I recently bought my 1st router/engraver similar to this one

It's more than adequate for plastic, MDF, and wood. But not steel, which suffers from severe vibration and runout. Here's a video of cutting mild steel with a 6mm carbide bit @ ~4000RPM = 247 surface feet/minute. Radial cut is ~2mm and depth of cut is < 1mm. If depth is increased, vibration gets worse. Also doing a climb cut.


Notes: the movement is jerky because I was manually jogging by 0.1mm. Also I mounted the machine on spring loaded feet to reduce vibration. Using the stock feet causes the steel shelf to vibrate like crazy.


I know routers aren't meant for steel, but is it hopeless or are there mods or ways to do it? Is my work holding sufficiently rigid?

The main problems I see are:
1. The spindle speed is too high. I can go lower but then torque is lost, causing end mill to get stuck.
2. The 3 axes are stacked, amplifying the play in the axis that has to support the most load. I don't know if this is a fundamental problem. If I had realized this earlier, I might've went for a Bridgeport style mill.
3. The distance from the bottom of the spindle clamp to the end mill tip is 12cm. Is that unbraced section causing a lot of play?