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Thread: Grizzly G0766 vibration issue. If you have this lathe, please comment

  1. Quote Originally Posted by Brice Rogers View Post
    When I first got my Griz 0766 it had some vibration. Not a lot but enough so I would adjust the speed control to either be above or below the resonance point.

    Now my Griz is over 2 years old. It seems to be a lot smoother. I'm wondering if perhaps there is something like the drive belt having some stiffness, or being oval when relaxed, or something that has changed over time.

    Just a thought....

    Are there others who think that seem to think that their 0766 got smoother over time?
    Good point Brice. Things, especially machinery alwys have a bit of a break in period. Cold winter weather could make the belt stiff as well, and cause some resonance. I know that my 0766 is smoother & quieter than when I uncrated it. I’m very happy with mine. I also went through my machine and tightened everything that could be tightened up before powering up the first time.
    Remember, in a moments time, everything can change!

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  2. #32
    Quote Originally Posted by dustin wassner View Post
    I have contacted Grizzly twice now about the issue and am still waiting to hear back.

    The spindle turns easily and freely through its rotation. It has no runout and has no play moving forward and back.

    I cleaned the underside of the headstock and after clamping it to the bed went along the entire area where the headstock and bed contact with a .0015 feeler gauge and could not slide it in anywhere.

    I have tried moving the headstock to the far left and right on the bed and the middle and the issue does not change. This tells me that it is NOT a platform issue, since moving the headstock will considerably change the weight on each leg.

    This morning I pulled the motor out and while holding it in my arms with the belt on its pulley and the spindle pulley I had my wife slowly turn the rpm up to the problem range. The vibration was not as much but was still there. That would eliminate the motor and its pulley from being the issue, so it must be either the headstock itself, the spindle, or its pulley.

    Not sure if I mentioned this, but I put the grizzly faceplate on the spindle, and also tried my large cast iron oneway faceplate, and brought it up to the problem rpm range and the range not only was a little wider, but was considerably worse.
    Wondering if you have an odd bearing issue.

  3. #33
    Join Date
    Feb 2017
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    with smooth rotation of the spindle even by hand, zero runout, and zero end play, its highly unlikely.

    A spindle for this costs $65. Grizzly probably pays less than $20 for it. Same situation with the bearings. They can't just send me a spindle / bearings / belt to see if that solves my issue?

    Fact is I got a dud machine and Grizzly is not willing to help me.
    DW

  4. You can purchase the belt online and bearings online for very little money. Belts from Vbelts.com or bearings from the big bearing store. Before I would take the spindle out of the headstock, I would try a new belt, and if that solved the problem, I'd call Grizzly back and tell them, then ask to speak to someone high up in the company, because if you have been getting the run around from tech support, then Shiraz Balolia needs to know about it. If it doesn't fix it, then perhaps talking to him by phone or email would be in order. My experience with tech support is mostly good, but I think sometimes they miss something in the communication, perhaps due to customers not being able to describe things correctly or inexperienced tech folks who just don't know.

    You might be able to send Mr. Balolia a private message through this forum.....just an idea...
    Remember, in a moments time, everything can change!

    Vision - not just seeing what is, but seeing what can be!




  5. #35
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    Quote Originally Posted by dustin wassner View Post
    with smooth rotation of the spindle even by hand, zero runout, and zero end play, its highly unlikely.

    A spindle for this costs $65. Grizzly probably pays less than $20 for it. Same situation with the bearings. They can't just send me a spindle / bearings / belt to see if that solves my issue?

    Fact is I got a dud machine and Grizzly is not willing to help me.
    Is it still under warranty? They sent me bearings and a spindle and touch-up paint both colors for free under warranty.
    Maker of Fine Kindling, and small metal chips on the floor.
    Embellishments to the Stars - or wannabees.

  6. #36
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    Quote Originally Posted by dustin wassner View Post
    with smooth rotation of the spindle even by hand, zero runout, and zero end play, its highly unlikely.

    A spindle for this costs $65. Grizzly probably pays less than $20 for it. Same situation with the bearings. They can't just send me a spindle / bearings / belt to see if that solves my issue?

    Fact is I got a dud machine and Grizzly is not willing to help me.
    Dustin, it is good that you measured end play and run out. I presume that you measured it at the working end of the spindle and applied some side or end pressure.

    Another thought and something to eliminate: take a look at the pulley end of the spindle while it is under power. I notice on mine that the smaller upper pulley on mine has some runout - - perhaps 0.010 to 0.015 (just a guess). I didn't take the belt off so I can't speak to the larger upper pulley (low range). But if your pulley is not concentric, that could be a source of vibration or resonance.

    It is unlikely that your spindle could lack concentricity based on how they are likely to machine it. But if you are up to it, take off the pulleys from the rear of the spindle and put a dial indicator on it while turning the spindle.

    How bad is your vibration? Is there any way that you could quantify it?

  7. #37
    It sounds like a harmonic issue with the primary vibration frequency at the approx 950 rpm and a second harmonic at double the primary. (I did vibration analysis for a living in a previous life).

