B-Axis Spindle Tilt Function - G400 IMPORTANT NOTE: A B C D When a tool is touched off in a manner that is normal to its cutting position as shown in figures A & B, the tool length is measured by the Q-Setter, including any tool nose radius built into the insert. A high degree of accuracy can be achieved without issue with this method because the reference point shown in figure B is included in the X and Z measurement. When a tool is touched off in a manner that is NOT normal to its cutting position (Figures C & D), The calculations from within G400 project the theoretical position of the tool based on the information defining the tool.
This definition includes the measured tool length of X and the described R value in the tool offset register. A higher degree of accuracy will be achieved with G400 if the radius of the tool is known. For example, A 0.0313 radius cannot be assumed with a CNMG432 insert. Typically, tool manufacturers use a +0 -.005 tolerance band for radii. It is common for the actual radii to be -0.003. When using G400 with a turning tool, it is best to start with a radius of minus (-) 0.003 of the published radius in R of the offset page. EXAMPLE: An ID Boring Bar or Grooving Tool is only used at B-90.0. Simply touch off the tool in the orientation it will be cutting.
The program should have an explicit command for positioning the B-Axis Angle. However, if you choose to use G400 in such a case, there are some facts users should be aware of. It is permissible to touch off ID Boring and Grooving Tools at B0. However, the Tool Nose Radius at the Touch-Off point MUST be entered in the Offset R-Field. Also, using J11 or J12 on a G400 command line requires a G490 S____ command PRIOR to the G400 line in order for compensation applied to be accurate. Using G490 S____ AFTER the G400 line will orient the spindle but your compensation will NOT be accurate. Please reference the Doosan Programming Manual page 14-4.
Due to the added complexity involved in touching off at B0 for ID tooling that is only used at B-90.0 , The use of G400 is discouraged in favor of the traditional method of touching off at the B-Axis Angle used in the operation. - 27 -