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Vibration Troubleshooting Ck 12 monarch

Franky6767

Plastic
Joined
Mar 31, 2018
So far this machine has stumped me with this vibration issue. Sounds like a soft thumping inside head stock but unsure were its actually coming from. You can disengage all speeds so that only input shaft turns and short shaft under it. Engage clutch and thumping starts....not making a sound or anything but you can feel it anywhere you lay your hand on the machine. Old 3 phase motor on lathe (5 hp) running off a newly "built" rotary phase converter. Take belts off motor runs fairly smooth....no more vibration than I would expect but Im certainly no expert. Lathe is on concrete

So far in no particular order....I have

Removed chuck.....same deal
Replaced motor pulley.....same thing...smaller pulley slower thumping rhythm
Changed belts...two different brands..........same thing
Replaced input/clutch shaft bearings......same thing.
Head stock cover off....looking hard in gears...no metal in gears or even any wear I can detect.....hose to ear.... stethoscope probe....can't tell were its coming from. Drained oil so I could really run it without getting oil showered....stethoscope...looking hard....cant see or hear exactly were its coming from.


Its almost like clutch is out of balance? Seems to engage smooth. Anyone had a motor do this....I haven't? Input/clutch shaft and short shaft under it look like they are running true....clutch engages good....brake works good....This thing has almost kicked my butt. Probably something silly but I sure ain't found it yet. Its not like its vibrating across the shop or anything....but I would think this machine should run a lot smoother if its right.
Im almost convinced its the motor somehow...cutting up under a load but I can't feel it in it. Thats gonna be a real pita pulling that heavy motor out to get checked if its for nothing.

ANy suggestions or ideas.... I would highly appreciate.
 
thanks for responce......Thats on the list of things to try next. Motor is bolted down on all original plate and pivot pin and tension adjustment screw deal...all look to be in good shape and everything tight...but motor has huge rubber washers under it. Seems to be "tightly" mounted on them but who knows...might be just that simple....but I can put my hand on motor and can't feel any thumping.....maybe its transmitting it through the belts? That just doesn't make sense to me but this problem has stopped making sense to me after only a few hours into it. I also haven't taken the clutch completely apart yet..
 
You've done good work to try and isolate it. Here's an idea - what if you mount a pulley in the chuck, and a small motor on the compound. Back drive it via the chuck, at lower speeds. That would allow you to run the 'front end' with the clutch disengaged.

That should allow you to exclude a few more things.
 
You've done good work to try and isolate it. Here's an idea - what if you mount a pulley in the chuck, and a small motor on the compound. Back drive it via the chuck, at lower speeds. That would allow you to run the 'front end' with the clutch disengaged.

That should allow you to exclude a few more things.

That a good idea! If I can figure that with what I got around

Old belts or new belts? Old belts, even if they look good, if machine has been sitting for long periods of time, get a "set" and can cause vibration/thumping sounds.

New belts.....two different brands so far. El cheapo 5L belts though thusfar.

Took the rubber mounts out of under motor today....seemed to help just a little suprisingly but its still there. I got ideas that clutch has got something going on.....old grease stacked up in outer drum....something....Thanks for all suggestions...means alot.
 
You say it is a thump. What is the frequency of the thump? From your description it sounds like it does not change with spindle speed? Can you run the motor backwards on that model?

You could audio record the thump. Then examine the audio file to determine the frequency by measuring the number of milliseconds between each, using an audio file editor like Audacity. Convert that to rpm.

Then, using the motor rpm and drivetrain ratios, identify corresponding drivetrain components that match that rpm. That should give you an idea whether it matches motor rpm, input shaft rpm, cluster rpm, etc.

You may need to touch the microphone or phone to the headstock to pickup the vibration.

Example:

34 ms between thumps
(1000 ms / 34 ) * 60 seconds = 1765 rpm
 
Replaced motor pulley.....same thing...smaller pulley slower thumping rhythm
So you have ruled out the motor because the thumping got slower. I would try to drive the spindle like Glug suggested to bypass the clutch assembly and rule out the spindle. I can send you a Moore tools vibration meter and magnetic probe if that will help.

I think you are on the right track about the clutch assembly. It may be an alignment issue there.
 
Turns out to be the clutch.....inter clutch plate is "timed" so to speak....so it can go in both straight up or 180 out. I might not have even noticed but someone had previously put witness marks on it....and then apparently someone else had put it in wrong after that. That and a bunch of dried grease on one side in the inter drum and balancing holes on back filled slap up....just years of neglect. Not sure exactly what one thing did it but it stopped thumping. I guess that why the input shaft bearings had wore in so.
Pulled the motor as well and put bearings in....not real bad but runs a little nicer....
I got a little work to do on cross slide and oil has all but stopped dripping through site glass in head stock for some reason out the blue smh....but I about got the old girl going my way now. Heck of a way to spend a day off lol but I got it done.

MANY thanks all the help and suggestions. Means a lot.
 
FWIW- The headstock oil pump, IIRC, is driven from the bull gear and thus its pumping speed is not directly correlated to spindle speed. If you change gears you may find that the pump works fine.

Sent from my SM-G930R4 using Tapatalk
 
Now perhaps Im dead wrong...but I thought I remembered that the headstock pump in my ck12 way pumped off a cam attached to the main spindle shaft. One revolution....one pump?
 








 
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