When cutting PCBs or other sheet material with the Roland MDX-15 it is hard to keep the height fixed. The material can deflect or pucker. This collar mounts on the Roland cutting block and has adjustable ball screws to set the height. use Mcmaster 98625A650 precision adjustment set screw and 98625A960 Brass bushing. The bushing holes need to be drilled to 0.312" When using: 1) insert the cutting tool zeroed at the surface. 2) adjust the set screws up so ~0.005" or about the thickness of heavy paper can fit under the ball. I have just started using this at http://www.makeitlabs.com there may still be issues.no raft or supports are required. 2 or 3 skins and at least 25% infill. A bit of post work is need on the faces that meet the block, minor scraping or sanding. The bushing holes need to be drilled to 0.312" ( 5/16 drill ). Insert the bushing from the bottom.