Generally, we'll be:
- Cleaning an edge of the piece
- Measuring its exact dimensions in-place
- Setting the zero on our DRO to measure out the rest of the cut
- Cutting, and finally
- Verifying that what we cut was correct
If you don't have a floor-standing mill with a DRO lying around your garage - head to your friendly neighborhood Tech Shop (http://techshop.ws) where I did the work for this Instructable.
Word to the wise: be very respectful of powered machinery whenever you are around it. There's no need to fear machine tools, but you would do better to have a healthy level of humility when operating them as their power can cause startling amounts of damage quickly if used improperly.
Step 1: How Big Is It? How Big Do You Want It?
First step is to clamp it down with the long edge sticking far enough out to cut to size. Because this piece is so thin, I used parallel bars to hold it up near the top of the clamp. Make sure to give whatever you put on the parallel bars a healthy tap with an impact hammer after tightening the clamp to seat it correctly.
Step 2: Cut One Edge Smooth
When I started, I knew I had 0.110" to cut off my piece, so I'll make sure this first cut doesn't eat away more material than I need to. Here roughly 0.020" was enough to get me the flat face I wanted.
Step 3: Re-measure the Piece Without Moving the Bed's X-axis, Set the DRO Origin
Now I'll set the zero position on the mill's digital readout to be exactly 0.086" to the left (X=0.0860) of where it is now - which means if I make my last finishing cut with the head at the origin (X=0.0000) my piece should be exactly 1.700" long.
Step 4: Cut in Passes Until DRO Reads 0.000
After the last pass, pull the cutting head away and measure the piece again. If you've done everything right, you should be spot on your mark.
In this case, 1.700" exactly makes me a happy maker.
You'll want to give your piece a good going-over with a file to remove any burrs from the edges before continuing... metal splinters really aren't that fun.