I have been using PCB milling machines for a while, One of the difficult parts in the milling process is the frequent tool changes required. An Automatic Tool Changer could be a solution to this problem. But there are no small cost-effective ATCs anywhere.
One of my primary criteria, while I started this project, was to make it easy to replicate → I know it's not as easy as its sounds. The machines which are accessible to the masses are not accurate enough to meet the precisions required for making a precise spindle but it could be a start for many others
A few of the references I had
Carvera - https://www.kickstarter.com/projects/makera-inc/carvera
Diy - https://shane.engineer/blog/power-drawbar-x2-mini-mill
- [https://www.youtube.com/watch?v=CFCo1EBo3cU](https://www.youtube.com/watch?v=CFCo1EBo3cU)
- [https://www.youtube.com/watch?v=NhHAEFwQcCA](https://www.youtube.com/watch?v=NhHAEFwQcCA)
https://shane.engineer/blog/power-drawbar-x2-mini-mill
My initial approach was to use a couple of magnets to attach the collet to the holder . Since we are using small diameter bits for PCB milling the axial cutting force should be minimal and hence a neodymium magnet could be able to handle the load. the rotation of the tool is arrested with a projection on the holder similar to BT40 holders
I also had few iterations of the same concept
The teethes on the holder and spindle will transfer the rotational motion from the spindle to the holder .
At the top of the collet holder a neodymium magnet is embedded it will get attracted towards another magnet in the spindle. the magnets will keep the holder attached to the spindle.
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I tried a different approaches to avoid the need of an extra holder .
The bit could be directly attached to the mechanism with a split collet and spring .
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