As a standard practice it is always best to get the between frame (BF) measurement from measuring the frame.
But what if you don’t have access to the frame or you just have a roller that has come out of a frame? Can you still get a good BF measurement?
The answer is yes.
One of the reasons it is important to get the BF measurement from the frame if possible is because roller manufactures don’t make rollers to a standard spec so rollers from different manufacturers will have slightly different dimensions. Many times, these slight differences can mean getting a roller that will properly fit and one that won’t. The best and most accurate way to measure a roller for the BF if you have the roller in front of you is to measure the “Overall Cone Dimension” or OAC.
What is the OAC?
The OAC (Overall Cone Dimension) is simply the furthest point the bearing set sticks out on either side of the roller. The drawing indicates the dimension to measure for the OAC: With this dimension roller manufacturers will deduct the proper clearance, for Rolcon it is 1/16″ on each side, so the roller will properly fit.
So, if all you have is the roller and you can’t get access to the frame by giving us the “Overall Cone Dimension” you can be assured that the rollers you receive will fit in your system.