Quieting a Noisey Bench Top Lathe. How ??

[Lloyd-ss]

I've had this Grizzly 10" x 22" benchtop lathe for about 13 years and it has served me well. I have babied it and never driven it too hard.
But it has been really noisey from the beginning and it is time to try and fix it. I know what a $$$$ Hardinge tool room lathe sounds like, and therefore I do have realistic expectations for what the the $ Grizzly should sound like, LOL.

I have only now started to track down the source(s) of the noise and it seems like there isn't going to be a magic bullet that fixes it; more like a bunch of improvements that all add up to less noise. It has 3 low speeds (150, 300, 560) and 3 high speeds (720, 1200, 2400) with an idler between the motor and spindle for the low range, and am almost embarrassed to say that I almost never use the the 3 high speeds because of the noise.

Today, I ran the motor just by itself. A little noisey, but not major. Then, to isolate the spindle, I ran the single belt from the big pulley on the motor to the small pulley on the spindle. I also removed the fiber idler rear that goes between the spindle and the feed gear box. With just the motor and the spindle, the noise was significant, but I know that the straight cut change gears add significantly more also. Without having a tenth indicator (.0001") I can't detect any spindle runout, so even though the spindle bearings sound noisey, it is not like they are bad.

I am not afraid of attacking the spindle assembly if people who know, think it will yield good results at removing noise. The motor bearings sound like a better place to start. There might also be some sympathetic noises from the bench, although it is pretty heavy and "dead." But at the same time, I do remember how much noise the big vise on my mill table makes unless the jaws are clamped shut.

Any thoughts, experiences, educated guesses, etc, will be appreciated. I would love to able able to run this lathe at 2400 rpm without it echoing all over the place.
Lloyd

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The picture with the safety door open shows it with just the single motor-to-spindle belt installed and it not driving the feed gear box at all.

 

[ShopShoe]

It might help isolate the noise source if you used a mechanic's stethoscope, like this one:

https://www.napaonline.com/en/p/BK_7769060?impressionRank=2
Or a substitute could be a length of plastic tubing held to one ear while the other end is pointed at places that could be noise sources.

You can also use a wooden dowel to track sound conductively between a suspected source of noise and your ear. (Just be careful not to stick the dowel in the gears.)

For high-tech: Use a shotgun microphone with an amplifier and background-noise-isolating earphones.

I have done all of the above and have tracked lots of noises these ways.

--ShopShoe

 

[Jasonb]

The change gears can often be the source of noise if they don't have the backlash correctly set or the packing washers in the right place to stop the sides of the gears rubbing

 

[Lloyd-ss]

It might help isolate the noise source if you used a mechanic's stethoscope, like this one:

https://www.napaonline.com/en/p/BK_7769060?impressionRank=2............

--ShopShoe

Quote snipped.........
It's funny, I clicked on the napa link, and darn if I don't have one of those in a tool box somewhere. It was one of those "I should have thought of that!" moments. I will put the search on and find it. Thx! Often, diagnosis is the toughest part.

 

[Lloyd-ss]

I found the stethoscope right where I thought it should be. How is that for luck? It is picking up a lot of noise from the motor housing, and it doesn't seem like the spindle adds too much more. I will see what I can do with the motor, starting with some noise isolation shims. We shall see!

 

[clockworkcheval]

Mass helps. Everything on a light lathe is a sound-board. A general help might be to mount the lathe on a solid length of square tubing filled with concrete.

 

[trlvn]

square tubing filled with concrete.

I'm not a concrete guy...but doesn't concrete shrink as it dries? Fairly significantly? Won't this result in a stick of concrete potentially rattling in a steel tube?

Craig

 

[Lloyd-ss]

I'm not a concrete guy...but doesn't concrete shrink as it dries? Fairly significantly? Won't this result in a stick of concrete potentially rattling in a steel tube?

Craig

Concrete that was mixed with too much water will shrink and crack and be of lower strength.
Much less water is needed than most people think, and just some extra effort in mixing it will get everything equally wet with minimal water (1.4 gallons per cuft of dry concrete mix). A shovel full of properly mixed concrete will seem too dry, and will hold its shaped if it is dumped in a cone-shaped pile. A soupy mix is way, way too wet. Tamping or vibrating are needed to get the concrete to "run", but over vibrating is detrimental because it can separate the coarse aggregate from the sand. Some rebar or wire mesh are always a help to control the cracks that do happen to occur. And yes, I have done a lot of concrete floors and walls. Properly mixed, shrinkage is very minimal. Non-shrink grout is available for setting machinery, but is expensive.
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The lathe Ihave is mounted on a surplus WW2 steel desk with heavy drawers filled with metal and tools. The "secondary" top is an old solid-core wooden door slab that is 50mm thick and very dense. The lathe is bolted through both tops and also through an additional oak timber back bone. I need to use pipe rollers to move it about once every 5 years, LOL. It is pretty dead, I think, but I guess it could possibly resonate.

 

[clockworkcheval]

You are quite right, Lloyd-ss. I remember that about 50 years ago an Italian manufacturer of machinetools offered a high precision lathe that was built upon two parallel heavy steel tubes filled with concrete.

 

[Lloyd-ss]

ANOTHER QUESTION
I have stripped the lathe headstock end down by removing all external idler gears and pulleys.
The spindle has the chuck removed and all it is is basically the 2 bearings, the drive pulley, and the spanner lock nuts. Basically the spindle items 11-14 and 17-24 (less the belts) are still in the machine. The spindle turns freely with a kind of over-tight rubbing noise. It does not spin freely, not at all. You can see a small dot in the picture above the bearing pockets that are oiler balls. I do oil it, but the bearings do not put a smile on my face. I am thinking it is time to take the spindle out and inspect the bearings.
The spindle in the machine should turn freely and quietly, but not necessarily spin freely? Correct?
Anyone agree? Disagree?
Thank you.