    A minor amount of imbalance in the spindle excites the harmonic issue. If the problem was a gross imbalance in the spindle/pulley or an out of round pulley, the vibration would exist at all frequencies and worsen as the rpm's increased. If the problem was related to a defective belt the problem would exist at the belt frequency i.e. once per revolution of the belt. Changing ranges would change the belt frequency as it relates to the rpm of the spindle.


    More than likely, even though the lathe is level , there is a difference in the weight on the feet side to side.

    I am not familiar with the leveling system your machine uses, but if it has leveling screws back off one of the lock nuts on a back foot leveling screw and run the lathe at the speed where the vibration is the worst without anything mounted on the spindle. With the vibration occurring, try turning the leveling screws on the outboard end down. If no improvement or vibration worsens, turn the screw up. You should be able to find a spot that minimizes vibration by balancing the weight on both back feet. With the weight even on both back feet, the weight will also be properly distributed on the front feet.

    I have had a PM 3520b and now have a OW 2436. On both of those machines I used/use the 'adjust back foot leveling screw' method to reduce vibration. Also have a Monarch engine lathe that weighs 6000# and has 8 feet. That machine takes the better part of a full day and a torque wrench to properly level.

  8. Excellent information, Dale! Thanks for sharing it with us! The leveling system is pretty much like the 3520b on the G0766.
    Remember, in a moments time, everything can change!

    Vision - not just seeing what is, but seeing what can be!




  9. #39
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    Feb 2008
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    E TN, near Knoxville
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    Check for twist in lathe bed

    Quote Originally Posted by Roger Chandler View Post
    .. The leveling system is pretty much like the 3520b on the G0766.
    (Sorry if this has been checked and I missed it. This is a long thread.)

    Before experimenting with the leg loading, I suggest testing for twist in the lathe by checking the alignment of the headstock and tailstock. Correcting twist with the leg levelers can equalize stress in the bed casting caused by even slight unevenness in the floor or improper leveler adjustment. The entire cast iron/steel bed can easily flex and twist significantly. Checking for and adjusting for this is the FIRST thing I do when moving a lathe, even if a short distance. I want the alignment perfect on my lathes.

    If you look up "wood lathe tailstock alignment" you will find all sorts of things recommended including adding shims and pressing on the tailstock while tightening. I actually shimmed the tailstock on my first Jet 1642 before I found out about the simple leg adjustment technique.

    The procedure, very quick. Put a drive center with a point in the headstock. Put a live center (or even another drive center with a point) in the tailstock and slide the tailstock until it the points almost touch. If the two points are in perfect alignment, good.

    If the points are in horizontal alignment when looking straight down but out of vertical alignment when looking from the side, this is bad. I have not yet seen this on any of the lathes I've checked.

    If the points are OUT of alignment horizontally, a common issue, the fix is usually easy.
    • If the tailstock point is too far towards you, twist the bed back into alignment by raising an appropriate leg - the easiest is the front leg on the tailstock end of the lathe. Untwist the bed by cranking UP a bit on the adjuster or with a shim under the leg. This should pull the two points into perfect alignment.
    • If the tailstock point is too far towards the far side of the lathe, adjust either the far right or front left leg.

    I have had to do this on both of my Jet 1642s and my Powermatic 3520b after moving them. Each time it brought the lathe back into alignment.


    A recent case: When turner Mark StLeger was doing an all-day demo at the Knoxville club last April he noticed the tailstock and headstock were out of alignment on the club's Jet 1642. This was a problem for a precise operation he was planning. I opened my big mouth and said I could fix it. During a break a few seconds of leg adjustment put the tailstock into perfect alignment. Whew! Actually, I wasn't worried since I had aligned that same lathe the same way several times in the past since it gets moved around a lot.

    When I'm demoing something that can benefit from the tailstock alignment I always check the lathe and align it before I start. Such alignment is as not critical for spindles between centers but it can cause all kinds of issues when using the tailstock close to the headstock, such as when working on turned boxes, vessels, platters and bowls, or with thin spindles held tightly on the drive end and with the tailstock on the other end. Problems from alignment can be worse with hard, dry woods.

    I don't know if this alignment will have any affect on the vibration issue in this thread, but I would check it first.

    BTW, leveling the lathe (or table saw, etc) to the earth's gravity is nice but usually not necessary. What IS necessary is that the bed of the lathe or the table of the saw be in a perfect plane. A twisted bed or frame can cause a variety of problems. IMHO. Now for a billiards table...

    JKJ

  10. #40
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    Feb 2017
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    funny you mention billiard table, as this is the very reason I bought the machinist's level. I was able to shim a 1917 full size brunswick to less than .003" on the entire playing surface. 1" slate.

