With these improvements I am able to reduce the runout to about 0.00025″ which should be more than enough for anything that I’m likely to do. I enlarged the pocket nearly to the inside wall of the housing and then added three set screws around the perimeter of the housing allowing for some adjustment in the position of the ball plate. The ball plate originally was pressed into a pocket in the bottom of the housing. A notch is taken from the edge of the plate to allow clearance for the 1/8″ stereo plug mounted in the touch probe’s housing.Īfter initial assembly I measured the runout of the probe tip and found it unacceptable. There is also a trough milled around the perimeter providing a place to secure the wire that will be used to construct the circuit. The bottom of the assembly is again turned from black delrin and has six pockets machined in it to receive steel balls. A spring in the top of the probe puts pressure on the assembly and helps make sure that the steel dowel pins stay in contact with the bottom of the assembly. You can purchase the styli here for a reasonable price.
At the end of the smaller diameter is a Renishaw styli. If you look for a better material remember that it must be non-conductive, the rods must be electrically isolated from each other or the probe will not work. It is a good idea to use a rigid material for this part and you could probably do better then delrin. The probe was turned from black delrin and has three 0.125″ steel dowel pins pressed into the larger diameter. The first was a TTS style holder and the second a housing that will hold the touch probe assembly. This was turned in the lathe to produce two pieces. Mine started off with a few inches of 12L14 2.25″ round rod. If any of the rods move and contact is lost with one or more balls then the circuit is broken and a detectable change in the signal occurs. The balls are wired together such that a signal will pass through the assembly when the rods are each in contact with their respective balls. They consist of three conductive rods, mounted perpendicular to the probe tip, each resting in a pair of conductive balls. The operating principle of this type of probe is pretty simple.
There had to be a better way…Īfter doing a bit of research it seemed like a touch probe would solve my problem and, lucky me, there are a few people who have had success building their own.
For me, this was a manual process of edge finding repeated for each axis. But I still didn’t have an easy way to locate the spindle in relation to my workpiece. That means that I can account for height offsets in my program and have one less thing to worry about when it is time for a tool change. One of the best things about the system is that the holders give each tool a very repeatable height. So far I’m really impressed with the set. I recently invested in the Tormach Tooling System (TTS) for my CNCed SX3.