ok need to get isolators for a friend (it's like a virus- an EAR infection) and at the same time wanted to piggyback some EAR harddrive grommets.

now mcmaster-carr is great and all but their site is too big and they have a horrid search function. combine that with their simple ommision of brand names and I'm clueless which of 35 million grommets are the ear ones.

I just want the ribbed ones that are squishy like on EAR's page.


Can anyone help me here?

not really time rushed so whenever.

Cheers!
-Liq

For starters, the grommets in question are on page 3436. You can access this from the Home Page by putting "3436" (w/o the quotes) into the search box. That'll take you to the page in question.

There are two different sizes/types of these grommets that are available from E.A.R., G-410 and G-411. The McMaster part numbers that match these sizes are: "9311K138" = "E.A.R. G-410", and "9311K139" = "E.A.R. G-411".

I know this is true because I ordered one pack of each and they are sitting on the desk in front of me as I'm typing this. FWIW, these appear to be the actual EAR grommets, they are identical to the ones shown in the pictures on EAR's site. They are the same color and configuration. BTW, the McMaster fan isolators are actually EAR isolators too, the label on the package even says "EAR". Look at my picture of the package in this thread.

I would say the G-410 would be the best one to use for HDD mounting as EAR rates them for up to 3lbs which should be plenty. I haven't used them yet because I'm using the SLK3700 case which comes stock with a lower-tech version of this grommet.

that's exactly the info I needed...

now of course looking at the EAR site I notice they have dedicated shoulder bolts for this.

grrr mcmaster is too big to find those.

Cheers!
-liq

AFAI can tell, McMaster doesn't carry the shoulder bolts. Does anyone have a supplier for them?

TIA

one thing you should know about the hard drive grommets, if your case wasn't designed to use some kind of grommet there's virtually no chance you'll be able to use these without destroying the grommet when trying to get the drive in place unless maybe you can bend the sides of drive cage outwards.

I may have smoked too much crack last night but I seem to remember someone here saying that E.A.R. has the correct shoulder bolts for their grommets listed on their site.

FWIW, I recently bought mounting bolts for some Seagate and Samsung HDDs and the screw size is metric, it's "M3". That should make finding the correct shoulder bolt here in the US even more of a challenge. Have a nice day!

FYI, in case anyone's interested, the Ever Case 4252 appears to have the correct mountings for these grommets on their HD cages. That won't do anyone much good without the right shoulder bolts though.

Liquidated -- May be you should try these grommets instead ?

Last time I looked, they even gave you all the important dimensions of the bolt (such as the length and diameter of the shoulder), so that should make it easier to find one that will fit. I once tried matching this up to McMaster's selection of shoulder bolts, but I couldn't even find one with the right thread (6-32) let alone the other measurements.

Maybe it's possible to make homemade ones by taking a 6-32 screw of the "right" length, then wrapping some electrical tape or something around it to make a shoulder, or else just letting the screw sit loose in the grommet.

Well McMaster lists lots of screws which have the thread 6-32, but they don't have any shoulder bolts which are as small as the one listed on the EAR site for the grommits. But looking at the listing for those bolts, it looks like the threaded length is about 2mm, (it lists two numbers 0.215cm and 0.185cm), including the shoulder length of about 3mm, it looks like the correct length screw would be about 3/16".

There are a number of these with different head styles and steel, zinc or nylon. Part Number 91400A143 seems to fit the bill, and it is $3.79 per pack of 50, cheap enough to just try out and see how they work.

The problems would be that without the shoulder you could screw it in too far, and harm the harddrive. And you couldn't screw it in "tight" so it might vibrate loose after awhile. But hey, the grommits are cheap, the screws are cheap, I might give this a try.

First off, we should probably include this link. Shoulder bolt info is linked at the bottom...


I think you got that one wrong, Douglas, since the measurements appear to be in inches. That makes sense, too, because the standard HD screws that came with my last case, which does not use grommets, are 1/4". So that makes the shoulder bolt lengths about 13/32" and 17/32".

