# CAM: 3-Axis VMC, Fusion 360, round dies (no “Rotary” toolpaths)

**Scope:** how to program **cylindrical dies** (main form die, rollers, **optional** “knife in vice / stock in spindle” play) in **Fusion 360 Manufacturing** when you **do not** have the **Rotary** / 4th-axis CAM package. Everything below assumes the usual **3-axis** mill **op set**: **2D** (face, pocket, contour, drill, boring, trace), **3D** (adaptive, parallel, contour, rest machining, **optional** flow/morph on license), and **WCS** gymnastics.

**Hard truth (read once):** Standard Fusion **3-axis** posts emit **G1/G2/G3** in **table X and Y** with **Z** as depth. That matches **a spinning end mill** moving in **X–Y** around a **rigid** workpiece, **or** a **rigid** workpiece in a **chuck** with the **spindle stopped** (M5) during the cut. It does **not** automatically model **C-axis** “part spins, tool is fixed in X” **lathe** motion. If you **really** need **S** synchronized with **radial infeed** on a **VMC** without a post that emulates a lathe, you will be in **custom G-code** or **rethinking the setup**—not in default Fusion mill ops.

**Practical split:**

| Mode | What to do in Fusion | When it works |
| :-- | :-- | :-- |
| **A — Spindle locked (M5) during the program; part in collet; tool in spindle (normal 3-axis)** | Full **2D/3D** toolpaths below. WCS **Z** along part axis, origin on center. | **Recommended** for actually getting **Fusion → post → machine** to match. “Stock in chuck” is just a **rigid** holder. |
| **B — Cutter in vice, work in spinning spindle (abused lathe)** | Fusion **3-axis** mill **will not** magic this into a lathe program. **Fallbacks:** (1) **Hand-written** or **reused** lathe sub ( **G1** **X** (radial) **+** **S** on **C** or hybrid post); (2) **lock** the spindle, move **work** to **a normal** 3axis setup; (3) do **turning** on a **real lathe** for the revolved work, only **milling** the rest. | **Creative in the machine**, not in **default** **Fusion** **3-axis**. |

The rest of this file is **Mode A** (or **normal** 3axis with part on **soft jaws** in a **vice** if you do not use the spindle for holding).

---

## 1. Model + setup orientation in Fusion (critical)

* Put the **part axis of revolution** on the **+Z** of the **WCS** you will use in CAM. **Origin (X0 Y0)** = **center of rotation**; **+Z** = from **front face of die** (or the face you want as **0**) **into** the hub / body.
* **Machine X Y Z:** match your **VMC** convention (e.g. **+Z = down** in CAM tool axis); Fusion **Setup** will align **WCS** to the **milling** directions so **2D** in **T** (top) view = **X–Y** in the plane **perpendicular** to **spindle** when the **part Z** = **spindle** axis. On a **vertical** mill, that means your **part model’s** **Z** is the **quill** axis: **2D T** = cuts in **planes of constant Z** = **facing the top of the disc** in that orientation.

If your part is **horizontal** in the file, use **Edit → Transform** in Design or a **WCS in Setup** to align the **cylinder axis to tool Z** (Setup → origin & orientation) before generating toolpaths.

---

## 2. 2D ops that carry most of the work (circular symmetry)

| Goal | Fusion op | How to be “creative” without Rotary |
| :-- | :-- | :-- |
| **Top face of disc; hub lip** | **2D Face** | **Pick** the **circular** boundary; **heights** in **Z**; multiple faces if you need **facing in steps**. |
| **Outer rim Ø (e.g. 270)** — “turning” the OD | **2D Contour** (outer circle) **or** **2D Pocket** (annular **outer − inner** ring) | **Roughing:** enable **multiple** **roughing** **offset** **passes** in **2D** **Contour** **(stock to leave + stepover)**. **Z:** use **Helical** **ramp** *or* **Multi-step** **depths** to walk **down** the **cylinder** height. **2D** **Pocket** (ring between two radii) is often faster for **bulk** **removal** on a **pancake** blank. |
| **Inner hub bore (e.g. Ø 40 finish)** | **2D** **Pocket** (circular) → **2D** **Bore** / **Boring** in fusion **(Drill** for spot + **Bore** with **spring** **passes)** or **2D** **Pocket** **spiral** to depth | Ream/ream-bore in machine if you need H7. |
| **Chamfer / break sharp lip on groove** | **2D Chamfer** | If geometry allows **2D** **chamfer**; else **3D** **Pencil** or file. |
| **Bolt hole circle on the face** | **Drill** (pattern) | **Canned** peck, **+Thread** in **second** op. |

**Tip:** for a **cylinder** in **+Z**, your **“turn”** in CAM is: **a stack of circular cuts** in **X–Y** with **Z** **stepping** = **2D** **Contour** (circle) **+** **multiple** **Z** **levels** in one operation (look at **Multiple Depths** / **Ramp**), **or** a **2D** **Pocket** **one** **ring** **thick** in **R** and **repeated** in **Z** in separate ops if the UI is finicky.

