- Joined
- Mar 25, 2018
- Messages
- 131
My ER32 chuck and collets arrived in a box large enough to hold a VW bug. But I got through the packing material and was excited to check out all of the pieces. My mill draw bar is M12, of course. Aren't all Chinesium draw bars M12? Slipped the MT3 chuck into the spindle and tightened the draw bar. All went smooth but the draw bar was a bit long and the assembly didn't mate like it should. Oh; I know. The threads in the collet chuck are a little short. So, I will lengthen them. Grabbed my M12 tap and went to work. Tap threaded in nicely and, when it came to the end of the threads (or so a assumed) it got tight. Just like a tap should when it reaches the end of the threads. I ran the M12 tap down a few turns. Now the draw bar moved as I thought it should and, eventhough the drawbar felt a bit sloppy in the hole, the assembly tightened nicely. Examining the newly tapped threads I find they look pretty gnarly. Then it hit me. Just because the ER32 collet set originates with a supplier that imports from China doesn't mean EVERYTHING in his inventory is metric. Oh s....! Yep, there was the answer to the resistance to the tap. The threads are 1/2-13. So much for crossing the street without looking both ways. No permanent damage done. It still works fine with a newly turned draw bar at 1/2-13. But I won't let my visitors look down the threaded shaft of the chuck if I can help it.