 

[Lloyd-ss]

I realized the spindle wasn't right, so I took it out. Tomorrow it will get cleaned up so it can be inspected. I noticed one thing as I took it apart. The drive key for the pulley was a bit oversize and the pulley was originally, I would say, a press fit onto the spindle. The lock nuts might have been used to force the pulley into place the final few mm's, preloading the bearings too much. When I removed the 2 locknuts, the the pulley wouldn't budge and I had to use a gear puller to get it off. Then the key wouldn't come out of the keyway in the spindle without a fight.

Nothing has been cleaned up yet, so too early to tell what condition the bearings are in, but I will probably order some new ones while it is apart. The only issue will be driving the outer races out of the headstock casting. Shouldn't be a big deal, ha ha. I'll feel better knowing the bearings are new and of good quality.
Lloyd

edit- having some trouble finding 32009x bearings with a quality rating listed. The existing ones are P6, so a P6, or hopefully a pair of P5 are available in the US quickly.

 

[Badhippie]

Have you checked the shaft to make sure it’s not bent?? Also what is all that pitting on the shaft from or is that just some debris on the shaft. Depending on what you see with the bearings you may need to check the line bore. What are the pre-load specs for the spindle. I am just guessing is it close to .0003 inches end play

 

[Lloyd-ss]

Have you checked the shaft to make sure it’s not bent?? Also what is all that pitting on the shaft from or is that just some debris on the shaft. Depending on what you see with the bearings you may need to check the line bore. What are the pre-load specs for the spindle. I am just guessing is it close to .0003 inches end play

Thank you for the comments. That is paint over-spray on the shaft. Probably incomplete masking when the finished unit was painted.
The accuracy of the machine has always been good and it has not been abused, plus, there is a limit to what I can inspect and repair, so if I can get it back together with the spindle rotating nicely with no measureable runout (.0005" indicator), I will be happy.
An inspection report came with the lathe with 9 different diagrams and recorded measurements. But, none of them were spindle endplay or preload. But the bearings were way, way, too preloaded. The drive pulley must have been pressed or forced onto the spindle and jammed the bearings tight. The double set of spanner locknuts on the end of the spindle really weren't doing anything at all.

I will first try just cleaning the bearings, honing out the pulley, lubing with oil, and re-assembly to see how it feels, sounds, and measures. Except for the jammed-on pulley it came apart easily, so I can take it apart again if I need to do more. Honestly, it just feels like a fancy set of wheel bearings.

 

[Badhippie]

I agree with you those are just plain tapper bearings they don’t look like a high speed bearing. And you are correct it it spun before with no tight spot while turning then I would say the line bore is probably good. And the shaft is probably ok but if you have a set of v/blocks I would just check it before reinstall just to be on the safe side. .0005 is probably ok for the shaft end play. I would probably set it at .0003 but that depends on if the lathe runs on the warm side then by all means .0005 would be fine. Either way it sounds like you have a great grasp on the system

 

[Lloyd-ss]

I agree with you those are just plain tapper bearings they don’t look like a high speed bearing. And you are correct it it spun before with no tight spot while turning then I would say the line bore is probably good. And the shaft is probably ok but if you have a set of v/blocks I would just check it before reinstall just to be on the safe side. .0005 is probably ok for the shaft end play. I would probably set it at .0003 but that depends on if the lathe runs on the warm side then by all means .0005 would be fine. Either way it sounds like you have a great grasp on the system

Thank you.

Gotta say, you have one of the coolest avatars I have seen!

 

[Badhippie]

Lol thank you it’s a wall paper from Hornaday shooting and hunting are my main hobbies or habits lol

 

[Lloyd-ss]

Nice. Getting totally off subject, but I originally got my machine shop equipment for building air rifles. Here is a short video of a handsome fella who was about 80 yards down from my bench of the 100yd air rifle range I have. Backstop is just out of the left side of the picture. I just noticed that I have the date on the camera set to last year, LOL.
Lloyd

 

[Badhippie]

Nice
So you build custom air rifles don’t mean to high jack your thread. I have a friend that has a custom air rifle and that thing smokes most 22 cal rifles

 

[Lloyd-ss]

And they are so much quieter.
Here is a .51cal I built. Weighs a ton. The big guy in the video would have been in the right side of the pic down near the 100yd targets.
Target is 4 shots at 100 yds, 950fps using 2,800psiair.
I hope nobody gets upset, but we are discussing machining the parts. We'll get out of the ditch very shortly.
Lloyd

 

[Scott_M]

Hi Lloyd
Not upset here Very nice ! 2800 psi I was pretty thrilled when I bumped my Gauntlet up to 1350psi And thanks for your input on the PCP's, I did end up getting a compressor and an SCBA tank.
OK Back to the lathe, when I rebuilt the spindle on my 12x36 the bearing on the back end was so tight I could not adjust preload accurately, it would load up as I tightened the preload nut then pop and move a couple of thou. . I pulled the spindle back out and took it to a buddies who also had a lathe. A 15 incher, and polished the rear bearing surface to just a bit over a close sliding fit. I still had to draw up the bearing but it no longer loaded and popped. If I went to far a solid bump on the spindle end with a dead blow moved it back for a redo. So make sure the back bearing inner moves on the spindle easy enough to get your preload set without surprises. My bearings were also tapered roller bearings. I found a set of Timkens for it.

Scott