I just ordered a bag of the G-410 grommets, which I will try with 3/8"-long nylon machine screws (McMaster #91766A146). However, I'd really prefer to get the EAR bolts, since they provide the correct radial preload as well.

Try a drill bushing over your 6-32 screws to create a shoulder. Go to McMaster page 2402 and look at the various headless drill bushings they have. These are all percision ground and have tight tolerences.

Looks like the one to start with (matches the dimensions of the EAR shoulder bolt shoulder the closest) is the number 8491A596. It's 5/16" OD (.312") x 1/4" long (.250") X .125" ID. This will fit over the screw and into the EAR 410 grommet just fine but is about .020" too long. Too long is better than too short though. You can do a little Dremeling on it to get it to the correct length.

They even have some metric sizes on page 2404 that might work out even better but I don't feel like getting out my calculator right now.

Huh? The SB-4102 shoulder's OD is .163", so .312" sounds a little high. In addition, the $4.66 unit price would make me consider a Smartdrive...

McMaster #91145A143 may be a good bet though - they're only $5.43 per 100 and nylon (easy to machine). This piece needs to come down .007" in OD, and .029" in length to match an SB-4102, and the thickness spec for washer #90945A726 ($6.04 for 250) is .029-.035". Might be able to make that combo work okay.

Sure would be nice to find the EAR bolts!

So I looked at that EAR pdf and phoned the 800 number at the bottom of it so I could order the shoulder bolts directly from them. The lady on the phone said, "sure you can order them. They come in bags of 500 pcs for $106/bag with a minimum order of only 3 bags" she brightly told me. After I picked myself up off the floor i asked her if she new of any distributors that carried them. She immediately said "Mcmaster-Carr carries them but I don't have the part number. Just search their catalog by our part number and you should find them". I spent a while searching the Mcmaster catalog but of course I couldn't find them so I called Mcmaster Customer Service. They couldn't find them either but said they could probably order direct from E.A.R. She said she'd find out the particulars and get back to me so I'm waiting to hear from her.

Let's see: $318 divided by how many SPCR forum members? Thanks for taking the initiative, Ralf. BTW, I just got 95% of the McMaster order I placed yesterday, and that was with UPS ground. I'll be playing with the G-410 grommets soon.

Actually that's not so bad. That works out to 375 sets of 4 bolts for only 85¢ per set. Now to find 374 other people that need shoulder bolts for a set of EAR 410 grommets.

JC purchased the HDD shock proof kit for the E4252 from Ever Case, in another post he said this about it...
1 Kit $1.75 + 6.02 shipping. 8 grommets, 8 long hard drive screws, 8 thin metal disks to block em interference - enough to mount two hard drives. Instructions for using the grommets actually comes with the case itself.

I'm assuming that the grommets in this kit are the same blue E.A.R. grommets that are shown in the article on E4252 here. If so then it looks like a good deal (cheaper than McMaster), and it includes the long screw, and the little metal disk.

How does the little metal disk (I assume this is a little thin metal washer] prevent em interference? Do you people use these little washers when you install rubber grommets that you buy separately? I certainly would not have known that such a thing was needed.

I read that if you mount a drive with rubber grommets that you need to provide an alternate ground connection from the drive to the case. Is this what I should do since I plan to use grommets?

On the topic of making your own bolt for use with the grommet, in this article the author is using the E4252 case, and regular black rubber grommets purchased from the hardware store for $1-$2. He makes the bolts using parts from items in the spare parts bag that comes with the E4252. It's in this article about modding the E4252 here. Towards the end of the article is the mod where he glues a motherboard standoff and another screw together to make a screw that will go through the rubber grommet into the hard drive.

Lilla

I thought I saw that somewhere else as well. I thought it goes something along the line of spinning discs generating static electricity.

But Aphonos DIY suspension doesn't show any grounding, and the Sonata case does not come with instructions (or parts) on grounding the drives.

Comments, please?

IBM used to warn about this but the whole issue seems to be moot these days. Truth is that the black (ground) wires to the PSU do result in everything being grounded to the chassis anyway.

My theory is that IBM's engineers were hunting for something, anything, to blame for 100,000 dead drives...besides themselves that is.

