Vibration

[Dan Bevilacqua]

As a relatively new wood turner, one of the often mentioned qualities of a lathe I have encountered is the issue of "vibration". I was considering reviving odie's excellent thread title "Define Harmonic Vibration" started on 3/30/17. However, I decided to start this one with a more specific parameter. Based on odie's thread, the consensus is that lathes have some vibration at certain speeds with wood mounted on them.

My observation is that lathes have some degree of vibration without wood or anything mounted on them (just bare spindle or chuck). When I speak of vibration, I am speaking of just a very slight amount, not even perceptible to the naked eye (except maybe of a nickle placed on the headstock or bed.). I am also speaking of vibration that is reproduced only at a certain motor speed.

First of all, is this type of vibration that is so minimal only at certain speeds that a nickel is seen to move slightly and maybe fall over until it has passed this speed range any concern to expert wood turners or do all your lathes do this?

Please allow me to provide some personal observations with a bare spindle or just a chuck.

I have one variable speed lathe that if I place a nickle on the headstock (which, by the way, is sometimes difficult to get to stand up on edge even with the lathe off), I can see the nickle start to move ever so slightly at around 950 rpm on faster belt pulley (the speed is different, around 400) on the slower speed pulley but the control knob is at the same position). As I slowly increase the speed, the nickle starts to dance a little and sometimes falls over, up until the around 1100 rpm mark where the nickle will settle down and not vibrate at all. Do all lathes do this, and is this a concern?

I also have observed another variable lathe (midi) that does the same thing, but at a different speed range. I also have observed a mini that does the same at a different speed range. I have also checked out a very expensive lathe that may not have been set up properly that had much more vibration at certain speeds with a faceplate on the spindle. The vibration on that lathe at certain speeds was such that I could see the tool rest move significantly. In my opinion, a nickle would not have stood a chance at the certain speeds on this high end lathe. Note, there is no vibration on any of the lathes at higher speeds.

Normal, or of any concern?

 

[Gary Beasley]

Seems to me this is all from the belts. My Nova direct drive doesnt vibrate with no load.

 

[Dan Bevilacqua]

Thanks, Gary. You may be on to something there. Makes sense.

 

[Bill Boehme]

In the real world no rotating machine is perfectly balanced, but there is some level of vibration that is acceptable. If we just look at the motor by itself there are two main sources of low level vibration: rotor imbalance and electrically induced vibration. An obvious statement is that not all motors are created equal when it comes to vibration.

Three phase motors driven by a sinusoidal source (utility power) have essentially no torque ripple. Some inverters can induce high pitched audio frequency vibration into the motor, but that is more of an annoyance than an operational problem. Four-pole AC induction motors (1750 RPM) have enough torque ripple that you can just barely feel the vibration while the torque ripple in two-pole AC induction motors (3500 RPM) is much more noticeable. The Nova DVR uses a stepping motor which basically steps from one pole position to the next, but with a large number of poles and sophisticated driving schemes the vibration level is very low. Small DC motors usually produce more vibration than other types because of commutation and rotor imbalance.

Drive belts and pulleys are significant contributors to vibration. By far the worst would be Reeves drives ... especially those on low cost lathes. The ubiquitous half-inch A-section belt tends to be a bit stiff so it is likely to flutter. The wide and thin J-section (AKA poly-V, multi-V, micro-V) belts run much more smoothly.

Having said all this, are we building parts for the International Space Station or are we cutting wood? If you're chasing your lathe around the shop even without a piece of wood mounted then for certain the lathe is vibrating too much. If you have to shut off the lathe to hear another person talking maybe the lathe has a significant vibration problem (this describes my first lathe). If your hands are going numb and you don't have carpal tunnel yet then ... But, I'm not sure that I would give 2¢ for the nickel test. Even with the lathe off, I've lost too many nickels in the shavings. I think that I would favor the glass of wine test.

 

[Odie]

Good post by Bill. I just finished lunch, and am writing myself a note to check for vibration with nothing mounted to the spindle. Never checked that before. As Bill noted......just how much very minute vibrations will effect, or is acceptable for operating a wood lathe......is probably a minor concern. I don't worry about it, if I can't feel it with my fingertips on the bedways, or see my magnetic base lamps vibrate. (I can detect vibrations with those lamps that I have a difficult time feeling with my fingertips on the bedways.)

