Need 6' x 4' bed, 4 axis router design.. Help..!

[routercnc]

Critical speed is related to stiffness, but dynamic stiffness not static stiffness. The difference is the mass term. Nat freq is related to SQRT(k/m), so although the stiffness drops for a hollow section, the mass drops more. Therefore the frequency increases, as does the whirl speed.

[fasteddy]

Hi..

Am using a chain drive now, which works ok, but as this is my 3rd build I was looking to upgrade wherever I could.. Have a feeling that motors and electronic are going to be the biggest buy but those will be very dependent on the type of drive mechanism. One thing I will say about chain drive, get a good quality chain! I was shown the difference between a cheapo one (which I have) and a decent make and was very surprised at the accuracy difference.. 2nd thing is, keep them tucked away cause they attract dust like flies to poo..

Steve..

[Jonathan]

Why not use ballscrews on the X-axis, but spin the ballnut instead of the screw. I know it's a bit more work to set this up, but it removes the resonance issues and greatly reduces the rotating mass...

I'm doing this on my router, just with threaded rod not ballscrews:



One of those on each side of the gantry.