Centering the Mill using Video Camera
My expert friend Stuart Tankard suggested that I try a digital video camera to locate work on my milling machine.
I have various gadgets for finding edges and tool heights, and I find that the electronic edge and height finders are the most accurate. But, I have never been satisfied with accurately locating other points in workpieces.
So I purchased this small video camera which is attached to a shaft for attachment to a collet or chuck which is held in the spindle.
The camera on the left is as supplied. It needs to be adjusted so that the camera is pointing exactly to the centre under the spindle. The adjustment is made to the 3 grub screws in the metal disk shown. When the unit is inserted into the collet, the screws are inaccessible unless only a fraction of the shaft engages in the collet. Also, the setting which is eventually determined seems quite precarious and liable to be altered with a slight bump. A very unsatisfactory arrangement.
So Stuart came up with the modification on the right. A CNC’d perspex disk replaces the back of the camera case. The new camera back is attached to a larger, more solid, steel disk. The screws are now accessible when the shaft is fully engaged in the milling machine spindle collet. Altogether, a superior setup.
Lining up cross hairs with the centre of the spindle is still fiddly and time consuming, but with the new, more solid setup, it should need to be done only once. It is done by loosening the cap screws and nudging the camera laterally.
Any slight angulation in the camera lens, or the chip, or the steel backing plate or shaft is compensated by fixing the focal distance. This is accomplished by making a small sleeve to fit between the lens and the camera body. It is the brass bit in the photo.
The following photos show some of the steps in making the modifications.
The camera is a TP-03 Machining Camera, purchased from Homann Designs. It cost $AUD88 plus postage plus GST.
The software to put the fine cross hairs on the screen was downloaded from http://www.kd-dietz.de and it is version 3.02 of “WebcamPlugin” for Mach3.
Check out the following link suggested by reader Hamish. It is a more complete discussion of the process and the technology. It is in the comments section below.