project : tube-bender 1/2

projects/tube-bender/cad/README.md

@@ -0,0 +1,56 @@
+# CAD Files — Tube Bender
+
+All CAD source files live here.  
+Export chain: **OpenSCAD → FreeCAD → STEP → Fusion 360 → CAM**
+
+## Files
+
+| File | Description | Status |
+|------|-------------|--------|
+| `base_plate.scad` | Parametric base plate (400 × 300 × 12 mm, fully adjustable) | ✅ |
+| `side_plates.scad` | Vertical side plates with pivot bore | 🔜 |
+| `bend_die.scad` | Main form die (parametric by tube OD + CLR) | 🔜 |
+| `clamp_block.scad` | Clamp / clamp die | 🔜 |
+| `pressure_die.scad` | Follower / pressure die assembly | 🔜 |
+| `bending_arm.scad` | Lever arm with handle provision (3-piece assembly) | ✅ |
+| `pivot_shaft.scad` | Pivot shaft + bushing | 🔜 |
+| `assembly.scad` | Full machine assembly (includes all parts) | 🔜 |
+
+## Export Workflow
+
+### 1. OpenSCAD → STL / AMF
+```
+File → Export → Export as STL…
+```
+For FreeCAD import, **AMF** or **STL** both work.  
+Use `$fn = 128` or higher before final export.
+
+### 2. FreeCAD — STL/AMF → STEP
+1. Open FreeCAD → **Part** workbench.
+2. `File → Import` → select `.stl` / `.amf`.
+3. `Part → Convert to Solid`.
+4. `File → Export` → choose **STEP (*.step)**.
+
+### 3. Fusion 360 — STEP import
+1. `File → Open → Open from my computer` → select `.step`.
+2. Review bodies, set material.
+3. Proceed to **CAM** workspace.
+
+### 4. CAM
+- Set up stock, WCS (Work Coordinate System) at plate bottom face, front-left corner.
+- Operations: face mill, drill (mount holes, side-plate holes), pocket (if enabled).
+
+## Key Parameters (base_plate.scad)
+
+| Variable | Default | Notes |
+|----------|---------|-------|
+| `plate_length` | 400 mm | Front → back |
+| `plate_width` | 300 mm | Left → right |
+| `plate_thickness` | 12 mm | Steel stock |
+| `corner_radius` | 8 mm | Plate corner fillet |
+| `mount_bolt_d` | 14 mm | M12 bench holes |
+| `mount_cbore_d` | 24 mm | Counterbore Ø (0 = none) |
+| `side_plate_gap` | 65 mm | Clear inner gap between side plates |
+| `side_plate_cx` | 220 mm | Bolt pattern centre from front |
+| `receiver_slot_enable` | false | Slot for receiver-tube stand |
+| `pocket_enable` | false | Lightening/chip pockets |

projects/tube-bender/cad/base_plate.scad

@@ -0,0 +1,180 @@
+// =============================================================================
+//  TUBE BENDER — BASE PLATE  (Aluminium)
+//  File   : base_plate.scad
+//  Project: OSR Machines / Tube Bender
+//  Author : PolyMech
+//  Date   : 2026-04-05
+//  Mat    : Aluminium plate (6061-T6 or similar)
+//
+//  Parametric base plate for a manual rotary-draw tube bender.
+//  All critical dimensions are exposed as top-level variables.
