Questions for You Thread Cutters

[me2]

I just made a holder on a small gram scale and started cutting some thread. My questions start with what kind of thread do you use? I used some sewing thread, and got cuts from 25-180 grams on various knives in various states of sharpness. Fresh off the leather belt was 25-40, a touched up knife off the Sharpmaker was about 45-60, with the duller tip coming in at 180. It was used for dinner one night and hit the plate. Another used to cut SFRM (sprayed on fire-proofing) went over the limit of the scale, which is 200 grams. The thread was not cut with this blade, as I was not willing to push as hard as it would take. The spine of a knife also went off scale, without cutting, just as a worst possible edge. A chef's knife sharpened only on my 800 grit waterstone came in at 160 grams. The thread is very light, and I suspect the others here are using a heavier thread for this test, to allow them to see differences in sharpness better.

 

[me2]

Ok, just finished testing the same knife at different stages on the Sharpmaker. After the brown stone corners, the thread was cut at 60 grams. After the brown flats, it dropped to 40. The white corners were surpising, as the cut happened at about 35 grams. The white flats were around 20. There is a definite progression from the brown to white stones and a noticable difference from corner to flat. The brown flats to white corners were surprising. The knife used was a RADA paring knife, sharpened on an 800 grit waterstone at 12 degrees per side. The 15 degree slots were used on the Sharpmaker. This knife has been in service for a while since the last full sharpening on the waterstone, with touch-ups on the sharpmaker. The initial test was done using the brown flats, then the white flats. There were some rough spots on the edge, so I went back to the brown corners and went through all 4 steps to see what the changes were. The numbers given in grams for the thread cutting have a variation of about 10 grams plus or minus, since I have to read them directly w/o a high max load recording device on the scale. I took each measurement 2 or 3 times at each stage on the Sharpmaker.

 

[HoB]

I use for fine edge Coats&Clarks 40wt. Rayon thread T30 and for more sturdy edges Coats&Clarks Mercerized Cotton T39.