User guide
For Lure Parts Modeler v0.7 · Size charts and material data: Articles
1. What the tool does
Enter the dimensions of a small metal lure part and get its 3D model, ready to download as a file for CAD, 3D printing or simulation.
- Parts: cylinder (weights, pins), sphere (weights, beads), olive (natsume) sinker, flattened split ring, eight ring (figure-8 eye)
- Calculated values: volume, mass, weight in fresh and sea water, center of mass
- Export formats: STEP, 3MF, STL, OBJ, PLY, glTF
All calculation and modelling happens in your browser. The dimensions you enter are never sent to a server.
2. Free version and the planned paid version
The tool is being developed in two stages.
- Now: improve the free version with your feedback
What is online now is the free version. Feedback, requests and bug reports from real use guide the updates: new parts, better ways to set dimensions and more accurate calculations. - Next: an Autodesk Fusion script as a paid version
Building on the free version, a "Fusion script" that draws the parts directly inside Autodesk Fusion is planned as a paid version. The aim is exact geometry drawn with Fusion's own features, the physical material (density) set automatically, and dimensions you can change later.
| Free version (this tool) | Paid version (planned) | |
|---|---|---|
| Create and preview parts | Yes | Yes (inside Fusion) |
| Mass, weight in water and center of mass | Yes | Yes |
| Export STEP, 3MF, STL and more | Yes | — |
| Exact drawing, material setup and later edits in Fusion | — (import the STEP instead) | Yes |
Timing, price and contents will be announced in this guide once decided. The free version will stay online.
Want another part, a size the tool cannot make, or a particular Fusion workflow? Tell us through the contact form. It shapes both the free version and the paid one.
3. Basic use
- Choose a part from the tabs at the top left (Cylinder / Sphere / Split ring / 8-ring / Olive sinker).
- Enter the dimensions. They are in mm (or inches with the switch at the top right). The preview on the right updates as you type.
- Choose a material. It is used for mass and underwater weight and is written into the exported file.
- Choose an export format and press "Generate & download".
Drag the preview to rotate it and scroll to zoom. "Preview" brings the camera back to show the whole part. The size of one grid square is shown at the top left of the preview.
If a value cannot work, the reason appears in red above the buttons (for example "Top chamfer must be less than the radius").
The language switch at the top right changes the language of the tool. Your choice is remembered in the browser. This guide is available in Japanese and English; the terms and privacy policy are in Japanese only.
The "mm | inch" switch at the top right changes the unit for showing and entering lengths. In inches, dimensions and the center of mass are in inches, volume in in³, and mass and underwater weight in grams plus ounces; the preview grid also switches to inches. The shape does not change, and switching back and forth never shifts the values. Your choice is remembered in the browser.
Even in inch mode, exported files stay in mm. STEP, STL, 3MF and the like use mm as the standard, so CAD software and slicers read the unit correctly.
4. Dimensions of each part
Cylinder
| Field | Meaning |
|---|---|
| Diameter, Length | Outer diameter and length of the cylinder |
| Chamfer (45°) | How much to cut off the top and bottom edges at 45°, only on the edges you tick. You can also click the blue edges in the preview (selected edges turn orange). Each chamfer must be less than the radius, and the two together less than the length. |
Sphere
| Field | Meaning |
|---|---|
| Diameter | Outer diameter of the sphere |
| Through-hole | Tick it to drill a hole through the center. The value is the hole diameter and must be less than the sphere diameter. |
Olive (natsume) sinker
A sliding sinker shaped like a jujube (natsume), common in Japan. The outline is an oval that narrows towards both ends, the ends are flat, and a hole for the line runs along the axis.
| Field | Meaning |
|---|---|
| Max diameter, Length | Diameter at the thickest point, and length from end face to end face |
| End-face diameter | Diameter of the flat ends. It must be smaller than the max diameter and larger than the hole. |
| Hole diameter | Diameter of the hole for the line. 0 means no hole. |
| Fullness (shape factor) | How full the outline is (1.2 to 4). 2 is an exact ellipse; smaller is slimmer towards the ends, larger has a fuller body. |
Size from weight
Under "Size from weight", choose a size and press "Fit to this weight". The max diameter, length and end face are scaled together (the hole stays the same) so the sinker reaches that weight in the selected material. This lets you compare, say, how much smaller a 3 gō sinker is in tungsten than in lead.
- Sizes follow the usual Japanese olive sinker lineup: 27 sizes from 0.2 to 100 gō (号).
- 1 gō is 3.75 g. The mass field also shows the value converted to gō.
