9.8 Tool Setup
Micky R. Jennings
Setting up tooling on a milling machine requires some calculation, checks, and adjustments to make sure the cutting process will be successful. A couple of the most important things to think of when setting up tooling on a milling machine is to use the correct tool for the cut and to keep the tool setup as rigid as possible.
When selecting tools, a good rule to follow is to use the largest diameter and shortest tool that will be able to complete the job. Keep in mind that end mills are the most common cutting tool and generally come in sizes from ⅛” to ¾” for manual milling. If the print requires a deep cut with a lot of metal removal, a larger diameter tool will be more rigid and remove the material faster than a smaller diameter tool. If the print requires a narrow, shallow cut, a shorter tool would be better suited for the cut than a long tool because it will be more rigid and cut more accurately with fewer problems.
When loading the tool, the operator must think of how to optimize the rigidity of the tool they have selected. The operator should choose a type of holder that is capable of holding the cutting forces of the tool. End mills should never be put into a drill chuck. When installing the tool into the tool holding device, the operator should engage as much of the solid shank of the tool as possible, generally within ⅛” of the flutes. Likewise, the tool should never be gripped over the flutes of the cutting edges.
Loading Tools into and Removing Tools from the Milling Machine
As with all machining setups, cleanliness is going to be key when loading tools into the milling machine. Clean tools and holders reduce the chance of damage and help maintain the accuracy of the spindle and tooling. Modern manual milling machines utilize an R8 taper and a draw bar for securing tooling. Some tools, such as endmills, are held in R8 tool holders or R8 collets. Other tools, such as face mills, may be held by an integral R8 shank that is part of the tool itself. Twist drills are usually held in drill chucks, unless there is a specific need to hold the tool tighter, and there is a collet in the same size as the drill shank. Holding a reduced shank drill in a ½” collet is a good example of this instance.
For safety, a box end wrench or vise handle is not recommended when tightening the draw bar. An open-ended wrench is safer because it cannot be accidentally left on the draw bar and, inadvertently, have the machine turned on. Not heeding this warning could result in the operator being injured, the machine becoming damaged, or the tooling being broken.
The following process is for loading and unloading tools from a milling spindle with an R8 spring collet as the holding device. The process is similar for loading integral shank R8 tools or end mill holders. The main difference is that end mill holders should have tools installed and removed from the machine before being installed into the spindle. On specific machinery in t