9" SM Utilathe Restoration
- Thread starter YYCHM
- Start date
Marc Moreau
Marc Moreau
Stop and clean stop and clean stop and clean But the result will be fantastic.
OK..... I need to do something about the vibration this lathe is exhibiting, it's noticeable to say the least.
As far as I can tell it's all coming from these two pulleys. If I remove the belt the motor just purrs. Install the belt and she starts to shake. At some speeds you can see the motor rocking/bouncing. Disengaging the feed box and lead screw has no effect other than reduce the noise level.
This is the metal bench it's mounted on. The table top has a sheet of 1-1/2" MDF in it, and the U channel legs are welded on. There are diagonal cross braces across the back side, and the legs are stabilized depth wise with welded U channel and L channel across the front and back. I braced the bench against the adjacent wood bench with that L bracket you see on the right.
And these aluminum pucks and a bolt sucking the two tables together.
I can feel the lathe vibrations clear down to the far end of this wood bench. My mill doesn't do this, and it has two belts and three pulleys, it just humms.
So what would you suggest I do here? Is it wonky pulleys? Need a heavier bench to soak up the vibrations?
Craig
As far as I can tell it's all coming from these two pulleys. If I remove the belt the motor just purrs. Install the belt and she starts to shake. At some speeds you can see the motor rocking/bouncing. Disengaging the feed box and lead screw has no effect other than reduce the noise level.
This is the metal bench it's mounted on. The table top has a sheet of 1-1/2" MDF in it, and the U channel legs are welded on. There are diagonal cross braces across the back side, and the legs are stabilized depth wise with welded U channel and L channel across the front and back. I braced the bench against the adjacent wood bench with that L bracket you see on the right.
And these aluminum pucks and a bolt sucking the two tables together.
I can feel the lathe vibrations clear down to the far end of this wood bench. My mill doesn't do this, and it has two belts and three pulleys, it just humms.
So what would you suggest I do here? Is it wonky pulleys? Need a heavier bench to soak up the vibrations?
Craig
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Your belts appear to be in good shape but I have table saw that has old belts on it and partly because it doesn't get used often it always runs rough with a vibration for the first few minutes because of the "memory" in the belts of the curvature of the pulleys. It does get smoother after continuous running however. Do you notice if it is any better with your lathe after running for a while?
On my lathe I was getting kind of a harmonic vibration shortly after I changed my belt to a new one. First I thought something was up with the belt but eventually determined I kind of misunderstood the motor hinge plate. I assumed the hinge action allowed the motor weight to add belt tension by its weight. The clue was I could see the motor kind of oscillating & then could get worse - resonance or harmonics or whatever the right word is. The plate actually has to be locked down to prevent float (with appropriate belt tension). Problem went away after that, at least on my lathe.
You could have other issues as people have mentioned but maybe worth a check.
You could have other issues as people have mentioned but maybe worth a check.
Hmmn....I think I better check my table saw Peter. I know it has a hinged mechanism that floats and is not locked i to position....maybe its SUPPOSED to be locked also.
No mechanism to locking down, just a spring tensioner. I'm now playing the mag base game trying to DI the runout on the pulleys.
Craig
Well, a table saw was my mental reference point too. But it might also be OK for table saw but not necessarily for metal lathe. I happened to see a different table saw and it had a rudimentary lock down. On belted sanders I've seen the motor hard bolted & the tensioner axle on a cam swivel (but hard mounted) or heavy spring. So who knows. But the thing about a spring is... well, it springs. It doesn't dampen.
Well..... on the surfaces I could reach with a mag base and DI I got the following.
Head Pulley - 0.007 radial and 0.006 axial runout.
Motor Pulley - 0.007 radial and 0.016 axial runout.
I dunno, what does that tell you?
What's the expectation on a pulley? They look pretty crude from the get go.
Craig
Head Pulley - 0.007 radial and 0.006 axial runout.
Motor Pulley - 0.007 radial and 0.016 axial runout.
I dunno, what does that tell you?
What's the expectation on a pulley? They look pretty crude from the get go.
Craig
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Looks to me they are out of plane with each other by about 1/8". Which may explain why I had one pulley that had a habit of walking down it's shaft over time. No heat issues, no abnormal belt wear.
Craig
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This is a Standard Modern 9" Utilathe not a South Bend. The motor is not original, but it's mounted on the factory mounting plate.
Vibration hasn't been a problem. I do have a hard time keeping the spindle nut tight, it likes to back off and that causes chatter but at least it's an easy fix. There is a slug under the set screw but it just doesn't want to stay tight.
Here's a pic of my bench, it's okay but not very solid, there is a lot of wobble from the base only being sheet metal. I'm going to add a 1x3 tube frame to the base and proper legs to stiffen it up. All the storage is a good thing to have, it keeps everything close and easy to find.
Here's a pic of my bench, it's okay but not very solid, there is a lot of wobble from the base only being sheet metal. I'm going to add a 1x3 tube frame to the base and proper legs to stiffen it up. All the storage is a good thing to have, it keeps everything close and easy to find.
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Your bench looks beefy to me & guessing you have the machine mounted securely on the lugs so that should be OK.
What I was getting at is if your replacement motor is substantially heavier, then possibly its no longer a match for the stock spring if it was intended/sized for a lighter motor. Whether it fits the plate bolt pattern is kind of inconsequential. But I still don't have a clear read on the spring. Is it just meant to kind of keep some temporary tension on the belt but you are supposed to secure the motor plate down vs the spring/plate combination is 'live' and free to pivot?
Was it doing this all along & you just started noticing it? Or was it running fine up a point & now something different? Is the spring tension adjustable to see if it improves? Something has loosened up over time? A picture or more information would be helpful.