Knocking Noise

dusty · Post by **dusty** » Tue Sep 14, 2010 12:24 pm

If I was working on an internal combustion engine, I would know just what I might be hearing. But this Mark V is NOT an internal combustion engine and I still have a knocking noise.

Over the past few weeks I have not felt that the Mark V sounded quite right. When I had it running and then turned if off as it slowed down I thought I could hear a knock-knock-knock as it came to a stop.

With power off, turning the drive shaft by hand with a sanding disk, I hear a distinctive noise that occurs approximately ever half revolution. Using the largest screwdriver as a stethoscope, it seems as though it is coming from the area of the drive sleeve bearing.

The periodic nature of the noise is what confuses me. If it was a grinding, gritty sound I would immediately assume bad bearing.

Added comments:

With the drive belt pulled off the pulley, the clicking noise is still present.

With the control loop pulled off, the noise goes away. Guess I better put the control loop back on to make sure.

Ideas, please.

nuhobby · Post by **nuhobby** » Tue Sep 14, 2010 3:37 pm

Just ideas for now....

A lot of the Sawdust Sessions show perfectly good Mark V's having a knock-knock sound during shutdown. This is probably a transient event where the Poly-V belt is tight and the motor-belt is slackening.

The idler bearing is only quiet when its cantilevering is well-balanced between the upper and lower belts. In the Mark V this was traditionally set by upper-belt pre-tensioning via the idler eccentric adjustment. You could probably also make a judgment by adjusting the eccentric "live," during operation. In fact the Power Pro adjustment procedure does just this sort of thing.

But.... if you're fully sure the noise is from the upper sleeve, the noise may be something else than what I'm getting at.

dusty · Post by **dusty** » Tue Sep 14, 2010 4:09 pm

Your input is greatly appreciated.

I removed the drive belt, as stated earlier, and the clicking noise persisted. I disconnected the control loop (don't know why - just did) and the noise seemed to cease. Put the belt and control loop back in place and I have the clicking noise again.

No, I am not certain whether that the noise emanates from the idler shaft or from the drive shaft.

billmayo · Post by **billmayo** » Tue Sep 14, 2010 9:38 pm

dusty wrote:Your input is greatly appreciated.

I removed the drive belt, as stated earlier, and the clicking noise persisted. I disconnected the control loop (don't know why - just did) and the noise seemed to cease. Put the belt and control loop back in place and I have the clicking noise again.

No, I am not certain whether that the noise emanates from the idler shaft or from the drive shaft.

Dusty, Your Private message file is full. Sounds like the control sheave end bearing. By setting the speed control to FAST, with the retaining loop unhooked, try turning the button in the end of the control sheave.

I have only found one idler shaft bearing which was making a clicking noise. The eccentric bushing set screw had been over tighten and deformed the outter bearing race. Also, I find bearing problems in the drive sleeve assembly and the drive sleeve pulley set screw being loose. But you have to remove the drive sleeve to make sure the bearings and set screw is OK.

gucho · Post by **gucho** » Sun Mar 04, 2012 10:10 pm

I think im having the same issue and I cant quite see whats causing it.
what did you end up doing to fix it?

thanks!!

dusty · Post by **dusty** » Mon Mar 05, 2012 4:48 am

gucho wrote:I think im having the same issue and I cant quite see whats causing it.
what did you end up doing to fix it?

thanks!!

I am sorry but I am unable to answer your question. I do not recall. I try not to leave issues hanging like this but I screwed up on this one.