Precision

Problem



The machine was not precise enough to suit the needs of our customer. He requires a precision of .010 in and a side to side tolerance of .001 in.  While the head of the sanding machine moves evenly down its tracks, the sanding bed itself was not flat.  According to our measurements, done with a dial indicator on a milling machine, the bed deviated from flat by up to .055 in.  This was not nearly flat
enough for our proposed application.

The other problem is that the pivot point may not be parallel to the sanding bed.  This
means that even if we could make the table flat, it might not be flat relative to the sanding
head if the taper angle were anything but 0 in/in.

The last problem is that it is difficult to see if the strip is properly placed on the sanding
bed.  If it is placed crookedly, it will come out angled and have to be discarded.
 
 

Solution 


We removed all of the steel screws that help hold the aluminum to the steel, re-countersunk the holes, and machined the table flat.  We incorporated several adjustments into the bed so that it can be made parallel to the sanding drum. 

To set the taper, we developed a cam system that has several discrete settings that allow the user to quickly and easily adjust the taper angle.  Simply depress the button and rotate the handle until you are at the desired setting.  Each part of the cam system is adjustable so the machine can be fine-tuned for precision. 

To align the strips, we placed a sacrificial block of wood at the start of the sanding bed that the strips can be butted against to ensure that they are straight.