I have a newly living and breathing OX (thanks SWM3D for the kit). I opted for a TinyG to control the 300W spindle as I am just starting out and primarily cutting softer materials (acrylic and Alu 6061). The machine itself is working pretty well and my general finish is good. However, I am experiencing vibration during cutting which could be down to a number of things but I thought I'd throw it out there..... 1. 3/4" thick MDF as the spoil board - this thick enough not to flex or should I go to 1"? 2. Spindle attachment - I'm using the quick/dirty mount..... this seems solid enough but is it really? 3. Z axis attachment to the X gantry - everything is tight and all wheels are getting good contact with the V-slot. My x gantry is also epoxied to make that a bit more solid. 4. The spindle itself. I've seen a review of the cheap 300W spindle (here: ) and it's not complimentary. In this respect, I don't think the 400W would be any better. To give some numbers, for 10,000rpm with a 3 flute alu endmill (0.125") I should be able to move the feed at about 25-30ipm with a depth of cut up to 0.2 (from: http://zero-divide.net/?page=fswizard) but in reality, I'm back at 0.05" DOC and about 10ipm (and still getting occasional vibration). Will the OX really go this quickly through 6061?? I've not had big issues with missed steps but next up is double-belting and larger grub screws on the pulleys. This is unrelated to the above. As I said, the finished work doesn't look too bad. The image attached is a bit of engraving combined with cutting of 0.09" 6061-T6 . Thanks, John.