What might very well be the third-to-last CNC lathe update this year:

What might very well be the third-to-last CNC lathe update this year:

Joined: January 1st, 1970, 12:00 am

December 29th, 2017, 10:10 am #1

Got another long holiday weekend coming up, and I'm hoping to spend some quality time with my CNC lathe conversion, maybe finally cut some actual chips this time.

Spent a few spare minutes this afternoon throwing a limit switch on the X-axis (the cross-slide) which will be used as a "home" signal.



If I have a few minutes on Friday (that is, later today as I type this ) the Z-axis (left-right) switch should be nearly as easy to install. Although the easy part puts it all the way at the right hand end, and I'm not sure if the thing's going to want to "home" each time it calls for a tool change. If it does, that's going to add a LOT of cycle time.

Then again, I do plan on using a tailstock on this thing on occasion, so I have in mind a movable limit switch that clamps to the bed, and can be adjusted to whatever length is needed.

After that, I get to learn about things like tool offsets! (whee.)

Doc.
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Joined: October 26th, 2015, 2:44 pm

December 29th, 2017, 4:19 pm #2

The safest position (usually) for toolchange is the home coordinate, so it's often described as the default toolchange location when writing a new program. I like to use that approach for trying out new programs, or if I don't care about the wasted motion. That's how most CAM systems do it as well, including Fusion.

That said, you can program it to be any coordinate you want, which can be different for each tool if you really want to go that far. For instance if the programmed Z-origin is the right end of your workpiece, giving it Z3.0 might be plenty enough toolchange space for a typical turning tool. But if the next tool is a boring bar or drill, you'll need to add in extra space to account for the next tool's lengthier overhang.
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