+//
+//  Workflow: OpenSCAD → STL/AMF → FreeCAD → STEP → Fusion 360 → CAM
+//
+//  Coordinate origin:
+//    X = along plate length (front → back)
+//    Y = along plate width  (symmetric, left = −Y, right = +Y)
+//    Z = upward  (bottom face at Z = 0)
+// =============================================================================
+
+/* [Plate Body] */
+plate_length = 400; // mm  — front-to-back  (X)
+plate_width = 300; // mm  — left-to-right  (Y)
+plate_thickness = 30; // mm  — stock thickness (12 mm alu plate)
+
+/* [Corner Rounding] */
+corner_radius = 8; // mm  — plate corner fillet (0 = sharp)
+
+/* [Bench / Floor Mounting — 4× corner holes] */
+// M10 cap-head bolt:  clearance hole Ø 11 mm, cbore Ø 18 mm × 10 mm deep
+mount_bolt_d = 11; // mm  — through-hole diameter
+mount_inset_x = 25; // mm  — hole centre inset from plate edge (X)
+mount_inset_y = 25; // mm  — hole centre inset from plate edge (Y)
+mount_cbore_d = 19; // mm  — counterbore Ø on underside  (0 = none)
+mount_cbore_h = 10; // mm  — counterbore depth (must be < plate_thickness)
+
+/* [Side Plate Bolt Holes — 2 holes per side plate, 4 total] */
+// Each vertical side plate lands on the base and is bolted with 2× M10 bolts.
+// The two holes per plate are spaced along X (front / rear) for rotational
+// stability.  Both sides are symmetric about the plate Y centreline.
+//
+// Layout (top view):
+//   front of plate  ←→  back of plate
+//   [SP_BH_F] .............. [SP_BH_R]    ← right side plate
+//   ────────── gap ──────────────────
+//   [SP_BH_F] .............. [SP_BH_R]    ← left  side plate
+
+sp_gap = 65; // mm  — clear gap between inner faces of side plates
+sp_bolt_d = 11; // mm  — M10 clearance hole Ø
+sp_cbore_d = 19; // mm  — counterbore Ø on underside  (0 = none)
+sp_cbore_h = 10; // mm  — counterbore depth
+sp_bolt_y_offset = 20; // mm  — bolt centre offset outward from inner face
+//        (= half side-plate thickness + bolt-edge margin)
+sp_bolt_x_front = 160; // mm  — X position of front bolt (from front edge)
+sp_bolt_x_rear = 280; // mm  — X position of rear  bolt (from front edge)
+
+/* [Pivot Shaft Datum Hole] */
+// Small through-hole on the plate centreline directly below where the pivot
+// shaft will be.  Used as a layout / alignment datum — not structural.
+pivot_datum_x = 220; // mm  — from front edge (should be between sp bolts)
+pivot_datum_d = 8; // mm  — hole Ø  (set 0 to omit)
+
+/* [Receiver Slot — optional, back edge] */
+// Open slot at the back edge so the base can sit over a square receiver tube
+// for stand/vice mounting.  Disabled by default.
+receiver_enable = false;
+receiver_w = 52; // mm  — slot width  (50 mm sq. tube + 2 mm clearance)
+receiver_depth = 50; // mm  — slot depth into plate from back edge
+
+/* [Render Quality] */
+$fn = 64; // facets — use 128+ for final STL export
+
+// =============================================================================
+//  DERIVED VALUES  (calculated — do not edit)
+// =============================================================================
+
+_half_W = plate_width / 2;
+
+// Y centre of each side plate bolt group (measured from plate Y centre)
+_sp_y_R = sp_gap / 2 + sp_bolt_y_offset; // right side  (+Y)
+_sp_y_L = -sp_gap / 2 - sp_bolt_y_offset; // left  side  (−Y)
+
+// =============================================================================
+//  ENTRY POINT
+// =============================================================================
+
+base_plate();
+
+// =============================================================================
+//  MODULE: base_plate
+// =============================================================================
+module base_plate() {
+  difference() {
+    rounded_box(plate_length, plate_width, plate_thickness, corner_radius);
+
+    corner_mount_holes();
+    side_plate_bolt_holes();
+
+    if (pivot_datum_d > 0)
+      translate([pivot_datum_x, 0, -1])
+        cylinder(d=pivot_datum_d, h=plate_thickness + 2);
+
+    if (receiver_enable)
+      receiver_slot();
+  }
+}
+
+// =============================================================================
+//  MODULE: rounded_box
+//  Rectangular solid with optional corner rounding.
+//  Plate front-left-bottom corner sits at origin.
+//  Plate spans [0..L] in X, [−W/2..+W/2] in Y, [0..T] in Z.
