Just a wild thought.
We sold off our 'Shark' CNC because we could not get around it cutting too deep for end mill cuts, even shallow depth cuts.
What happened was the bit dug into the work piece with enough pressure to pull itself further into the work piece.
After research into CNC designs and specifications, we feel this was a design fault of our particular 'Shark' model it was a few years old when we purchased it second hand.
OK if you only wanted to carve but definitely not for cutting with end mills.