I usually can find an rpm where I can't detect any vibration......sometimes the rpm can get pretty slow to get no detectable vibration. As wood is removed, many times the rpm can be increased. For most purposes, the better cleaner cut can be had at the highest rpm without any detectable vibration......to a point, though. (99% of my bowl turning is done on the 1200rpm belt setting, so this applies to that speed range. There is a point where adding rpm isn't any help for getting the cleanest slicing cut, but it's somewhere above 1200 rpm IMHO.

Headed to the shop now........will check on that.

-----odie-----

 

[robo hippy]

One thing I am still trying to conquer, and yes, it is a battle, is how much pushing too hard on the bevel can contribute to the piece of wood vibration... The bevel should rub the wood, but the wood should not know it......

robo hippy

 

[Bill Boehme]

One thing I am still trying to conquer, and yes, it is a battle, is how much pushing too hard on the bevel can contribute to the piece of wood vibration... The bevel should rub the wood, but the wood should not know it......

robo hippy

Wood is flexible and the thinner it gets the more flexible it becomes. Cutting wood causes it to vibrate whether we're slicing, scraping, or grinding it. Gentle bevel contact with a sharp tool is better than bludgeoning it with a blunt instrument, but it will still vibrate. Sometimes the lathe speed is just right to reinforce the vibrations so that is why changing the speed will reduce the level of vibration. Running the speed too high creates another issue: centrifugal force can cause a turning to distort. Even without touching a tool to the wood, the distortion might put the piece out of balance. An even worse scenario is to turn the wood back to round while centrifugal force is distorting it. So, you remove some wood and then because it is thinner and more flexible, it distorts even further. If we don't figure out what's happening we might be headed to a bowl wrecking catch. Even if the bowl survives and we get it round at high speed with centrifugal forces pulling on it, when the lathe stops and centrifugal forces are gone we might be surprised to find that it is now slightly oval shaped.

 

[Dan Bevilacqua]

Bill, if I correctly understand what you are saying, it is normal for most lathes (even the quality ones) to have some vibration at certain speed ranges due to factors such as motors, belts, and inverter frequency, and that the amount of vibration I described is very acceptable for woodturning, even for the experts.

The reason for this thread was that I have often heard and read that it is very important for turning that a lathe have minimal or no vibration. I guess in what I have read or heard, no one quantifies the term "vibration".

So am I correct in thinking that it is perfectly normal for most lathes with nothing on spindle or just a chuck or faceplate to have some vibration, although minimal, at certain speed ranges?

 

[John Torchick]

Bill, would the glass of wine make it from the wine rack to the lathe? It is said that Rolls-Royce tunes their engines so a glass of water will barely ripple at idle.

 

[Dean Center]

Dan,
I also have not done a nickel test, but you've motivated me to check my own lathe to see how much vibration I have with nothing mounted.

I am concerned that 'built in' vibration, from electronics, belts, or pixies, may actually be from a sub-optimal set up. If the headstock is not quite precisely aligned, if the bed is not level and square, if the legs aren't leveled all the same or have a screw loose, if the belt is not tensioned correctly, if the tool rest isn't solidly locked, etc, then the vibration level can be improved.

If any of us is concerned about the amount of vibration in our lathe, it would be wise to have an experienced turner take a look, or go through the set up steps, or both, before accepting the vibration as inescapable. Now where's that Mustard Monster manual....

 

[Dan Bevilacqua]

Dan,
I also have not done a nickel test, but you've motivated me to check my own lathe to see how much vibration I have with nothing mounted.

...

...

Will be interested in the results of your test. Thanks.

 

[Bill Boehme]

.... So am I correct in thinking that it is perfectly normal for most lathes with nothing on spindle or just a chuck or faceplate to have some vibration, although minimal, at certain speed ranges?

I think that you are correct. Woodturners are often a perfectionist breed of cat or at least those who participate in online forums seem to have that tendency. So we seem to always be in pursuit of the ideal even if we know that the desired goal may not always exist.

My curiosity was piqued about the nickel test so I dug through my pile of coins and it took quite a while before I came across one that was new enough that I could stand it on edge on the kitchen counter. Next I tried it on the lathe. When I finally got it oriented so that it wouldn't roll off the bed I turned the lathe on and slowly ramped it up to full speed. The nickel never budged.There was a Stronghold chuck on the spindle and I didn't bother taking it off for this little experiment. At full RPM I could just barely feel any vibration in the tool rest. It was so slight that I had to use a very light touch to detect it. I couldn't feel the vibration anywhere else on the lathe.

