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South Bend 9a spindle squeak

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dansawyer

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#1
This is a new to me 9a. I picked it up about 6 weeks ago and after extensive cleaning, mounting on a new table, and getting a drive flat belt in place was able to turn it on. Yeah!! That was the good news. The bad news is there is a squeak in the spindle. I started by turning off all everything, the forward / reverse lever, and the back gears, and the bull pin. The squeak remained constant with each change. The squeak remained the same with the bull pin in and out.
This leaves the only constant moving bearing the rear bearing, the parts list labels this 'thrust bearing'. I have ensured the bearing is adequately lubricated.
Has anyone had this issue? Is there an adjustment? Is there a replacement part?
Thank you in advance for your input. Dan
 

coffmajt

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#2
do you have a mechanics stethoscope available to try to isolate where the squeak is coming from? It also could be from another bearing or bushing. Does it change volume with load? Have you checked your bearing clearances yet and do they fall within the SB recommended range? Is the thrust bearing the fiber washer type or has it been changed to a needle roller? Jack
 

dansawyer

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I haven't checked the clearances yet. I did examine the thrust bearing and it is 'loose'. That is there appears to be excessive clearance by examination, the races are loose. I am currently researching the spindle longitudinal adjustment. I have not found a document on how to adjust it.
 

craptain

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#4
I would start with the lubrication chart and ensure that every point is adequately or even more than, lubricated. The thrust bearing is an important adjustment but is unlikely to squeak. Dry bearing surfaces, however, do. An often overlooked place is the set screw in the spindle pulley. Remove this and oil it. Come to think about it, that set screw is occasionally tightened right down, causing friction and perhaps squeaking. It's purpose is simply a plug for the lubrication point and should be simply screwed below the surface of the pulley.
Another cause of inadequate lubrication is the felts drying all the way out. These are cheap to replace.
Does the squeak occur when turning the spindle by hand? I am thinking of completely disengaged from gears and drive belts then turn the chuck. Or is it only at speed?
I'm just throwing out ideas so please don't be offended if you have already covered them.
Oh and I got some documentation for mine from Vintage Machinery website.



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//cloud.tapatalk.com/s/5b710727c7da5/lubrication_chart_6503.pdf
 
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dansawyer

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Thank you for the reply. The squeak does not occur when spinning by hand.
The lathe has been out of operation for at least several months. I do not know before that. I suspect perhaps at least a year. I was concerned about the spindle felts as well. I do not believe the spindle is turning when the bull pin is disengaged and the back gears are not engaged.
The squeak occurs in two configurations: bull pin engaged and bull pin disengaged. In the disengaged configuration the cone pulley contacts are the thrust bearing, the spindle, and the bull gear. With the bull pin engaged the pulley is locked with the spindle and the bull gear. As I see it the only common remaining surface is the thrust bearing.
Is this reasoning sound?
 

craptain

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Yes, from my recollection you are correct. I am not at my shop right now so I cannot lay eyes on my lathe to be certain.


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derf

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#7
Are you sure it's not just the belt squeaking?
 

dansawyer

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It's the belt!. The belt is working itself toward the right or tail stock and squeaking on the pulley to the right. The belt is a spliced serpentine belt.
The lathe table is custom welded stainless steel.
I assume this an alignment issue. I can think of four axis, 1. left right, 2. vertical shaft angle, 3. horizontal shaft angle.
The lathe is not permanently mounted. I have tried left to right and that did not have an effect. I will try horizontal next by moving the tail stock in and out. Changing vertical alignment will be more difficult, it will require adjusting the horizontal mounting of the under drive assembly.
Does anyone have a source for what alignment causes a flat belt to walk one way or the other?
(BTW: I have tried all three pulleys, they all walk in the same direction on the spindle pulley. ) Thanks in advance Dan
 

craptain

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#9
If the belt is walking, you have an alignment issue between the countershaft and the spindle pulleys. I don't know how, but you need to adjust the countershaft to run parallel to the spindle.
 
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