Maintenance issue to watch for regarding the T-nuts

[Larry Stobbs]

I have been running my shark for a long time with great results. I had an issue yesterday were I was running a tool path and the the tool seemed to be stuck on the Y axis. Ruined an ice piece of walnut in the process and after determining that it would jog in the X and Z axis, I figured the motor for the Y axis was shot. The controller said it was moving but all the motor did was make a noise with no movement of the shaft. I did check to make sure the allen hae set screws had not worked loose from the shaft and they were tight as a drum. I went ahead and ordered a new Y axis motor figuring I will get it the first part of next week and I can get my shark back running.

Went down this morning and started taking the Y axis Motor off and getting it ready to put the new part on and I soon found that the issues wasnt the motor. Once I had it off, the motor runs fine. I did find that I couldnt turn the Y shaft screw by hand and it was like it was welded in place. Took everything apart and was able to back the screw out of the black T-nut. Once I did that, there was a black fine material rolled onto the screw shaft. I am thinking from all those hours of running back and forth it finally left had built up just enough powder from the t-nut wearing that it got to the point that it just froze everything up.

I thought I would pass this on to the long time users so that if they have this happen to them, they wont automatically assume like I did that the motor was locked up and that the T-nut could be the culprit. The T-nuts are available for $65 to replace all three axis and I will go ahead and get me set ordered, but after cleaning the material off the screws, I am running again. By the way the residue doesnt show on the screw when mounted in the machine, I think the electro static property of the plastic keeps the stuff stuck inside the t-nut and I didnt see any of it until I took the t-nut off the screw assembly.

[Larry Stobbs]

Someone asked me to post a picture of the T-nut so everyone would know what I was talking about. this is it. there is a pretty good angle to the threads and they looked completely clean up until I actually disassembled the t-nut from the shaft, the moment I started to unscrew the t-nut from the shaft, it looked like there was balck plastic threads on that area of the steel threaded shaft. The moment I touched the black stuf, it literally fell off in pieces so I couldnt get a good picture of what it looked like. Again I think what caused this is that over time the material used to make the t-nut tends to get a little "chalky" from the constant friction and adheres to the plastic rather than the metal so it tends to stay inside the t-nut and continues to build up until it totally locks up which is what I had experienced.

[afs2ovi]

Hello Larry!
Read your post a couple of days ago and it found my problem. My machine made a chattering noise on the Y plus every time it used that direction, this could be heard and felt in the Y axis motor but as yet had not become visible in the carving. I did as you did, disassembled the Y axis shaft and T-nut and found exactly what you describe, cleaned it reassembled and no more chattering.
I have had my machine for about 18 months or so but it sat unused in my shop for almost a year while I recovered from Cancer Surgery. I love it.
thanks for the post
Allen