+// =============================================================================
+module rounded_box(L, W, T, r) {
+  if (r <= 0) {
+    translate([0, -W / 2, 0]) cube([L, W, T]);
+  } else {
+    union() {
+      translate([r, -W / 2, 0]) cube([L - 2*r, W, T]);
+      translate([0, -W / 2 + r, 0]) cube([L, W - 2*r, T]);
+      for (xp = [r, L - r], yp = [-W / 2 + r, W / 2 - r])
+        translate([xp, yp, 0]) cylinder(r=r, h=T);
+    }
+  }
+}
+
+// =============================================================================
+//  MODULE: corner_mount_holes
+//  4× M10 through-holes at corners with underside counterbores.
+// =============================================================================
+module corner_mount_holes() {
+  xs = [mount_inset_x, plate_length - mount_inset_x];
+  ys = [-_half_W + mount_inset_y, _half_W - mount_inset_y];
+
+  for (xp = xs, yp = ys) {
+    translate([xp, yp, -1]) {
+      cylinder(d=mount_bolt_d, h=plate_thickness + 2); // through
+      if (mount_cbore_d > 0 && mount_cbore_h > 0)
+        cylinder(d=mount_cbore_d, h=mount_cbore_h + 1);
+      // cbore
+    }
+  }
+}
+
+// =============================================================================
+//  MODULE: side_plate_bolt_holes
+//  2 holes per side plate × 2 sides = 4 holes total.
+//  Each hole pair (front / rear) sits at a fixed Y, one per side.
+// =============================================================================
+module side_plate_bolt_holes() {
+  xs = [sp_bolt_x_front, sp_bolt_x_rear];
+  ycs = [_sp_y_R, _sp_y_L];
+
+  for (xp = xs, yp = ycs) {
+    translate([xp, yp, -1]) {
+      cylinder(d=sp_bolt_d, h=plate_thickness + 2); // through
+      if (sp_cbore_d > 0 && sp_cbore_h > 0)
+        cylinder(d=sp_cbore_d, h=sp_cbore_h + 1);
+      // cbore
+    }
+  }
+}
+
+// =============================================================================
+//  MODULE: receiver_slot
+//  Open slot cut into the back edge, centred on Y = 0.
+// =============================================================================
+module receiver_slot() {
+  translate(
+    [
+      plate_length - receiver_depth,
+      -receiver_w / 2,
+      -1,
+    ]
+  )
+    cube([receiver_depth + 1, receiver_w, plate_thickness + 2]);
+}
+
+// =============================================================================
+//  END OF FILE
+// =============================================================================

projects/tube-bender/cad/bending_arm.scad

@@ -0,0 +1,187 @@
+// =============================================================================
+//  TUBE BENDER — BENDING ARM (U-Bracket)
+//  File   : bending_arm.scad
+//  Project: OSR Machines / Tube Bender
+//  Author : PolyMech
+//  Date   : 2026-04-05
+//  Mat    : Aluminium plate (30 mm stock)
+//
+//  Parametric 3-piece bending arm assembly. Includes the top plate, bottom
+//  plate, and the rear spacer block. 
+//
+//  Workflow: OpenSCAD → STL/AMF → FreeCAD → STEP → Fusion 360 → CAM
+// =============================================================================
+
+/* [Export Selection] */
+// Select which part to view or export
+part = "assembly"; // [assembly, top_plate, bottom_plate, spacer]
+
+/* [Basic Dimensions & Stock] */
+plate_thickness = 30; // mm — Stock thickness of top/bottom plates
+inner_gap       = 51; // mm — Clear gap between top and bottom plates (50mm die + 1mm clear)
+arm_width       = 90; // mm — Overall width of the arm
+arm_length      = 250;// mm — Distance from main pivot center to back edge
+
+/* [Pivot Holes] */
+main_pivot_d    = 40; // mm — Main die shaft clearance hole
+counter_die_d   = 30; // mm — Counter/pressure die shaft clearance hole
+pivot_dist      = 130;// mm — Center-to-center distance between main and counter die
+
+/* [Spacer & Assembly Bolts] */
+// Spacer block sits at the back. By setting length to 30, it can be cut 
+// from the same 30mm plate stock as the arms, just stood vertically on edge!
