Tool Length Offset setting for tools exceeding quill travel
Posted: Fri Mar 29, 2024 1:59 pm
I did a Centroid conversion on a Trak DPM bed mill I bought for my home shop. I program on GibbsCAM, and use the same post processor we developed for the Haas VF-3 SSYT at work with no problems.
A couple years ago, my employer purchased a new Clausing knee mill equipped with a Fagor 8055 control. They claimed that they too could sum Z (quill) and W (knee) axes, like the Centroid I was familiar with. This was important to us, since we regularly need to use a variety of tools on jobs that vary in length nearly as much or greater than the available CNC controlled quill travel. Long story short, it didn't perform as advertised and the operator interface was not nearly as user friendly as what I was accustomed to on my Centroid equipped home mill. So, on my suggestion, we had Granite Controls out of South Dakota retrofit a Centroid control in place of the Fagor, reusing the servo amps and drive motors.
Although the post processor for the Haas VF-3 SSYT at my employer works just fine to output code for my Trak DPM bed mill conversion at home; it gives Z axis overtravel alarms near constantly on the knee mill at work running the same Centroid control configured for Z/W axis summing. Always happens at the beginning of a program or during tool changes (manual, no ATC). I was hampered by the fact we don't have a lot of spare time at work to tweak outputted g-code or mess with parameters, then run tests to see if it changes the behavior. Granite Controls hasn't been the most helpful either, so we are left with a machine we all avoid because it takes so long to try to get programs we generate with GibbsCAM to work on it.
Recently, because I am working on installing a rotary axis on my home mill, I stumbled upon Centroid's YouTube channel and video explaining TLO procedures and the use of "Reference Tool", along with CNCSNW's page graphically showing how Centroid calculates TLO along with his writeup of post processor development "rules".
Those post processor "rules" will hopefully help me understand what to tell GibbsCAM what to modify in the post to get code that runs without generating alarms. I'm sure it has to do with how we are setting TLO and the fact that we are limited to such short Z axis CNC control. I thought the axis summing would have handled that issue. Your graphic explanation of TLO and the use of "Reference Tool" along with Centroid's YouTube video on the same are helping me understand how all that is being calculated by the control. BUT, what do you do if the length change from your shortest tool to your longest tool exceeds the quill travel and you MUST reposition the knee during the program?
A couple years ago, my employer purchased a new Clausing knee mill equipped with a Fagor 8055 control. They claimed that they too could sum Z (quill) and W (knee) axes, like the Centroid I was familiar with. This was important to us, since we regularly need to use a variety of tools on jobs that vary in length nearly as much or greater than the available CNC controlled quill travel. Long story short, it didn't perform as advertised and the operator interface was not nearly as user friendly as what I was accustomed to on my Centroid equipped home mill. So, on my suggestion, we had Granite Controls out of South Dakota retrofit a Centroid control in place of the Fagor, reusing the servo amps and drive motors.
Although the post processor for the Haas VF-3 SSYT at my employer works just fine to output code for my Trak DPM bed mill conversion at home; it gives Z axis overtravel alarms near constantly on the knee mill at work running the same Centroid control configured for Z/W axis summing. Always happens at the beginning of a program or during tool changes (manual, no ATC). I was hampered by the fact we don't have a lot of spare time at work to tweak outputted g-code or mess with parameters, then run tests to see if it changes the behavior. Granite Controls hasn't been the most helpful either, so we are left with a machine we all avoid because it takes so long to try to get programs we generate with GibbsCAM to work on it.
Recently, because I am working on installing a rotary axis on my home mill, I stumbled upon Centroid's YouTube channel and video explaining TLO procedures and the use of "Reference Tool", along with CNCSNW's page graphically showing how Centroid calculates TLO along with his writeup of post processor development "rules".
Those post processor "rules" will hopefully help me understand what to tell GibbsCAM what to modify in the post to get code that runs without generating alarms. I'm sure it has to do with how we are setting TLO and the fact that we are limited to such short Z axis CNC control. I thought the axis summing would have handled that issue. Your graphic explanation of TLO and the use of "Reference Tool" along with Centroid's YouTube video on the same are helping me understand how all that is being calculated by the control. BUT, what do you do if the length change from your shortest tool to your longest tool exceeds the quill travel and you MUST reposition the knee during the program?