- The olive sinker starts in lead (the other parts start in stainless steel SUS304). To calculate in another material, choose it before pressing the button. If you change the material afterwards, press the button again to recalculate.
The default proportions (length = 2.55 × max diameter, end face = 0.25 × max diameter, fullness 1.7) come from measured commercial sliding olive sinkers (60 to 100 gō) and their weights; calculated in lead they match the real weight within about ±3%. Shapes vary a little by maker and size, so adjust to the real part if needed. See also the olive sinker size chart.
Split ring
The default is a flattened split ring, made from wire pressed flat. The turns lie flat on each other, and where the wire ends face each other each turn steps up by one layer (the jog).
| Field | Meaning |
|---|---|
| Outer diameter | Diameter at the very outside of the ring. The inner diameter (outer − 2 × width) is shown in the dimensions panel. |
| Section width, thickness | Size of the wire section: width along the ring radius, thickness along the axis (the stacking direction). |
| Section shape | "Flattened (rounded sides)" has flat top and bottom and rounded sides; "Rectangle" has square corners. |
| Side radius | Radius of the rounded sides. Half the thickness gives a semicircle; larger gives a gentler curve. It must be at least half the thickness. |
| Coil shape | "Flat turns + jog" is close to a real flattened ring; "Helix" climbs at a constant pitch. |
| Jog angle | The angle over which the step happens (5 to 180°). Smaller is a steeper step. |
| Turns | 1.9 by default. Fractions such as 2.1 or 1.95 work; anything beyond two turns stacks as a third layer. |
| Gap between turns | Gap between stacked turns. Even at 0 the turns are kept 0.001 mm apart inside so the solid stays valid (this does not affect volume or mass). |
Eight ring
One wire forms a loop at each end; at the waist the two strands run side by side and touch. The wire never crosses itself. The dimensions follow the definitions common in maker size tables.
| Field | Meaning |
|---|---|
| Preset | Common market sizes (wire / loop inner diameters / overall length). Choosing one fills in all dimensions; changing a value switches to "Custom". |
| Wire diameter | Thickness of the wire |
| Loop 1 inner dia. D1, Loop 2 inner dia. D2 | Inner diameter of each loop. The two can differ. |
| Center distance E | Distance between the centers of the two loops |
| Waist width F | Outer width of the waist. When the two strands touch it is twice the wire diameter. |
| Neck radius | Radius of the bend joining each loop to the waist. If E is too short for it, it is reduced automatically and "(auto-adjusted)" appears in the details. |
| Gap at the loop 2 tip | Gap between the two wire ends. 0 closes the loop. |
| A, B, C (calculated) | A and B are the loop outer diameters (D + 2 × wire); C is the overall length (E + (A + B) ÷ 2). |
See also the eight ring size chart.
5. Materials and calculated values
Materials: stainless steel (SUS304, SUS316), lead, tungsten (pure and alloy), bismuth, brass, copper, steel, zinc, tin, titanium and aluminium. "Custom" lets you enter your own material name and density (g/cm³). Alloy densities are typical values; check your supplier's specification for exact figures.
| Value | How it is calculated |
|---|---|
| Volume | From the shape of the part (mm³) |
| Mass | Volume × density of the material |
| Weight in fresh water | Mass − volume × 1.000 g/cm³ (the weight you feel under water) |
| Weight in seawater | Mass − volume × 1.025 g/cm³ |
| Center of mass (x, y, z) | Position of the center of mass in the exported file's coordinates (mm). See Coordinates and origin. |
Volume, mass and center of mass come from the formulas of the shape, not from the preview's polygons, so changing "Segments" does not change them. More on densities: Metal densities and underwater weight.
6. Choosing an export format
| Use | Format | Notes |
|---|---|---|
| Modelling in Autodesk Fusion | STEP | Opens in Fusion. Set the material after import (steps). A "Fusion script" that draws directly inside Fusion is planned as a paid version; it is listed but cannot be selected yet. |
| Modelling in Shapr3D | STEP | Works with Shapr3D on iPad, Windows and Mac. On iPad, send it with the Share button; on Windows and Mac, download and import it (steps for each). |
| CAD, or sending to a machine shop | STEP | Every part is exported with exact surfaces (B-rep). |
| 3D printing | 3MF (or STL) | 3MF carries the unit (mm), material and metadata. STL opens in almost any slicer. |
| 3D viewers, game engines, the web | glTF / GLB | With the material color and data such as density (extras). Units are metres. |
| Other software | OBJ / PLY | Material data goes into comment lines at the top of the file. |
Segments sets how finely curved surfaces are split into polygons in mesh formats such as STL and 3MF. Higher is smoother but makes larger files. The default of 64 is usually enough.
