I recently rebuilt my old Dremel rotary tool. It is a model 380-6 from the 80s. It had been sitting unused for years because the bearings had failed causing terrible noise and bad performance. Due to its age, I was told bearings for this model weren't available and that the unit was obsolete. Wrong. Boca bearing has exact replacements, so off I went (Boca Part # R4-ZZC/.281 PS2). I disassembled the tool and installed new bearings. It came right on and worked like new. However, it seemed that it spun the wrong direction and got rather hot. Every forum I found said that it would only spin clockwise in the same orientation as a drill. Mine was now spinning opposite. Some suggested reversing the motor brushes. Wrong; that makes no difference since the current at the brushes is A/C. Here is the issue. When I rebuilt mine, I installed the magnetic cylinder in the wrong orientation. I opened it back up, flipped the mag cylinder 180 degrees and screwed it back together. Now spinning correctly and works like new. Now you know where to get the "obsolete bearings" for your older Dremels. Be sure when you tear yours down to draw an arrow on the outside of the mag cylinder with a sharpie pointing up toward the collet (Nose), so you assemble it correctly. Hope this helps someone.
- posted
3 years ago