Tips, Tricks, and Insight into Process and Power Software

Calculating 45 Degree Elbow Radius For AutoCAD Plant 3D

This week I’ve been working on creating some Fusibond catalog content.  One of the items I’m creating is a 45 degree Flanged elbow.

What I’m given in the cutsheet is the B and C dimensions:


However, in the spec editor, I only have the option to enter the radius.



The question of the day was how to do I calculate the radius from the B length.  One easy solution is to draw the arcs and lines in AutoCAD and then take a radius measurement.  I wanted to use a formula so I can set up a spreadsheet to calculate it for me.

I had some help from Ken Fauver, the spec/catalog guru from Autodesk.  He gave me the formula that I was searching for.

R = B x SIN((90 – A /2)*PI /180)/SIN(( A /2)*PI/180)

where R is the radius, B is the takeout length (per image above), and A is the angle of the elbow.

I’ve posted a spreadsheet that utilizes this formula here:

One key note is that O31/O32 indicate whether the radius measures to the back of the flange or to the face of flange.



Feel free to make a copy or download the spreadsheet so you can automate some of the calculations.