Back in 2008/2009, I made several “tuna can” reels. The plans are elsewhere in this blog (search for “Reel 37 Plans”). The second owner of a pair of these was concerned that there was no line guard to protect the line from rubbing on an inside edge of the top pillar, so I fabricated some for him from bronze.
Machining small parts can be tricky; here is how I did these.
Start with an oversize material blank and cut the inside notch with a large diameter end mill.
Then use a conical cutter to make a slight bevel.
Next, use a sanding drum to abrade the bevel into an arc. It is good to have the oversize blank to hold onto while sanding.
Then do the rest of the profiling and finally cut the part free of the blank.
All I have done so far is make a flat pattern; it does not conform to outer diameter of the reel frame. I don’t have a 4 axis CNC mill. So the last bit of shaping is bending, I used a vise and a mallet to tap it into the final arc.
While forming in this way, the two arms of the part tend to splay outwards. They can be brought back by use of the vise.