    As I had mentioned before, the vibration was at the same rpm when the lathe sat on the concrete unbolted and unshimmed and more than likely twisted. It vibrated at the same rpm after shimming and bolting it to the floor, and it vibrates despite where I have the headstock on the bed. In each state, the weight per leg varies considerably, so I see no correlation to the platform of the machine and the vibration.
    Last edited by dustin wassner; 01-19-2018 at 9:40 AM.
    DW

  11. #41
    Quote Originally Posted by dustin wassner View Post
    funny you mention billiard table, as this is the very reason I bought the machinist's level. I was able to shim a 1917 full size brunswick to less than .003" on the entire playing surface. 1" slate.

    As I had mentioned before, the vibration was at the same rpm when the lathe sat on the concrete unbolted and unshimmed and more than likely twisted. It vibrated at the same rpm after shimming and bolting it to the floor, and it vibrates despite where I have the headstock on the bed. In each state, the weight per leg varies considerably, so I see no correlation to the platform of the machine and the vibration.
    If I understand correctly, you now have the lathe bolted to the concrete floor? When making my suggestion about tweaking the weight on each foot that detail was not understood.

    If the lathe is bolted down to the floor shimmed and leveled and a harmonic vibration presents itself, the problem exists elsewhere.

    You might take the headstock off and see it the mating surfaces between headstock and lathe bed are providing a solid fit.

    If there is a good solid fit, try running the lathe slowly with the headstock clamps loose and slowly bring the rpms up. If the headstock vibrates at all rpm's and the vibration gets expontially worse as the speed increases, there is an exciting force issue in the headstock.

    If vibration is low until the 950 rpm range is reached, then likely the either the headstock or bed has a natural frequency at the 950 rpm that is excited by a slight imbalance or pulley runout in the spindle assembly.

    Curious if you have tried running the lathe with the belt very loose? It is possible the pulley has radial run out that is exciting the natural frequency. Radial run out in the pulley would have a reduced tendency to cause a once per revolution vibration problem with a loose belt. Since you have a machinists level let me ask if you have a dial indicator and a way to measure radial run out of the pulley?

  12. Dustin, I am in the process of reaaranging my entire shop to accomodate a second large lathe. In moving my G0766 from one side of the shop to the other side, my floor required me to make some changes. At the new location, my centers were a bit out of alignment, and the slope of my floor on that end of the building is noticable, so I had to do a complete re-level of my lathe. Even then, due to the floor, I had a bit of a front to back wobble on the tailstock end, that no matter how I adjusted the foot pads, would not exactly align my centers, meaning there was some torque in the bed ways.

    Due to this, I decided to cut a 3”x3” square from a spare piece of anti fatique mat, and put it underneath the front foot pad on the tailstock end. That one small shim out of rubber brought my centers into perfect alignment, and eliminated any wobble and all vibration.

    In one of my earlier posts, I recommended trying a piece of rubber underneath the foot pads, as they can change the harmonics when nothing else seems to solve the issue. I have an observation from years of hearing these types of problems....99% + of the time it is not the lathe, it is the conditions in which the lathe is setup, and in my humble opinion, the fact that you have the lathe bolted down might be part of the issue, since it is bolted down with the problem not eliminated, which simply locks in the problem.

    I would also encourage you to back the bolts off that tighten the bed to the legs about 3 or 4 turns, let the thing settle with the weight of the headstock/banjo/and tailstock on its bed, and find a balance on it’s own with the legs unbolted from the floor. This will release any tension in the lathe, and it may eliminate the vibration. Bolted together parts, that have torque/tension in them will produce harmonics.....these steps and the rubber shims should dial this G0766 in for you.
    Of course, re-tighten the leg bolts.

    I hope you don’t feel like this is all too much of a pain, and please know many of us here are sincerely trying to help with our suggestions. I just have this gut feeling that there is tension somewhere in your setup that is causing this vibration and it can be eliminated. Of course, there is that very rare occurance where something may be amiss with the machine, so if that is what you find after trying these corrective measures, then you are in that less than .1% and have a legitimate case for a return of the lathe.

    I hope you will try these steps and find what most of us already have found with our G0766 lathes....that they are fine performing lathes with great value for the size/features they offer. Best of luck as you troubleshoot this problem.....we are all hoping for the best for you!
    Remember, in a moments time, everything can change!

    Vision - not just seeing what is, but seeing what can be!




  13. #43
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    Jan 2013
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    Dustin, did you ever get this resolved?

  14. Quote Originally Posted by tom lucas View Post
    Dustin, did you ever get this resolved?
    Tom, I hope you read the entirety of the thread here and not just the problem experienced by the poster. The G0766 is a fine lathe, and if you were to experience any issues, we are here to help in the GGMG. As mentioned, 99% + are problems in the individual setups and not with the lathe. Unless there is something amiss in the machining on a particular unit, the issues can be solved. Keep us up to date once you get your G0766 in your shop.
    Remember, in a moments time, everything can change!

    Vision - not just seeing what is, but seeing what can be!




  15. #45
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    Apr 2018
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    Cambridge Vermont
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    Now that it's a year older hopefully he got it resolved. If not (seeing he was able to measure the run out on the lathe) I would suggest doing the same on the tachometer pulley. With the belt cover off I think you should be able to find a spot.

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