+spacer_length   = 30; // mm — Length of the spacer block at the back edge (X)
+spacer_bolt_d   = 11; // mm — M10 clearance hole for top/bottom plates
+spacer_cbore_d  = 19; // mm — Counterbore diameter for M10 socket head
+spacer_cbore_h  = 10; // mm — Counterbore depth
+spacer_tap_d    = 8.5;// mm — Tap drill size for M10 threads in the spacer block itself
+spacer_bolt_pitch = 28; // mm — Y-distance between the 3 bolts
+
+/* [Handle attachment] */
+// Optional bore in the back face of the spacer to receive a pipe handle.
+// Note: verify it doesn't intersect your bolts!
+handle_bore_enable = false;
+handle_bore_d      = 34; // mm — Fits a ~33.7mm pipe (1" nominal)
+handle_bore_depth  = 20; // mm
+
+/* [Render Quality] */
+$fn = 64; // Use 128+ for final export
+
+// =============================================================================
+// DERIVED VALUES
+// =============================================================================
+// Origin (0,0,0) is center of main pivot on the bottom face of each respective plate.
+_r = arm_width / 2;
+
+// =============================================================================
+// ENTRY POINT SWITCH
+// =============================================================================
+if (part == "assembly") {
+    arm_assembly();
+} else if (part == "top_plate") {
+    arm_top_plate();
+} else if (part == "bottom_plate") {
+    arm_bottom_plate();
+} else if (part == "spacer") {
+    arm_spacer();
+}
+
+// =============================================================================
+// MODULES
+// =============================================================================
+
+module arm_assembly() {
+    // Bottom plate
+    color("#a0a0a0")
+        arm_bottom_plate();
+
+    // Spacer block
+    color("#606060")
+        translate([0, 0, plate_thickness])
+            arm_spacer();
+
+    // Top plate
+    color("#c0c0c0")
+        translate([0, 0, plate_thickness + inner_gap])
+            arm_top_plate();
+}
+
+// Shared 3D profile for top and bottom plates
+module _arm_profile_3d() {
+    union() {
+        cylinder(r = _r, h = plate_thickness);
+        translate([-arm_length, -_r, 0])
+            cube([arm_length, arm_width, plate_thickness]);
+    }
+}
+
+// Top Plate
+module arm_top_plate() {
+    difference() {
+        // Main body
+        _arm_profile_3d();
+
+        // Main pivot hole
+        translate([0, 0, -1])
+            cylinder(d = main_pivot_d, h = plate_thickness + 2);
+
+        // Counter die pivot hole
+        translate([-pivot_dist, 0, -1])
+            cylinder(d = counter_die_d, h = plate_thickness + 2);
+
+        // Spacer bolt holes (Counterbored from +Z face down)
+        _spacer_bolts() {
+            translate([0, 0, -1])
+                cylinder(d = spacer_bolt_d, h = plate_thickness + 2);
+                
+            if (spacer_cbore_d > 0 && spacer_cbore_h > 0)
+                translate([0, 0, plate_thickness - spacer_cbore_h])
+                    cylinder(d = spacer_cbore_d, h = spacer_cbore_h + 1);
+        }
+    }
+}
+
+// Bottom Plate
+module arm_bottom_plate() {
+    difference() {
+        // Main body
+        _arm_profile_3d();
+
+        // Main pivot hole
+        translate([0, 0, -1])
+            cylinder(d = main_pivot_d, h = plate_thickness + 2);
+
+        // Counter die pivot hole
+        translate([-pivot_dist, 0, -1])
+            cylinder(d = counter_die_d, h = plate_thickness + 2);
+
+        // Spacer bolt holes (Counterbored from -Z face up)
+        _spacer_bolts() {
+            translate([0, 0, -1])
+                cylinder(d = spacer_bolt_d, h = plate_thickness + 2);
+                
+            if (spacer_cbore_d > 0 && spacer_cbore_h > 0)
+                translate([0, 0, -1])
+                    cylinder(d = spacer_cbore_d, h = spacer_cbore_h + 1);
+        }
+    }
+}
+
+// Rear Spacer Block
+module arm_spacer() {
+    difference() {
+        // Main block
+        translate([-arm_length, -arm_width/2, 0])
+            cube([spacer_length, arm_width, inner_gap]);
+
+        // Through holes for bolts (Can be tapped or used as clearance for through-bolts)
