rubber isolation washers

I'm having a hard time finding simple rubber isolation washers used in mounting transformers on chassis.
The size I'm looking for is about 0.5" outer dia, about 0.185" hole dia and about 0.1" thick. Can be a little thicker and the outer dia can also be little larger, either in black or brown.
Can anybody please point me to a supplier, thanks.

thank you Bob!....much appreciate it!

I was thinking of getting some too. Now I know where to find them.  

Another option is to oversize the mounting holes a bit and use grommets.

I went with an oversized hole (10mm or thereabouts if I remember right) , an 00 washer between the transformer and chassis plate, and a 1/4" beveled washer underneath, bevel side in, with a flat meta washer between that and the nut. When compressed the two rubber washers actually touch each other, centering the bolt in the hole and preventing any chance of metal to metal contact.



Also available at the local hardware in the plumbing section.

Bit overkill, but I also added a thin nylon washer at the head end of each screw AND did a layer of heat shrink on the threads inside the iron. Just razor it off a bit proud of the chassis plate so it doesn't get in the way when you tighten the nuts.

And with all that, I still get a bit of transformer noise, but I've convinced myself it would have been worse without the extra steps. Yup ... that's my story, and I'm stickin' with it!  

if only we could levitate transformers....hhhmmmmm...super conductor??   

sKiZo wrote:Another option is to oversize the mounting holes a bit and use grommets.

I went with an oversized hole (10mm or thereabouts if I remember right) , an 00 washer between the transformer and chassis plate, and a 1/4" beveled washer underneath, bevel side in, with a flat meta washer between that and the nut. When compressed the two rubber washers actually touch each other, centering the bolt in the hole and preventing any chance of metal to metal contact.



Also available at the local hardware in the plumbing section.

Bit overkill, but I also added a thin nylon washer at the head end of each screw AND did a layer of heat shrink on the threads inside the iron. Just razor it off a bit proud of the chassis plate so it doesn't get in the way when you tighten the nuts.

And with all that, I still get a bit of transformer noise, but I've convinced myself it would have been worse without the extra steps. Yup ... that's my story, and I'm stickin' with it!  

I like that 'squishing' effect, might get some and try it out!

MontanaWay wrote:if only we could levitate transformers....hhhmmmmm...super conductor??   

Or just levitate the whole amp.  Of course, it's gonna cost ya.


https://www.gcaudio.com/cgi-bin/store/showProduct.cgi?id=247

corndog71 wrote:

MontanaWay wrote:if only we could levitate transformers....hhhmmmmm...super conductor??   

Or just levitate the whole amp.  Of course, it's gonna cost ya.


https://www.gcaudio.com/cgi-bin/store/showProduct.cgi?id=247

damn!...and I thought I was joking..........   

My favorite part from the web page ...

I am strongly attracted to these magnetic feet ...

What ... too much iron in the diet?   

Maybe more practical to do an audiophile version of the nursery crib mobile ... only with 20 pound transformers ... might want to use some stronger string, eh.

Spade bit, Sawzall and an old inner-tube are the low-budget solutions.
I've resolved the transformer hum issue rather more elegantly. A solar-powered helicopter drone hovers above the roof-line, with the xformers chained to it and the amps by wires of unobtanium. Works beautifully when the sun is out.

I used some grommets I had kicking around. There's more of a buzz than a hum now.

Captain Coconut wrote:I used some grommets I had kicking around. There's more of a buzz than a hum now.

The buzz might not be emanating from the electronics.

Oh oh!

Bob Latino wrote:Just one other note ... Those 00 flat plumbing washers are made of "neoprene" which is a synthetic rubber and is much more heat resistant than regular rubber. Neoprene will take up to 200 degrees Fahrenheit without degradation of its physical characteristics. The power transformer can get up to 120+ degrees. The washers are unaffected by the heat from the power transformer.

Bob

I guess I could always cut up my old neoprene diving suit.......  

MontanaWay wrote:

Bob Latino wrote:Just one other note ... Those 00 flat plumbing washers are made of "neoprene" which is a synthetic rubber and is much more heat resistant than regular rubber. Neoprene will take up to 200 degrees Fahrenheit without degradation of its physical characteristics. The power transformer can get up to 120+ degrees. The washers are unaffected by the heat from the power transformer.

Bob

I guess I could always cut up my old neoprene diving suit.......  

