shaking problems when i do holes


I using an bosch 8mm flute with 2 straight bits, it can go up to 20mm deep. Making cuts and pocket work great on mdf, i using 2mm (Z) for each pass.
But the problem is when i try to make an 15mm hole, at 5 or 6 mm deep the flute start to shake very violently and i end up with an big hole of 20mm or more.

I do not know how to solve this…

  • My cnc legs was 20cm, maybe using short legs like 15 or 10 cm?
  • Use an 6mm or 4mm flute to make the 8mm holes?

I would suggest moving the work closer to the xy axes (instead of shortening the legs), and slowing the machine down.

I agree, move the work piece as close to the gantry as possible, Although shorter legs is actually a better option. You could also try climb vs conventional milling. Single flute is also probably a better option for the speeds we go and how fast out spindle rotate. Believe it or not more and faster is not better. You need to maintain an appropriate chip load.