Hashrate-Tiered Fees and PPLNS Settlement for Home-Miner Pools on a Sharded Proof-of-Work Blockchain: Design, Deployment and Simulation on SCDO

Miners who use one home graphics card or desktop CPU earn very irregular income when they mine alone: a small device can go several hours without finding a block. We present two mining pools that are running in production on the SCDO sharded proof-of-work (PoW) blockchain and that pay miners automatically on chain under Pay-Per-Last-N-Shares (PPLNS) accounting with hashrate-tiered fees of 5 %, 3 % and 1 %. The first pool serves GPU miners on SCDO Shard0, an EVM-compatible Ethash shard (chain ID 5680). The second, zpool, is a purpose-built Go pool for CPU miners on SCDO Classic Shard1, whose zpow algorithm rewards finding a large determinant of a 30 × 30 matrix derived from the block header. Because the work behind a zpow share does not grow linearly with share difficulty, zpool weights every share by its empirically measured expected number of hashes. We report production records, including 28,823 blocks found by the Shard0 pool and 587 automatic payouts, with sample transactions that anyone can check on chain. We also report a share-level Monte-Carlo simulation whose parameters come from the live pool configurations. Across 30 simulated days on each shard, every miner's share of gross rewards stayed within 0.3 % of its share of hashrate. For the smallest simulated home miner, the coefficient of variation (CV) of hourly income fell from 1.44 when mining alone to 0.075 in the pool on Shard0, and from 0.86 to 0.098 on Classic Shard1. Hours without income fell from 61.7 % and 25.6 % to zero. Under the tier schedule, net income never decreases as hashrate rises, and splitting one miner into several addresses can never lower its fee rate. Half of the pool-fee revenue is passed on to full-node operators.