How to cut sorbothane?

I recently read a glowing review of Herbie's Big Fat Discs, which are 5/16" thick by 1 5/16" diameter sorbothane discs. So, I did some research and I found a huge variety of sorbothane sheets available at McMaster-Carr. I bought a 12"x12" by 1/4" sheet of 40 durometer sorbothane for $29.

Does anyone have a clever and easy method for cutting discs out of this sheet other than scissors? I was thinking of a sharpened cookie cutter type thing as a tool which could be hammered down on the sorbothane, effectively cuttting a disc...

BTW, I can get 8 discs out of this $29 12"x12" sheet (with useful scrap left over), and 8 Herbie's Big Fat Discs would cost just under $90.
It's not easy.

I tried a model knife and sciccors, but they came out a little rough.
If you're handy at all you might visit Home Depot and buy a piece of pipe of the appropriate diameter and then grind the end so that it has a sharp edge. Or you could buy a cookie cutter and sharpen its edge.
11-15-06: Newbee
If you're handy at all you might visit Home Depot and buy a piece of pipe
of the appropriate diameter and then grind the end so that it has a sharp
edge. Or you could buy a cookie cutter and sharpen its edge.

Both options I had considered.

Ironically, once I've gone to HD, purchased the pipe, sharpened the
edge, I'd probably have been better off buying some pre-cut sorbothane
discs on E-Bay! :)

Probably, I'll cut 1 1/2" squares. No need for discs as far as I can tell. I'm
going to place them between the upper and lower cabinets of my VR4
loudspeakers, so they won't be seen anyway.
I'd be tempted to try a cookie cutter, a piece of wood and a woodworking G clamp, and leave it clamped overnight to see if it cuts through.

I have no idea if it would work, though.

If it does work you could make them in the shape of gingerbread men !
If it does work you could make them in the shape of gingerbread men !
Seandtaylor99  (Reviews | Threads | Answers)
I wonder if gingerbread men would sound better than X-mas trees?
I would try a roller cutter. M wife has one for cutting material and it cuts about anything I need it to. I think it will cut cleanly because it rolls instead of drags across the surface
First, I doubt that what you purchased is exactly the same material as Herbie's Big Fat Black Dots. I have them and they are somewhat stiffer than most sorbothane I've felt.

However, being a DYI tweaker myself I'd suggest you find a supplier of leather-working tools like Tandy. They carry hole punches for belts and leather projects and may well carry larger diameter hole cutters.

I just did a search and although most of their punches are small diameter you could use a strap end punch to cut half of the circle at a time. Here's a link:
If you decide to go back to 1 5/16" circles, you can probably find an "arch" punch at that dia. or something close. McMaster Carr or MSC Industrial Supply would have them. It is just a heavy duty version of the pipe and already sharpened for use with a heavy hammer. You can also have a rule die made (sharpened steel blade set in a wood base), but that would be better if you have access to a small arbor press. You can also cut the sheet on a laser. If you have a sign making or trophy making shop around they could very well have a low power etching laser that would work.

And when you decide that is all too expensive and too industrial - tin cutting shears. Lots of leaverage to cut through the polymer. MSC or McMaster or local industrial supply. The HD or Lowes versions wouldn't be as sturdy.

Jim S.
Grant, The best and probably the safest way to cut your circles is on page 2165 of the McMaster catalog (#112). Alas, the cost is ~$29.
Sharp edge of a tin can? Seems also there is a leather working tool that cuts circles. Is Tandy leathercraft still in business?
11-15-06: Jgiacalo
First, I doubt that what you purchased is exactly the same material as
Herbie's Big Fat Black Dots. I have them and they are somewhat stiffer
than most sorbothane I've felt.

Thank you for the leather tool suggestion. It appears to be
similar in principle to the arch punch suggested by Stilljd. Do you think
the manufacturer of sorbothane makes a specific product
for a small boutique audio tweak company? I'll bet you any amount of
money McMaster-Carr stocks precisely the same sorbothane used by
Herbie. I may not have purchased the same durometer rating
sorbothane used in the Big Black Dots, but McMaster-Carr carries about
all the various sorbothane made as far as I can tell...durometer rating
(40, 50, 60, 70...), elasticity rating, etc., and in a wide variety of
thicknesses. Herbie has done all the work though, so he's entitled to
charge whatever he likes for his product. Most knuckleheads wouldn't
choose to go through the research, cutting etc. that I've done to make
their own and save $50. I don't blame them for buying Herbie's product
or the discs sold for audio use on E-Bay

Thanks Stilljd and Ronnjay for your suggestions. The arch punch is
EXACTLY the right tool, but at $39 for a 1 1/2" version
purchasing one negates the advantage of buying the raw material versus
the pre-fashioned discs offered on E-Bay and by Herbie's.
I am not sure what diameter you are looking for. How about a bulb (tulips, etc.) planter. They even come with a nice handle.

