1. ## Ball joint taper

Hi I 'm looking how to measure the taper of the ball joint shaft need help anyone.. I need to figure this out to buy the correct taper reamer... thanks Luke

2. ## Re: Ball joint taper

Luke,
The Formula you need is Tan A = opposite / adjacent

You will need to measure how thick is the plate going to be that the ball joint will fit into. Lets just say it is 1" thick for this example

The next step is to measure the diameter of the shaft and the lower portion, this is where the ball joint will be pressed into the plate. for this example lets say it is 1"

The next step is to measure the shaft diameter at the top of the plate (1" higher the the lower measurement. for this example lets say it is 3/4" (0.75)

Now subtract the upper diameter from the lower (1 - .75 = .25)
Divide that answer into 2 (2/.25 = .125)

The next step is to divide the .125 by the height 1" (.125 / 1 = .125)

to use the tangent function on your calculator you actually need to use the inverse tangent (inverse Tan .125 = 7.125 )

This is the angle of 1 side. Multiple that by 2 and that is your angle 7.125 * 2 = 14.25

hope that helps

3. ## Re: Ball joint taper

mr berlinetta, very comprehensive, math solves many problems for me too.

4. ## Re: Ball joint taper

You set up the ball joint in a lathe by grabbing the threads in the lathe chuck gently. Touch the taper with the bit at the bottom and the top of the taper. Set the lathe to put a fine scratch on the taper, now you have it recorded and tighten the lathe bit holder bed.
Remove the ball joint, insert your metal and cut away using an inside cutter. The angle is already set so it will be a perfect match.