Speaker To-Dirt wrote: > Hi All: > > Being new to EMC 2 and g-code I have yet another question to ask. When you > do a tool change what's the best procedure for determining the tool length, > and then how do you communicate that to the g-code? I hate to admit this, but > I've been using the knee to adjust out the differences in length from one > tool to another. > > I'd love to hear how other people do it, esp how it's done in industry, > and hwo EMC2 expects you to do it. > First, do you use collets or tool holders? Collets usually don't reproduce the same length each time. If you don't have repeatable tool positioning, you need to "touch off" the tool after each tool change.
If you have a repeatable tool position (quick-change spindle, toolholders, etc.) then EMC has a tool table that holds tool length and diameter. G43 applies the value in the table to the current tool. There are a couple ways to use it. I made a simulated R8 taper fixture that can be set on a surface plate and the tool length measured with a height gauge. You can then reference all your tools to a specific tool you use as the "reference tool". That reference tool has its length entered in the tool table as zero. All other tools have the difference in length from the reference tool entered in the tool table. Longer tools have a positive length, shorter ones are negative. The methods of switching in tool length or radius compensation are a bit tricky, but you want to be away from the workpiece when giving the G43 and G40 (cancel compensation) commands. These commands are interpolated in over the length of the move following them, so they can cause crashes if not well thought out. Anyway, if you don't have an automatic tool changer, it may be much easier to do all work with one tool, even putting all workpieces through a particular step before changing the tool, touching off and then doing the next step, with different tool, on all parts. In "industry" there's a guy, maybe in the metrology department, who has a tool presetter. He puts the tools in the presetter, measures the length and diameter, and enters those in a database. When the tool is mounted on the machine's tool carousel, that data is entered into the machine's tool table. You will even see on some CNC machining centers there is another CRT and keyboard behind the machine where the tool changer can be accessed, for entering this data. Another system is to put a tool probe on the machine table, and the operator can go and measure all the tools on the sensor when setting up for a job. Jon ------------------------------------------------------------------------------ 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
