Belt Sander Drive Drum Slipping

[andyyoung]

Hello, I have an old Shopsmith inherited from my dad. Probably from the 80's. The Belt Sander has worked great for the last few years, but recently is giving problems. The belt runs fine until I place a workpiece on to sand. After placing work against the belt, the belt stops after a couple seconds. I assumed this was just loose tension. The Tension knob seems to be working fine. The one thing I notice that I can't find anything online about - When the belt stops spinning, the Drive Drum also stops. So the belt is not loose from the Drive Drum. Or, at least, it's not that the belt stops but the drum keeps spinning - they both stop. However, the drive Hub continues to spin. Any advice on what to check would be greatly appreciated.

[andyyoung]

Update. I detached the coupling between the motor and the sander. The metal collar that engages the plastic coupling on the sander side that sits over the drive shaft of the sander was completely loose on the shaft. The first picture shows wear on the flat side of the shaft, presumably from the set screw spinning loosley over the shaft. The second photo shows the set screw with magnetized metal filings, presumably created from the spinning against the shaft. The photo of the set screw is after I'd taken the screw out, cleaned it, and put it back in multiple times. Originally the shavings were much worse than what you see in the photo. Also the sander end of the coupling was very hot after the sander has been running for a couple minutes. Do I simply need to replace the set screw? Or do do I need a new shaft?

[andyyoung]

Update. I detached the coupling between the motor and the sander. The metal collar that engages the plastic coupling on the sander side that sits over the drive shaft of the sander was completely loose on the shaft. The first picture shows wear on the flat side of the shaft, presumably from the set screw spinning loosley over the shaft. The second photo shows the set screw with magnetized metal filings, presumably created from the spinning against the shaft. The photo of the set screw is after I'd taken the screw out, cleaned it, and put it back in multiple times. Originally the shavings were much worse than what you see in the photo. Also the sander end of the coupling was very hot after the sander has been running for a couple minutes. Do I simply need to replace the set screw? Or do do I need a new shaft?

[JPG]

IIWM, I would clean up the shaft with a fine flat file to remove high spots, then use a NEW setscrew centered on the shaft flat and very securely tightened. The scaring on the shaft flat may make that difficult.

Lastly be sure the coupling hub is not too loose on the shaft. If so, replace it as well.

Do make sure the power station shaft accurately aligns with the belt sander shaft

[andyyoung]

Thanks. I just ordered a new coupling kit that comes with a new hub and (hopefully) the set screw. I'll try as you suggested. Thanks!