$29 for 4 sorbothane domes, 3 different densitiy options.
G_m_c, I've already made my purchase of sorbothane.
Tvad, fwiw, I don`t think that Herbies stuff is sorbothane. I pulled this from his web site.


What it is: Herbie's isolation materials are proprietary silicone-based vinyl elastomers with varying compliance and firmness qualities. The materials will absorb vibration with very little pressure applied. As weight load increases, the materials become increasingly resistant to compression. Unlike Sorbothane, Vibrapods, Isonodes, Clouds, and other squishy isolation materials, these compliant, non-vulcanized compounds are not dependent on a precise weight load to be most effective. They are equally effective under a wide range of weight and have no inherent resonance or "coloration." Invented and formulated solely for audio and video applications, these proprietary materials are unsurpassed in their ability to absorb microphonic vibrations and reduce audio distortion. Materials are smudge-free and residue-free, with excellent dielectric (insulating) properties.

Our new SuperSonic fluorocarbons are proprietary composites developed for absolute sonic neutrality and microphonics-absorbing ability.

Common sense, and an undergraduate course in Building Construction tells me the following statement from the Herbie's website applies to any material, until that material reaches the failure point:
As weight load increases, the materials become increasingly resistant to compression.
Does anyone know of a material that becomes increasingly less resistant to compression as the weight load increases?

I'm going to try the 40 durometer sorbothane. If I hear no benefit, then I'll chalk it up to an experiment and move on.

BTW, McMaster-Carr carries a plethora of denser and less compliant materials than the various grades of sorbothane.
I think that I read in some reviews that whatever synthetic composite that Herbies uses is sonically better than Sorbothane. I could be wrong on that tho.

I did place Herbies footers under my cdp 2 days ago and am very happy with the result. Increased size of sound stage, better instrument separation while maintaining natural instrument timbre. The results were not subtle.

Good luck.
Sorbothane is a proprietary thermoset polyurethane formulation. They have a patent on the specific formulas, blend to the various durometers, and add modifiers for specific applications (chemical resistance, fire retardation, etc.). Several polyurethane blenders make similar products, Sorbothane is just marketed for vibration isolation and absorption applications.

Thermoset polyurethanes are an isocyanate and a polyol (resin and hardener) that are mixed together and allowed to set. They cannot be remelted, hence thermoset - not thermoplastic. Most specialty polyurethane manufacturers' have large drums of polyols, isocyanates, and the modifiers they use in their formulations, going from drum to drum by hand, creating the specific formulation of their products.

Within the same polyurethane product category, a change of durometer is often as simple as a change of one element in the hardener or mix ratio.

In other words, you wouldn't believe how simple it is to blend polyurethane compounds. We have several polyurethane mixes in our facility that produce the same "isolation effect". Sorbothane just found a modifier (probably a plasticizer) that they can sink their marketing teeth into, did the work to document the properties, and applied for a patent/s.

The point kinda is - each manufacturers' formulation will be slighty different (but patentable) leading to a very similar effect in material properties.

Sorry for answering a question that nobody really asked, but you happen to be talking about a subject I actually have a little knowledge in.(Now some bona-fide PhD Chemist/Audiophool is going to burn my noogies for opening my mouth and show me just how little I really know).

And yes, when I got around to it, I was going to put together isolation devices from the polyurethanes I work with and see if it works/helps.

Jim S.

Thanks, Jim. That was educational.
Grant- i think that your idea of just cutting some squares or rectangles is the best solution. The cost of the proper tool is only viable if you are making dozens of discs. let us know how it sounds.
11-16-06: Swampwalker
Grant- i think that your idea of just cutting some squares or rectangles is the best solution. The cost of the proper tool is only viable if you are making dozens of discs. let us know how it sounds.
I believe you're right. If I happen to find a tool for $30 or so, I could conceivably make 36 discs out of the one sheet of sorbothane that I purchased for $35 shipped to me. That would more than make up for the cost of the tool.

I will let you know how it sounds. As I mentioned (I think), I plan to put them between the speaker modules of my VR4 loudspeakers. Others have commented that this makes a nice improvement.