+        _spacer_bolts() {
+            translate([0, 0, -1])
+                cylinder(d = spacer_tap_d, h = inner_gap + 2);
+        }
+
+        // Optional handle bore into the back face
+        if (handle_bore_enable) {
+            // Cut from X = -arm_length extending positively into the block
+            // Centered in Z based on inner_gap
+            translate([-arm_length - 1, 0, inner_gap / 2])
+                rotate([0, 90, 0])
+                    cylinder(d = handle_bore_d, h = handle_bore_depth + 1);
+        }
+    }
+}
+
+// Helper: Bolt Positions
+module _spacer_bolts() {
+    // Holes are centered in the spacer piece on the X axis
+    bx = -arm_length + spacer_length / 2;
+    // 3 bolts spread along the Y axis
+    for (by = [-spacer_bolt_pitch, 0, spacer_bolt_pitch]) {
+        translate([bx, by, 0])
+            children();
+    }
+}
+
+// =============================================================================
+//  END OF FILE
+// =============================================================================

projects/tube-bender/readme.md

@@ -0,0 +1,310 @@
+---
+title: "Overview: Manual Round Tube Bending Device"
+slug: "overview-manual-round-tube-bending-device"
+date: "2026-04-05"
+author: "PolyMech"
+---
+
+# Table of Contents
+
+- [Overview: Manual Round Tube Bending Device](#overview-manual-round-tube-bending-device)
+  - [1. Functional Principle](#1-functional-principle)
+  - [2. Main Components](#2-main-components)
+    - [2.1 Frame and Base](#21-frame-and-base)
+    - [2.2 Main Bend Die (Form Die)](#22-main-bend-die-form-die)
+    - [2.3 Clamp Block / Clamp Die](#23-clamp-block-clamp-die)
+    - [2.4 Follower / Pressure Die Assembly](#24-follower-pressure-die-assembly)
+    - [2.5 Bending Arm / Handle](#25-bending-arm-handle)
+    - [2.6 Optional Accessories](#26-optional-accessories)
+  - [3. Dies: Types and Design Notes](#3-dies-types-and-design-notes)
+    - [3.1 Bend Die Geometry](#31-bend-die-geometry)
+    - [3.2 Groove Shape](#32-groove-shape)
+    - [3.3 Materials](#33-materials)
+  - [4. Typical Limits for a Manual Tube Bender](#4-typical-limits-for-a-manual-tube-bender)
+    - [4.1 Tube Size Range (Common DIY)](#41-tube-size-range-common-diy)
+    - [4.2 Minimum Bend Radius](#42-minimum-bend-radius)
+    - [4.3 Bend Angle Limits](#43-bend-angle-limits)
+    - [4.4 Repeatability and Springback](#44-repeatability-and-springback)
+  - [5. Sketches and Concept Layout for Building One](#5-sketches-and-concept-layout-for-building-one)
+    - [5.1 Side View – Overall Arrangement](#51-side-view-overall-arrangement)
+    - [5.2 Front View – Die Stack and Clamp](#52-front-view-die-stack-and-clamp)
+    - [5.3 Simple Dimensions to Start From (Example)](#53-simple-dimensions-to-start-from-example)
+    - [5.4 Simple Build Sequence](#54-simple-build-sequence)
+  - [6. Practical Tips and Safety](#6-practical-tips-and-safety)
+  - [7. Summary](#7-summary)
+
+---
+
+*Figure 1 – Conceptual side view of a manual round tube bender with main components labeled.*
+
+![Selected image](https://ytoadlpbdguriiccjnip.supabase.co/storage/v1/object/public/pictures/cache/919bafebbb1c7a6480a763d3fbe13c7056afc911259f0bbbac0042911d967d6b.jpeg)
+
+![image](https://ytoadlpbdguriiccjnip.supabase.co/storage/v1/object/public/pictures/cache/41483eaa457dcebbd72118d0d0e50cbae535344a37cf98307d95329d6e6f7527.jpeg "image")
+
+[Youtube Source](https://www.youtube.com/watch?v=k1hlAYbiNHY "Youtube Source")
+
+# Overview: Manual Round Tube Bending Device
+
+This page gives a practical overview of a **manual round tube bender** suitable for a small workshop or DIY fabrication. It covers:
+
+* Functional principle
+* Main components and dies
+* Typical limits (diameter, wall, bend radius)
+* Simple design sketches and build notes (concept-level, not certified drawings)
+
+***
+
+## 1. Functional Principle
+
+A manual round tube bender for smooth, repeatable bends usually works on the **rotary draw** principle:
+
+1. The tube is clamped against a **form die** (also called bend die) that has a groove matching the tube OD.
