Smartcore noise and vibration reduction

Technical discussion

By the way, I don't profess to have technical proficiency, but I would like to start a discussion about:

a) whether noise and vibration is an issue worth treating in smartcore design and build.

b) if it is, what design and build approaches might help.

A starting hypothesis for noise is that noise is a nuisance to printer users and others (e.g family) which impacts our times we can print in the house. Keeping printers in garages/unheated spaces can be a catalyst for (ferrous) parts corrosion, so making printers as quiet as possible is desirable.

A starting hypothesis for lower frequency vibration is that this can directly affect the dimensional accuracy and precision of prints, so should be minimised or mitigated.

Possible approaches:

a) isolation of the surfaces which drive noise into the air (e.g box panels) from the motors/vibration sources.

i) Can be isolation such as rubber/foam/damping material between the motors and brackets or brackets and box.

ii) Can be cuts (holes or slots or large cut-outs) in the box sides which minimise the energy transferred to the majority of the box side material (or remove that material altogether). This could significantly reduce the stiffness against racking forces though (unless cuts could improve noise/vibration without cutting full depth). I.e. we might reduce noise at the expense of vibration.

b) Change the vibration characteristics of the structure. E.g. was thinking that adding mass would reduce the magnitude of deflection and alter the resonance of the structure and it's elements. This is why I went for 18mm MDF. Another way of doing this might be to build a frame around the outside (ie another box) and fill the void between the outside and 3 inside faces with something like dry sand (using a bag to line the void). This would add significant mass and might perform a damping function as the loose grains of sand absorb the vibration energy.

Please all chip in on any aspect of this topic!

My Techincal Level: Idiot, but as idiots go... I'm a smarter one...


My thoughts... never having finished a SmartrapCore...

You could just line then interior with cheap dollar store foam board, and use rubber feet to lessen the noise level.

Edited 1 time(s). Last edit at 05/07/2015 01:39PM by madmike8.

Well, not exactly in line with your thinking but I can tell you I adjusted down my v-ref stepper voltage to .25 which significantly reduced noise. you could place cork gasket material between the motors and the walls to further reduce sound. I'll be following to see how this plays out and your tests...

@madmike8 I thought the noise was mainly coming from the side panels but @djinn5150 mentioned in my build log that the rubber feet do help. My printer is on the carpet at the moment, so perhaps that's having a similar effect. Any chance of a link to dollar store foam? I'm in UK but might be able to source if I know what you mean.

@djinn5150 "not in line with [my] thinking" is exactly what I was after by putting this thread up - thank you for the VREF idea!

It's a $1 a board at the local Dollar Tree... Use it for signs, crafts, and sometimes R/C airplanes.


Dollar Tree Foam Board Link.

will changing the VREF down to 0.25 have any effect on missing steps?

I'm not a stepper motor expert but I believe that it's only excessive loads which cause missed steps. What "excessive" is set at depends on the available current and voltage to drive the motor, so a low VREF will find smaller mechanical loads excessive than a large VREF setting.

As I reported in my build thread, x and y axes didn't miss steps in a manual move when I dropped VREF = 0.25V (my A4988s were set at 0.6V) but higher speeds would produce more mechanical load from friction.

That said, I wouldn't expect a drastic increase in friction load at printing speed. However, the extruder is a different matter as it has to generate the pressure to squeeze out the melted plastic (extrudate) and I think this would be a more likely place to find excessive load at VREF = 0.25V. As regards z axis, in smartcore the z height increases in line with gravitational force on the build plate, so I would expect to see missed steps in a z axis homing routine before I saw them in a print.

Fortunately, VREF remains adjustable so we can tune for the balance between heat/noise and performing every step.

Dollar store foam sheet doesn't look like it would absorb much sound. I have just become the proud owner of some carpet offcuts and was thinking of mounting rectangles of it, pile towards the MDF, on the outside of the printer.

