Does adding weight on say the lower shelves on a lathe really help with reducing chatter or is it the extra mass in the headstock of bigger lathes that cuts down on it?
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Weight and vibration
- Thread starter Mark Warden
- Start date
Weight
Mark,
I think it's both. At one time I owned a Woodfast lathe that was only about 400#. I bolted it to the floor and it was a tremendous difference. Having said that, I belive that a bigger, heavier lathe is simply less susceptible to vibration to begin with. But ballast does help as well.
Kurt
Mark,
I think it's both. At one time I owned a Woodfast lathe that was only about 400#. I bolted it to the floor and it was a tremendous difference. Having said that, I belive that a bigger, heavier lathe is simply less susceptible to vibration to begin with. But ballast does help as well.
Kurt
john lucas
AAW Forum Expert
I took my old Nova 3000 and added 400lbs of sand to a heavy wooden stand I built and it made a huge difference. I don't notice as much vibration reduction in my Powermatic but it doesn't try to walk on me when I have really unbalanced pieces. I added 300 lbs of pea gravel to that lathe.
Steve Worcester
Admin Emeritus
Additionally, having the lathe leveled helps a lot. Not necessarily level to earth, but level to the ground it sits on.
On my Oneway it has levelers in the feet and putting an of balance piece on turning it on and adjusting the feet, you can easily tell the difference.
On my Oneway it has levelers in the feet and putting an of balance piece on turning it on and adjusting the feet, you can easily tell the difference.
Steve's right. I've made my 700 lb Stubby walk without an awful lot of vibration when the feet were not level. If the feet are adjusted right, it won't move a bit, even when oval turning.
If your lathe is jumping around, then it's either not weighted down enough, or your speed is way too high. I have seen my 3520b jump around...but I just turn the speed down till it stops.
But "chatter" is usually not a term usually used to describe the lathe jumping around. Chatter is something that happens with tool presentation to the wood. It happens when the tool flexes slightly, or bounces off the turning in a rhythmic way that often produces equally spaced marks or ridges on the surface. It has nothing to do with the mass or weight of the lathe.
But "chatter" is usually not a term usually used to describe the lathe jumping around. Chatter is something that happens with tool presentation to the wood. It happens when the tool flexes slightly, or bounces off the turning in a rhythmic way that often produces equally spaced marks or ridges on the surface. It has nothing to do with the mass or weight of the lathe.
My 12" Jet lathe vibrate when I walk by it. 🙂
At various times and places, I have read that it is much more effective to place weight above the headstock than below. Perhaps someone with more knowledge than I can provide a link.
Google ["tuned mass damper"] for more than you ever, ever, ever, wanted to know.
Above the headstock might be more effective, but where and how could be a major safety challenge.
Joe
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Is the talk about vibration or oscillation? Seems some are talking about the latter. Rigidity in the lathe and stand, and good stand geometry will keep uneven mass from lifting the legs. Of course, as mentioned, it helps to have all on the floor, otherwise a gap up front will provide all the opportunity needed. Extra mass with the same gap will take a little longer to work up to resonance, but it will. Where to place extra mass - opposite the heavy point on the piece.
The high-speed-low-magnitude stuff is what I'd call vibration. That's what the structure of the iron eats up, according to the people who make the lathe. Interference nulling. More or less the same as putting a counterweight on the piece, actually. Happens from the motor/belt combination, little bit of bearing flex, or maybe even mounting.
The high-speed-low-magnitude stuff is what I'd call vibration. That's what the structure of the iron eats up, according to the people who make the lathe. Interference nulling. More or less the same as putting a counterweight on the piece, actually. Happens from the motor/belt combination, little bit of bearing flex, or maybe even mounting.
With my VB bolted to the concrete floor I can turn the speed up and go past the vibration point. Often there are two or three levels at which the vibration will appear as I raise the speed. So I get to the highest speed I can without entering that last vibration point. Without the machine bolted I was limited to the slowest speed before the first vibration point. I much prefer turning at the higher speeds.
- Scott
mass down below definitely helps. I tested this. I took an out of balance piece and made my mustard vibrate a little bit. Then I stood on my ballast and the vibration disappeared. I stepped off and the vibration returned. A ballast or bolting it down definitely helps.
Mike Gibson
Recognized Professional Artist
Bearings
Wouldn't adding mass to stop vibrations to run faster speeds put extra pressure on the bearings and wear them out faster. Mike
Wouldn't adding mass to stop vibrations to run faster speeds put extra pressure on the bearings and wear them out faster. Mike
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Not necessarily -- what is happening when you run the speed up higher is that you are moving further away from a resonance point. When the lathe is running with the load at a resonance is the time when the loads reach a peak -- getting past that "hump" by increasing the lathe speed actually results in lower bearing loads.
