For almost all of my acrylic cutting, I use an Amana HSS1621, which is a 3/16" HSS single flute upcut bit. They're cheap, only about $8 each. Ballparking, I can cut around 5000 inches with one until the cut quality degrades enough to replace it. I can get the same bit in carbide but the cost is near $40. So, 5X the price & I'd need maybe 8X the life to justify? Would a carbide bit last that much longer than HSS? And if I stay with HSS: I have over 50 worn HSS1621 bits that I'd LOVE to try sharpening, but I can't find anybody to do it. Nucut Grinding had been suggested. I inquired back when I only had a dozen or so & they said it wasn't worth it; I've tried contacting them twice since then with no response, so I'm not interested in them. Do any of you know of somebody who might be interested in sharpening these for me?
Carbide, by definition, is more blunt than HSS- it can't generally be ground to as fine an edge because it's a ceramic matrix and not a metallic crystal. For plastics, going sharper and slower is typically a better option than going blunter and faster. On metals, blunter and faster is a great option because they can take the heat without issue, any minor rubbing with a carbide tool/insert that can take it often simply burnishes the workpiece, producing a better finish, and it takes an enormous amount of force to cut slowly- a problem for lightweight machines. Sharpening cheap HSS is probably a waste of time. Expensive, high-end manufacturer HSS might be worth the re-grind if you can generate enough of it, but you need to be measuring your trash in kilos and not pieces to even make that worth it.
