Grinding the cylinder saddle to remove the bolt heads felt like the best option. Having considered flycutting was possible too aggressive. One thing to point out is that this is the cylinder for the miniature Burrell that is currently on my bench.
The grinding drum was machined from a piece of hardwood. However, first task was to make a mandrel from a nut and bolt.
Mandrel
Take an 8mm bolt with the nut wound on to roughly the same point as when the drum is in place. Place this bolt head first into a 3 jaw metal lathe chuck. Tighten the jaws on the bolt head and the nut.
Now machine the thread of the bolt up to the nut down to a smooth 6mm shaft. You can go slightly under 6mm. This gives you the mandrel.
Drill a hole through a piece of hardwood and fit this to the mandrel and tighten the nut. Now hold the shaft of the mandrel in the lathe chuck and turn the wood cylindrical.
Gluing the Abrasive
Cut a piece of abrasive paper slightly wider than the drum and slightly longer than required. Coat both back of the abrasive and the drum with Evo-Stik impact adhesive (or similar impact adhesive). Ensure the glue is spread thin using a scraper or straight edge of a piece of wood as a scraper. Let the glue dry as per instructions before wrapping the paper onto the drum.
Mark the both sides at the overlap and use these marks to align a knife blade to cut off the excess length. This will give you a very crisp joint.
Cut excess material off around the drum. Otherwise this can get caught and rip more paper off.
Using the Abrasive Drum
Cover the surface of the milling table to protect it from abrasive grit. Apply cutting oil or just oil to the surface of the abrasive drum. Start at a slow speed (~200rpm) and with very light pressure.
Initially there was concern that the bolt heads would rip the paper off the drum, but take your time and do this gently.
I moved the drum up and down in Z so as to not leave it it one position. This helps spread out any issues with wear on the abrasive and grits scoring deeper lines.
The base of the saddle was soon ground to form. The grinding of this part only took about 5 minutes in total. The countersunk heads of the bolts were ground flush with the phosphor bronze saddle.
The are some fine lines visible on the surface. However, as these will not be seen I’m leaving this finish here.
Grinding the cylinder saddle has been a lot easier than I first thought.