---

## 3. 3D ops for the **tube groove** (no wrap, no Rotary)

The groove is **3D** even if the solid is a **surface of revolution**: Fusion will not cut it with a **single** 2D pocket on the **T** view unless the groove is modeled as a **2D** profile and **swept** in a way that is **milled** with **2D** **Pocket** on **multiple** **C**-positions (see §4).

| Goal | Fusion op | Notes |
| :-- | :-- | :-- |
| **Rough the groove (material removal)** | **3D** **Adaptive Clearing** | **Stock** and **containment** to **cylinder** **only**; **rough** first with **larger** tool, **ball** or **flat**. |
| **Semi-finish** walls / floor | **3D** **Parallel** | **Tilt** in **0**; limit **containment** to **the** **groove** **region**; **climb** **only** if you want. |
| **Flow along** the **groove** **center** | **3D** **Contour** | **Select** the **driven** **chain** (bottom, walls); **tolerance 0.05** class. |
| **Pencil** **corners** | **3D** **Pencil** (if in your build) or **2nd** **Contour** with **tight** **tolerance** | For **U**-groove **fillets** if **ball** **does** **not** **get** in. |
| **Steep and shallow** | **3D** **Scallop** (sometimes) / **3D** **Morphed** (extension) | **License**-dependent. |

**Geometry trick:** If you have **only** a **partial** model, **export** a **simplified** **solid** with a **recess** the **U**-groove, **3D** **Pocket** / **3D** **adaptive** **+** **rest** **roughing** will clear.

**If** **3D** is fighting you: use **a round** (ball) end mill, **3D** **Parallel** on the **cylindrical** **OD** with **Z** **limits** **only** **where** the **groove** **wraps**—it is **wasteful** but **dumb and robust**.

---

## 4. “Creative” = **indexing** + 2D (poor man’s 4th axis, still no Rotary in CAM)

When the **groove** must be cut **without** full 3D surfacing, **segment** the **perimeter** of the **cylinder** into **N** **stops** (e.g. **N = 12** → 30°):

1. **M0** / **M5**; **reorient** the **chuck** by hand (DRO, **punch** marks) so the **next** **sector** of the **rim** is **facing** **+X** (or **+Y**), **WCS** unchanged.
2. **2D** **Pocket** or **2D** **Contour** that **only** **covers** **1/N** of the **cross-section** in **T** (top) **view** = **a** **wedge** **pocket** **+** **depth** **=** **groove** **depth** **—** *approximate* **a** **slice** of the **groove**.
3. **Repeat** **N** **times** (duplicate **op** in Fusion or **N** **Setups** with different **C** in **name** for **post**-merge **manually**).

**Quality** is only as good as **N**; **N** large = more **operator** time; for a **continuous** **groove** **rim**, **3D** **ops** in §3 are **usually** **less** **pain** than `N > 8`.

---

## 5. “Knife in vice” and Fusion: what is realistic

* If the **spindle** stays **locked** and you **milled** the **diameter** with **2D** **G2** / **G3** in **X–Y**, the **cutting** tool is normally **in** the **spindle** (end mill), not a **fixed** knife in the vice, unless you have a **second** head (not pure 3-axis). So “knife in vice + Fusion 3-axis **mill** G-code” and **G2**/**G3** **in the table** **X–Y** are **in conflict** unless the post maps moves to a **lathe**-style **X** feed and **spindle** as **C** (not a default 3-axis post).
* If you still run **Mode B** in the real machine, this file cannot name a **universal** Fusion op; use a **control**-appropriate **sub** or **hand** G-code, or a **dedicated** turning CAM path if your post supports it.

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## 6. Cheat sheet (3-axis mill / Fusion, **no** Rotary)

| Part feature | Prefer these Fusion ops (Mode A) |
| :-- | :-- |
| **Flat** face, **facing** | **2D Face** |
| **Cyl** **OD** **rough/finish** | **2D Contour** (circle) **+** **roughing** **&** **multi-depth Z**; or **2D** **Pocket** **(ring)** |
| **Hub** **bore** | **2D Pocket** / **Bore** / peck **Drill** |
| **Groove** in **round** **rim** | **3D** **Adaptive** → **3D** **Parallel** / **3D** **Contour** (ball/ bull for floor) |
| **Groove** **despair** | **Indexed 2D** (§4) or **turn** the **rough** on a **real** **lathe**, then **2D/3D** for **the** **flank** only |

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## 7. Links in this repo

* **Sizes, bill, tolerances:** `readme` **Section 7**.
* **Conventional** **plate** **CAM** (table **VMC**): `cad/base_plate.scad` and **2D** from **T** in Fusion.

*Guidance only; your **post, machine, and safe practice** are on you.*