I have build my MPCNC a few month ago and already had some good success with it. I only have one problem I can’t really solve. When slotting semi hard materials like wood, aluminum and plastics the Z-Azembly randomly starts vibrating. If I don’t immedeatly dampen this vibration by grabbing the running router with my hand, it usually gets worse for some seconds until it vibrates massively (sometimes I guess more than 1cm), the bit snaps and the part is ruined.This only happens when milling slots. When the tool is only used on one side it’s working perfectly and with pretty good accuracy.
For some materials I found a way to eliminate this by reducing the stepdown to 0,3mm, but with other materials this doesn’t help. To me it seems like the problem is that when doing multiple stepdowns the tool starts rubbing along the walls until one flut catches and throws the tool to the other side of the slot and from this point on it never stops without grabbing it.
Has anyone else this problem? Or does anyone know what could be the issue? One way I found to minimize this, is by increasing the rpms to the maximum and going slower. But this doesn’t always work, because for example in plastics the will start melting when doing this. Looking forward to any ideas.