A passive automatic CNC tool changer

[Marius Hornberger] His “Hammer” CNC router is busy hacking again, and now it’s a very desirable feature – an automatic tool-changer. Wanted one for a while, [Marius] Only the tool-changer was dissatisfied with the magazine dedicating a large portion of the bed area to be used for parking. An obvious solution is to keep the magazine away from the bed outside the workplace. Sadly, the CNC controller only had enough extra output to run the pneumatic tool changer (mounted on the spindle) which left nothing extra to control the magazine assembly. So, only one obvious path had to be taken, instead use some simple spring-load mechanics to move the magazine to the tool-picking range with Y axis motion.

Clearly, the whole thing is built into the CNC machine, with just a few repetitions and table-s action smudges to fit everything well and work smoothly without being tied or colliding with the moving gantry. A cunning pair of levers at each end of the magazine allows it to move much further than the advancing gantry, allowing the Y axis to swing rapidly in position when it is at the peak of its travels, and the gantry to move backwards. Another nice addition to the build was a tool depth sensor (AKA: a switch) mounted on one side, which allows the machine to find the bottom of each tool, if it is not known, so the Z axis can compensate. When combined with the automatically retracted dust shoe, this is definitely a CNC build that we would like to see in a store near us!

We’ve hacked a number of CNCs over the years, including tool changers, but 3D printers can also use some tool changers!

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