I've had this bit for about 4 years. Only thing I've used it on before is routing the recess for my Woodpecker PRL to sit in the router table. Worked flawlessly for that. I'm trying to finish up my ZCI for the table saw, and I have ruined 2 blanks now because I can't get the collar to lock down. I've tried a 1/16" key, when about tight, it spins in the set screw. The 5/64" and 3/32" will not fit into the set screw. So I think it must be metric. Tried a 1.5mm...not as tight as the 1/16", so won't tighten up at all. 2.0 mm won't fit into the set screw. Is there a 1.75 mm or a 9/128" size? I emailed Jesada yesterday before my last problem thinking I had it tight enough to work. Now I'm thinking I need a new bit. Anyone have the same problem and find the answer? I would have thought that if it was an odd ball size, a wrench would have been included with the bit. TIA Jim.