# Fillet Indicator or Potential Tolerancing

Currently working on some drawing from the Spitfire Mk. V. I am working on this piece from part of the undercarriage legs.

I am working with Inventor LT 2021. In the source drawing I can see tolerance styles that inventor refers to as Symmetric and Deviation.

Symmetric

Deviation

For fillets/rounds I am seeing a note like this which simply sets the upper limit:

I am however confused by the following

I understand the typical 4 places part. I do not have a definitive understanding of 0.3/0.1 RAD. Does this mean:

1. Fillets on the outside edge with a max of 0.3 and min of 0.1;
2. Fillets on the outside edge of 0.3 and fillets at the bottom of the groove of 0.1;
3. Fillets on the outside edge of 0.3 on the left and 0.1 on the right; or
4. Something I have not considered.

In addition, there are a series of dimensions with tolerances for the dimension and what I am gathering is fillet notes for the edges underneath. The "1/RAD 0.# MAX" note confuses me. The "1/" part appears like this in multiple locations. How should this be interpreted?

So while the Spitfire was designed and modified through out WWII and onward, it appears that this particular drawing was issued in 1991 and as such may follow some modern drafting conventions.

In case the over all image helps any, here it is:

• It's (1) "Fillets on the outside edge with a max of 0.3 and min of 0.1" .... Also as I was taught at least - in the US - the term "fillet" refers specifically to a radius on an inside edge (becoming a concave geometry). Whereas the terms "radius" or "round" were used for both inside/outside edges. Commented May 21 at 14:14
• Not sure about the "1/" where it says e.g. "GROOVE 1 / RAD 0.2 MAX" , but I wonder if it is a reference to NOTE 1 Commented May 21 at 14:21
• @PeteW I had been thinking it might have been a revision tag, but there was only one issue of the drawing. I read general note 1 in the bottom left corner of the over all drawing and it partially applies in my opinion as it talks about removing all sharp edges and corners and supplies a default max RAD of 0.5. Commented May 21 at 20:17
• @PeteW, I agree there is a technical difference between fillets and rounds. I am just lazy as in most CAD programs I deal with the button for applying a fillet or round, is almost always labelled fillet. Commented May 21 at 21:38