How much does making its own spare parts cut the cost of repairing a printer?

What it found

Follow-up to selfrep-repair. The spare-part cost share of a repair is derived from the Prusa Mendel’s wear parts (belts, bearings, hot end, switches), each with an assumed life, and from which of them a seed shop can make. The printer alone makes none and adding a router and laser cutter makes only the pulleys, so the share stays near 0.021 and the fleet is unchanged (62.5 vs 63.0 machines, against 7.3 with replacement only). Swapping the linear bearings for a printed bushing lowers the share to 0.019, but if the bushing lasts half as long the fleet falls to 43, so breakdown rate matters more than where the spare comes from. Stylised: every life and cost is assumed.

A figure from its own output

Paper, code and results

• README and method
• Experiments and results
• Code
• Tests

More in Self-replicating manufacturing

• Does a printer shop lose its printed-bushing gain once a printed spare takes print hours?Does charging printed spares their print hours erase the printed-bushing gain (stylised, assumed inputs): the fleet ignores waits up to ~500 h per repair because it is import-limited, and the gain was within noise anyway.
• Is the lone-printer die-out an early birth-death accident?Exact Markov-chain test of why a lone replicating printer dies out (stylised, assumed inputs): about a fifth die before a fleet forms at 500 h mean life; wear-out lives remove it.
• Can a quasi-stationary approximation predict how long a small printer fleet lasts?Quasi-stationary approximation of how long a small replicating-printer fleet lasts (stylised, assumed inputs): within 5% of the exact mean time once a correction for early die-out is applied, poor for the shortest lives.
• Why do two exact extinction chains of the same printer shop disagree?Reconciles the two exact extinction chains of the lone printer shop (stylised, assumed inputs): the fleet-size chain is 1.5 to 7 times longer; adding the kit wait fixes small fleets but over-corrects large ones.
• Which part substitutions cut a printer's vitamins most, within a performance budget?Which assumed part substitutions (printed bushings and nuts, wooden rods) cut the Prusa Mendel's vitamins most under a penalty budget: all seven take closure from 43/22/16% to 60/36/48% (lines/mass/cost); best set depends on the assumed penalties. Stylised.
• What does a wooden rod cost a printer in stiffness?Beam model of the Prusa Mendel's smooth rods: a wooden rod sags 20 times a steel one at 8 mm and needs about 17 mm to match it, and selfrep-redesign's assumed dowel mass was twice the geometric one (stylised).

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Proper scoring & elicitation28Effort & peer prediction9Verification games & slashing19Detection & tolerances14Markets as routers13Prediction-market design9Paying contributors8Decentralised training systems23Digital twins & sim-to-real164LLM chip design loops40Robot manufacturing loops53Ambient AI assistant46Self-replicating manufacturing34Simulation-first design64Engineered clothing45Task-specific AI accelerators40Algorithmic chip-design loops42Open-source purpose-built robots44The software-engineering loop43Adversarial human imitation41Open-source residential construction41Autonomous multi-angle capture34Sensing, imaging and 3D31Energy supply and dense energy storage39Robot societies among people31Agentic co-design of low-cost robots27Laundry-hanging robots25Machine learning on qualitative data23Robots on the building site27Civilizations & group psychology1History & human sciences1

Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.