On Sun, 25 Jul 2010 18:32:40 -0500, you wrote: >I don't know the physical requirements. If the pawl is not needed for >rigidity but is only used for positioning then with an encoder the pawl can >be removed.
The pawl and the and the worm gear work in combination are essential to the rigidity. Without the pawl the stepper wouldn't stall and the changer wouldn't! (reliably ;) The physical requirements, like anything mechanical are the primary requirement. It's a doddle to set on up in Mach3, it's a worm and wheel gearbox driven by a stepper. Simple macro moves it forward x number of steps to pass the pawl to the next approximate position. Direction reverses by a few more steps than is needed to stall the stepper against the pawl and the changer is locked. The worm and wheel takes the cutting load as the pawl is spring loaded. There are NO switches or encoders. System is 100% reliable under Mach - never figured out how to run it under EMC. Here's a link to my first prototype changer that I still use regularly. http://www.youtube.com/watch?v=5dvLbb-HNsE it now changes tools in under 2 seconds. ( Tool 1 to Tool 8). Several changes have been made and the design is waiting for the Chinese manufacturer to pull their finger out <G>. I have another changer. An expensive fancy horizontal design, with positional switches, that lifts, rotates, then descends to lock - it only lasted days. Swarf got in it. It failed to lock. A few days later, swarf got in again, this time it stopped in the wrong position and sheared the central shaft. That was caused by having those positional switches - it insisted it wasn't in the right position and destroyed itself trying to get there. - It's now a $900 door stop, literally! It hold my shop door open - all it's fit for:) Steve Blackmore -- ------------------------------------------------------------------------------ The Palm PDK Hot Apps Program offers developers who use the Plug-In Development Kit to bring their C/C++ apps to Palm for a share of $1 Million in cash or HP Products. Visit us here for more details: http://ad.doubleclick.net/clk;226879339;13503038;l? http://clk.atdmt.com/CRS/go/247765532/direct/01/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
