Posted: 9/17/2025 9:03:58 PM EDT
[Last Edit: Firestarter123][Edited]
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It’s a Buffalo Power BP-1236 and is one of those Taiwanese lathes from the 80’s. The belts are new, however, the sound has been there since I got it from my Grandpa’s estate. https://nextcloud.fstech.ltd/s/ErrfbmCRyZEEBag I’ve checked every set screw and everything else I can possibly think of. Sometimes it starts right when I start the machine, sometimes it waits 30 seconds or so, sometimes it happens during the cut, and sometimes it goes away during the cut. I put layout fluid on the back gear and pulley in the front to make sure they aren’t hitting each other and they aren’t. The sound doesn’t happen when running in back gear or when the drive pin is disengaged and the pulleys are just free spinning without turning the spindle. Using a mechanics stethoscope the knocking is the loudest when the tip of the stethoscope is placed on or around the handle that it highlighted which makes no sense as it’s not doing anything as the back gear isn’t even engaged. Attached File I’m just at a loss as to what to check next. The spindle bearings themselves seem fine and you can barely hear the knocking when placing the tip of the stethoscope all over the part of the casting that holds those bearings. Any thoughts would be appreciated. |
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Originally Posted By Firestarter123: Both sets of belts have done it though. The original set was a standard B30/B33 combo that I replaced with the link belts. the link belt is susceptible to getting gunge stuck in it or deformation on the underside, it's the only thing that I can think of that could do knocking due to its inherent design. or the bearing |
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I wound up playing with tightening the belts and it seems that as I went tighter the knocking went away. Engaging the bels - https://nextcloud.fstech.ltd/s/TReAwtM4CGafErb Running at 720rpm on 4140 and hand fed - https://nextcloud.fstech.ltd/s/zSmg3EN5ySrDxXa The belts still have flex (1/2” over a foot) but when I did less tension they just slipped. The pulleys are all painted cast iron and I find it odd that they're painted but I didn't expect to need to go that tight. |
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Also, I ordered a new Gates B33 belt to replace the B33 that I took off of it. I got it today and it's too long so that's crazy. I took the original in to Napa and I needed a B31 to match the length which is crazy to me. The B30 I got was too long for the back pulley setup as well so I ordered a B28 as nobody had one locally. I found out that I can sneak it on so I'll replace the link belt with that when it arrives. |