Also at high RPM There is a soft whining sound which is caused by the inverter. I hear the same sound if I just run the inverter and motor disconnected from the lathe. I don't know that this proves anything about what is essential. I turned some halfway decent things on my old Delta Reeves drive lathe despite it's strong vibration and loud clattering noise. I'm sure it would be a challenge to turn a delicate finial or a trembleur on that lathe.

Bill, would the glass of wine make it from the wine rack to the lathe? It is said that Rolls-Royce tunes their engines so a glass of water will barely ripple at idle.

You know how volatile alcohol is. The transportation from the bottle to the lathe might require multiple attempts.

Gentle reader, Rolls Royce, while being a fine ride, seems to be so awkward in social grace for using ordinary tap water. Even a bumpkin like me knows that engine tuning calls for a vintage dry red wine. And, please, no cardboard box or screw on cap.

 

[Emiliano Achaval]

One thing I am still trying to conquer, and yes, it is a battle, is how much pushing too hard on the bevel can contribute to the piece of wood vibration... The bevel should rub the wood, but the wood should not know it......

robo hippy

I like to say I "float the bevel" and not rub it... If you rub, she will know it, LOL

 

[Emiliano Achaval]

As a relatively new wood turner, one of the often mentioned qualities of a lathe I have encountered is the issue of "vibration". I was considering reviving odie's excellent thread title "Define Harmonic Vibration" started on 3/30/17. However, I decided to start this one with a more specific parameter. Based on odie's thread, the consensus is that lathes have some vibration at certain speeds with wood mounted on them.

My observation is that lathes have some degree of vibration without wood or anything mounted on them (just bare spindle or chuck). When I speak of vibration, I am speaking of just a very slight amount, not even perceptible to the naked eye (except maybe of a nickle placed on the headstock or bed.). I am also speaking of vibration that is reproduced only at a certain motor speed.

First of all, is this type of vibration that is so minimal only at certain speeds that a nickel is seen to move slightly and maybe fall over until it has passed this speed range any concern to expert wood turners or do all your lathes do this?

Please allow me to provide some personal observations with a bare spindle or just a chuck.

I have one variable speed lathe that if I place a nickle on the headstock (which, by the way, is sometimes difficult to get to stand up on edge even with the lathe off), I can see the nickle start to move ever so slightly at around 950 rpm on faster belt pulley (the speed is different, around 400) on the slower speed pulley but the control knob is at the same position). As I slowly increase the speed, the nickle starts to dance a little and sometimes falls over, up until the around 1100 rpm mark where the nickle will settle down and not vibrate at all. Do all lathes do this, and is this a concern?

I also have observed another variable lathe (midi) that does the same thing, but at a different speed range. I also have observed a mini that does the same at a different speed range. I have also checked out a very expensive lathe that may not have been set up properly that had much more vibration at certain speeds with a faceplate on the spindle. The vibration on that lathe at certain speeds was such that I could see the tool rest move significantly. In my opinion, a nickle would not have stood a chance at the certain speeds on this high end lathe. Note, there is no vibration on any of the lathes at higher speeds.

Normal, or of any concern?

You are probably right, all lathes vibrate to one degree or another. But a $500 Midi will vibrate more than a Stubby 1000. That's why I would never buy a lathe that is not cast iron, welded metal lathes have more vibration harmonics that cast iron...

 

[Bill Boehme]

...... That's why I would never buy a lathe that is not cast iron, welded metal lathes have more vibration harmonics that cast iron...

You do know that iron and steel are the same thing? A little difference in the amount of carbon and processing. The advantage of iron is mainly lower cost to produce complex shapes in low production runs. On the Robust the headstock, banjo, and tailstock are cast iron. The bed and stand are steel. On the Oneway the banjo and tailstock are cast iron and everything else is steel. The Vicmarc has a steel stand. The Stubby has a steel stand, steel spindle, steel tailstock quill, steel motor, and steel bearings. Maybe steel pulleys. When Bill Rubenstein was still living I got to fondle the Stubby at SWAT but he didn't have them hooked up to power so I couldn't try them out. I miss talking to him. He was a great guy.

Individual lathes can have problems that can be either from not being set up correctly or from a manufacturing flaw. Lathes at a school get abused and there may not be anybody that takes care of them. I've turned on lathes that were terrible, but it was because they were mistreated by others who didn't know what they were doing. I didn't trash that brand of lathe ... Just the dummkopf who mistreated it.