...or you could try these  http://www.dynakitparts.com/dynakit-products/hardware/POWER-TRANSFORMER-ISOLATION-MOUNTS

aren't you guys still having transformer contact the chassis when using these thin rubber washers?
I use 1/8" sorbothane under the transformers, and then use the neoprene washers.
Sometimes easier to find (or maybe the same) are fiber (fibre) washers, made of a semi-hard material, like dense cardboard,
usually easy to find in any hardware store. Lots of sorbothane on ebay.
Cut one of these in 4 pieces for your transformers
http://www.ebay.com/itm/Sorbothane-SHEET-6X6x1-8IN-VIBRATION-ISOLATION-RUBBER-PAD-150MM-SQUAREx3-2-70D-/370764126470?pt=LH_DefaultDomain_0&hash=item5653439906

tubes4hifi wrote:aren't you guys still having transformer contact the chassis when using these thin rubber washers?
I use 1/8" sorbothane under the transformers, and then use the neoprene washers.
Sometimes easier to find (or maybe the same) are fiber (fibre) washers, made of a semi-hard material, like dense cardboard,
usually easy to find in any hardware store.   Lots of sorbothane on ebay.
Cut one of these in 4 pieces for your transformers    
http://www.ebay.com/itm/Sorbothane-SHEET-6X6x1-8IN-VIBRATION-ISOLATION-RUBBER-PAD-150MM-SQUAREx3-2-70D-/370764126470?pt=LH_DefaultDomain_0&hash=item5653439906

if as a previous post suggested, you use a beveled washer on the bottom/inside the chassis, flat washer on top of the chassis, that pretty much isolates the transformer from the chassis. Once you tighten the nut, the beveled washer gets squeezed up through the chassis hole and makes contact with the top washer. I would also use a washer under the beveled washer so that the nut does not damage it.

MontanaWay wrote:

tubes4hifi wrote:aren't you guys still having transformer contact the chassis when using these thin rubber washers?
I use 1/8" sorbothane under the transformers, and then use the neoprene washers.
Sometimes easier to find (or maybe the same) are fiber (fibre) washers, made of a semi-hard material, like dense cardboard,
usually easy to find in any hardware store.   Lots of sorbothane on ebay.
Cut one of these in 4 pieces for your transformers    
http://www.ebay.com/itm/Sorbothane-SHEET-6X6x1-8IN-VIBRATION-ISOLATION-RUBBER-PAD-150MM-SQUAREx3-2-70D-/370764126470?pt=LH_DefaultDomain_0&hash=item5653439906

if as a previous post suggested, you use a beveled washer on the bottom/inside the chassis, flat washer on top of the chassis, that pretty much isolates the transformer from the chassis. Once you tighten the nut, the beveled washer gets squeezed up through the chassis hole and makes contact with the top washer. I would also use a washer under the beveled washer so that the nut does not damage it.

Just turn the sucker up loud enough and the music will drown out the mechanical hum. Hmmmmm

Should be able to diy those magnetic levitators with some pvc tubing and strong magnets.

Captain Coconut wrote:I used some grommets I had kicking around. There's more of a buzz than a hum now.

Just for the record, the transformer is almost silent now; you have to have your ear within 4" and the hum is hardly discernible. This is a bucker I'm talking about. It's mounted to the top of my pony panel with grommets - screws not in contact with any metal.

Bit of a derail, but how's that muther bucker working out for you? Mine's rated at 6a, plugging right along and barely gets warm. For mostly salvage odds and ends, a real nice addition to the system.



As you can see, I just hard riveted mine together. Perfectly quiet.

It's working great! I picked up a Hammond 167U5 at their warehouse for less than $30. It's rated for 15A so I run everything off it. It gets ever so slightly warm to the touch and is now very quiet.

I had 124 VAC wall voltage yesterday and the bucker knocked it down to 118.5VAC.   

Just for the record, I've found that audible noise from power transformers was most often conducted through the chassis to the shelf. The shelf acts like a sound board and increases the audibility of the noise. Vibrapods or some other type of Sorbothene feet should resolve this problem. If you want to experiment before buying these, get several (cheap) art gum erasers from a school or art supply store and rest the chassis on three or four of these. Heck, you might even decide to just keep the erasers and spend your serious money elsewhere.

Best Regards,
Charlie