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Summary: Detailing corners after adding fillets

ptc-726111
1-Newbie

Summary: Detailing corners after adding fillets

Thanks for the quick replies. Because the Pro-E model had a long model tree, I wanted to reduce the number of created dimensions as much as possible. The attached JPG was only an example and did not reflect the actual part.

Adding a note in the dimension to theoretical sharp corner (TSC) seems the best option. This could also be called out in the drawings notes, but having the note in the dimension maybe more clear. I am curious if more moldmakers are relying on the CAD model since some complex surfaces cannot be easily dimensioned, especially if the Freeform Surfacing Module (ISDX) is used.

These are the responses I received to my question:

a.. At my old job I did a lot of injection molded parts, and we would often dimension to the TPI (theoretical point of intersection), and the vendor usually didn't have any questions about it.

Of course, more recently, with some of our vendors, we only had 3 reference dimensions on the drawing: height, width & length, so that they could quickly see the envelope. If needed, we'd put a few inspection dimensions on there. It was understood that the solid model was the master record.


b.. I don't do much mold design, but most of the time I just leave the original driving dim and mark it 'to theoretical sharp'. This is lets the machinist know what you're doing since most or at least a lot will reconstruct the feature in a CAM program of some sort. If they use the Pro/E model directly, it obviously doesn't matter much.

c.. Standard drafting practice is to either dimension to the theoretical intersection or dimension to the center of the radii. Either of these can still use shown dimensions. For the radii, you would need to add an axis to dimension to. For the theoretical intersection, I would add draft entities to show the intersection. This requires extra work and then the entities need to be related to the view. They still can easily become offset and out of position.

d.. I have no idea what the standard practice is, but the way we do it on the mold design print is to specify the dim to the theoretical square corner. This makes it difficult to inspect the part, but not impossible. Obviously the tolerance could not be very tight but it works fine for us. We often require a inspection print with looser tolerances & other acceptable deviances that do not effect the performance of the part.

Theoretical square corners are detailed as: .XXX S.C.

e.. If the inside 500 dimension is important to fit or function, the outside .624 dimension is not an acceptable substitute although it would be easier to measure. Either add TSC (To Sharp Corner) to the .500 dimension or dimension the taper part way up. If the taper is really important then there should be a basic width dimension with a toleranced height dimension.


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