Here are just a few of the frequently asked questions woodworkers have with regards to widebelt sander usage.
Chatter & Other Marks
Q: What causes chatter?
A: Chatter marks on the product are most often caused by the sanding belt splice. A good way to check is to use a black crayon to mark the splice. Then, run a new, clean workpiece through the machine. If the belt splice is the problem, the black crayon will mark the workpiece with chatter marks. Most of the time, using more pressure or making a heavier cut into the product will cure chatter. An exception to this guideline is a product application on a machine with a hard contact drum, that is not designed for finishing. Causes . Belt splice · Worn contact drum bearing . Vibration in the machine . Worn drive motor bearings · Worn idler roll bearings . Loose or worn drive belts · Flat spots on the drum · Out of balance drum or idler · Conveyor bed not feeding at a constant rate — submitted by Timesavers Inc.
Q: How do you solve chatter?
A: Actions to cure chatter marks: Use an abrasive belt with a butt splice · Replace the contact drum bearings · Identify and stop the machine vibration · Replace the drive motor bearings· Replace the idler roll bearings· Tighten the drive belts · Replace or dress the contact drum · Balance the contact drum · Check the conveyor bed drive coupler/drive belt · Relieve tension from the abrasive belt when it is not in use to avoid flat spots on drums. — submitted by Timesavers Inc.
Q: How do I identify chatter marks and eliminate them from the operation?
A: Chatter marks are the most common sanding defect and problem. If the marks are uniformly spread across the board, the rollers being out of balance can cause the problem, or the bearings may be worn. The rollers may have become “oval” or the pad, where fitted, may have become stuck. Another cause can be vibration caused by poor machine mounting or loose foundation plates. The spacing between the chatter marks will indicate whether it is the contact roller or a defective abrasive belt. To determine whether the belt is causing the marks, one of two things can be done.
Measure the distance between the chatter marks, mark the belt with a wax or graphite stick and pass a trial piece though the machine. The wax or graphite mark will show up on the trial piece, to indicate if the distance between marks is the same. If the belt is suspected as the cause, try fitting another belt, preferably from a different supplier in case one batch was faulty. If this fails to cure the problem, then look for another cause i.e. the machine bearings. Listen with a stethoscope, or a screwdriver, placed on the bearing race and place your ear to the screwdriver handle to listen for bearing rattle, or place a coin on the bearing head to see the vibration. Also feel the bearing race with the hand for heat build-up during running.