[SH...] Posted January 15, 2021 Share Posted January 15, 2021 Recently I get more jobs related to threads position such as M8 , M10 etc. What would be best strategy for measuring threads, cylinders with LSQ or MIE, 3D line using two circles?. Link to comment Share on other sites More sharing options...
[Ün...] Posted January 15, 2021 Share Posted January 15, 2021 I made a conical gauge like this for checking the M8 thread position. Repeatability is very good. Link to comment Share on other sites More sharing options...
[SH...] Posted January 15, 2021 Author Share Posted January 15, 2021 Please sign in to view this quote. I have pattern holes, l have to buy more gauges like this. Second point, my QA head will not permit this method. This is good Idea, I tried it in my past company. Link to comment Share on other sites More sharing options...
[Th...] Posted January 15, 2021 Share Posted January 15, 2021 My strategy: - Online with Four-Point Circle Macro (doesn't work offline) - Offline with a Cylinder's Helix path If you have the correct gradient, it doesn't matter if your element's position is on minimum or maximum of the thread diameter for True Positions/Bore Patterns. Link to comment Share on other sites More sharing options...
[To...] Posted January 15, 2021 Share Posted January 15, 2021 Attached is a long standing experiment done by Ryan Staufer.Threaded_Holes_metrology_conf_2011.pdf Link to comment Share on other sites More sharing options...
[Ri...] Posted January 15, 2021 Share Posted January 15, 2021 If you want the most accurate and repeatable you will need a true-position plug. If you can sacrifice some repeatability you can either do two methods: - Helix path up the pitch using self-centering. This only works on active scanning heads - Linear line scans up the thread. I do a minimum of 5 lines, on the evaluation side you will need to set your Outlier Elimination to 1/3 with at least an iteration of 3 times. In order for this to work well, you will need to have a high amount of point density on the lines. If the thread pitch is large enough, like for example a buttress thread for the oil/gas guys I'd use the helix no matter what. If it is a small fine pitch thread, the linear line scans will work perfectly. Link to comment Share on other sites More sharing options...
[Ke...] Posted January 15, 2021 Share Posted January 15, 2021 I'm not sure what the ISO requirements are. I believe for ASME the position applies to the pitch diameter, unless specified on the print, otherwise. If the only option available is to use linear scans on the thread, I would note that the use of threaded hole location gages were not permitted... I'm guessing due to the cost. Link to comment Share on other sites More sharing options...
[Ch...] Posted January 15, 2021 Share Posted January 15, 2021 Please sign in to view this quote. This is not always true, e.g. using a standard plug on a cast surface(read page 51-54 of the presentation). If the casting surface is sufficiently rough, then it will cock the plug at an angle. You will be able to miniplate the results by how much torque you put on the plug. Not every threaded bore lies on a machined surface. In this particular instance, you will get more accurate and repeatable results measuring on threads. Note, this does not apply to the threadlock plugs that don't interface with the surface. Link to comment Share on other sites More sharing options...
[Cl...] Posted January 15, 2021 Share Posted January 15, 2021 [quote= - Linear line scans up the thread. I do a minimum of 5 lines, on the evaluation side you will need to set your Outlier Elimination to 1/3 with at least an iteration of 3 times. In order for this to work well, you will need to have a high amount of point density on the lines. [/quote] I did this yesterday on a gage with a tolerance of +/- .0005 for Z location 3x. Worked great, all three came in. Link to comment Share on other sites More sharing options...
[SH...] Posted January 15, 2021 Author Share Posted January 15, 2021 Please sign in to view this quote. Tecnicaly it might be pitch circle diameter, how we can check pitch circle diameter in CMM??. Usually, the drawing I get mentioned minour diameter, bottom of the FCF. Link to comment Share on other sites More sharing options...
[Jo...] Posted January 15, 2021 Share Posted January 15, 2021 Please sign in to view this quote. If there is a modifier for size I ignore it for this reason. Link to comment Share on other sites More sharing options...
[Ri...] Posted January 15, 2021 Share Posted January 15, 2021 Please sign in to view this quote. I can see the argument for a casted surface - fair enough. Link to comment Share on other sites More sharing options...
[Me...] Posted January 15, 2021 Share Posted January 15, 2021 Please sign in to view this quote. To go even further I would suggest using the plugs that have the slot cut in them so they tighten up at a certain depth because we have the regular plugs and when they're tightened down to a face, the results were a little sporadic compared to my double helix path scans. Link to comment Share on other sites More sharing options...
[Ri...] Posted January 15, 2021 Share Posted January 15, 2021 Were they the flex-plugs? Link to comment Share on other sites More sharing options...
[Ch...] Posted January 15, 2021 Share Posted January 15, 2021 Please sign in to view this quote. Precisely. For example, suppose your threaded cylinder is not very perpendicular to the machined face. When you use a standard plug that mates with the machined plane, then the perpendicularity error will again cock the plug to the side. Again, you will see differences in results based on how much torque is applied to the plug. Link to comment Share on other sites More sharing options...
[Ri...] Posted January 15, 2021 Share Posted January 15, 2021 How often do you see tight tolerance threaded-holes on casted parts like described? If the tolerance is very open, just directly measure it. I should have clarified, but my position about thread plugs refers to machined surfaces, and tight tolerances. They are also great for heli-coils. Link to comment Share on other sites More sharing options...
[Ch...] Posted January 15, 2021 Share Posted January 15, 2021 yeah, we're kinda picking on ya Richard. You set yourself up by saying "if X, then always Y." You know that we can't let anything be black and white around here. Please sign in to view this quote. More than what you would think. One reason is designers using what I call "feel good tolerances." Also, more and more standards are holding features to 1.33CPK and even 1.66CPK. These are the situations where it comes up. Link to comment Share on other sites More sharing options...
[Jo...] Posted January 15, 2021 Share Posted January 15, 2021 Please sign in to view this quote. But the measured cylinder on the thread locator is not the thread location. It is a projected position. Link to comment Share on other sites More sharing options...
[Ch...] Posted January 15, 2021 Share Posted January 15, 2021 Please sign in to view this quote. I agree. I think what you said is true and also what I said is true that the way in which the plug interfaces with the mating surface has an impact on repeatability. Link to comment Share on other sites More sharing options...
[Me...] Posted January 15, 2021 Share Posted January 15, 2021 Please sign in to view this quote. Lol I definitely wouldn't slight Richard for anything on here, that man has helped me with so much! I just wanted to relay my experience in case someone wants to buy these plug gages. They would definitely do well to buy the slotted ones. Link to comment Share on other sites More sharing options...
[Ni...] Posted May 8 Share Posted May 8 What's a strategy for a call out in the notes "all dimensions profile blah blah" on a complex part? Sorry to resurrect lol Link to comment Share on other sites More sharing options...
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