I just finished a homework assignment on the use of the sine bar, and I found one concept rather confusing. The following picture shows a part on a sine bar with a gage pin, and it says that 1/2 the diameter of the pin must be subtracted from the length of the part, which is actually 6.000" with a 0.200" pin:

I think I understand the concept, but the drawing is confusing because it appears that the actual length of the part has changed to 5.900". I think the proper way to understand this is that the height of the center of the gage pin is 1.7148"-0.1000" or 1.6148", and the part is moved that same distance from the center along its angle. Thus, the height of the angled flat of the part from the lower left corner would be 6*sin(34) + 1*cos(34), or 4.1842". The gage pin pushes the block up by 0.2*sin(34) or 0.1118". The location of the lower left corner of the piece will be at the center of the gage pin + 0.1*sin(34) - 0.1*cos(34), or 1.6148 + 0.0559 - 0.0829 or 1.5878, so the height of the surface from the surface plate should be 5.7720"-0.1118" = 5.6602, which is the answer.

This seems extremely complicated, and perhaps the way the lesson explained how to get the answer is a little less so. Here is the lesson:

http://enginuitysystems.com/files/CA...Bar_800225.pdf

I could not find anything other than the ToolingU reference describing this process. I'm not really comfortable with using the surface plate and height gages and gage blocks anyway, and this sine bar makes sense for angles but not so much for this procedure. Does anyone here actually do this? Or is there an easier way?

I think I understand the concept, but the drawing is confusing because it appears that the actual length of the part has changed to 5.900". I think the proper way to understand this is that the height of the center of the gage pin is 1.7148"-0.1000" or 1.6148", and the part is moved that same distance from the center along its angle. Thus, the height of the angled flat of the part from the lower left corner would be 6*sin(34) + 1*cos(34), or 4.1842". The gage pin pushes the block up by 0.2*sin(34) or 0.1118". The location of the lower left corner of the piece will be at the center of the gage pin + 0.1*sin(34) - 0.1*cos(34), or 1.6148 + 0.0559 - 0.0829 or 1.5878, so the height of the surface from the surface plate should be 5.7720"-0.1118" = 5.6602, which is the answer.

This seems extremely complicated, and perhaps the way the lesson explained how to get the answer is a little less so. Here is the lesson:

http://enginuitysystems.com/files/CA...Bar_800225.pdf

I could not find anything other than the ToolingU reference describing this process. I'm not really comfortable with using the surface plate and height gages and gage blocks anyway, and this sine bar makes sense for angles but not so much for this procedure. Does anyone here actually do this? Or is there an easier way?

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