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docs/machines/desktop_cnc/Rationale.md

+## Rationale for the Desktop CNC
+
+In this file an initial bunch of considerations, links and references.
+
+### Router motor
+
+Current choice: FM 1000 PV-ER
+
+Main reasons:
+
+- it is one of the cheapest (355€) router that can be externally controlled
+- it is compatible with the ER 16 standard
+- offer several safety and protection features
+- uses 43mm standard clamping
+- does not need a VFD
+- it is quite compact
+- it is light (1.65Kg) in comparison to professional spindle (eg ELTE 450W is 3.1Kg)
+- it maybe adapted in some kind of tool changing (not requiring compressor!)
+
+Alternatives:
+
+- AMB 530, cheapest, but manually controlled, low power, no ER collet
+- AMB 1050 FME-W DI, with Tool Changer (air pressure) but 1200€ cost
+
+### Machine configuration
+
+Current choice:
+
+- gantry CNC (aka portal milling machine)
+