"Chatter" Marks
Many times drum sanders are brought to the Repair Department and the operator reports that "chattering" is the problem. Generally this is not the case. "Chatter" is confined to marks on the floor made by the vibration of the machine while in operation. "Chatter" is caused by components of the driving and driven parts. Other factors may also cause the drum to mark the floor.

Problems are identifiable as marks across the line of travel of the sanding machine. The marks show up best when the floor or test board is wiped with a damp cloth.

Generally, non "chatter" marks are spaced one or two inches or more apart with either a regular or irregular pattern. They may be corrected by making one or more of the following inspections:

	Check wheels for-- out-of-roundness, worn axles, or imbedded particles.
	Check wheel bearings for roughness.
	Check rear caster for-- excessive up and down play as well as first two suggested checks.

If the wheels, bearings, etc. have been checked and found to be OK, and the machine still marks, the following procedure should help locate the trouble:

	Check the condition of the drum. If "OK," check bearings for roughness.
	Check drum shaft, motor shaft, and fan shaft for roughness and/or for excessive play.
	Check pulley alignment, check belts for hard spots or unbalance.
	Check for worn shafts, or worn pulleys. If "OK," check inside drum. Blow out the inside space and paper slot with compressed air. Repeat the blowing process several times, rotating and tapping drum in between.

Finally, be sure paper has not been applied too tightly, or too loosely as either can cause "chatter" marks.

If all the above fails, it is probably necessary to install a new drum. (Test any new drum)

CAUTION - In some areas the operator will put on a fresh sheet of paper and with the drum running take the old sheet and pass it from one side of the drum to the other - this is known as "slicking" and almost inevitably causes "satin" appearing, cross marks spaced from 1/4" to 1/2" apart over the entire plane of travel for the life of that particular sheet of paper.

NOTE: - The use of a hardwood test board is invaluable in making the above check for corrective measures. Wiping the sanded area with a damp cloth highlights the marks so they can be analyzed.