 

[john lucas]

We have 2 different discussions here. One is the lathe itself, and one is unbalanced wood, and well there is a third which is putting too much pressure on the bevel. When I first purchased my Powermatic I did the nickel test. Not vibration at all. In fact I turned a small bowl and the nickel never moved. 15 years later there is some vibration. I now turn faster speeds than I used to and wood is particularly unbalanced so the nickle won't stay put. I have learned to put a lot less pressure on the bevel which has really helped all of the above. Sharp tool, I mean really sharp tools, help you cut without putting pressure on the bevel.

 

[Michael Nathal]

You do know that iron and steel are the same thing? A little difference in the amount of carbon and processing. The advantage of iron is mainly lower cost to produce complex shapes in low production runs

I am pretty sure that cast iron and steel have roughly the same stiffness(elastic modulus) , but cast iron has better damping capacity, and thus dampens vibrations more than steel. IIRC, cast iron has higher carbon, and that high carbon leads to tiny graphite particles distributed through the iron, and this results in the higher damping. .

 

[Odie]

So am I correct in thinking that it is perfectly normal for most lathes with nothing on spindle or just a chuck or faceplate to have some vibration, although minimal, at certain speed ranges?

Well, that's how it turned out for me. With a bare spindle, I went from 0-1200 rpm with a very slight detectable vibration at around 1100 rpm.....this was with my fingers lightly pressed on the bedways. I did the same test with a nickel balanced on edge on top of the headstock, and on the bedways. In both cases, the nickel looked rock steady throughout the speed range. I did not do any checking with the poly-v belt at any positions, other than the 1200 rpm setting.

Funny, how I never thought to do this test before, but glad I did......just for my own curiosity.

-----odie-----

 

[John Torchick]

Lots of good info here. Need to check out my own Rikon lathe. First, I need to borrow a nickel from SWMBO.
Bill, repeated trips between the wine rack and the lathe will eventually result in negating the axiom of "the shortest distance between two points is a straight line."

 

[Mike Johnson]

All rotating power driven machines have a harmonic frequency that will induce a level of vibration, depending on the mass of the machine and the design, this vibration can become very noticeable. Each one of these machines will have a specific frequency that will set up a harmonic response causing the vibrations to magnify and resonate. By adding weight to the machine or stiffening the machine you will change the frequency that the machine will vibrate at. By adding ballast to a wood lathe you are basically changing the frequency that the machine will vibrate at.

Every billet of wood will react differently on a wood lathe as some are more balanced and others are extremely out of balance which causes the lathe to quickly reach the critical frequency causing harmonic resonance. Slowing or Increasing the speed of the lathe, balancing the wood billet, or adding ballast to the machine, or stiffening the machine are your main options for overcoming harmonic vibrations on rotating equipment.

 

[robo hippy]

When I switched from a 3520A to my Robust, the only difference I noticed between them was that they made different noises when I turn. No vibration issues. I have thought about filling the hollow tube of the lathe bed with sand at some point, but haven't gotten 'a-round-2-it' yet...

robo hippy

 

[Bill Boehme]

I am pretty sure that cast iron and steel have roughly the same stiffness(elastic modulus) , but cast iron has better damping capacity, and thus dampens vibrations more than steel. IIRC, cast iron has higher carbon, and that high carbon leads to tiny graphite particles distributed through the iron, and this results in the higher damping. .

Michael, I thought that the higher carbon content of cast gray iron would make it more brittle and therefore less damping. But regardless of that I don't think that the issue has much if anything to do with the natural frequency of any part of the lathe, but rather low frequencies from the wood or even lower frequencies caused by out of balance wood. If I hit any part of my lathe with my wooden mallet all that I hear is a thump sound. It's the complex structure (irregular shapes, webbing, etc) that damp any ringing and not the material itself.

A good case to study vibration would be my recent attempts at coring with the McNaughton rig using a long and relatively flexible blade hanging quite a long distance past the gate and buried deep into the wood. The blade flexing like the dickens and causing the wood to howl and the banjo to walk around. I can't blame damping of my cast iron headstock, cast iron banjo, or steel bed for any of this.

Another example is a 20 inch diameter and ⅝ inch thick box elder bowl that I am currently working on. It's bone dry and wants to howl like a demented bell when a bowl gouge touches it. This has nothing to do with the iron and steel. The only thing that helps is to slow rhe RPM's way down really slow to get away from the broad resonant frequency of this wooden "bell".