+2. The die rotates around its center, pulling the tube with it.
+3. A **pressure/follower die** supports the tube on the tangent side and keeps it in the groove.
+4. Optionally, a **wiper** or roller can be used to reduce flattening and wrinkling.
+
+Compared to simple "pipe hickey" benders or crude pinch benders, a die-based rotary bender gives:
+
+* Better control of bend radius
+* Less flattening of the tube cross‑section
+* Repeatable angles
+
+***
+
+## 2. Main Components
+
+A typical manual rotary tube bender you can build in a small shop includes:
+
+### 2.1 Frame and Base
+
+* **Base plate**: Thick steel plate or welded frame that bolts to the floor, a large bench, or a receiver tube on a stand.
+* **Vertical post / side plates**:
+  * Support the pivot shaft of the main bend die
+  * Take bending loads; use adequate section (e.g., 10–15 mm thick plates or heavy channel/box)
+* **Reinforcement gussets** between base and posts to resist twisting.
+
+### 2.2 Main Bend Die (Form Die)
+
+Function: Sets the **centerline bend radius** and supports the tube during bending.
+
+Key features:
+
+* **Outside diameter and profile**:
+  * Large circular form with a **groove** machined or turned into the rim to match the tube OD.
+  * Groove profile: usually a **semi‑circular or slightly open U** shape, just larger than tube OD.
+* **Center bore / hub**:
+  * Fits on a strong **pivot shaft** (e.g., 30–40 mm or more, depending on tube size and force).
+  * May have a **keyway** or bolt‑on interface to the bending arm.
+* **Detent or hole pattern** (optional):
+  * For a spring pin to lock the die at standard angles (0°, 45°, 90°, etc.).
+
+You will typically need **multiple bend dies**, each tailored to:
+
+* Tube OD (e.g., 19, 25, 32, 38, 50 mm)
+* Desired bend radius (e.g., 2×D, 3×D, 4×D)
+
+### 2.3 Clamp Block / Clamp Die
+
+Function: Grips the tube to the main die so the tube rotates with the die.
+
+* Shaped with a matching groove for the tube.
+* Bolts or pins into the main die.
+* Uses a **clamping bolt** or lever to tighten onto the tube.
+* Often split into two halves for quick loading/unloading.
+
+### 2.4 Follower / Pressure Die Assembly
+
+Function: Supports the straight tube just as it enters the bend, minimizing flattening and kinks.
+
+Typical DIY options:
+
+1. **Sliding block pressure die**:
+   * A block with a matching groove riding on guide rails.
+   * Spring‑loaded or cam‑adjusted to press the tube into the main die.
+2. **Roller pressure die**:
+   * A hardened or machined roller with a groove.
+   * Mounted on a pivoting arm with adjustable pressure.
+
+Key considerations:
+
+* Low friction (use bronze bushings, bearings, or good lubrication).
+* Sufficient adjustment range for different tube diameters and wall thicknesses.
+
+### 2.5 Bending Arm / Handle
+
+* Long lever arm attached to the main die hub.
