Sickle mower grinding stone dressing

[halftonstude]

Does anybody know the angle at which the sickle sharpening stone is supposed to be dressed? I did some looking around and didn't come up with an angle, and would probably like to post a "how to" on what I did, but would welcome any advice for the next one I'm going to do this weekend. I purchased a very nice shape sickle sharpening tool (the hand crank with the stone that goes up and down the cutter sections) but the stone was very badly loaded up and worn. I found a couple posts asking for the angle, but couldn't find any numbers so I set about doing it myself. I put the stone on its shaft centered in a four jaw chuck in my lathe (within 1 thou was as close as i could get it using the teeth of the gear), and since the end of the shaft was very badly banged up I didn't want to try putting a center drill in it to use a live center, so I just put a bushing into the jacobs chuck in my tailstock and when turning added a drop of oil once in a while. I messed with the compound slide and continued to adjust until I got a measurement that provided the same clearance at one end of the stone and the center of the stone, which was just about 70 degrees; figuring those two portions were never used since the stone never touched the bottom of the sections and the outer edge of the stone never hit them at all. Probably within 1/2 of a degree. 70 may be the magic number. My stone was worn so that as it rode up and down the cutter sections the angle would be ground differently which isn't ideal. So, setting the combination set at 70 degrees i used a 1/2" .75 carat dressing tool and took away 4 to 5 thousandths per pass, very slow passes so as to not blow out the dresser diamond. It is to be noted that the nut that holds the stone is left hand thread, so I had the lathe turning backwards (clockwise) to keep the nut from spinning off. With all the gunk gone the stone is now very flat and concentric, I'll be re-assembling this week so i can sharpen my sickle. we've only cut 150 acres so far cause it's been so wet, but i'd like to have it nice and sharp to mow Friday afternoon. here are some photos. If you've done this before or have any suggestions i'd be glad to hear them and i'd be happy to do a writeup for the how to section on implements...

THanks all, happy cutting ;o)
chris