Anyway, that's my 2¢.

 

[Roger Chandler]

Great discussion! I like Bill's observation about the setup of the lathe, and I have had numerous new owners of lathes call or email me about some particular models with issues they thought had defects from the factory, and were upset. When I gave them tips on leveling the bed, and other types of tweaks to make, then they email me back or call me with appreciation because they actually found out it was operator error/or setup mistakes that caused them their problems.
That was one of the reasons I started the Grizzly Green Monster Group over on Sawmill Creek.

I'm the type that is a stickler for precision, and I will work until I'm satisfied that my setup is as good as I can get it. My table saw has the rip fence adjusted with a dial indicator, and is parallel to the miter slot within less than 1/2 of .001" front to rear of the saw. I know that is crazy to some, but its just the way I like it!

Sometimes there are things such as the type floor you have your machine on that will affect vibration, and then there are harmonics induced by things such as bed torque, even how the feet are adjusted. I even helped one turner to get the harmonics out of his lathe by telling him to loosen the bolts holding the bed to the legs, for a day, run the lathe with a small bowl blank on it for a while, to allow the lathe to find its settling point. He did this and reported back to me that it solved his issues. He had some screws torqued down tighter than others, and in his setting, that was an issue. Seems crazy, huh?

I also agree with what Mike Johnson posted above.....there are numerous reasons for harmonics. When I got my newest lathe, the G0800 into my shop, I had to move my other big lathe to a new location on the other side of my shop building, and it took a complete going thru the setup to get it right, and then I only got it real close. I had to then add a piece of anti-fatigue mat underneath one of the foot pads, and it made it dead on. It purrs like a finely tuned instrument now, so that goes to show that sometimes it is the littlest of things that make a big difference.......in my case the wooden floor of my building being the foundation on which my lathes stand, that makes me have to tweak things that a lot of people would not think to do, or think might be silly.........not so!

 

[Dan Bevilacqua]

Great discussion! ...
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...

...

...

Agree completely. Thanks you to all for participating. Some excellent information.

I guess that the beauty of an electronic variable speed lathe is that you can usually tune the vibration out.

 

[Odie]

I guess that the beauty of an electronic variable speed lathe is that you can usually tune the vibration out.

True dat, Dan.....

Eliminating major vibrations will have an immediate dividend to all levels of turning expertise.

Eliminating minor vibrations become more meaningful, the more developed other lathe skills become.....

-----odie-----

 

[Gerald Lawrence]

You are probably right, all lathes vibrate to one degree or another. But a $500 Midi will vibrate more than a Stubby 1000. That's why I would never buy a lathe that is not cast iron, welded metal lathes have more vibration harmonics that cast iron...

Ok had to jump in with a factor not mentioned... MASS. The difference between the Midi and Stubby (other than HP,bed length and motor) is MASS and if you put 500 pounds of weight on the Midi stand I would bet it would be just as smooth. Even Robust is equipped such that MASS (sand ) can be added. All of the expensive lathes have large masses of "metal" and therefore more weight.

 

[Emiliano Achaval]

I am pretty sure that cast iron and steel have roughly the same stiffness(elastic modulus) , but cast iron has better damping capacity, and thus dampens vibrations more than steel. IIRC, cast iron has higher carbon, and that high carbon leads to tiny graphite particles distributed through the iron, and this results in the higher damping. .

Something interesting for the doubters to read...

 

[robo hippy]

Michael, I thought that the higher carbon content of cast gray iron would make it more brittle and therefore less damping. But regardless of that I don't think that the issue has much if anything to do with the natural frequency of any part of the lathe, but rather low frequencies from the wood or even lower frequencies caused by out of balance wood. If I hit any part of my lathe with my wooden mallet all that I hear is a thump sound. It's the complex structure (irregular shapes, webbing, etc) that damp any ringing and not the material itself.

A good case to study vibration would be my recent attempts at coring with the McNaughton rig using a long and relatively flexible blade hanging quite a long distance past the gate and buried deep into the wood. The blade flexing like the dickens and causing the wood to howl and the banjo to walk around. I can't blame damping of my cast iron headstock, cast iron banjo, or steel bed for any of this.

