Formula Used
The calculator uses a planning model for a square stock cube and concentric face bores. It assumes each new cube is reduced on both sides by the wall thickness and clearance.
Per side reduction = wall thickness + clearance.
Inner cube side = parent side - 2 × per side reduction.
Opening diameter = parent side - 2 × wall thickness.
Rough opening = final opening - 2 × finish allowance.
Target depth = (stock side - inner cube side) ÷ 2 + depth allowance.
Diameter range = final opening ± tolerance.
How to Use This Calculator
Enter the outside cube side length first. Choose the same unit for every dimension. Add the number of nested cubes you want to plan. Enter a wall thickness that your stock and machine can support. Add running clearance for deburring and movement. Enter cutter diameter, finish allowance, tolerance, and safe depth limit. Press the calculate button. Review the result table above the form. Export the CSV or PDF report for shop use.
Example Data Table
| Stock Side |
Levels |
Wall |
Clearance |
Cutter |
Final Inner Cube |
| 50 mm |
3 |
4 mm |
1 mm |
8 mm |
20 mm |
| 2 in |
2 |
0.125 in |
0.035 in |
0.250 in |
1.36 in |
| 75 mm |
4 |
5 mm |
1.5 mm |
10 mm |
23 mm |
Turner’s Cube Calculator Guide
A Turner’s cube is a classic shop project. It tests layout, centering, boring, and patience. The cube looks simple, yet each face hides a chain of nested cuts. A small mistake can remove a wall or trap an inner cube. This calculator helps plan those cuts before metal reaches the vise.
What the calculator estimates
The tool starts with the outside cube size. It then subtracts wall thickness and running clearance from both sides of each nested level. The result is a practical inner cube size for every stage. It also gives the face opening diameter, rough opening, cut depth, and estimated pass count. These values support planning, not inspection. Final dimensions still depend on machine rigidity, tool deflection, material, and setup skill.
Why clearance matters
A Turner’s cube needs enough clearance around each inner block. Too little clearance may lock the cube after deburring. Too much clearance can make the project look loose. The calculator separates wall thickness, clearance, finish allowance, and tolerance. That makes tradeoffs easier to see. You can compare a strong wall against a freer moving inner cube.
Good shop practice
Start with squared stock. Mark the center of every face. Use the same datum plan for all six faces. Bore gradually and measure often. Leave a small finish allowance when the material is hard or the setup is light. Use sharp tools and conservative feeds. Deburr after each stage, because burrs can hide real clearance.
Using the results
Read the level table from top to bottom. Level one is the first nested cube inside the parent stock. Later levels are smaller cubes inside earlier cubes. If the status warns you, reduce the level count, increase stock size, or lower the wall and clearance values carefully. The final table is best used as a planning sheet. Print it or export it, then keep it near the machine during the job.
Limits of the model
The calculator uses a simplified geometric plan. It does not replace toolpath simulation. It does not test stress, chatter, or collision risk. Always verify bore depth and cutter reach on your own machine. Use safe workholding and make trial cuts when dimensions are tight before final machining begins.
FAQs
What is a Turner’s cube?
A Turner’s cube is a machined cube with smaller nested cubes inside it. It is usually made by boring centered holes from each face. The project tests setup accuracy, squareness, tool control, and careful measurement.
Can this calculator create exact machine code?
No. It creates planning dimensions only. Use the values to guide layout, bore sizes, and depth checks. Always verify toolpaths, workholding, and machine limits before cutting material.
Which unit should I use?
You can use millimeters or inches. Keep every input in the same unit. The calculator does not mix unit systems inside one job, so all displayed outputs follow the selected unit.
Why does the status show tight clearance?
That warning appears when clearance is too close to the entered tolerance. In real machining, burrs, tool deflection, and measurement error can remove that small gap. Increase clearance or reduce tolerance demand.
What does rough opening mean?
Rough opening is the diameter before the final finishing pass. It subtracts finish allowance from both sides. This helps leave material for a cleaner final cut.
How many nested levels are practical?
Small cubes may only support two or three levels. Larger stock and precise machines may allow more. If the final inner cube becomes too small, reduce levels or increase stock size.
Why is safe depth clipped?
The calculator limits bore depth to the maximum depth percent entered. This helps avoid planning a cut that passes too far through the cube from one face.
Should I trust the volume estimate?
Treat it as a rough planning indicator. Six face bores overlap, and real toolpaths vary. Use it for comparison only, not for final material removal proof.