Recognizing workholding requirements

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Before machining a part, it is important to first determine what

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kind of workholding is required to support the part.

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For this video, open the files Workholding.f3d and Workholding Drawing.pdf.

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With Workholding.f3d active in the canvas, on the Toolbar, Design workspace, Solid tab, Inspect panel, click Measure.

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Solid tab, Select panel, click Inspect to activate window selection.

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The MEASURE dialog displays.

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Use the selection tool to measure the various dimensions of the part,

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such as the overall length, diameters, and the distance between different faces.

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From this information, you know that you are going to have some challenges in

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being able to hold onto and support this part.

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Machining it will require more than just creating a chuck for the back end.

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From the design of the part, you know that you are potentially going to need a

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steady rest that you can clamp onto, or even a tail stock.

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This hole could be drilled so that a tail stock could hold and support it from the front.

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Or, you might need a combination of both.

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When you are working with a part like this one

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—one that does not have a feature where you can add a tail stock—

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you either need to come up with a creative way to add more material to the part

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so that you can use the tail stock, or you need to approach the designer

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and find out if there is a way to add a feature like a hole to the front of the part.

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On the Application Bar, click the Workholding Drawing tab.

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The drawing shows you that there is more to think about.

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The notes tell you to use a tolerance of plus or minus three ten-thousandths of an inch for anything from the model.

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However, there are some dimensions on the drawing that are critical.

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The diameter of the front end of the part has an upper tolerance of three ten-thousandths of an inch (+.0003),

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but a lower tolerance of one ten-thousandth of an inch (-.0001).

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This means that you are going to need to be precise about the workholding for the front side of the part.

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This may not be an issue if you are using a lathe that does not have live tooling.

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But, if you zoom in on the circular view on the right,

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notice that there is a hole callout, and that the holes on the front are slightly rotated.

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Zoom in on the circular view on the left,

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and notice that these holes are not as rotated, and that they are on the centerline.

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So, somehow, whoever makes this part is also going to need to figure out

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how to time the front and the back if they are using a lathe with live tooling.

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These are some of the things you must look for when you begin looking at a part.

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Determining how you are going to hold onto a part

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may be more important than how you are going to machine a part.