## Looking to settle a dispute with my boss about fillet/corner/bend radii

The question seems a little esoteric, but who knows. Also, we are making spares and replacements for the Gov. These parts were designed in the 50's and 60's. So I can't just ask the customer. Also this issue comes up a few times a year. So I'd like to find some information to finally settle it.

My boss says that a fillet radius only has to be tangent to both surfaces if the drawing says it is a full radius. I say that I have never seen a radius value given with a full radius because full radii are used in places where they want a radius around the entire material thickness. So a radius value is not needed since it is controlled by the material thickness (tangent to three surfaces).

The question is when a radius value is given, is the expectation that the radius is tangent to the two surfaces or is the expectation that you only need to put in as much of the radius as you feel is needed, leaving sharp corners that would then be smoothed out a bit, but resulting in a a much tighter radius at the end of the larger radius? If doing this is allowed, then I need to see a spec that shows how much of the larger radius needs to be put on, and how much of the small unspecified radius is allowed to get it to work.

This image shows the two methods I am talking about.
img24.imageshack. us/img24/9307/fillets.png (remove the space. I can't post links yet)

The .50 radius on the right is tangent to both surfaces, while the .50 radius on the left is not. If the radius on the left is allowed, I need to see the spec that tells me how I'm allowed to do that. The following is a description of the actual issue. In this case whats going on is that I am modeling an angle (a long narrow piece of sheet metal bent at a 90 degree angle.) There is also another bend in it that makes this part trickier to form, but that's besides the point for this question. At one end of the angle, a tongue sticks out, but the way the flat pattern is laid out with the radius that is specified, that tongue, which should be flat, gets partially bent by the radius.

My boss is like, just don't make the radius "full" or tangent and I'm like, the spec for forming this type of sheet metal says that the minimum radius is the one on the drawing, if I don't make the radius "full" then I'll have a tighter radii on there, and that would seem to go against the forming spec. He's like that doesn't matter, and I'm asking him to show me a spec that explains that. He says it's just understood. I think that's BS.

 PhysOrg.com science news on PhysOrg.com >> 'Whodunnit' of Irish potato famine solved>> The mammoth's lament: Study shows how cosmic impact sparked devastating climate change>> Curiosity Mars rover drills second rock target
 Blog Entries: 2 Recognitions: Gold Member Science Advisor Just call out the radius per ASME Y14.5, and specify on the drawing that the dimensions and tolerances are per ASME Y14.5. Problem solved.
 Thanks for the response. I have ASME Y14.5 and in section 2.15 it would seem to suggest that you can't do what my boss is saying, though its not at all explicit. Also, I am not making a drawing, I am interpreting a drawing. So I don't think the problem is solved.

Recognitions:

## Looking to settle a dispute with my boss about fillet/corner/bend radii

IMO the drawing shows arc radius 0.5 with its center position .46 from the straight edges. The two arcs radius 0.1 are tangent to this arc and the straiight edges.

That is enough to define the centers of the R 0.1 arcs, and therefore they are not dimensioned on the drawing.

Presumably there is a reason why somebody specified the radius as 0.1, rather than just saying "break sharp corners".