1 Topic by pricecg44

  • pricecg44
  • Member
  • Offline
  • Registered: 2014-12-20
  • Posts: 135

Topic: dc motor noise reduction

Not electrical rather audio.

As I work at home in a room next to the garage with the extruder on the wall the noise is getting unaceptable.
I tried covering the motor.

However investigating what causes noise in a dc motor, I came across this:
http://last.hit.bme.hu/download/fulop/P … _DCMot.pdf

This proclaims that the source of noise is the brushes against the commutator.

So as I have already pulled the armature out of the motor, and successfully put it back in, I will try to epoxy fill the gap between the commutator lags. I will use two part epoxy stiffened with flour to stop it running. I will be careful with electrical cleanlyness of course.

Any others desperate as me?

2 Reply by elmoret

  • elmoret
  • Filastruder
  • Offline
  • Registered: 2012-10-11
  • Posts: 6,048

Re: dc motor noise reduction

The majority of the noise is from the spur gears in the gearbox, not the motor. You can run the motor at a reduced voltage to make it quieter if you don't want an enclosure.

Filastruder - the robust, inexpensive filament extruder
E3Dv6 All Metal Hotend - the premier 3D printing hotend

3 Reply by richh001

  • richh001
  • Member
  • Offline
  • Registered: 2015-01-30
  • Posts: 75

Re: dc motor noise reduction

if it is too loud, then make an enclosure from thin foam board and masking tape, keep boxing it in until the noise is bearable for you. make sure there is some ventilation and that the sides are non-parallel.....

Motors make very little noise, noise is generated by the gear train, not the motor...exactly as elmoret posted.

If you mess with the commutator at all, you will be looking to buy a new motor afterward.

4 Reply by pricecg44 (edited by pricecg44 2015-06-01 04:28:47)

  • pricecg44
  • Member
  • Offline
  • Registered: 2014-12-20
  • Posts: 135

Re: dc motor noise reduction

I have just put the armature back in and there is significant noise reduction.
I did grease the armature pinion so maybe that was it. But I filled the gap between the commutator lags,
looked thru a 15x magnifier to ensure the edge is smoothed over.

But this noise level is nothing like the loud whining sound that I had to shut two doors to muffle. I put a large wrench on the shaft to
get the torque up and the motor growling.  I will have to confirm that with the extruder back in operation.

And I made two enclosures that did not work, the sound vibrations went straight through. I put cardboard inside the walls for sound suppression.

The DC motors are tough things. These large toy motors are quite hackable in that the tiny ones you cannot get into.

Phew I feel  vindicated on upsetting Elmoret on disregarding his advice. Elmoret appologies for upsetting you, but you need to be more humble on such matters.

5 Reply by elmoret

  • elmoret
  • Filastruder
  • Offline
  • Registered: 2012-10-11
  • Posts: 6,048

Re: dc motor noise reduction

You tested the motor not installed, not under the same load, with no objective data, and you consider that that "vindication"?

If you look in that paper, putting resin in the commutator gaps reduced noise by 2dB. This is right at the limit of human perception. No one would call that "signifigant".

Without a doubt, the noise comes from the spur gears. This was backed up by rich001, and backed up by anyone that has studied mechanical engineering.  I recognize that not everyone has studied mechanical engineering, so here's a nice read on gears:

http://www.anaheimautomation.com/manual … OAV2g.dpbs

Note that the only gear type with the disadvantage of noise is spur gears, they type of gears used in the gearbox.

Maybe you changed the alignment of the spur gears in your numerous assembly and disassembly cycles, making it worse and then better again. You definitely tested under two different conditions, one loaded and one not, one mounted and one not.

But whatever floats your boat, as they say.

Filastruder - the robust, inexpensive filament extruder
E3Dv6 All Metal Hotend - the premier 3D printing hotend

6 Reply by pricecg44

  • pricecg44
  • Member
  • Offline
  • Registered: 2014-12-20
  • Posts: 135

Re: dc motor noise reduction

I will report back when I put it in operation maybe a week.

7 Reply by pricecg44

  • pricecg44
  • Member
  • Offline
  • Registered: 2014-12-20
  • Posts: 135

Re: dc motor noise reduction

It made no difference. Apologies to Elmoret for annoying him.

8 Reply by elmoret

  • elmoret
  • Filastruder
  • Offline
  • Registered: 2012-10-11
  • Posts: 6,048

Re: dc motor noise reduction

No apology needed, just wish I could have saved you the time and effort.

Filastruder - the robust, inexpensive filament extruder
E3Dv6 All Metal Hotend - the premier 3D printing hotend