Troubleshooting Vibration for my SB 9A

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ryanj1234

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H-M Supporter - Silver Member
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Hey all,

Recently acquired a 1947 SB 9A. The only other lathe I've owned is a Grizzly mini lathe so I am very new to this, apologies for beginner questions.

I purchased the ILION restoration book and kit, and in going through it I've taken everything apart and thoroughly cleaned, replaced wicks and oiled. Also painted because why not. Not quite finished in the following pics, but it will show the drive assembly which is the root of my question here.
IMG_3183.JPG
IMG_3180.JPG

The lathe runs and I'm happy with it at low speeds, but at higher speeds it seems to vibrate quite a lot. I'd like to start checking some things to see if I can reduce this.

Things I've checked:
  • Spindle runout is very minimal. I've adjusted the headstock bearing screws to get .001" deflection on the spindle pulling on a bar with 75 lbs of force (ok, didn't measure force exactly, but I did guesstimate)
  • Squareness of belts/pulleys. As best as I can messure with a large carpenter square everything is aligned, the belts don't quickly wander to the side when I run things

I've seen in other threads people mention the run-out on the motor and counter-shaft, what would be considered normal/acceptable values for those? I can see in the current motor the bushings look pretty worn out, so I'd like to replace those. My lathe does not appear to have replaceable bronze bushings for the counter-shaft, so if that is worn do I just need to buy a new one (whatever that whole assembly the motor mounts to is called)?

What about belts? Can/should I replace with a link belt so I never accidentally put the spindle in without the belt wrapped around it??

Anything else you would check?

Any and all help appreciated.
 
To isolate the countershaft from the head stock I'd drop the flat belt to the side of the countershaft and see if there's vibration in just the countershaft assembly.
 
Thanks for the replies. I know the vibration was not nearly as bad with the flat belt from the counter shaft to headstock pulled to the side, although it's hard to assign a percentage.

I don't remember now what it was like without the chuck, I had not considered that it could be out of balance. I will definitely check that this evening when I get back from work a report back.
 
What is the lathe mounted on? It looks like a metal plate
Usually a thick wooden table is best, with fat solid legs down to the floor
 
There is an app for smart phones called vibrations. It will give you a visual readout of vibration. You can place the phone on various parts of the lathe in various orientations to see if you can isolate the cause.
Another old trick is to place a nickel on edge and see if it falls over.
Definitely take the chuck off and move the flat belt aside. Try both countershaft pulleys and take the belt off the motor to see how much the motor is contributing.
It should just be a process of elimination from there. Once you find where the most vibration is coming from, you can start to figure out why.
Once my 10K started making a strange noise but only under load. Turned out the pulley on the motor had come loose. :oops:
 
markba633csi said:
What is the lathe mounted on? It looks like a metal plate
Usually a thick wooden table is best, with fat solid legs down to the floor
Click to expand...
Unfortunately I've got a lot of variables here. This table was built by the previous owner, it feels pretty solid to me, as in I can make it wobble just a bit if I really throw my whole weight at it. I figured it would be a very small contribution to the problem, but I may be mistaken.

Also, the metal on top is actually just a veneer, its got about 2 inches thick of wood all underneath.

Building a sturdier bench is on my to do list and might get bumped in priority if nothing else obvious comes up for the vibration.
 
piper184 said:
There is an app for smart phones called vibrations. It will give you a visual readout of vibration. You can place the phone on various parts of the lathe in various orientations to see if you can isolate the cause.
Another old trick is to place a nickel on edge and see if it falls over.
Definitely take the chuck off and move the flat belt aside. Try both countershaft pulleys and take the belt off the motor to see how much the motor is contributing.
It should just be a process of elimination from there. Once you find where the most vibration is coming from, you can start to figure out why.
Once my 10K started making a strange noise but only under load. Turned out the pulley on the motor had come loose. :oops:
Click to expand...
The phone app idea is genius, I will absolutely be using that
 
Recently I tried turning between centers for the first time. I was shocked at how much vibration was caused by the lathe dog even though there was a cutout in the face plate. I definitely need to make a new face plate where I can tap a bunch of holes for mounting counter weights.

If the source is an imbalance that you can't remove, you might be able to counter act it by adding weight in the proper place. Stick on wheel weights come to mind. Could be useful in troubleshooting too.
 
markba633csi said:
What is the lathe mounted on? It looks like a metal plate
Usually a thick wooden table is best, with fat solid legs down to the floor
Click to expand...
A metal sheet on top of wood is fine.. Or MDF, or pressboard. All are vibration and sound dampening (except the sheet of metal).
I don't have mine on wood, it's on an old electronic table.. I won't go into the core, but as long as his table is not a drum he should be good.
 
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