U-bend Tube

The Radius of a bend is the centerline radius as measured from the center of the tubing to the actual center of the bend itself. Another way of looking at this is that the diameter of a bend (NOT the diameter of the tubing the bend is made out of) is double the radius of the bend so that if you measured ACROSS the bend from the center of one bend leg to the center of the other bend

leg that measurement would be twice the radius of the bend. 

A 2" OD x 3" Radius U Bend would measure 6" across the bend from the center of one leg to the center of the other leg. Dividing that measurement by 2 gives you the bend radius 3" in this case.

If you need the measurement of a bend on the INSIDE from leg to leg, take the bend radius and double it to find the bend diameter and then SUBTRACT the bend TUBE diameter from that amount. For example:

A 2" OD x 3" Radius U Bend would have a bend diameter of 6". SUBTRACTING the tube diameter of 2" would give you 4" the INSIDE measurement of the bend from the inside of one bend leg to the inside of the other bend leg.

If you need the measurement of a bend on the OUTSIDE from leg to leg, take the bend radius and double it to find the bend diameter and then ADD the bend TUBE diameter from that amount. For example:

A 2" OD x 3" Radius U Bend would have a bend diameter of 6". ADDING the tube diameter of 2" would give you 8" the OUTSIDE measurement of the bend from the outside of one bend leg to the outside of the other bend leg.

1.mandrel:

spindle: any of various rotating shafts that serve as axes for larger rotating parts