Quick question about threading with LinuxCNC. If you do a feed hold between passes for cutting a thread and during that feed hold change the spindle speed what will happen? >From a start it takes a certain amount of time to accelerate up to the >required speed. If the spindle is turning twice as fast as the previous pass >it then turns twice as far. That doesn't line up the cutter with the previous >thread. The observation comment assumes a standard acceleration rate for the Z axis. However, the system could also be configured to accelerate up to arrive at a specific spindle position once it reaches threading speed. For example. The system knows using the fastest Z axis acceleration+speed and spindle speed means it can arrive at threading speed in 30 degrees of spindle rotation. At slower spindle speeds it would not accelerate so fast that it might be there at 5 degrees of spindle rotation. Instead it would ramp up much slower so that when it reaches the much slower Z axis speed it also has reached the 30 degree spindle position. At that point it doesn't matter anymore as long as the Z axis tracks the spindle speed the tool bit will follow the previous thread. So what does LinuxCNC do? Is the thread mucked up if spindle speed is changed during a feed hold and then start? Thanks John Dammeyer "ELS! Nothing else works as well for your Lathe" Automation Artisans Inc. www dot autoartisans dot com
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