We've got a new sharpening jig for our screw in heads, thanks to a customer in Canada. He's a taxidermist who made a mold for us to be able to make these plastic jigs that work with either sandpaper on glass (like I do all of my chisels and plane blades) or you can use a KME stone and a card. Here's the jig.
Front view with broadhead in the jig
Side view showing how to lock the broadhead in with an old insert turned around so the threads grab right away
To use the jig you simply run it back and forth across the sandpaper or stone making sure to count strokes to do an even job on all sides. I also try to put even pressure on the jig without pressing too hard. I use a small stone to take a little bit of the Teflon off of the back of the heads to get down to bare steel. After raising the burr I swipe it off with the stone again and one more time when I strop after the final polishing.
If the heads are really dull, you can smooth them out quickly by using a KME Coarse Grit stone. These things are DYNAMITE and I found out quickly that I could get the broadheads to hunting sharp with just this stone. To keep the adjustment screw from wearing out on the stone you can simply lay an old card down on the stone.
Here's a pic of the jig in action on sandpaper mounted on glass. I've got 320, 600 and 1000 grit on mounted on my glass.
The adjustment screw allows you to fine tune the angle to just about anything you want. This pic shows how it keeps one edge just off the sandpaper.
The finished result
If you prefer a mirror polish this is the jig for you, extremely sharp. I'm sure you could get even sharper with 2000 grit paper, but honestly these shave hair so well I don't know that it'd be worth the extra effort.
The jigs should be available on the website by tomorrow at the latest.