M2 Frame Vibration Dampeners

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Slipshine
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M2 Frame Vibration Dampeners

Post by Slipshine » Sun Aug 09, 2015 10:44 pm

There has been allot of discussion on getting rid of the vibration on parts by electronic measures.
So I thought I would try something mechanical. So I built a shocks system to put under the M2.

It is set so it seems like it is floating on the table. I wanted it to be sensitive enough to absorb micro vibrations from the system but stiff enough to not bottom out during operation.

The results were a improvement but it did not totally eliminate the problem.

http://www.thingiverse.com/thing:961971

One added benefit is that the table it is sitting on is now virtually motionless. If I was working on the laptop I use to print with I could feel every movement. Now almost nothing.

The other thing is it looks funny printing. But you get used to it.

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innkeeper
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Re: M2 Frame Vibration Dampeners

Post by innkeeper » Sun Aug 09, 2015 10:55 pm

Interesting, seems like a similar approach as used by audiophiles to isolate equipment.
There is another approach audiophiles use for isolation, and that is to use a sharpened point as each leg. that gives less surface area for vibrations to transmit themselves to another object.
that might give you another approach to try :)
M2 - MKS SBase w Smoothieware, GLCD, 24v, Upg Z & extruder stepper - IR bed leveling, Astrosyn dampers X/Y/Z, MIC 6, Zebra, PEI, & glass Build Plates - E3D, V3B Hotends, & more - many other 3d printers - production printing.

lem
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Re: M2 Frame Vibration Dampeners

Post by lem » Mon Aug 10, 2015 5:55 am

Although this method seems to reduce/eliminate vibration of the table, I would think that it would introduce problems with the printed item. The idea behind having a rigid frame is to provide a stiffness/mass so that when motion changes directions you don't get things like ringing.

Maybe melted plastic has so much slop in it that it doesn't matter.

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jimc
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Re: M2 Frame Vibration Dampeners

Post by jimc » Mon Aug 10, 2015 12:10 pm

Lem i was thinking the same thing but maybe i am just over thinking it. Proof would be in the print results i guess.

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ednisley
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Re: M2 Frame Vibration Dampeners

Post by ednisley » Mon Aug 10, 2015 1:45 pm

lem wrote:problems with the printed item
The only thing that influences the print quality is the positioning accuracy / stability of the nozzle with respect to the platform. How the entire printer chassis moves doesn't affect that relation; if it was floating free inside the ISS, the nozzle would still have the same position over the platform.

That'd be fun to watch, though...

Slipshine
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Re: M2 Frame Vibration Dampeners

Post by Slipshine » Mon Aug 10, 2015 3:47 pm

I tried to attach a short video of it running .
It really is a sight to see. I will try and attach it as a zip file.

On the thingiverse post for the item I included a picture of a part from the most unflattering angle I could so you can see the results.
They were improved from the first time I printed the item but not perfect.

Think about it like a harp or a guitar if you put rubber on the strings or mounted the neck to the body through rubber.
As the inertia from the reversing table vibrates the belts the hole assembly picks up micro vibrations.
which are then transferred back to the table and the pattern repeats and you see it in your part. By isolating the frame from the environment
it gives the vibrations a place to dissipate other than the table. Doesn't get them all but it helps.

Ill try to get the video online.

lem
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Re: M2 Frame Vibration Dampeners

Post by lem » Mon Aug 10, 2015 7:24 pm

stability of the nozzle with respect to the platform
I agree with that to a point, however, if belt tension can bow the upper support of the frame, stability of the nozzle with respect to the platform is already questionable.

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ednisley
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Re: M2 Frame Vibration Dampeners

Post by ednisley » Mon Aug 10, 2015 8:15 pm

lem wrote:stability of the nozzle with respect to the platform is already questionable.
That's a static warp that can be compensated out with, say, platform grid-probing code.

What's important for print quality is the dynamic stability, which isn't affected by movement of the printer's center-of-mass with respect to its surroundings. I'll grant that the Reprap platform-on-springs design can be iffy under high Y-axis acceleration, but that doesn't depend on how the frame moves with respect to the outside world: the forces applied to the platform are identical, minus the 1 G downward preload if your shop happens to be in the ISS.

For example, your (clever!) spring supports act as an underdamped suspension that lets the printer move as the reaction forces compress & expand the springs, which attempt to restore the printer to its original position. Imagine suspending the printer from the ceiling with one very long spring: it would twitch as those forces move the frame, with the spring eventually restoring the printer to its original position & orientation. Now, remove both the 1 G downward acceleration and the spring; the printer floats in the middle of the room, twitching like crazy, with the same result.

I should have our Larval Engineer work out the force diagrams... [grin]

Slipshine
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Re: M2 Frame Vibration Dampeners

Post by Slipshine » Mon Aug 10, 2015 9:40 pm

Can't argue with any of that.

Its funny you mention the Spring from the ceiling. I was going to bungee cord the m2 to the ceiling and put a stabilizing line from the bottom to the table top.

But there were no cool parts to print.

But the target of the test was aimed at micro vibration not reduction of motion to the table.
Unfortunately It worked way better at reducing the motion.

Would still be cool to see it print on ISS.

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ednisley
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Re: M2 Frame Vibration Dampeners

Post by ednisley » Mon Aug 10, 2015 11:58 pm

Slipshine wrote:bungee cord the m2 to the ceiling
That I want to see: video or it didn't happen! [grin]

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