i had an idea to make a main construction for cnc router out of square steel tubing, and for "silencing" vibrations i thought to put sand into frame. would this make any significant improvement or is this waste of time ?
i had an idea to make a main construction for cnc router out of square steel tubing, and for "silencing" vibrations i thought to put sand into frame. would this make any significant improvement or is this waste of time ?
pozdravi,Turpija,
I am one of the guys{caknut}from the Epoxy granite machine bases thread where we a attempting vibration reduction.Hollow steel tubes will resonate like a pipe organ because of the hollow nature.Sand is a good choice to dampen resonances as it is cheap and if not suitable can be removed.The next step is epoxy and sand and not changeable.Read the posts on the epoxy granite and decide if you want to try it.Raw sand is a good starting point.
Hvala
Larry
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Great info Mr Larryard!
And speaking of pipe organ.. Where are you guys buying your steel tubing?
I need some for my project. Not really loud but some good sounding steel.
_
Good sounding steel is for Steel drum bands,not for CNC machines.Steel drums go ding,ding boom,boom,sand damping is not suitable as you will get dud,dud.The various sizes and lengths of steel tubeing in a CNC machine will resonate at different frequencys hopefully in key and in concert,making a new hit single.If not you could possibly us it to cut aluinium,I understand servos are smooth,while steppers resonate possibly adding to the musical experience.Nesretan Turpiga,I kazano we are the ludovati decki.
Αποτελέσματα αναζήτησης για 'apollonius de perga': Δεν βρέθηκαν λέξεις.
AdamAnt:good sounding steel is no sounding steel
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i was thinking if the steel tubing will echo any noise on my system i will try spray foam (insulation) , it would be light and should dampen any vibrations
Pozdrav lgalla !
So sand would make a difference (improvement) considering dampening vibrations, that's nice to hear
And i've saw some of those epoxy with sand solutions, but i did't research where could i get all the supplies, and for first hand sand seems like a logical solution epoxy sand can allways be added later ...
2 derstap: that (poliurethane) foam, yellow right, would probably make it better than just tubes alone but sand is way havier, and that's also what good machine makes better
I over engineer everything. Lead shot in 90w gear lube with a drain hole large enough for media changes if it doesn't work. Doesn't work for the pipe organ thing however.
DZASTR
I have an 80/20 router and was thinking of trying the urethane foam in the extrusion.
Dertsap,I was wondering if you tried the foam in yours or just thinking of trying it?
I agree it should help.
Cutmore
Richard, have you actually done something like this?? I'm working on a harmonics problem in my Z axis [it's a 6 x 6 .250Hss post over 4ft long] and am wondering if this would do what I need. It's fairly straight forward, well except that a person can't buy lead shot anymore.. Would steel shot work as well in the same situation??
Can a person even buy lead anymore??
Jerry
JerryFlyGuy
The more I know... the more I realize I don't
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
Look up a company called Metallex. I think that is the name, they refine lead from old batteries and may be able to put you onto a source for lead shot. Steel shot will work it is just not as heavy.
You should also read a bit about constrained layer damping and elastomeric damping with weights. This is based on finding the location of maximum deflection along the beam and gluing on weights via a rubber interface. The weight and rubber have a different resonant frequency so they interfere with the harmonic vibration of the structure. You are quite likely familiar with this idea in the form of crankshaft dampers which have a ring of metal bonded to a hub via soft rubber. Also I think it is applied in propeller design but this could date back a few years.
An open mind is a virtue...so long as all the common sense has not leaked out.
If one was to fill a frame with anything,depending on the size of the machine,The verticals are easy.How would you fill the horizontal tubes? Larry
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IGALLA,
If you use something like expanding foam it would be easy to fill in any direction.
Dertsap,
Thanks for the reply.
Cutmore
DZASTR
I thought the pipes of a pipe organ were traditionally made out of lead?
