This afternoon Jimmy, one of our Machinist, walks into my office and asks me stop by a friends of his machine shop when I get off of work. They bought a CMM and were having trouble getting the computer it was hooked up to to recognize it. Aside from only know what a CMM is and the basic principles behind it, I know nothing about CMMs, so naturally I said "yes, I'll be right over"..I love a technical challenge. In fact the less I know about something the more I want to get my hands on it. To make the pot even sweeter, the machine was built in 1985 and the computer was "upgraded" in 1993. I tuely had no idea what I was going to be walking into. Jimmy only told me that three others had tried to get it to work but no luck.
So I jet off to the shop after work. It's a typical machine shop with a bunch of lathes and all kind of goodies. I introduced my self to the owner Dickie, who is a down to earth, easy going, guy. Dickie shows me the CMM.
I have seen two other CMM's in my life. One when I worked at Filtronic Comtek. Comtek's was brand new in 2000 and state of the art. The other was the one that PSI had, PSI was one of the companies I used to pick up at when I was a truck driver back in the day. The one PSI had was only a few years younger than me. Of the three of them that I have used Dickie bought what I perceive as the mid range of the two extremes I have personly seen. All in all I think he made a good choice for getting it an auction and not knowing much about them himself.
I take a look at this CMM and quickly come to the conclusion that at a minimum I am going to have to pull all the wiring and start from scratch. The CMM itself is connected to a controller (which I keep referring to as a head unit for some strange reason) and that controller is then connected to the computer. I put my hand on the controller and felt that it was cold, thinking that was unusual too while I had the wires all disconnected it would not be a bad idea to crack it open and make sure that no fuses were blown and it was getting power for sure. It was.
A CMM at its most basic level uses trigonometry to create a coordinated diagram of the object you are measuring. You have three axises X,Y, & Z that you make your measurements on(read the Wikipedia article for a much better description). For this particular CMM each axis has its own corresponding plug that comes out of the table and plugs into the controller. Those were labeled so it was a no brainer to figure those out. That left me with three cables to hook up. One cable went to the stylus. Of the two left I determined that one was not needed and the last one left was the one that came out of the controller and connected to the computer via the RS-232 port. I fired the computer up and sure enough the controller was found.
Now for the real interesting part and really the whole purpose of this post. The computer was an old box running FreeDOS. You can imagine my surprise and my delight. But it gets even better. in order to run the software without any user interaction required, whoever set the computer up originally was setting a couple of batch files to run at start up that detect the controller and then put you into the software. I wanted to get a better idea of what was going on so I started to nose around and came across C:\DOS\EMACS. WOW!!! WOW!!! Freemacs comes standard with FreeDOS. Manna from heaven. So now I have the unit up and ready to be calibrated. What a great way to end a day.