+* Provides mechanical advantage; typical length: 1–1.5 m for hand power on smaller tubes.
+* May be detachable for storage.
+* Often includes:
+  * **Angle scale** (protractor, engraved scale, or pointer on a stationary reference plate).
+  * **Handle grip** or crossbar for two‑handed operation.
+
+### 2.6 Optional Accessories
+
+* **Angle stop**: Adjustable mechanical stop to repeat a given bend angle.
+* **Backstop / start position gauge**: For consistent bend location from the tube end.
+* **Wiper die**: Small, sharpened block near the tangent to reduce inside‑radius wrinkling.
+
+***
+
+## 3. Dies: Types and Design Notes
+
+### 3.1 Bend Die Geometry
+
+For a round tube of **outside diameter D**:
+
+* **Centerline radius (CLR)** \= distance from die center to tube centerline.
+* Outer diameter of die OD\_die ≈ 2 × (CLR + D/2).
+* Groove:
+  * Depth ≈ 0.55–0.65 × D
+  * Width a bit larger than D to allow easy loading but still support the tube.
+
+Example: For 25 mm tube, CLR \= 75 mm (≈3×D):
+
+* OD\_die ≈ 2 × (75 + 12.5) \= 175 mm
+* Groove depth \~ 14–16 mm, width slightly larger than 25 mm.
+
+### 3.2 Groove Shape
+
+* **Best**: Proper machined radius matching the tube OD, with smooth surface finish.
+* **DIY compromise**: Multi‑pass machining with a ball end mill, or turning on a lathe using form tools.
+* Avoid sharp edges; always **chamfer or radius** the edges of the groove to avoid scoring the tube.
+
+### 3.3 Materials
+
+* **Dies**: Medium‑carbon steel (e.g., C45/1045) or similar. For light duty, mild steel is often acceptable.
+* **Clamp blocks**: Same as main die, optionally with **replaceable aluminum or nylon inserts** to reduce marking.
+
+**Rollers**: Hardened or case‑hardened if high wear is expected.
+
+***
+
+## 4. Typical Limits for a Manual Tube Bender
+
+Exact capabilities depend on materials, dimensions, and workmanship, but for a well‑built manual bender (no hydraulic assist):
+
+### 4.1 Tube Size Range (Common DIY)
+
+* OD: \~10–38 mm (3/8"–1 1/2") is practical by hand.
+* Material: Mild steel, stainless, or aluminum tube (not heavy schedule pipe).
+* Wall thickness: \~1–3 mm.
+
+Above these, bending force increases quickly; you may need **hydraulic assistance** or longer handles.
+
+### 4.2 Minimum Bend Radius
+
+Depends on tube material and wall thickness. Approximate guidelines:
+
+* Steel tube: **CLR ≥ 2.5–3 × OD** for general work without mandrel.
+* Thin‑wall tube or tight cosmetic bends may require:
+  * **CLR ≥ 3–4 × OD**, or
+  * Internal support (packing sand, low‑melt alloy, or a proper internal mandrel).
+
+### 4.3 Bend Angle Limits
+
+* Mechanically, you can design for 0–180°.
+* Common useful range: **0–120°** for hand‑operated, as force gets high at large angles.
+* Ensure frame clearance: the tube and bending arm must not hit the base or floor as you approach maximum angle.
+
+### 4.4 Repeatability and Springback
+
+* Metals will **spring back**, so you must over‑bend slightly.
+* Typical springback for steel tube: **2–5°**, more for harder materials.
+* A simple **angle scale** and test bends in scrap will help you dial in accurate angles.
+
+***
+
+## 5. Sketches and Concept Layout for Building One
+
+Below is a conceptual layout. Dimensions are **indicative** only; adapt to your materials and tube sizes.
+
+### 5.1 Side View – Overall Arrangement
+
+Key elements in a side view sketch:
+
+* Base plate
+* Vertical side plates with pivot hole
+* Main die on pivot shaft
+* Bending arm fixed to die hub
+* Pressure die arm supporting the straight tube
+
+> Build tip: Start the design around your **largest bend die** and required **frame clearances**. Ensure that at full bend angle the handle and tube do not clash with the floor or base.
