My question is with regard to the: WEN 42704B 4-Piece Sharpening Accessory Kit for 10-Inch Sharpening Systems. I have purchased this set and want to modify it. Can anyone tell me the THREAD COUNT and details for the end of each knife holder (that threads into the plastic handles). I want to fabricate an extension to the holder(s) by adding a Barrel Bolt and threaded rod to match. Is it a Metric thread ? Thanks in advance !