The Y-Axis was by far the easiest of the three axis to design and make. Due to the size of the knee on the Comet, I decided to put the servo motor inside the knee rather than underneath the knee as I would have done with a Bridgeport.

Y-Axis_Assembly.jpg One problem with this design is it will be very hard to tell what the belt tension is when it is all assembled. I haven't figured out what to do about that yet. IMG_7857.jpg In order to make a square/parallel rectangular block, I first faced one side.
IMG_7858.jpg Then I turned it over and faced the opposite side. In theory, I should now have two faces that are flat and parallel. IMG_7859.jpg Next I clamped the block in the vise on the two parallel sides and faced the top face. I did not put the piece all the way down in the vise, so the bottom side, which is not square to anything should not have any effect.
IMG_7860.jpg Next I took a precision angle block and put it against the side I faced last. This should give me four sides that are perpendicular to each other. IMG_7861.jpg I did the last two sides, checking squareness with a precision square.
IMG_7862.jpg I did this one much quicker than the bearing block for the quill as the only two sides that are really important are the front and back. Still, it came out within +/-0.0015". for size and squareness. IMG_7863.jpg I used a drill to rough out the inside of the piece.
IMG_7864.jpg IMG_7867.jpg
IMG_7868.jpg Then I used a 1" end mill to do the final roughing. IMG_7869.jpg I did the final cleanup passes with a 5/8" endmill as it was the longest endmill I had. Unfortunately it wasn't quite long enough so I had to cut a clearance on the first 1/2" of depth. The finish is pretty crappy but it was 5am and I didn't want to make too much noise!
IMG_7871.jpg I then cut some steps on the inside corner and finished the curve on my belt sander IMG_7872.jpg
IMG_7873.jpg The motor mounting plate was almost a relief!

Also see: CNC Conversion, Pt 2, CNC Conversion, Pt 4

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Text, photography and layout by C.S. Mo
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