Your welcome. I didn't mean to dis anyones' product. It is just a matter of playing with formulations and doing the testing to prove effectiveness. The testing can be set up up prove anything (sound audiophilish?). One isolation products site compares the product results against various common rubber compounds. Guess what has a ton of rebound (relatively speaking), common rubber compounds. When modified they would be less so.

Point is - your getting at least 95% of the isolation benefit buying and cutting the sheet for 50% of the cost. Yeh, that works. That's what I want in my gear and that is why I read this forum.

And I still am a wanna-be audiophool. I went to my local dealer today and they just started carrying McIntosh. The first question out of my mouth was how do those 501's sound with Magnepan 3.6s'. I am going back when the 3.6's are in place!

God help us.

Jim S.
i would think that it would work there. i have read that many folks tweak their VRs with some form of isolation btwn the cabinets.
I plan to put them between the speaker modules of my VR4 loudspeakers
Speaking of which, Audio Physics Medea had a sheet covering the whole surface b/ween the two modules. You may wish to try that before going into further cutting?
Tvad, I know you know this but just in case..........

Sorbothane can destroy furniture finishes. Unfortunately I can prove it! :-(

Best to put some waxed paper between the wood and the sorbothane.
Thanks for the tip, Newbee. I did not know that. It won't be an issue on the loudspeakers, but it would be an issue if I tried it on a component.
Oh my gosh. I forgot to add what Newbee pointed out. A lot of thermoset polyurethanes outgas forever and will leach out oils and plasticizers. They also react with a certain classes of thermoplastics in a very unpleasent way (melt the thermoplastic). They can also stain your carpet. Cut a polyethylene (ziplock) bag in a slightly larger diameter to place underneath the pucks. Shouldn't be any reaction. Sorry!
Well, I received the 40 durometer sorbothane and looked again at my
VR4 cabinets...and voila...the top cabinet is essentially supported by four
small sorbothane footers. I had remembered them as being harder
rubber. Since the sorbothane I purchased is the same height as the VR4
footers, I'm going to bag that idea unless I decide to return what I
purchased for a thicker piece. In the meantime, I'm using the
12"x12" sorbothane sheet under my Paradisea DAC.

As for cutting the sorbothane, I've been watching arch punches on E-Bay
for nearly three weeks. I've lost a couple of auctions. At this point, I
believe I can likely cut the 5/16" thick sorbothane with a pair of
Finally purchased a 1 1/2" arch punch on E-Bay. Hopefully, this will work to cut the 5/8" sorbothane sheet.

I'll have a few more discs than I require. If you might be interested in some, send me an email. They won't be free, but they'll be a lot less expensive than if purchased through an audio dealer.
Well, I received the 1 1/2" arch punch today, and it's absolutely perfect for the job. Thanks, Stilljd, for the suggestion.

I have a few extra sets of four 1 1/2", 3/8" (not 5/8" as previously stated), 40 durometer discs available for a very reasonable price.
I have some miscellaneous pieces remaining. They are about 1/2"x1/2" and shaped like four pointed stars. Imagine a square with four circles cut out. The remaining "star" in the middle is what I have. I use a couple sets of these starfish footers under power supplies. If anyone is interested in some sets of four, I will offer them for the cost of mailing plus a small handling fee to cover the padded mailing envelope and my time to go to the Post Office. Basically, I want to get the leftover stuff out of my office, and I hate to throw it away (or store it).

These are really great tweaks, and available for less than a good deli sandwich. :)
Do you have any pictures of the completed discs you can post somewhere? I wouldn't mind seeing how they turned out with the punch.

01-14-07: Riffer
Do you have any pictures of the completed discs you can post somewhere?
I can email photos if you send me your email address.
Herbie's Big Fat Dots are NOT Sorbothane, and have virtually no similarity to Sorbothane. Big Fat Dots are a unique blend of barium sulfate-filled platinum-cured silicones and vinyl siloxanes. They are not "squishy" like Sorbothane, but rather are a very firm, vibration blocking material. (And, by the way, the raw materials themselves are quite expensive.) Please do not compare Herbie's products with others; it's like comparing apples to soda pop.

Thank you very much,

Steve Herbelin
Herbie's Audio Lab
To describe all sorbothane generally as squishy is not accurate. Sorbothane (or ultra-soft polyurethane) is squishy or firm...depending on the durometer, which ranges from 30 to 70: 30 being about like a racquetball and 70 being similar to a pencil eraser.