Exported files record the material name, density, volume, mass, center of mass, dimensions and tool version, so programs that calculate weight or buoyancy later can read them. Binary STL has very little room by its specification, so it carries only the material, density and mass.
7. Using it with Autodesk Fusion
Import a STEP file (current method)
- Choose "STEP" as the export format and download it.
- In Fusion, open the STEP file with File → Open, or upload it to the Data Panel.
- Right-click the imported body and set the material under "Physical Material". Fusion does not read the material and density written in the STEP file.
Every part comes in as a solid with exact surfaces, ready for fillets, holes, joining to other parts and so on. Cylinders and spheres use planes, cylinders and spheres; the eight ring uses cylinders and tori; the olive sinker is a smooth revolved curve; the split ring is a smooth freeform surface.
Fusion script (planned for the paid version)
A "Fusion script" that draws the part inside Fusion, sets the physical material and keeps the dimensions editable is being prepared as a paid version. It appears in the export format list but cannot be selected yet.
8. Using it with Shapr3D
Shapr3D runs on iPad, Windows and Mac with the same modelling features, and every version can import this tool's STEP file (all parts come in as solids with exact surfaces). Shapr3D has no API for drawing from outside, so the two work together by passing files.
The only difference is how the file gets there: the iPad app receives it directly from the Share button, while Windows and Mac import a downloaded file.
| Shapr3D app | Open this tool on | How to pass the STEP file |
|---|---|---|
| iPad | Safari or another browser on the iPad | "Share (send to Shapr3D on iPad, etc.)" → choose Shapr3D in the share sheet |
| Windows | A browser on Windows | "Generate & download" → open the file with Import in Shapr3D |
| Mac | A browser on the Mac | "Generate & download" → open the file with Import in Shapr3D |
With "STEP" selected, a one-line hint under the buttons explains the route for your device. The Share button appears only on mobile devices such as iPad and iPhone, not on Windows or Mac.
iPad
- Open this tool on the iPad, set the dimensions and material, and choose "STEP".
- Tap "Share (send to Shapr3D on iPad, etc.)" and choose Shapr3D in the share sheet.
- If Shapr3D is not in the share sheet, use "Save to Files" to save it On My iPad, then open the file from Import in Shapr3D.
Some users report that a STEP file in a cloud folder appears greyed out and cannot be picked in the Files dialog on iPad. If so, save it On My iPad (for example in Downloads) first.
Windows and Mac
- Open this tool in a browser on the computer, choose "STEP" and press "Generate & download".
- In Shapr3D, open the downloaded STEP file with Import.
Shapr3D syncs projects across devices on the same account, so you can import a part on Windows and keep editing it on the iPad.
Notes for every version
- Shapr3D may not read the material name and density in the STEP file. Use this tool's figures for mass and underwater weight.
- The unit is mm. If Shapr3D is set to another unit, check the unit when importing.
- Imported parts have no history. To change a dimension, make the part again in this tool or edit it directly in Shapr3D.
9. Coordinates and origin
- Exported files are Z-up in mm (glTF alone is Y-up in metres, as its specification requires).
- Origin: cylinder = center of the bottom face; sphere, olive sinker and split ring = center; eight ring = midway between the two loops.
- The sphere's through-hole, the sinker's hole and the cylinder's axis run along Z; the eight ring is long along X.
10. FAQ and troubleshooting
The preview does not appear
Use a recent version of Chrome, Edge, Safari or Firefox. Reloading the page (Ctrl + F5) often helps.
A red message appears and the preview does not change
The values cannot make a valid shape together. Fix them as the message says (for example, the eight ring's E is too short, or the side radius is less than half the thickness).
The real part weighs something different
The figures are estimates from the dimensions you entered and typical material densities. Real parts vary with manufacturing tolerances, alloy composition and surface treatments such as plating. If you need exact numbers, weigh the real part and adjust the density with the "Custom" material.
Holes and gaps come out small when 3D printed
3D printers often make holes and gaps a little smaller than designed. Enter slightly larger dimensions to suit your printer.
"Autodesk Fusion script" cannot be selected
It is still being prepared, so it is listed but disabled. It is planned as a paid version (Free version and the planned paid version). Until then, import the STEP file into Fusion.
Please note
The calculated values are estimates; the strength and safety of the generated shapes are not guaranteed. See the terms and disclaimer (in Japanese). Send feedback and requests through the contact form.