Luna
CNC Machining | Tool & Die Making
My first CNC machining project, a simple punch and die to make useful punches and blanks
Materials.
| Low carbon steel
| 3/8” Steel pins
| .020” copper and brass sheet
Processes.
| CAD modeling (Solidworks)
| CAM programming (HSM Works)
| CNC milling (Haas VF2)
Timeline.
| 3 weeks
Design.
Luna is a punch and die set that produces useful punches and blanks from thin (.020”) sheet metal. Luna is intended to be used with copper or brass sheet but will also work well with aluminum. The clearance between the cutting edge of the punch and the die is between .001” and .002”, which produces high quality punches and blanks with clean edges and no burrs. This punch and die can be operated using a small, bench-top arbor press. Luna enables one to quickly create multiples of delightful products out of sheet metal, such as the folded night light covers and earrings pictured above.
Manufacturing lessons.
Luna is manufactured from low carbon steel and utilizes 3/8” steel dowel pins as both alignment features and slide linear bearings between the punch and the die. As a punch and die tool, Luna lacks longevity. The quality and life of the tool could be improved and extended if the surface were hardened with heat treatment. The punch side of the tool would cut even cleaner and last longer with a back taper of roughly 1°. Additionally, the alignment pins are prone to binding. In future iterations of the tool, the binding problem could be improved by lengthening interaction with the dowel pins, adding linear bushings, and by locating the slide bearings on either side of the punching force. The current design makes binding almost inevitable because the punching force applies a moment on the two linear bearings.
Having fun on a Bridgeport manual mill, prepping stock before CNC milling.
CNC machining the die side of the tool. Marks from facing with a shell mill visible.
Checking fit for the slide bearing to withing .001" using pin gauge.
Finished die next to square stock for the punch side.
Finished punch and die with parallels for manual machining. Note the tabs for tool separation on the punch side.
Reaming the slide bearing holes on a manual mill.
Completed punch and die with test pieces. The quality was remarkably good – Luna made punches and blanks clean edges and no need for de-burring.
Lining up the workpiece with the tool.
Punching with a small arbor press. Note: this was not a user friendly process due to the pin binding problem explained above.
Bending a small night-light enclosure on the box-and-pan brake.
An example night-light, using a small tea candle, made with punches from Luna.
Blanks, some of which have been sanded and/or given a hammer-tone pattern with a ball peen hammer.
Two other night-light prototypes, made using Luna and manual sheet metal tools.