For the inside, I'm thinking of packing foam (about 3mm thick and comes in a roll - not bubble wrap). This might also help maintain a stable temperature inside the eventual enclosure for ABS printing.

I started a discussion about it on the smartfriendz forum (http://smartraptalk.smartfriendz.com/index.php?topic=437.0 but it is in french ...so i'll trasnlate it here)

Improvement for noise improvement for the smartrapcore

Mechanical
Structural modification
- Motors are directly against the wood planks : Move them away (2/3mm) to limit the vibration against the planks
- Drilling holes in the wood frame could help
- Change linear bearing for igus one (http://www.igus.fr/wpck/7188/DryLin__R__RJMP) or homemade version (http://www.thingiverse.com/thing:120441 these ones worked well). I printed them (two parts at 6.2mm d'ID) works well and does not make tchiktchik anymore Still working fine.

Damping and isolation
Three possible solutions

• Isolating the motors from the other parts
• Isolating the box from the ground
• Isolating the coreXY structure from the box

Isolating the motors from the other parts
Assuming the X/Y motors are the one that are generating the most noise, there is some approach :
- Astrosyn vibration damper (http://astrosyn.com/section.php/44/1/vibration_dampers) : great but could be hard to install (Only two screws)
- Homemade Astrosyn (https://www.youmagine.com/designs/printable-vibration-dampers) : cheap version ....string enough ?
- Cylinder dampers (http://mikrokopter.altigator.com/entretoises-antivibrations-m3x6-p-40598.html) : could be interresting
- damper strip : the key idea would be to isolate the motor for the coreXY( using [www.rs-particuliers.com] for exemple). I tested this solution with double adhesive tape...it works quite well Be sure to use strong enought adhesive with some thickness
The main problem with astrosyn dampers would be that it will makes the motors lower (I'll try to use a specifi part if I order some astrosyn)

Isolating the box from the ground
Some solutions
Isolating foam : cheap ..Why not ? (http://www.hobbyking.com/hobbyking/store/__41759__Anti_Vibration_foam_Orange_Latex_190mm_x_140mm_x_6mm_EU_Warehouse_.html used in quadcopter)
Printed one : [www.thingiverse.com]
Magnetic printer :see first answer of [www.reddit.com]
=> Tested with not much improvement. The sounds seem to come from the wood panel

Isolating the coreXY structure from the box
Put some insulating pieces between the coreXY structure and the box ... doesnt not seems too hard to do ....but this will keep the vibration in the printing ..head ..snot so good !


Electronique
Réglage des drivers
Having a nice verf cost nothing and help a lot with the noise !

Changing the drivers
There are some more silent than the others
Gadgets3D (http://reprap.org/wiki/G3D_driver) : not so much feedback on it
silent stepstick (https://github.com/watterott/SilentStepStick) : quite new and seems to be quite good but with a lot less torque !


Well ....that was the point of the discussion on the french forum !
What I have done yet :
- double sided tape (thick) to hold XYmotor (I can put a picture) seems to improve a bit. (I taped the extruder one too)
- pololu adjustement improve a bit too

I have modified this one (http://www.thingiverse.com/thing:390323, see attachement ) to be able to tape it on the side of the box (being on the bottom of the motor) but couldn't print it well ....I'll try again soon as my printer is much better calibrated now ! If you manage to build it ...tell me

I am pretty conviced that the noise could be greatly reduced by insulating the motor from the wooden box ^^

very good points .. so much things to try

On our side we did a box with ...holes ! big holes ( I've used this thing you have for holes in wall to install electricity... 70mm holes ! ). It makes a nice box and the result is for me very good . same sound as a smartrap ( very low ) . No more vibrations or speaker effect.

soon pinctures to come !

you will see those boxes soon as we are 3 days in 3dprinting show in london with them !

If you're in UK , don't hesitate to visit us, it's our first show .. hehe .

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the Smartrap project

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what so a load of 70mm round holes in a cool pattern?