+
+### 5.2 Front View – Die Stack and Clamp
+
+Elements to show in a front view sketch:
+
+* Tube running horizontally through the die groove.
+* Clamp block on the front face of the die, bolted with two or more M10–M12 bolts.
+* Pivot shaft through die and side plates, retained with nut or collar.
+* Pressure die block or roller just tangent to the die.
+
+### 5.3 Simple Dimensions to Start From (Example)
+
+For a bender intended for up to 32 mm OD mild‑steel tube:
+
+* **Base plate**: 300 × 400 × 12 mm
+* **Side plates**: 250 mm high, 12–15 mm thick, spaced 60–70 mm
+* **Pivot shaft**: 35–40 mm diameter, medium‑carbon steel
+* **Largest bend die**: OD ≈ 220–250 mm (e.g., CLR ≈ 100–110 mm for 32 mm tube)
+* **Bending arm**: 1.2–1.4 m long, 40 × 20 rectangular tube or 40 mm round solid/pipe
+* **Pressure die block**: 50 × 80 × 80 mm with a 32 mm groove and adjustable mount
+
+These values are a **starting point**; verify against:
+
+* Available stock sizes
+* Intended tube material
+* Your own strength / acceptable effort
+
+### 5.4 Simple Build Sequence
+
+1. **Design dies first**:
+   * Choose tube sizes and CLRs.
+   * Draw each die full scale (even on paper/card) to check clearances.
+2. **Design frame around dies**:
+   * Set pivot height so that your longest tube can swing without hitting the floor.
+   * Confirm maximum bend angle.
+3. **Build frame and mount pivot**:
+   * Weld base and side plates.
+   * Drill/ream pivot holes, fit shaft and bushings.
+4. **Machine main die and clamp block**:
+   * Turn OD and face on lathe.
+   * Cut hub bore and keyway or bolt pattern.
+   * Machine groove.
+5. **Make pressure die and arm**:
+   * Simple block on adjustable slide or a roller on a pivot.
+   * Ensure smooth movement and easy adjustment.
+6. **Add handle, angle pointer, and stops**:
+   * Fit long bending arm.
+   * Add a pointer and fixed scale or mark common angles.
+7. **Test and refine**:
+   * Make test bends, note springback and any flattening.
+   * Adjust pressure die, add lubrication, or increase radius if necessary.
+
+***
+
+## 6. Practical Tips and Safety
+
+* **Clamping**: The most common DIY issue is tube slipping in the clamp. Use enough bolt area, roughen clamp surface slightly, or add a soft insert with high friction.
+* **Lubrication**: Use bending lubricant (wax/grease) in the groove to reduce marking and flattening.
+* **Fasteners**: Use high‑strength bolts for clamp and handle connections.
+* **Welding**: If frame is welded, brace and cool slowly to minimize distortion; check pivot bores afterwards.
+* **Safety**:
+  * Keep fingers away from pinch points between tube, dies, and frame.
+  * Long tubes can swing with force—keep the area clear.
+  * Wear eye and hand protection.
+
+***
+
+## 7. Summary
+
+A manual round tube bender with **proper dies** and a **robust frame** can reliably bend mild‑steel and aluminum tubing for roll cages, furniture, handrails, and general fabrication.
+
+Key design steps:
+
+1. Choose your target **tube sizes** and **minimum bend radii**.
+2. Design and dimension **main dies** first.
+3. Build a **stiff frame** and **long handle** around those dies.
+4. Add a **pressure die** and **good clamping** for clean, repeatable bends.
+
+Use the conceptual sketches and guidelines above as a base, then adapt details to your tools, materials, and accuracy requirements.

vfs-settings.json

@@ -17,6 +17,14 @@
         "list"
       ],
       "userId": "authenticated"
+    },
+    {
+      "path": "/3dprint",
+      "permissions": [
+        "read",
+        "list"
+      ],
+      "group": "Pacbot-Pro"
     }
   ]
 }