Profile of a Slot

[[Me...]]

Can anyone tell me how to program a profile of a slot? I have attached a snip of the drawing.

Capture.PNG

[[De...]]

Can you use freeform?

[[Aa...]]

Profile at MMC? 🤣 Now there's a good one.

[[Vi...]]

MMC can't apply to the geometry and tolerance you're looking at! But you can use the feature "Rectangle" if you are looking at getting width and length out of this "Slot". You can do a line profile on the rectangle but no regular profile the workaround to get a profile would be to create two rectangles at different height then recall those point into a "Freeform"

Hope it makes sense!

[[Ka...]]

I've never had a permanent curve license, so I usually break features like this into separate single entities (8 lines or planes, in this case). It usually does the machinist more good to tell which surface is the problem, anyway.

[[An...]]

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[[Aa...]]

Interesting fantasy. MMC/LMC on profiles is strictly forbidden by Y14.5:2009 section 8.5, but it's an interesting exercise, nonetheless. However, your illustrations don't quite fit the definition of MMC/LMC.

You seem to be creating a hybrid of axis interpretation and surface interpretation. Axis interpretation checks whether the axis is inside a diameter of the tolerance plus the bonus at the true position of the axis. Surface Interpretation checks whether the surface violates a virtual condition that is not allowed to shift at all from the true position. (There's no bonus in surface interpretation.)

When it's a Profile at MMC, there are no inherent size limits from which to establish the virtual condition boundary.

[[An...]]

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[[Ri...]]

Let's say the slot length is 1.000 +/- .005 and the slot width is .500 +/- .005. In the field where we enter the Position tolerance we can right click and have access to Formula. Here we can enter in "((getActual("Slot 1").length - 0.995) + (getAtcual("Slot 1").width - 0.495)) + whatever our Position tolerance is. That will give us the total tolerance with MMC. This is a cheat, to be sure. Serious analysis should be done to determine what the probability is of accepting a non-functional part. If this is "for fit" and I had a robust and stable manufacturing process, I wouldn't lose any sleep over it.

[[To...]]

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Richard, Are you working in INCHES? Sacrilege!!! 🤣 🤣 🤣

[[Ri...]]

Like I always said to the Germans who busted us for inches, "How many German flags are there on the moon?"

[[An...]]

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[[Aa...]]

I've never sat on any of the Y14 subcommittees, so I can only guess.

As I alluded before, profile tolerance isn't directly about controlling the location of the "center" of anything. It's all about controlling the surface. (For simple geometries, like round holes and slots, discussions about locations of centers might make sense, but for more complex geometries, all that breaks down.)

That's not to say there isn't merit in allowing for something like the "swimming tolerance" as you've described it, as the surface moves away from its maximum material condition. But the Y14.5 standard already has three acceptable ways to accomplish that: multiple single-segment profile, composite profile, and combined controls.

Andreas, it's the Combined Controls approach I think you'll find the most interesting. Please consider your "swimming tolerance" example in light of section 8.8 and Figure 8-24.