I have been cutting 1/8" plywood using a 1/16" bit. I have run into severe chatter. I have been trying to figure out the problem and finally figured it out.
My X-carve is the 500mm model and uses a 1/2" wasteboard.
I finally realized that my “Z” carriage was vibrating. I found that my 1/16" bit was fastened into the spindle as deeply as possible and while everything was good when homing, as soon as I started to cut the carriage would go lower and the wheels began to slip off the track causing the cutter to shudder and vibraate.
Two solutions, 1st don’t insert the cutter as deeply into the spinle. 2nd Use a thicker wasteboard so spindle carriage won’t go so low on the track This will require some creative cutting to fit while still clearing the “Y” axis wheels, or third, add a sacrificial piece on top of the wasteboard drilled to match.
Or, just lowering your z-axis maker slide a tad.
Or lowering your spindle within the mount.
I would try to keep your bit as deeply seated in your spindle as possible. The less stick out, the better.
I use a sacrificial wasteboard on top of mine because I prefer to simply screw my work pieces down into the sacrificial waste board instead of fussing with clamps. This allows me to surface the waste board with an end mill to make it perfectly flat to the machine (no high spots). Plus, i make a lot of “through” cuts so my sacrificial takes a beating. When I need a new surface, I just shave a few mm off the top.
I use the same method as Earwigger, with a sacrificial wasteboard. Mine is a 12" square, because most of the parts I work on fit within that footprint anyway. I just come back and face that board off to make sure it’s truly square to the machine after I install it the first time. As an added bonus, it gives me a vertical wall on X and Y to slide my pieces up to for alignment.
That is a really good point. I heavily rely on those aligment “walls” when milling tiny pieces. Every once in a while I am tempted to test them to see if in fact, they are still in alignment.