I have a Honda HRC 216 and I think the blades for the HRX models are the same (except for some minor differences in the diameter for the attachment bolts). The Honda OEM blades are ground at 40° (as opposed to vast majority of blades that I’ve encountered where the angle is set at 30° ) so be aware. I use the All American sharpener system (
https://www.allamericansharpener.com/5005) with the Honda attachment plate to maintain that angle. As for discs, I use a 60 grit flapper disc, set the sharpener to 40°, and make 4 or 5 gentle passes, and the blade is more than factory sharp. I finish each blade with a couple swipes of a hand file, to knock off any burs that were created from the grinder and spray them with some oil to prevent any rust. The whole process from removal to re-attachment of the blade takes no more than 10minutes.
The first time you sharpen the OEM Honda blade takes the longest- Honda coats them a heavy duty paint and the angles are always a bit off. I suppose you could you a 30 grit for the first sharpening. I found that if I sharpen more frequently, I have to take off less material, the blades wear evenly and overall the sharpening process is much faster.
Blades that have been on for while, tend to have deeper gouges in them, require a lot more metal to ground off, which then requires a longer balancing process.