Another example is a 20 inch diameter and ⅝ inch thick box elder bowl that I am currently working on. It's bone dry and wants to howl like a demented bell when a bowl gouge touches it. This has nothing to do with the iron and steel. The only thing that helps is to slow rhe RPM's way down really slow to get away from the broad resonant frequency of this wooden "bell".

Anyway, that's my 2¢.

I have had that same experience with the McNasty.... Biggest cause of the vibration, other than hanging out so far is that with any load, the tip goes down, which means on a deep core, by the time you get near the end, you are below center, which also makes for catches. Well, unless you are coring black locust or osage or some thing similar... It also tends to bounce more when you are rounding the bottom where rather than going down through the grain, you are cutting into it. Same as what happens when you go across the bottom of a bowl. Every time the end grain comes round, you are head butting it with a scraper.....

With the bowl 'harmonics', I can generally eliminate them by using my left hand as a very gentle steady on the outside of the bowl, and a feather light bevel rub on the inside. Tool pressure = hand pressure. The howling generally is gone about half or more of the way down the inside.

robo hippy

 

[William Rogers]

Well I thought I would have a little fun with the nickel. I hadn't done that test before. Like Roger I was very particular when I set up my Laguna 18-36. I wanted to make sure there would be no issues with my setup. Also my lathe does not have near the mass of the more expensive lathes. I added 350# ballast to the lathe. While I don't believe this is as good as the built in weight of the heaver lathes, it will still help. First with just a chuck and on high speed with the nickel on the ways I ran the lathe all the way to full power and it didn't fall. I then switched the lathe to low speed and put a 15"+ ash blank on the lathe. I tested the nickel at various stages of the turning ( I stopped the lathe and set the nickel, then started the lathe) and the nickel never did fall. To me what this proves is setup and ballast are important. I was also actually able to make some cuts before the nickel fell.


However the piece has a crack that opened up, so this will be a 12" platter or firewood.



Edit: I figured I need to add a photo showing the nickel on the headstock. The blank is just shy of 14" and the 648 rpm is the max recommended for this size. I did turn the crack out and should get about a 12" platter.

 

[Dan Bevilacqua]

True dat, Dan.....

Eliminating major vibrations will have an immediate dividend to all levels of turning expertise.

Eliminating minor vibrations become more meaningful, the more developed other lathe skills become.....

-----odie-----

Got a question for everyone regarding odie's last paragraph, and this question was alluded to in my original post, above.

What effect would minor vibrations have upon woodturning for experienced woodturners, or does it really matter in the scheme of things?

 

[Mike Johnson]

It is amazing how much abuse these machines will tolerate with the out of balance loads we throw at them.

 

[Bill Boehme]

Got a question for everyone regarding odie's last paragraph, and this question was alluded to in my original post, above.

What effect would minor vibrations have upon woodturning for experienced woodturners, or does it really matter in the scheme of things?

I think that folks are picking at nits that don't matter in the slightest bit. Now, it's a different matter if talking about shaking caused by out of balance wood.

 

[hockenbery]

What effect would minor vibrations have upon woodturning for experienced woodturners, or does it really matter in the scheme of things?

Hope. This makes sense
Once you add the wood you always have some vibration at cutting speed.

It’s all relative. I accept a lot of vibrationwhen roughing.
When I am roughing a natural edge blank weight is out of balance ( I may shift the tail center some to balance for weight initially) as I turn the speed up it will vibrate before I get to a a good cutting speed. I have learned through experience find a compromise where there is some vibration but the the lathe isn’t moving across the floor. I know that every initial cut will Improve the balance and the vibrations decrease. I also employ a pivoting roughing technique that cuts the out of balance blank cleanly,

For finish cuts I want minimal vibration.
When I put a NE bowl in the chuck it is still out of balance unless the log was close to perfectly round.
I do something hollowing leaving a thick wall this improves the weight balance. I can then fI finish turn the outside at higher speed to get a cleaner with little vibration. I can hollow with little viration.

If I have the gouge extended 4-6” over the tool rest I have to take shallow cuts and reduce the bevel contact either through choice of cut or creating a secondary bevel.

 

[John Torchick]

Lyle Jamieson has a section on balancing a piece of wood on the lathe; his video Bowl Basics, The Easy Way. Good video. He shaves off a bit of bark on opposite sides of the wood. He is cutting side grain. Put it on the headstock and tailstock and watch. If it turns, adjust accordingly- raise or lower one side. When the wood is static, you are balanced. Hope I explained it clearly. I did stay at a Holiday Inn Express once.

