Nice part. I make a lot of "ring" shaped parts for my fishing reels. I used to use tabs like you did but then spent a lot of time cleaning up the tabs. I now mill the inside of the part first, issue an G0Z6M1 to move the mill up and turn it off while I add a hold down disk to hold the part in place.
I have a 3/4" fixture plate under the part that has a 10-24 hole about where the center of the part is (actually, I do 4 at a time so there are 4 holes). These do not have to be terribly precise to the middle of the part. I made round hold downs with an oversized center hole so with a washer and cap head 10-32 I can position it precisely.
So the process is:
- clamp down the stock to the fixture plate (which can be held in the vise or clamped to the table). It has 1/4-20 holes for the clamps.
- mill the center of the ring
- position the center hold down and remove the perimeter clamps
- mill the outside of the ring
No tabs and a perfect part requiring only some polishing in my vibratory setup.
Cheers,
Michael
Reelsmith, Angling Historian, and Author of "The Reelsmith's Primer"
www.EclecticAngler.com | www.ReelLinesPress.com