Quote from: the nitro man on December 18, 2009, 09:04:00 PM
are the typing eraser's still available?

That's a good question. I need to get to an office supply store and buy a couple of dozen, hoping that will last me until I'm dead (I'm 60). I hope they still make them.

A typing eraser is like a wood pencil, except instead of a lead there is a abrasive eraser inside. You sharpen it in a pencil sharpener giving a sharp point to the eraser. Some had a plastic brush at the other end which was used to brush eraser crumbs out of a typewriter mechanism. Now I guess you're going to ask me what a pencil sharpener is 

A type eraser is an ink version, more abrasive than the soft ones used for pencil markings. Yet the abrasive is in a soft rubber matrix which is more forgiving than a hard file or sand paper. I used to work on electronics for the Navy and used these erasers for burnishing small copper contacts. I imagine that 400 paper would not be a very good idea for these small motor parts.

Robert

I occasionally have an Athearn motor that is mechanically noisy or runs badly. I have found that the commutator on some has a burr or raised edge on one or more of the segments. The brushes then bounce over that raised edge (it eats the brushes up too). This also might explain why a motor would run with less mechanical resistance in one direction only. I have repaired this by removing the motor from the model. Take a dental pick and check between the commutator segments for any crud. Run the motor from a power pack while gently applying an alcohol wetted Q-tip to the commutator to remove any grease. The apply a typing eraser tip (the pencil type) to the running commutator in both directions. Sometimes you can feel a roughness go away while doing this. You will also observe the commutator get bright and shiny. Be careful as you're removing material from the motor. Then with the motor running give the commutator a good blast with a compressed air can all over and in both running directions. Apply appropriate oil to the shaft bearings at each end and test run before reinstalling the motor. I recently did this to a used purchase and turned a noisy loco into a smooth, quiet running gem. Hope this helps

Cheers, Robert