You can make your own shoulder bolts for free.



Is there much advantage to using this kind of rubber bushing, as compared to a generic rubber grommet, such as McMaster-Carr's 9600K28?

*EDIT* I just notived Lilla's reference to my article previously. Sorry for reposting.

Bit of an aside here… I don’t quite understand this determined search for grommets when none of them are truly effective in eliminating HDD vibrations.

Elastic suspension is unbeatable for mechanical decoupling of HDD vibrations. You can hear and feel the difference. Putting your hand on a case with HDDs that are elastically suspended, you can feel no vibration whatsoever. None of the grommets I’ve tried – including the soft blue EAR grommets with proper shoulder bolts – achieves as good isolation.

My ranking of HDD silencing methods (assuming a quiet HDD like ‘cuda or Samsung):

Best
- My original soft elastic suspension – using stretchy elastic from a sewing shop.
- Aphonos’ frameless elastic suspension alternative – his elastic looks kind of thick but you could use a thinner stretchier one…
- NoVibesIII– but without last top O-ring (which forces drive to bottom out) – heat a potential problem when mounted in CD bay though.
- Soft foam under HDD on floor of case – this is as effective as all the above and even keeps HDD cool if in a low airflow impedance case near front vent.

Better
- EAR grommets w/ proper bolts in proper cage
- Ralf Hutter’s sorbothane strips under HDD solution used for his Antec 3700BQE (guesstimate of performance)

Good- Rubber grommets as used in Antec & Evercase HDD mounts and similar

OK - Plastic screwless rails as used in some cases

Worst- “normal” tight screw mounting

I have actually tried all the above ( ) except the sorbothane.

The suspension systems do fine for transport just by temporarily wedging some foam around to keep the HDDs from getting jostled out/knocked. 2 HDD silencers not yet considered: LEY FEK-Pro and Zalman heatpipe cage

I agree Mike. Elastic suspensions are slightly better than grommet mounting. I've felt and heard the difference, too. (though the difference is small)

Grommet mounting is my recommendation for systems that will be transported a lot. For example, I just built three computers for a customer in California and I live in Tennessee. For him, since I had to ship the computers through the mail, I used rubber grommet mounting. For my own home systems, I use elastic suspension. I've transported my home systems a lot, too, but I don't trust the elastic suspension to live through UPS or Fedex shipping

Having used both of these methods I have to place the sorbothane method WAAAY above the EAR elastomer grommets, at least as it applies to vibration and seek noise of the Samsung SP1614N.

OK, RH. The next thing to do is to get you to try elastic suspension... Maybe I send you a length of elastic to try and you send me a bit of sorbothane to try & we both report back?

I don't have anywhere to try it right now.

I already have the same elastic as Aphonos used in his suspension article (mine is the less-cool black color however). Unfortunately there's no room in the sideways BQE drive cage (I tried suspnding the drive before I used the sorbothane but the drive cage is so narrow that the elastic rubs on both sides of the cage. Probably not too condusive to isolating the drive from the case!) and I'm using a mobile rack now to mount the drive in my older AMB.

Ralf Hutter --

I didn't mean necessarily to try it in that case in the normal bay, but just to compare -- generically -- elastic suspension to sorbothane. The only place you can do that in the 3700BQE is in the CD drive bays, which naturally makes the HDD hot... but this is just as an experiment.

Turns out I have some bits of sorbothane I can try -- will use it and report whether it is on par with elastic suspension.

So how much did enough sorbothane for 1 HDD cost?

I have Sorbothane as well. I'll compare and report as soon as I can get some shock cord. Just tried, actually, but Ace ain't the place.

Try any sewing shop. Look for elastic used for clothing.

I got mine from McMaster-Carr. Search for page 3264 of their catalog to see their entire selection.

I use a 1/2" thick sheet and I ordered the adhesive backed sheet so I could stick it onto the drive sled. A 4 x 4" piece cost $13.73 (that's about $21,000CAD if I have the current exchange rates correct ). You could just get the non-adhesive sheet instead for $7.32 and just super-glue it to the drive sled.