As far as adding extra mass to the lathe (things like sandbags) is actually improving thing in two significant ways:
- It is lowering structural resonance frequency of the lathe itself -- remember, there are two different resonances to consider -- the load and the lathe.
- The sandbags are especially good in that they also provide vibration dampening -- which means that it lowers the peak amplitude of the resonance.
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Lowering the speed to get past that hump means lower bearing load still. Of course, if you're an impatient turner, you don't care.
Just digging in a bit more when hogging slows the lathe, even if you don't tension the belt to slip safe.
Thank you for all the replies I was concerned with chatter i thought maybe it had something to do with the overall machine and not just the tool. I did however purchace a hevier tool rest than came with my lathe and it seems to have helped.I will definetly also be adding weight to the base just cause sand is cheap and it can't hurt.Again thanks for all the help I'm glad I found this forum.
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If you are experiencing chatter, it very likely has more to do with technique than anything else. For instance, a bowl will chatter when the wall thickness is very thin and you are trying to work near the rim of the bowl. The proper technique is to turn the bowl to final thickness in sections beginning at the rim and working towards the center such that the part towards the center remains very thick in order to provide more support for the outer part. After finishing turning a section to final thickness and beginning work on the next section, never go back to the previous section to do any touch up work.
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I just can't help myself. Maybe the weight you have isn't to be found on the lathe stand.😉😀
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While it would be a good idea for me to go on a diet. I suspect my Jet lathe will still be vibrating when there is a out of round blank closer then 10 feet to it 🙂
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Actually bowls are not a problem but a good tip Bo. My problem is with pens I only made 3 so far but it seems like I have to do more sanding than I think i should.
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Vibration & cost are the reason I built my stand out of on hand material i.e concrete block & a 2x4 laminated up top.
Alexc if you really want to see vibration exchange your mustard for jello.😀
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Boy is that ever good advice! Yesterday I turned two 12" bowls, from nearly identical pieces of cherry, on my mustard. The first went like clockwork and needed only very light sanding starting at 240 grit to remove the few errant scratches. But the second one.... I had it turned to "completion" then decided to make it a bit thinner. Nuff said. 😱
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It is a good thing that this old thread has been exhumed since the problem you were having with pens was not addressed. I think that the answer is quite simple in this case -- you are very likely putting too much tailstock pressure on the pen turning arbor (mandrel, in British English, but what do they know). The way that I test tailstock pressure is to slowly crank the quill until the live center point barely seats in the dimple in the end of the pen arbor with just enough pressure so that the live center will rotate without slipping when the lathe spindle is running. Turn the lathe on and then apply very light pressure with the thumb and forefinger on the live center rotating part -- if you are easily able to stop its rotation, add a tiny amount of tailstock pressure and test again. Do not add any more pressure than that. When excessive pressure is added, the thin pen arbor shaft will flex by a few thousandths of an inch and the cutting force will only make it worse.
Awww ..... we would like to hear the rest of the story. 😀
Too, make sure you are using sharp tools in a cutting action - not scraping and going in a direction appropriate to the grain. Scraping across the grain - like in a pen orientation - and cutting into grain runout will tear most woods.
Thanks again Bo that is what I was doing wrong made a big difference.
Well, vibration is not my friend. I have a 3520B PM, but I can make it walk all over the place. I've been considering extending a "splayed" leg style as another thread has suggested, but eventually, (when I'm finished with school), I want a SERIOUS LATHE. Not that a PM 3520B isn't serious, but I want a www.serioustoolworks.com lathe. I can't remember the owner's name, but he came to a club meeting of ours when he was in the area, and he's really a great guy. As I told him at our meeting, eventually I WILL own one; its just a matter of having the space to put it; the shop (read, shed) can't handle any more weight; one corner has a slab under it for the lathe......
I saw the Serious at the Richmond symposium and it was seriously impressive! You certainly don't want to put it on anything but a slab floor. As to vibration: I can make my 700+ lb Stubby go on 'walk about' if I don't have the feet completely level on the floor (no itsy bitsy rocking of any kind) and I try spinning a good sized out of balance piece. Its stand does have splayed legs, but if the feet aren't all four solid on the floor, things will start rocking.
I'm having that problem with my PM. They're level now, but the floor is a slab built to the level of the floor above; There's a 2x8 joist/1" plywood floor in the shop, and I put the plywood back over the slab to keep the structural integrity of the plywood around the lathe; The TINY oscillation of the plywood compressing & rebounding is the problem I'm having. It is perfectly level with all feet firmly down, until I start roughing an out of round piece!
Hindsight is 20/20!