[Aa...] Posted June 11, 2021 Share Posted June 11, 2021 I've been fighting with some weird (and frustrating) behavior from Calypso. I'm having to measure a square thread. It's an internal thread, and I'm measuring the major diameter. Obviously, I have to measure it with helical paths with the "Gradient/Slope" set to the pitch of the thread. Even though it is driving in and starting the first path correctly (a minor miracle, since it's a shortened 0.5 mm probe in a 90 degree holder), it doesn't seem to be following the thread. It's going down when it should be going up, and plowing into the flank. The yellow paths on the cad model look right when I open the cylinder feature. I've sheared off two custom ground 0.5 mm probes so far. 😠 Does anyone else have experience with Calypso helixing the wrong direction when it runs? Link to comment Share on other sites More sharing options...
[Ch...] Posted June 11, 2021 Share Posted June 11, 2021 I measure a lot of threads with helical scans. Just as a sanity check, have you reversed the polarity of your 'gradient/slope(helix angle)' . I could just be trying to measure in the wrong direction. If that doesn't work then linear scan paths with a max inscribed cylinder would get you major ID. Link to comment Share on other sites More sharing options...
[Aa...] Posted June 11, 2021 Author Share Posted June 11, 2021 Please sign in to view this quote. Thanks, but I don't think linear scan paths will work in getting the major diameter on an internal thread. 🙂 Link to comment Share on other sites More sharing options...
[Me...] Posted June 11, 2021 Share Posted June 11, 2021 I never understand which way I should be looking. Top down or bottom up. So changing direction doesn't help? Link to comment Share on other sites More sharing options...
[Ch...] Posted June 11, 2021 Share Posted June 11, 2021 Well ya can't say I didn't try. Here is a little food for thought.Threaded_Holes_metrology_conf_2011.pdf Link to comment Share on other sites More sharing options...
[Jo...] Posted June 11, 2021 Share Posted June 11, 2021 I can't envision how you are able to measure the major without shanking out. A 90 degree stylus with rotary table ? Link to comment Share on other sites More sharing options...
[Aa...] Posted June 11, 2021 Author Share Posted June 11, 2021 There are clearance openings on two sides of the thread. (Which I have positioned at the front and back. I'm only measuring about 45 degrees with each scan. Yes, a 90 degree stylus, but no rotary table. Oh, and I have two 90 degree styli, one left and one right. The help says that if the rotation direction is activated, it will be clockwise. However, if I activate it, the path visualization on the CAD runs CCW from it's start angle when viewed from the feature's Z+ direction. (Also, my problem isn't knowing whether it will go CW or CCW, but rather whether it will go up or down.) Maybe I need to start at the top end of the path and have it helix down... Or maybe I just need someone from Zeiss to weigh in and explain how to know what's going on... Link to comment Share on other sites More sharing options...
[Jo...] Posted June 11, 2021 Share Posted June 11, 2021 Please sign in to view this quote. How do you measure less than a full rotation ? My helix choices are 1 to 10 rotations. I am using cylinder feature. Link to comment Share on other sites More sharing options...
[Aa...] Posted June 11, 2021 Author Share Posted June 11, 2021 Please sign in to view this quote. Thanks for the powerpoint. I've used those methods for locating tapped holes many times. However, in this case, our customer is looking for verification of the major diameter of a custom thread ring gauge, and the helical path I'm looking for should be no sweat. (That is, so long as Calypso does what it's supposed to.) I just verified on a master ring gauge with a standard stylus that activating the "Rotation Direction" control causes it to helix clockwise when viewed from the feature's +Z direction. And it always went "up" and "down"on the feature when I expected it to. Link to comment Share on other sites More sharing options...
[Aa...] Posted June 11, 2021 Author Share Posted June 11, 2021 Please sign in to view this quote. I'm selecting that combo box and typing in a decimal value of .125. Link to comment Share on other sites More sharing options...
[Jo...] Posted June 11, 2021 Share Posted June 11, 2021 Please sign in to view this quote. wow, I never realized you could do that. Link to comment Share on other sites More sharing options...
[Aa...] Posted June 16, 2021 Author Share Posted June 16, 2021 Interesting. Originally, It appeared the machine was trying to drive pretty much straight down, instead of helixing up. Now that I laid the helix path out to run from top to bottom instead of from bottom to top, it appears to be trying to drive pretty much straight up. I've been entering the thread pitch in the Gradient/Slope field, but if instead, I enter the product of the pitch and the decimal number of rotations, the machine appears to be driving along the actual thread helix. This is aggrivating, as the yellow path in the CAD window doesn't show that. What's the point of the yellow path if it doesn't show what the machine will do? Link to comment Share on other sites More sharing options...
[Aa...] Posted June 16, 2021 Author Share Posted June 16, 2021 I succeeded. I believe the problem had to do with the target height. I recreated the helical paths, using formulas for the start and target heights. I'm not sure why this was needed or successful. Link to comment Share on other sites More sharing options...
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