I use one of these diamond lap disks http://www.ebay.com/sch/i.html?_from...p2045573.m1684 on a cheap 6" bench grinder with no guard. 360 or 600 grit will work fine. I've had the same one for 3 years with no noticeable wear. I spin my tungsten in a drill while holding it at an angle where any scratch marks will be in line with the tungsten. The angle is about the same as a pencil sharpener produces.. a little more angle for high amps keeps the point from melting so easy. 3/32 tungsten will do 95% of your work. I like 2% lanthanated for everything. A box of 10 7" pieces cost $20 here in the US http://www.amazon.com/gp/product/B00...rhf_pe_p_img_4. If you only use one type of tungsten you can take the blue paint off and sharpen both ends. One box should last years in my opinion.