A lathe upgrade or just a silly idea?

[Steuss Moore]

Hi, i`ve been thinking recently about the finer things in life, and i landed my thoughts on the idea of harmonic dampers being used on a lathe...
Now there are a few ways of going about the whole idea... One is using a harmo. damp. on the motor shaft to attempt to nullify the harmonic vibrations caused by the impulses that appear to be driving the rotor or the shaft of the motor in a nice steady rotation...
Another way would be to mount the harmo. damp. on the lathe spindle or whatever shaft drives your spindle(talking about countershaft gearboxes and such transmissions where the spindle doesnt see direct transmission via pulleys)... The best scenario for that is the spindle pulley... And i say that, as the cutting forces are also an amazing source of vibration, vibration that twists the spindle shaft on a micro scale, and thus induces harmonic noise or vibration, which the harmonic damper is exactly designed to reduce or alleviate to whatever extent possible...
The final option is of course, the ``why not both?`` approach, where you slap a damper pulley on the motor and one on the spindle... Now of course, im talking custom made(i assume that you have a lathe if we are talking lathe modifications...), fluid filled, inertia internal ring style harmonic dampers, that can be finished to whatever style of pulley you need, be it a multi-v belt for cnc style lathes or a regular good old multiple ratio pulley for a single V belt, or be it the cogging belt design akin to those of a timing belt on a car... A belt is a belt, and a pulley is a pulley, but a pulley setup for the lathe that both reduces or undoes the harmonic noise of the motor and of the spindle in action do sound to me like a good idea overall... It would definitely have to have at least a microscopic level impact on the surface finish(talking about honed and sub micron lapped cutting edges here, not dull inserts or edges)... It would also have to have a somewhat positive effect on the cutter life, as it would if nothing, negate some motor to spindle vibrations... It would likely increase the life of the bearings in the same stroke... Im not talking some ridiculous differences here, but as a concept, i bring this out here for speculation and healthy perspective of broad, analytical minds... If you think its a waste of time or ****, do preach brother, but preach the details, share with me your insights and analysis that brought you to that conclusion... And yes, i know that the belt itself is capable and does soak up vibration... This is just an idea that popped into my mind recently... Im not claiming **** here...
I know its a bit of a wild project and a technical waste of time, so to speak from the business perspective - to custom make damper pulleys, but i seem to recall that we are in the hobby machinist lobby, not business management corporate lobby... So there you go, an idea... Who knows, if it works, it may be mainstreamed, i may be uninformed and it already is something done by the industry today... If its a tangible upgrade, the industry would have little issues applying that from custom to general production... Hell, a decent shop could pump those out in large numbers, let alone a large company...
I dont know, i dont follow the news, or try to keep up with the world... I enjoy machining and machines in general... They are the one pleasant and enjoyable thing in this world that never seems to **** me off, no matter the situation - unlike everything else, so yeah, i keep to my shop and my interests, not the trending fads and news...

Also, i put this under accessories, as i dont see this really belonging anywhere else... If i done goofed, sorry, it clearly isnt a spamming attempt to mess up the accessory forum...

All the best,
Steuss

 

[Ischgl99]

These are used in industry, I don’t know if they would work at lower horsepowers, but you might be able to adapt the idea to a lathe drive.

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[pontiac428]

Welcome, Steuss!

One thing to beware of when engaging in such an experiment is when you isolate one variable, another becomes prominent. So don't go after only (monoaxial) spindle harmonics as a singular fixation. Instead, use that line of thinking and go for system rigidity. Assess all of the inputs as a group, then prioritize, divide, and conquer.

Balancers (fluid or elastomeric dampers) absorb very fast transient changes in torque. That's kinetic damping, the other half is mass damping. Adding mass to a shaft changes it's fundamental frequency, and moves all the harmonic nodes along with it. Then Newton says it's harder to change the motion of the more massive object. You know this already. So do the companies making the capital machines, they are everywhere. Just not normally on our old shop tools.

You could add "epoxy granite" to casting voids in your machinery to increase mass and for the purpose of improving finish.

Of course, if it's ultimate precision you are seeking, you should be looking at grinding processes. It kind of makes sinking effort into eking extreme precision capabilities out of mills and lathes seem moot.

 

[markba633csi]

I think the benefits are pretty small for hobby shop applications
If you are making NASA parts maybe...

 

[Janderso]

Yes, welcome to the forum.
I may have missed it, do you have three phase?
What lathe do you have? Size, HP?
Interesting topic

 

[benmychree]

Another solution in search of a problem ---

 

[FOMOGO]

First I would have your motor/pulleys dynamically balanced, and check alignment, but as Mark said the gains might not be worth the investment. Mike

 

[RJSakowski]

One intriguing solution to chatter that often can accompanies turning was to dither the spindle speed. The speed is varied slightly aeound the set speed which will nullify the oscillations. I have no personal knowledge concerning how effective it is though.

 

[matthewsx]

Pictures of your current setup, there might be something obvious that you’ve overlooked that will improve your outcomes.

 

[682bear]

One intriguing solution to chatter that often can accompanies turning was to dither the spindle speed. The speed is varied slightly aeound the set speed which will nullify the oscillations. I have no personal knowledge concerning how effective it is though.

It does work... I do this at work occasionally.

Many of the parts I work on are large diameter, thin wall configurations, making them prone to chatter... when I first begin hearing the humming, I'll bump the manual spindle override down one click, then back up after a few seconds.

We have various methods of nullifying the harmonics, but sometimes it's difficult to completely eliminate it.

-Bear