Let the Mudslinging and Name Calling Commence

Up to now, I have been pretty mild. Now, I am going to take off the gloves and say what I think.

Precision Police bullhorn:
"Put down the Dial Test Indicator and
Step Away from the machine!"

Precision measurement and positioning. Wow. These people are living in a fantasy world. I was reading someone describing their 5' x 10' CNC machine. Their claim was "movement to 0.0005" and better" over the entire span of the machine. OK, let's give them the benefit of the doubt for a second. The first thing that comes to my mind is:

 Why??

Where would you even get cutters that approach that precision to match it? Where would you get a spindle that can come close either?  Are you going to measure runout and pull out the DTI every bit change? Just the heat from the cut would change the diameter of the bit from the beginning of the cut to the end. The heat generated by the cut will propagate through the material  and change the dimensions more than that.

At their estimation, the gantry weighs ~300 lbs. Now at the 150 inch/min that they are claiming for the positioning speed, how much stretch does that put on the lead screw? How much will the spiders in the couplings compress? What about the fasteners? Shoving that much mass around with 1100 oz/in motors and claiming 0.0005 in accuracy is just lunacy.

Now, I am not picking on them specifically but this is just an example of the garbage that is out there.