# need help measuring piece

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hi there, i am new to solidworks, been teaching myself, i have been able to kinda make small basic shapes but i am still learning. i did not go to school for any of this and not very good at math but i try to research. i need help to measure this, i think from my research the top and bottom parts are considered arches. i need to measure the perimeter so i can import the shape to solidworks but just having a hard time because i need a piece to be cnc'ed for this so i cant have room for error on this as this is my first time trying to reverse engineer or just copy a basic shape.

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i guess if anything my main question is, how would you guys measure the red lines or where all of the arrow points in trying to recreate the shape in solidworks

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You state " i cant have room for error". Whenever something is measured there is error. The question is how much error is acceptable and what process would help to achieve the necessary level of precision. I would use the calipers you have n the image to measure the overall width and height. I would make a plot of several concentric arcs with a variation in radii of perhaps 0.05" in a range that you determine to be close to the radius of the top and bottom. Slide the piece on top of the plot and see if you can get one of the concentric arcs to line up with the part. More likely than not the corners are 45° chamfer. Plot a straight line with a line that intersects it at 45° and see if it is a good fit.

BTW, "The Measure of All Things" by Ken Alder is a great book on how measurement error was first addressed in a formal manner. It is a great read.

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Like Lrm draw a rectang the size of the outside width and height.

Lay a ruler on the straightest side, second ruler measure up to the Chamfer point. This is what you would use for the chamfer command which will draw a corner at 45.

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thanks guys, I will attempt to measure it, I did the first one and 3d printed and I can see my errors big time. when I said no error I mean just as close as possible because I need a place to machine it, and if I get it wrong it won't fit over the sleeve thats all.

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Another way is to 2D scan the part, gain an overall dimension with the calipers and insert the scan as an image in sketch / desired sketch plane and you can scale to the caliper dimension. Then play around with various radius etc to get a good idea of the original measurements.....but as above if absolute precision is required its not going to happen. I have used this method many times and achieved good results, you will often find when reverse engineering a part it becomes obvious what dimensions were used as you'll sketch a line and it will be 49.89898 etc so you know there is a good chance this is a 50mm measurement in reality.

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