0569cd4f02
Adds depreciation/electricity as a separate line item in the production cost breakdown. Included in the markup base so it contributes to margin. Configurable via PRINTER_COST_PER_HOUR env var (default 0.35). Bracket gross total updates automatically. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
81 lines
3.2 KiB
Python
81 lines
3.2 KiB
Python
"""Job cost and time estimation from STL geometry."""
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import math
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import os
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# g/cm³ per material
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_DENSITY: dict[str, float] = {
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"PLA": 1.24,
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"PETG": 1.27,
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"ABS": 1.04,
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"ASA": 1.07,
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"TPU": 1.20,
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"Nylon": 1.14,
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"PC": 1.20,
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}
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_DEFAULT_DENSITY = 1.24
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# Volume (cm³) at which MATERIAL_FACTOR applies exactly.
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# Calibrated to Bambu Lab Studio: 26 cm³ lid → 50 % factor → 16.2 g (actual 16.24 g).
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_REF_VOLUME = 25.0
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# Factor change per decade of volume.
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# Each 10× increase in volume → factor drops by this amount (models get fluffier).
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# Each 10× decrease → factor rises by this amount (models get denser).
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# 0.15 gives: 1 cm³ → +0.21, 250 cm³ → −0.15 relative to base.
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_SIZE_SLOPE = 0.15
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def _effective_factor(volume_ccm: float, base: float) -> float:
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"""Scale material factor by model size using log-linear interpolation."""
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factor = base - math.log10(volume_ccm / _REF_VOLUME) * _SIZE_SLOPE
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return round(max(0.25, min(0.85, factor)), 3)
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def estimate(volume_ccm: float, material: str | None) -> dict:
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"""
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Returns a cost/time estimate dict for one job.
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MATERIAL_FACTOR (env, default 0.50):
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Base fraction of model volume that becomes filament, calibrated at
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25 cm³. Scaled up for small models (wall-dominated) and down for large
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models (infill-dominated). Approximate scale:
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~1 cm³ → ×1.4 (tiny clip, almost all walls)
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~25 cm³ → ×1.0 (reference — validated against slicer)
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~250 cm³ → ×0.7 (large box, infill dominates)
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PRINT_SPEED_G_PER_HOUR (env, default 32):
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~32 g/h matches Bambu Lab at normal quality; use ~20 for slower printers.
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"""
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vat_rate = float(os.environ.get("VAT_RATE", 19))
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price_per_kg = float(os.environ.get("FILAMENT_PRICE_PER_KG", 15))
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base_factor = float(os.environ.get("MATERIAL_FACTOR", 0.50))
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print_speed = float(os.environ.get("PRINT_SPEED_G_PER_HOUR", 32))
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printer_cost_per_hour = float(os.environ.get("PRINTER_COST_PER_HOUR", 0.35))
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density = _DENSITY.get(material or "", _DEFAULT_DENSITY)
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eff_factor = _effective_factor(volume_ccm, base_factor)
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material_ccm = volume_ccm * eff_factor
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weight_g = material_ccm * density
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print_minutes = round((weight_g / print_speed) * 60)
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filament_cost = weight_g / 1000 * price_per_kg
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after_misprint = filament_cost * 1.20
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printer_cost = (print_minutes / 60) * printer_cost_per_hour
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net_price = (after_misprint + printer_cost) * 1.30
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gross_price = net_price * (1 + vat_rate / 100)
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return {
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"material_ccm": round(material_ccm, 2),
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"weight_g": round(weight_g, 1),
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"print_minutes": print_minutes,
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"filament_cost": round(filament_cost, 2),
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"printer_cost": round(printer_cost, 2),
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"net_price": round(net_price, 2),
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"gross_price": round(gross_price, 2),
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"vat_rate": vat_rate,
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"price_per_kg": price_per_kg,
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"material_factor": eff_factor,
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"print_speed": print_speed,
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"printer_cost_per_hour": printer_cost_per_hour,
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}
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