To continue from my previous project, a Cheap Z-Axis DRO, I present the Y-Axis upgrade. I chose this orientation so that the read out increases as you move the cross slide out (towards your self). This is so you don't accidentally turn any parts with a negative diameter and cause the universe to collapse.
The one drawback with this is that it doesn't have a 'lathe' mode. 2 axis DRO packages will have this option that doubles the Y-axis reading, giving a true diameter of a part being turrned. It will, of course be correct for milling.
Step 1: Materials / Tools
Raw Materials Needed:
~ 6" 3/8" steel rod
~ 6" #8 threaded rod
~ 6" 1/4 threaded rod
3 #8 nuts
4 1/4" nuts
1 Cheap 8" digital caliper
Dremel (Cut off wheels, 1/8" carbide cutter, 1/4" cylinder grinding stone)
3/16" drill bit
5/32" drill bit
Small screw driver (for the digital caliper)
Step 2: Preparing the Caliper
Begin by removing the thumbwheel and back of your digital caliper. Remember that evil designers often hide screws under labels. (under label screws instructable comming soon)
Cut off the inside and outside jaws on the beam (Dremel + cutoff wheel). On the display part, remove the inside jaw and only part of the' outside jaw. Make sure you leave enough of it so a #8 nut will clear the plastic housing. Drill a 5/32" hole.
Make a 1/4" hole in the end of the beam. I found a solid carbide straight 1/8" ball end cutter that worked fantastically compared to the grinding stones I used the last time I did this. Tip: use disposable gloves to prevent the tiny metal slivers from burying themselves in you hand. It's like fiberglass that doesn't wash off :( You could also try attaching a magnet to the workpiece to retain the slivers.
Step 3: Prepare the Cross Slide
The cross slide is drilled and tapped to accept the 1/4" threaded rod. This hole should be up near the corner as illustrated (about 1/2" form the top and side). Drill and tap the saddle for the #8 threaded rod.
Step 4: Mounting Brackets
This time I used wire dykes to deform the threads on the rods where I wanted to lock the nuts on.
Step 5: Attach to the Machine
After it's mounted, move the cross slide all the way in and measure the distance between the beam and the table near the display and at the end of the beam. Adjust the nuts on the 1/4" threaded rod until the two measurements are the same, thus ensuring that it is parallel to the Y-axis.
I should note that the end of the beam is just under the hight of the table. With the original 3 jaw chuck I have, the jaws can stick out about 1/4" before they hit the table. Make sure you don't run it into the jaws if you are working on something with a large diameter. As an improvement, I think I will make another 1/4" hole on the table at the bottom edge to lower the DRO a bit closer to the saddle. I can probably drop it about 3/4" which will give me some more clearance.