For more info, search "sorbothane" on

Earlier in the thread, I stated that Herbie's Big Fat Dots are sorbothane. This was erroneous, and I should have been more careful about that statement. For that I extend my apologies to Steve (Herbie's).

It still may be valuable for those interested to compare the Big Fat Dots to sorbothane of a similar firmness. One never knows what's going to work best in any given system.
I'll bet you any amount of money McMaster-Carr stocks precisely the same sorbothane used by Herbie.-Tvad

Okay, I'll bet one million dollars. (Herbie's Audio Lab does not use Sorbothane or any variant of Sorbothane.)

Best regards,

Steve Herbelin
Herbie's Audio Lab
See if you can access a lab supply catalog. There is a device used to cut holes in rubber stoppers used to connect various pieces of glass ware. I don't know max diameter available. The device is basically T shaped - the horizontal being a handle (like a wine bottle opener). The vertical being a cylindrical cutting tool (circumference of bottom edge sharpened)...the diameter determining the size of the hole you create in the rubber stopper. Haven't worked in a lab in some years...might be old tech now replaced by something more convenient. Typically, these came as a "nested set" of multiple sized tools...smaller diameter inside larger inside large etc etc. The rubber we cut was very hard (and thick, 1" or so). Seems like it should work on sorbothane - I just don't know what diameter you are looking for.

Check out the link want a hollow puch gasket cutting tool (I think). Don't know costs or if you can just buy one size.
Tvad - Hey - sorry, I missed that you'd already purchased a punch! ("nevermind")
As I understand it, different durometers of Sorbothane absorb different frequencies. Anyone ever stack different durometers on each other to create a more universal frequency absorbing pad?
I see a lot of misinformation here, some of it corrected. Sorbothane is designed to be compressed to a precise weight loading, which is directly correlated to its effectiveness (absorption coefficent); you have to use the Sorbothane calculator to determine the correct size for the weight you have. I doubt the Herbie Discs have any where near the same capability, but I have a few sets and still find them useful for many situations.  Sorbothane occasionally has a negative synergy on sound, whereas Herbie's Discs almost never do.

Use durometer 40, unless supporting something very light. Heavy duty sheers is probably the best tool. Cut squares, as you will not be able to cut accurate circles or use a punch (unless you can apply at least a few hundred pounds of pressure).

I experimented extensively with Sorbothane when I was starting out, using it under my components and even under my speakers (some products on eBay or Amazon, with names like SorboGel are not actual Sorbothane and are a waste of time). Sorbothane is the most economical absorber/isolator on a tight budget. As I got into higher end systems I moved to Townshend Pods and the adjustable Gyrotension Vega, which are much more expensive, but also deliver much more effective isolation.
I would suggest buying a pair of ARSuper shears. They can cut through Kevlar. The model number is NH-11. Making discs, though, may be a bit laborious, but if you are patient....
Whoops, I also didn't see that you got the discs made.
In the words of Roseann Roseannadanna
I get a kick out of some "diyers". While I understand the idea of saving a few bucks when you can, it's interesting the extent some people go to saving those few dollars. As a person that has sold industrial products my entire life I get a kick out of those that just know they can do things cheaper, better, faster..............until they try. They run around trying to find the right tool 'cause they know they can do it. But they spend more time and expense chasing after just the right thing than if they would have bought the original product in the first place. Personally, I just bought some vibra-pods that corresponded to the weight of the items I wanted to insulate, cut some manilla folder material to fit the same profile as the vibra-pod (using a standard pair of scissors) and I was done. I don't mean to chide anyone's efforts at saving a few bucks but there comes a time when it's just not worth it. Just buying the right product for the job may actually be the best answer.
Correction to my earlier post.  I recommend Durometer 70.  I don't know if you can buy it from McMaster (I bought mine directly from Sorbothane), but higher is better.  If you were able to cut the other with a punch you may be able to do it with 70, but the hardness is about double.

Someone referenced the relationship between Durometer and absorbing different frequencies, which is partly true.  All durometers absorb higher bass frequencies (50-100Hz) effectively.  Higher durometers will compress less with the same weight and have higher absorption coefficients in the 15-50Hz range.  Note that you can't compress the material more than 20% or it will internally cook and degrade over time. 
Falconquest, sometimes a better education results from trying things for yourself.
True, it would be 'easier' to have it made to order, but, sometimes building it yourself not only gives you the pleasure of accomplishment, but also greater understanding of what works and what doesn't.