9" SM Utilathe Restoration

[YotaBota]

Would I lie to you??????? never,,,,,, I might BS you a bunch but never lie to you,LOL.
So if you have the same jiggle with the spindle in neutral or engaged then I think I would take out the pulley shaft and check the bearings. Even if the bearings seem okay I would still remove the gear, reinstall the shaft, run it up and see if the vibration goes away.

 

[YYCHM]

Would I lie to you??????? never,,,,,, I might BS you a bunch but never lie to you,LOL.
So if you have the same jiggle with the spindle in neutral or engaged then I think I would take out the pulley shaft and check the bearings. Even if the bearings seem okay I would still remove the gear, reinstall the shaft, run it up and see if the vibration goes away.

Ok, I pulled the lid on the headstock and had a peek inside. How do you get that shaft and gear out without pulling out the spindle and everything in between?

 

[YotaBota]

On top of the headstock behind the lid (just in front of the power cord) is a 1/4-20 bolt that secures the shaft into the headstock, remove the bolt and the pulley shaft will pull out. Knock out the roll pin and the gear will come off, you may need to use a puller on the gear but it's not on overly tight.

 

[YYCHM]

On top of the headstock behind the lid (just in front of the power cord) is a 1/4-20 bolt that secures the shaft into the headstock, remove the bolt and the pulley shaft will pull out. Knock out the roll pin and the gear will come off, you may need to use a puller on the gear but it's not on overly tight.

The shaft and gear will come out as one? You don't have to remove the gear from the interior side of the headstock?

 

[YYCHM]

OK...… what is this telling us????

If I lift the motor ever so slightly, 80%-90% of the vibration diminishes. Almost down to the same level as with the belt removed, and this is with the spindle in neutral and turning.

As a side note, I removed the motor tensioning spring all together as it didn't seem to accomplish anything.

 

[Brent H]

Does lifting the motor loosen or tighten the belt?

 

[YYCHM]

Does lifting the motor loosen or tighten the belt?

Loosens the belt. In it's current configuration only motor weight tensions the belt.

I'm quit surprised as I don't have to lift it much and it just settles right down.

 

[YotaBota]

Yup, the shaft, pulley, bearing and gear slide out as one piece. Did you find the bolt? It may be a setscrew or some other fastener, mine is a 7/16 hex-head.

Lifting the motor takes tension off the belt but I wonder if the belt is to long and allowing the motor or motor mount to touch the frame. Or the pulley shaft bearing is gone, either way we're getting closer.

 

[Brent H]

Interesting - could be a bearing in the motor or as Yota says the shaft bearing. Since the weight of the motor will add a load to the bearing it may be shifting the shaft out of proper alignment.

 

[YYCHM]

Yup, the shaft, pulley, bearing and gear slide out as one piece. Did you find the bolt? It may be a setscrew or some other fastener, mine is a 7/16 hex-head.

Lifting the motor takes tension off the belt but I wonder if the belt is to long and allowing the motor or motor mount to touch the frame. Or the pulley shaft bearing is gone, either way we're getting closer.

Is that screw/bolt on the top of the headstock to the back side? I have a slotted screw on the top side.

 

[YYCHM]

Interesting - could be a bearing in the motor or as Yota says the shaft bearing. Since the weight of the motor will add a load to the bearing it may be shifting the shaft out of proper alignment.

I've taken that head stock pulley and shaft and pushed and pulled and shook it as hard as I can and I can't feel any play in it. The motor..... that might be a different story.

 

[YotaBota]

Yes, the screw/bolt, is on top to the back side. If you follow down the orange power cable from the for/rev switch it should put you finger right on the screw/bolt head.

 

[Brent H]

@YYCHobbyMachinist I have seen lots of motors where the drive end bearing is still ok but the non drive end one is buggered. You move the shaft about and it seems fine until you take the back of the motor off and the bearing is shot. - something to look at anyway.

 

[YYCHM]

@YYCHobbyMachinist I have seen lots of motors where the drive end bearing is still ok but the non drive end one is buggered. You move the shaft about and it seems fine until you take the back of the motor off and the bearing is shot. - something to look at anyway.

Do those things just purr when you run them no load in that condition?

 

[DPittman]

How's this for a more scientific approach for measuring the vibration?

View attachment 10037

How much does the water in a shot glass placed on top of the head stock jiggle.

Essentially nothing with the belt removed and I get the same result placing the shot glass on the mill running at 770 RPM.

With the belt installed and the spindle in neutral, it jiggles quite a bit and about the same amount when turning the spindle at 900 RPM.

On another note. How much run out should I be seeing or should I say is acceptable on the outside of the tail end of the spindle? I'm seeing 0.001 with a DI, but is that considered a trued surface?

Hey I use almost the same method when my machinery is vibrating! except I use southern comfort instead of water. The shot glass almost always shakes on the first attempt so I empty the glass and try again, I never take a reading on the first 2 or 3 tests. By test #4 or 5 things always SMOOTH right out. But then the wobble somehow seems to transfer to me. By then I'm ready to quit working in the shop anyhow and don't feel like dealing with the issue anymore.

 

[YYCHM]

Hey I use almost the same method when my machinery is vibrating! except I use southern comfort instead of water. The shot glass almost always shakes on the first attempt so I empty the glass and try again, I never take a reading on the first 2 or 3 tests. By test #4 or 5 things always SMOOTH right out. But then the wobble somehow seems to transfer to me. By then I'm ready to quit working in the shop anyhow and don't feel like dealing with the issue anymore.

Ya, I thought some one would comment on the shot glass thing LOL, and don't get me started with the Southern Comfort, after about test three it would be something like..... What Problem? Lets see what this does.

 

[YotaBota]

That ranks right up there with,,, "HOLD MY BEER!!!!!" LOL

 

[YYCHM]

Yup, the shaft, pulley, bearing and gear slide out as one piece

There are two bearings? One on the head stock casting and one in the interior of the headstock. Which one comes out with the shaft or do they both come out?

 

[YotaBota]

The bearings are pressed onto the shaft so all come out as a unit. The manual, pg 8, shows a picture of the shaft assy, item #2.

 

[YYCHM]

The bearings are pressed onto the shaft so all come out as a unit. The manual, pg 8, shows a picture of the shaft assy, item #2.

Have to ask lots of questions here as the last bears I played with were re-packing the front wheel bearing on my first car a 61 Falcon and that was over 45 years ago LOL.

So, just take the screw out and pull (by hand) the whole assembly out? No pullers, hammers or punches needed?