 

[Odie]

What effect would minor vibrations have upon woodturning for experienced woodturners, or does it really matter in the scheme of things?

Hi Dan.....
In some cases, Bill would be correct, when he states:

I think that folks are picking at nits that don't matter in the slightest bit.

In other cases, it's very critical to have the least amount of vibration, as is possible......and, this would apply to what most of us would call "minor vibrations". Al is undoubtedly correct to state that there is always some amount of vibration.....meaning it's there, even if you can't detect it without using specialized equipment available to mechanical engineers. To my thinking, as long as I can't detect a minor vibration, by either felt through my fingers on the bedways, or by observing the several lamps, and laser extension mounted to the top of my headstock......then I'm not going to worry about it much. At that point, then it's probably "picking nits" to pursue it any further.

The kind of turning I do, requires me to have the least amount of sanding as I can possibly manage. Otherwise, my turnings would be a nightmare for sanding. There are just too many nooks, crannies, and corners with intersecting planes, across long grain/end grain, to do that much detail sanding......and, keep it looking cleanly done. The only way I can do what I do, is to have the cleanest cut tooled surfaces, prior to the sanding stage. THAT......requires the least amount of vibrations I can manage while doing the tool-work. It is a combination of rpm, sharp tools, and "time in the saddle", to understand how all of the pieces of this puzzle fit......and, it's not something many turners are going to fully understand, until they've "been there, and done that"!

It’s all relative. I accept a lot of vibrationwhen roughing.

Yes, I agree, Al........it is relative to what a turner intends to accomplish, and how he intends to get there. True, the roughing stage is less critical than the finish turning, but that doesn't mean there isn't an advantage to finding minimal vibration during the roughing stage that won't ultimately effect the quality of the work possible during the final turning stage. What I'm getting at here.....is forcing a cut during the roughing stage will disrupt wood fibers beneath the surface. Those disrupted fibers will definitely effect just how well the wood will react to sharp tools, and skill, during the finish turning stage.......after that, if those disrupted fibers are still present after sanding, and during application of the finish, it will dull the sheen. It all comes back to what a turner did in the roughing stage. If he completely ignores eliminating vibrations that were possible to eliminate early on, it can.....and sometimes will effect the visual aesthetics of the finished bowl.

For finish cuts I want minimal vibration.

Yes, absolutely.......Your point is well taken, AL.....and it's an extremely important point.....however if the disrupted fibers are deep enough, and aren't completely removed.......well then......see above. ^^^^^

The finish cuts........Ah, yes......that is most definitely a critical element to what is possible. If one intends to sand his way through some tough spots.....that can be done with all the modern power sanding supplies and methods.....and, it is.....Just take a look at what other bowl turners are doing, and you'll see most all of them have bowl profiles and interiors that are easily power sanded. Observing alternatively, you will see quite a lot of fine tooled details on spindle turning, and end grain boxes, specifically because the end-grain in this type of turning is much more easily negotiated using traditional tools and skills.

So, to sum it up for Dan.......Yes, it is my opinion that doing everything you can to eliminate vibrations (short of employing specialized equipment specifically designed to detect these very minor vibrations) is something that is critical to my kind of turning, but not necessarily as important to some other styles of turning. For me, eliminating those vibrations are just as important in the roughing stage, as it is in the final turning stage. I guess we all have to decide what our goals are, and put ourselves on a path specifically intended achieve our own successes.

-----odie-----

 

[Mike Johnson]

Odie,

I was going to post what you mentioned about finishing, if you have an out of balance piece on the lathe it is very difficult to get a good finish on the piece as the heavy out of balance side gets sanded and the lighter side tends to not get sanded evenly. The only solution is turning the speed way down and sanding slowly which can take a very long time on a large piece. Trying to get an even fine detail cut into a large out of balance piece is also very challenging. You usually want a faster speed to cut the fine details and the out of balance piece pretty much throws that option out. This is when a large lathe with plenty of mass and ballast really helps.

 

[hughie]

For me steel transmits vibration and cast iron absorbs. However, you can fabricate steel equipment in such a way that it can mimic cast iron. But at the end of the day, wood lathes have vibration imperceptible or not and I tend not to pay a lot of attention to the small vibration rather concern myself with large threatening vibrations that threaten the job and my safety or both.
Woodturning is a free-form hobby for me, so there will never be any hard and fast methods with exception of those guided by safety and practicality.