Post
by cvoinescu » Mon Feb 03, 2014 12:40 am
Krayvis, I have watched your video and enjoyed it. I have just two little comments about it.
Many people mill a fraction of a millimeter into the wasteboard when they cut their parts. You want any metal (T-nuts, threaded inserts) to be at least a millimeter below the top of the wasteboard, to avoid hitting it with the endmill. Or, you can treat the bed as permanent (non-consumable), and always add a waste sheet under the workpiece, like I've seen you doing. A sheet of MDF with the same hole pattern as the workholding table would come in handy (or several -- say, a small one, a medium-sized one, and one the size of the bed that's used only for full-size jobs; when one becomes too tattered, just mill another one).
The paper method of finding the zero height works great, but there's one that's almost as quick and more accurate: instead of sliding a sheet of paper, try to roll a cylinder of known diameter -- say, the shank of another 1/8" endmill -- under your tool. Jog the Z until the cylinder barely touches the tool as you roll it under it. Tell the machine that the Z coordinate is now the known diameter of the cylinder, and you're set (for example G92 Z3.175). When you don't need the accuracy, as in your case, the paper method is indeed quicker.
