to place the model at the top, center or bottom of the material.

Model Resolution: it only affects the 3D model, not 2D geometry. A higher resolution gives more detail in 3D but slower calculation. For a job with a large material area and a small 3D model, set the job size close to the model size so the resolution is spent where you need it.

Reducing Model Thickness Without Losing Detail

When an imported full 3D model is too tall for your material, you have two options:

1. Scale Model Height: scales the Z values proportionally. It works well for modest reductions but can lose fine detail at extreme reductions.
2. Emboss Component (Aspire): the better approach for large height reductions on imported high-relief models, because it preserves surface detail better than simple scaling. Select the component, open Emboss Component, set the target height with the Scale Height slider, and use Detail Smoothness to reduce the noise from the rescaling. The documentation says that in general, the greater the Scale Height, the more Detail Smoothness is needed.

Which to use: for components built in Aspire (Create Shape, Two Rail Sweep and so on), Scale Model Height is fine. For imported full 3D models, use Emboss for significant reductions.

Boundary Offset

In the 3D Roughing and 3D Finishing forms, the Machining Limit Boundary is the area in which the tool operates. If you are machining a raised object, the tool often will not fully machine down the edge. Boundary Offset increases the size of the selected machining boundary so the tool can go past the actual edge. In the roughing toolpath, the tool tip (not the cutting side) will not leave the machining boundary. A starting point is an offset of about the tool radius. Check the preview to confirm the edges are fully cut.

Choosing Bits for 3D Work

Roughing (3D Rough Toolpath):

• A flat end mill, or a larger tapered ball nose, is commonly used. Size it to the model.
• Set a Machining Allowance. This virtual thickness is added to the model so roughing leaves a skin of material. The skin helps prevent chipping on the finished surface, and it ensures the finishing tool always has some material to remove. Set it appropriately for the tool used in finishing, to avoid damaging the bit. A few hundredths of an inch is a common starting point.

Finishing (3D Finish Toolpath):

• A ball nose or tapered ball nose end mill. A tapered ball nose may offer more strength with smaller tool sizes.
• Common sizes are 1/8 inch for general work and 1/16 inch for fine detail.
• The documentation gives a stepover of 8 to 12 percent of the tool diameter as typical.
• The finishing toolpath is always a single pass and does not use the tool's pass depth.

When roughing is not needed: if the model is shallow and your finishing tool can safely take the full depth, you may skip roughing and go straight to finishing.

Toolpath Preview Simulation Quality

Two things control 3D preview quality:

1. Toolpaths menu > Preview Simulation Quality: controls the number of points in the toolpath preview simulation. The higher the quality, the slower the simulation, but it does not affect the actual cutting.
2. Job and material size: the preview uses a limited number of points across the whole job. A large job spreads them thin. Sizing the job to just fit your project concentrates them on the model for a sharper preview.