hankster
01-31-2005, 11:19 PM
Cleaning the slots with an Exacto knife after cutting to remove the copper chips is a necessary part of the job.
However, you should be careful and not drag the edge of the Exacto too hard against the edges of the slots. This could turn up an almost invisible lip on the edge of the copper and cause problems. Sometime the blade is too wide to prevent this and I grind it thinner with a Dremel.
I do three things to avoid this problem.
1. I am very careful not to drag the knife edge down the sides of the slot. I just run it down the center to clean the copper and crud out. Run the back side of the Exacto down the slot, not the sharp side.
2. You should do this while it's still in the lathe. Then after you clean the slots, spin the lathe and use the "Pink Pearl" eraser (that I mentioned earlier) lightly on the comm to smooth the finish and take care of small burrs that you might have missed. Take the arm out and clean with motor spray to remove the pink fuzzy stuff in the slots.
3. After cleaning, do the ball-point pen trick. But you can't use just any ball-point pen. First of all, the slot is wider than most ball tips in pens. You have to have a pen that has a very large ball. Otherwise, the ball-point just goes down in the slot and you end up rubbing the edges of the slot against the pen barrel and could cause a bigger problem than the one you're trying to fix.
Sanford Uniball makes a pen with a 1.0mm ball which works really well. The ink in these pens writes on almost anything so it's a good idea to clean the ink out first. But you can clean the comm again to remove the ink after you're done.
One more thing I just thought about. You can make the brush serrations easier on the comm initially. Take one of those rubberized round comm sticks and chuck one end in a drill and use it to take the sharp edges off the serrations. This is one of the problems with the Reedy #767 and the Putnam Pro brushes. The serrations are like little saw-teeth and complicates things if you don't do the other steps I've mentioned.
However, you should be careful and not drag the edge of the Exacto too hard against the edges of the slots. This could turn up an almost invisible lip on the edge of the copper and cause problems. Sometime the blade is too wide to prevent this and I grind it thinner with a Dremel.
I do three things to avoid this problem.
1. I am very careful not to drag the knife edge down the sides of the slot. I just run it down the center to clean the copper and crud out. Run the back side of the Exacto down the slot, not the sharp side.
2. You should do this while it's still in the lathe. Then after you clean the slots, spin the lathe and use the "Pink Pearl" eraser (that I mentioned earlier) lightly on the comm to smooth the finish and take care of small burrs that you might have missed. Take the arm out and clean with motor spray to remove the pink fuzzy stuff in the slots.
3. After cleaning, do the ball-point pen trick. But you can't use just any ball-point pen. First of all, the slot is wider than most ball tips in pens. You have to have a pen that has a very large ball. Otherwise, the ball-point just goes down in the slot and you end up rubbing the edges of the slot against the pen barrel and could cause a bigger problem than the one you're trying to fix.
Sanford Uniball makes a pen with a 1.0mm ball which works really well. The ink in these pens writes on almost anything so it's a good idea to clean the ink out first. But you can clean the comm again to remove the ink after you're done.
One more thing I just thought about. You can make the brush serrations easier on the comm initially. Take one of those rubberized round comm sticks and chuck one end in a drill and use it to take the sharp edges off the serrations. This is one of the problems with the Reedy #767 and the Putnam Pro brushes. The serrations are like little saw-teeth and complicates things if you don't do the other steps I've mentioned.