Posted by Muzzer on 06/12/2016 21:11:40:
I think you said you would be boring it and chain drilling the slots? Is that what happened? This would be an ideal job for the Tormach, using 2D adaptive clearing courtesy of Fusion 360 CAM – all done in one operation.
Of course the easy peasy way would have been to use the CNC mill, although the 8" diameter is getting close to the 9.5" Y travel on the Tormach. But I have a daft idea of writing this up, so I thought I'd better stick to old school.
The 3/4" and 1" slots were drilled, "drilled" bigger with a slot drill, and then machined to final width with 3/4" and 1" slot drills.
For the 1-1/2" and 2" slots I chained drilled the circular end, and cleaned them up with a boring head:
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The chain drilling is easy using the bolt pattern function on the DRO. The waste simply needs a light tap with a hammer and brass drift to remove it.
I was planning to chain drill the remaining waste in the parellel portion of the slots. But it was quicker to just hog it out with an endmill. Full width cuts (20mm) and 2.5mm deep per pass with nice blue chips soon removed the waste. Really old school, as I used all manual feeds and the endmill was HSS. 
Andrew