Quick Google search:
http://www.madehow.com/Volume-5/Pipe-Organ.html
I saw someone restoring a pipe organ once, and there was enough lead in the pipe it was soft enough to bend by hand.Most pipes are made from metal. Metal pipes are most often made from alloys containing various amounts of tin and lead. Pipes may also be made from other metals, such as zinc and copper. The vibrating reeds inside reed pipes are usually made of brass.
Hi Jerr.How are you?
Ever heard the expression"Get the lead out"A 6"X6"X48" tube is one cu/ft or 500 lbs of shot.You got big motors?Why not try the sand idea first.
Is the resonance from the steppers or the spindle?
Appears we have a parallel universe or thread happening here.
Trumpet or trumbone?Really doesn't matter.If you filled it[the musical instrument] with foam or what ever nothing is going to resonate or make any music..The main irritation of the resonance is the air in the tube.Foam filling will eliminate the irritation but I don't know if it will eliminate the vibration.
Sorbothane to the rescue?Pads between joints absorb 94% shock and provides shock absorbing.Used as gaskets in speakers,provides reduction in vibration transfer from the motor or speaker.Useful in a machine.I donut know.
Edmond scientific has sorbothane sheets 12"X12"X1/8" for $20.
Apparently you can cover your hand with a sheet of sorbohane and hit it with a hammer and not feel a thing due to the high damping visco-elastic nature.
Maybe for a million bucks I would try it,other wise I will accept the claim.
Larry
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Dear Larry,
My limited understanding is that hollow tubes have a tendency to form standing waves acoustically if there is a length of tube in which they can form. That's how organ pipes work (I think). If you deny the airspace, the waves do not form, so stuffing tubes with anything should work on that front. Sand, lead shot or foam ought to work.
I am unsure about how to ensure that the "stuff-filled" tube performs best however.
If you go for a two part polyurethane foam (boat bouyancy type), you could fill the sections from any angle. That is not easy with sand or lead shot unless you can pour into vertical sections.
Lead shot and sand add mass to the tube which should mean that more energy is required to set up vibrations and resonance. Obviously, lead does that a lot better than sand. However, a foam fill probably does a better job of making the steel section stiffer for the simple reason that the foam links opposing faces of the tube together and therefore increases the I value, and hence reduces bending. Any thoughts on this?
This is something that loudspeaker stand designers know about.....(and I do not)
Best wishes,
Martin
It is not just a matter of increasing mass and it is certainly not a matter of making the tube stiffer.
The tube is behaving like a tuning fork not an organ pipe. Adding mass or making it stiffer merely changes the resonant frequency; extra mass lowers it increased stiffness raises it. Sometimes just adding mass will bring it down so low that it is of little consequence because the machine does not excite at low frequencies very well.
What the lead shot does very well and sand to a lesser extent is add mass that is not connected to the tube and which does not really have a resonant frequency. Lead shot is far more effective: When the tube vibrates it bounces against the shot which bounces away and into other shot. Because lead is soft the energy is not transferred very well and so it tends to get dissipated mostly by deforming the shot.
The most effective damping is constrained layer where there are two masses that are bonded together via an elastomeric material. Vibrational energy does not pass between the two masses very well because it has to cross two interfaces that have radically different elastic moduli and density. This is how the rubber paint-on compound Richard mentions works; it is lead particles in an elastomeric binder.
Do a Google using the following:
Principles of Rapid Machine Design
by
Eberhard Bamberg
M.Sc., Advanced Manufacturing Systems
Brunel University, 1993
This comes from a link someone put in a thread some time back. The author did his doctorate project designing and building a toolgrinder and he went into damping extensively. The most effective solution for hollow tubes was to line them with a rubber membrane and then pour concrete which contained an agent to creat expansion into the membrane lined cavity. This meant that there was a solid concrete core in intimate contact with the tube via the rubber. In some cases he put a hollow cardboard tube inside the concrete as a core and the effect was more or less the same; it is not the mass that is added it is the manner in which it is incorporated. This is the kind of thing I was referring to in my earlier post.
An open mind is a virtue...so long as all the common sense has not leaked out.