Troubleshooting a Wide Belt Sander Oscillation Problem

Info on dealing with electric eye issues and sander belt tracking. June 12, 2014

(WOODWEB Member):
I am looking for anyone who knows anything about wide belt commercial sanders. I have one that will work for a short period and then the electric eyes shut off and the sander belt slips to the side. I can't find anyone who works on them.

Forum Responses
From contributor P:
What is the brand? What is your location? Have you called the importer or supplier of the machine? Do you have good dust collection to the machine? Does the problem stop when you change belts? These are questions that a tech will need to know.

From contributor J:
It sounds like your oscillation control is not working well. You will probably need a factory tech to advise you how to check and correct it.

From contributor C:
Check your air pressure. Sometimes the oscillation of the machine depends on the air pressure.

From contributor M:
First make sure the eye is the culprit. Pass your hand in front of it. It should actuate the cylinder. If it works, you only need to adjust the tracking. If not, clean the dust off the eye and the reflector. Next check for dry-rotted ends on the small air lines that supply the tracking pistons. These are the easiest solutions.

From contributor B:
Any of the several hundred machinery dealers across the US will have people that work on machines. Most older machine manufacturers still have some presence in the US and there are plenty of independent service people that work on machines. What city are you in and what is the machine manufacturer and date?

From contributor J:
Here are a few things to look at. First, in electric tracking there are 3 basic types.
1) through beam: this uses a emitter unit and a receiver unit.
2) reflective: emitter and receiver are in the same unit and a beam of light is emitted and reflected from the unit back to itself.
3) diffuse: these sensors emit a signal and with the presence of a belt it is reflected back to the emitter/receiver.

It has been my experience that when the machine stops, the operator opens the door, resets the belt, wipes the tracking eye and restarts the machine. If this is your scenario, try this next time. Wipe the sensor with something mild like eyeglass cleaner. Here's why. When we sand, the dust will pick up a static charge. The emitters, receivers and reflector are typically plastic and hold their own charge. When you wipe them clean, you help to recharge the static, as well as leave the oil from your hands behind. This is a double smack - not only did you create a charge, now you gave it a way to stick. If this doesn't work for you, it could be a few other possibilities from low voltage to noise in the electrical grid. But my first guess is the static cling.