- Joined
- Dec 27, 2012
- Messages
- 39
Hi Jim:
I teach this to my students every quarter according to the universally accepted right hand rule. Turn your right hand palm, up. Extend your thumb, index and middle fingers. Your middle finger points to Z+, Your index finger points to Y+ and your thumb points to X +. These are tool movements, if you think of the table moving you will have major problems when you start programming. Though in reality the table moves, the relationship to part home (G54-G59) and current drawing conventions dictate that the tool moves relative to the part. This is easiest to grasp when you think of the tool moving. I teach the "normal convention". It is the tool moving. The end result is identical to what you have written, but everyone thinks of moving the tool relative to the work, not the table.
Axes are labelled thus:
Primary linear axes are X, Y and Z, Z is the axis of the spindle, X axis is the longest axis perpendicular to Z and Y is the second longest axis perpendicular to Z.
Secondary linear axes are parallel to the primary axes and are labelled U if parallel to X, V if parallel to Y and W if parallel to Z.
Primary Rotary axes are labelled A if they rotate about X, B if they rotate about Y and C if they rotate about Z.
I did not make this up. It is standard. Open any CNC programming manual and you will see these conventions.
W is actually a linear secondary axis parallel to Z, not a rotary axis.
We had a tough time with this very issue of tool changing on automated Bridgeports not long ago. My answer was exactly what you suggested, put a scale with a DRO on the knee and use it to adjust for different tool lengths giving the full 5 inches of quill travel to the tool movement. This of course requires repeatable tool insertion depths like using Tormach tool holders allows. That is what we came up with, Tormach, do you have another way of controlling tool lengths?
Barry
I teach this to my students every quarter according to the universally accepted right hand rule. Turn your right hand palm, up. Extend your thumb, index and middle fingers. Your middle finger points to Z+, Your index finger points to Y+ and your thumb points to X +. These are tool movements, if you think of the table moving you will have major problems when you start programming. Though in reality the table moves, the relationship to part home (G54-G59) and current drawing conventions dictate that the tool moves relative to the part. This is easiest to grasp when you think of the tool moving. I teach the "normal convention". It is the tool moving. The end result is identical to what you have written, but everyone thinks of moving the tool relative to the work, not the table.
Axes are labelled thus:
Primary linear axes are X, Y and Z, Z is the axis of the spindle, X axis is the longest axis perpendicular to Z and Y is the second longest axis perpendicular to Z.
Secondary linear axes are parallel to the primary axes and are labelled U if parallel to X, V if parallel to Y and W if parallel to Z.
Primary Rotary axes are labelled A if they rotate about X, B if they rotate about Y and C if they rotate about Z.
I did not make this up. It is standard. Open any CNC programming manual and you will see these conventions.
W is actually a linear secondary axis parallel to Z, not a rotary axis.
We had a tough time with this very issue of tool changing on automated Bridgeports not long ago. My answer was exactly what you suggested, put a scale with a DRO on the knee and use it to adjust for different tool lengths giving the full 5 inches of quill travel to the tool movement. This of course requires repeatable tool insertion depths like using Tormach tool holders allows. That is what we came up with, Tormach, do you have another way of controlling tool lengths?
Barry