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Wide Belt Sander Tracking Issue11/4
We've got a 37" AEM wide belt in the shop running Pasco belts. It's a great sander, but as equipment is known to do, it is acting up. Two problems: #1 When we initially turn the sander on it immediately tracks across the electronic eye and tears up the edge of the sanding belt. We've learned to crank the manual tracking to the left before start-up to avoid tearing up sanding belts until the underlying issue is resolved. The second problem is the belt is simply not oscillating. Before, the belt would slowly move away from the electronic eye, then a solenoid would trigger the roller to kick the sanding belt back over. The sanding belt now simply stays manually tracked.
Does anyone have some troubleshooting suggestions? We've cleaned the eye as well as checked wiring connectivity and air pressure. All seems normal. Electronic eyes and solenoids are not cheap, so I thought I'd run it by others in the forum before buying random replacement parts. Thanks.
You might try turning up your air pressure, and checking that the reflector is still on the machine, clean, and facing the eye. The eye is just an open/close switch, so you can fire it manually to see if everything else is in order. It should be shining a red light, by the way.
there should be a pneumatic piston that oscillates the top roller. little wd-40 on the (un-)moving parts should do it
All: thanks for the advise.Still no luck. We've taken half the sander apart, performed maintenance on everything and put it all back together. The sander continues to track abruptly across the eye at start up then not auto track at all. It remains pretty good at staying stable once manually tracked. We're still getting things sanded, but it's never fun to start a wide belt "hoping" it won't eat the belt.
Can you fire the tracking cylinder by moving your hand in front of the eye?
If you had the wiring diagram it would not be hard to find out if the eye was reading movement by the voltage sent to the tracking solenoid to fire the cylinder to track it back. If the eye sends voltage to track then you know the solenoid might need replaced or the valve might just be sticking.
Have you tried painting the edge of your belts. I have to do this as my eye will see right through the some of the newer belts. I just spray paint around the inside edge of the belt about 3 or 4" in and it solves my problem. 3M belts seem to be the worst.
The same was happening with my sander last week. In my case, it was because the oil level in the automatic inline oiler had fallen below the minimun level and was no longer supplying oil to the pnuematic tracking cylinder. Once it was refilled and cycled a few times, it went back to working as it should. One other thought, you do have a refrigerated air dryer between your compressor and the sander? If not, that could be part of the problem as any moisture in those tracking cylinders will cause them to seize.
Adam, I tried your advice and the eye apears to be working. Jeff and Duster had some ideas I hadn't thought of. I'll give those a shot and get back with the forum. Thanks.
Lots of good advice here. Another problem could be to low of air pressure and/or two high of spring tension on the cylinder that pivots the top idling roller.
Can you manually adjust your tracking roller until it just barely moves the belt towards the eye when the machine is fired up? It sounds like the belt is moving to quickly towards the eye.
Back and forth at the same speed is ideal. The speed is not important as long as the cylinder can bias the idler enough to send the belt back the other way again.
The first thing you should check are the tracking eyes. If it's not a dual eye tracking system, which I'm guessing it isn't, then one of the tracking eyes/black box will be the receiver and the other eye/black box is the emitter. If you still have the manual for this machine, sometimes AEM, which has been bought out by Timesavers, will put a small business card sized laminated piece of paper that has a square located in the center of it.This is used to see if the emitter is reflecting the beam to the receiver. Radio Shak may still sell the infrared detection cards as well. Once placed in front of the emitter, you should see the square box glow. If that is the case, then go to your air cylinder and pull the air supply line off it. Place your hand in front of the tracking eyes and you should feel a puff of air coming through the line. If not, then trace the air line back to the air solenoid valve (usually a blue Mac valve). Once located, do the same procedure of placing your hand in front of the eyes and listen/feel for a "clicking noise". If there is no "clicking noise", then either your valve has gone bad, or your tracking eye receiver has gone bad in which case I would recommend replacing both the emitter and receiver. One other thing to check is the exhaust port on the solenoid valve. Most times there will be an exhaust muffler screwed into it. If you have bad air, this muffler tends to clog up and will reduce the air being released, in which case you tracking cylinder will be slow to react, or not react at all. Also check the tracking cylinder piston. Spray Windex on the piston where it enters the body of the cylinder and see if you notice "bubbles coming from it. If you do, most likely you seal is worn and you will need to replace the cylinder or in some case rebuild it.