Originally Posted by
Zetopan
I have purchased three different Renishaw TP1S probes (5 axis) on eBay and they do not require any modification to work with the Tormach mills. I also bought some used Renishaw probe interface boxes (PI-7) since that will maximize the sensitivity and the longevity. Without the Renishaw probe interface box you directly rely on the internal contacts to make and break, resulting in a small amount or arcing and that reduces the lifetime, and it inherently reduces the sensitivity even without any arcing.
The Renishaw interface box detects *very* small changes in contact resistance and cuts off the current when the set threshold is reached. This reduces the arcing to zero and since the small resistance change is measured while the contacts are still touching the sensitivity is outstanding.
The Renishaw probes generally have a repeatability of well under 0.1 mil. My quite dated TP1S probes are rated at better than 0.1 mil for both repeatability and accuracy coming from any direction. This style of contact probe always has a bloated triangular sensitivity polar plot due to the three internal arms. The variation between the triangle maxima and minima adds to the inaccuracy but with the probe interface box this gets complete buried within the better than 0.1 mil accuracy spec. You can easily measure the polar angular sensitivity by taping a paper scale with marks every 15 degrees around the probe body and then measuring the touch point in the X axis with each orientation. Rotate the probe between measurements so that you only use the X axis for movement and always come from the same mill table direction. If the resulting polar plot shows up as a circle your probe is simply tilted.