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Hello everyone,
I am currently working on an electric Credenza motor although my question will be more generic.
I am trying to minimize the "hum" produced by this motor and have tried the wood shims for the coils and have also tried shims between the coils and the motor frame. Neither approach improved on the "hum" produced when this motor was fastened to the motor board.
My question:
Has anyone, perhaps with some industrial vibration damping "chops", researched what to use in place of the original felt washers which go on either side of the bolts when fastening this motor to the motor board? I can imagine that a good answer to this question might benefit the reduction of mechanical noise coming from spring driven motors as well. For my particular situation, someone else had installed "rubber" (neoprene?) washers which seem quite resilient and so I have reused them, but in this world of high tech problems and high tech solutions, I have to imagine there is a more elegant replacement for these washers. A quick Google search returns materials such as Sorbothane. I know that specialty materials can be very pricey, so does someone know the best-performing material and if it comes in a thickness from which washers can be cut or, even better, do such washers already exist?
Thank you for your input!
Don Mayer

Don,

Are the neoprene washers only between the motor & motor board, or are they also under the screw heads, on the top side of the motor board? I would try using them top & bottom, and also possibly enlarging the motor board bolt holes slightly to prevent the mounting bolts from touching the sides of the mounting holes.

Dyslexic Genius Hurt call me about it 864 326 1680

Any progress Don?

My apologies to each of you who replied to this post. I guess I hadn't toggled something that would have notified me of a response.
JerryVan: having just seen these responses, no progress as yet. I just used reused the rubbery washers that were installed by someone else but did not tighten them as much as they had been. Too much would have negated their shock absorbency I feel.
Dyslexic Genius Hurt: I'm sorry that I didn't see your invitation to call until now. I shall do that tomorrow and thanks for reaching out.
To everyone: Back in the day and when I started to work on these machines, my father worked at the Dockyard (Canada's west coast graving dock and maintenance yard) and was able to occasionally bring home products that were not readily available to me who lives on an island; a large one, but a location in which odd thread size fasteners, etc. are always a challenge to source out. I remember sheets of "live rubber" which made wonderful washers when I punched them out but that was decades ago now.
My best to all,
Don

JerryVan,
No forward motion as yet, but I'll call Dyslexic Genius Hurt tomorrow to see if he has any high tech alternatives to the usual felt or neoprene washers. Thanks for asking!
Don

Good to hear back from you. Let us know how it goes.

I just opened up an electric induction motor from an untouched 1929 Victor machine and it had rubber bushings. If anyone wants photos I can get them.

C.F.

Yes, it would be great to see a picture of those bushings. One of the orthophonics I have has felt washers and the other has rubber-y washers of unknown composition. Brett Hurt suggested black rubber but that is hard to source here on the island without getting into all the high tech variants. Makes me wish I lived in a big city where I could go to the local "rubber" manufacturer and look at sample sheets. I am currently looking into latex or silicone sheets which I would then turn into washers of the desired size. No resolution yet though.
Cheers,
Don

For the spring motors i use round felt furniture glides with adhesive on one side. They are aprox. one inch round and aprox ¼" thick. I use a ⅜" punch to make the hole in the center. Almost identical to the originals, perhaps slightly thicker.