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9" motor fly when shaking.

Bluecollarirons

Plastic
Joined
Apr 23, 2010
Location
Portland OR
9" motor Mount and fly wheel shaking

So I finally figured out what was making my lathe shake. I took my motor and mounted it on the wall apart from the table to isolate it..Then ran it without the belt tight to the head stock and sure enough its the motor mount and fly wheel assembly. Anyone ever hear of this happening. There is zero slop on the shaft. Its tight and spins fine. Maybe the cast was bad and casted uneven?? Im thinking going to a tire place and getting tire balance weights.. Any suggestions or experience with this happening? Or should I just buy a new mount??
 
I think in a previous post you had stated that the motor was 1725 RPM. Are you sure about that? I have a motor which is clearly marked as 3450 RPM but is actually 1725. They do get mis-marked some times.

You should also figure out how fast the countershaft is turning. If it's much beyond about 500 RPM you may be running it too fast. I think a previous poster (Promacjoe) mentioned that he can excite a countershaft vibration by running it too fast. You may have the same problem.

Balancing the big pulley would certainly help but it's not the cure of choice if you're running that shaft too fast because it's a steel shaft in an iron bearing with less than ideal lubrication so it will not tolerate high speed very well--of for very long!
 
The motor mount is not your problem. The problem can be in the motor, motor pulley, large pulley, flat belt pulley or a bent shaft. If the large pulley turns freely, no slop, It is probably not a bent shaft. But you still need to check for wobble on the large pulley. If run at the proper RPM, the large pulley should not give any problems whatsoever as far as vibration goes, if it is in good shape. If it is damaged, it should be repaired By someone who knows how to repair it, or replaced. Adding wheel weights to it is never a good idea. Automotive wheel weights or for very a large mass. The pulley is a very small mass in comparison. And if you do not know exactly what you're doing, and have the right equipment, you will probably make things worse.

There have been several members of this board give you a lot of good advice. What you do with the advice, is your business. But if you want advice from us, follow that advice and report back to us on the results. pictures/Video would be very helpful.

Putting rubber vibration mounts on your machine will only mask the problem. It will not fix it. You need to address the problem not the symptoms. A good example of that is years ago I worked for a company who had a very large fan to circulate air in the shop. When it was first installed, it would shake violently, So they added weights to it to help balance it. While working on it years later, I straightened the fan blades, remove the weights, and it all ran perfectly smooth. That was the proper way to fix the problem, not by adding weights to it. if you just want to throw money at it, you will eventually eliminate the problem. But you will learn nothing on how to fix the problem.

Stay safe and have fun.

Joe.
 
Have to agree about the rubber not fixing anything. My 10L underdrive setup is functionally very similar to the 9A drive, and it is very smooth. No rubber feet under the motor or any of that. The bearings on my countershaft were bad, though it really only caused it to make noise before I changed them.
 
Did you ever find out what the problem was. We would like to know, it may add to our knowledge base, and maybe help someone else later on.

Stay safe and have fun.

Joe.
 
Did you ever find out what the problem was. We would like to know, it may add to our knowledge base, and maybe help someone else later on.

Stay safe and have fun.

Joe.

Im having the same issue with my 1937 9”.... im running a serpentine belt to the countershaft. The counterhsaft pulley runs true. New v-belt..... looking at the pulley on the motor itself i see a distinct wobble. Indicator on the motor shaft is within .002” so its got to be that pulley. Gonna upgrade he motor while im at it.
 
Im having the same issue with my 1937 9”.... im running a serpentine belt to the countershaft. The counterhsaft pulley runs true. New v-belt..... looking at the pulley on the motor itself i see a distinct wobble. Indicator on the motor shaft is within .002” so its got to be that pulley. Gonna upgrade he motor while im at it.

Or a bad belt.. the belt is running in the V of the pulley but its on the Flat of the counter shaft pulley correct? so if you've got a belt that has a thick spot or a thin spot in it, the belt tension changes.
 








 
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