Monday, November 24, 2003

Hard Drive Anti-Shock Mounting

I've been starting to use external USB drives (like the Part II CA405U) for backups, but I'd like to isolate the hard drives somehow within the case. Well, according to Maxtor , the hard drive screws are 6x6-32 UNC 28 threaded or 4x6-32 UNC 28 threaded. In the CA405U case, the hard drive is mounted using the bottom (4) screw holes on the drive and there's about half an inch of space above the drive. So I could easily put 1/8" or 1/4" worth of rubber grommets between the metal mounting rail and the bottom of the hard drive....

That is, if I can find the proper bits and pieces to do it.

Most drive screws seem to be between 4mm and 6mm in length and I'll need something closer to 8mm length.

Update: Well, Lowe's had some rubber washers that were 5/32" internal diameter and 3/8" external diameter and 1/16" thick which is just the right size to fit around the #6 machine screws. (A few websites sell 3/16" internal diameter 3/8" external diameter 1/6" thick rubber washers, but the 3/16" diameter is a bit larger then necessary.) The rubber washers come in packs of 2 for $0.62/pack but I haven't found anywhere to bulk order them (I figure I could probably get a pack of 100 for a few bucks).

For the screws, I found some machine screws that are 6-32 and 3/8" long (with phillips style heads). Those came in packs of 6 for $0.97/pack. If I can find 5/16" length, I'd be happier, although 1/4" length might be long enough. They also sell nylon screws which may or may not be a good idea.

My guess (and I didn't buy enough washers to test) is that to use the 3/8" long machine screws I'll need 4 rubber washers per screw to get the proper fit (1 rubber washer outside the mounting plate, 3 between the plate and the drive). I plan on running out there later this week and cleaning Lowe's out of rubber washers (grin) then I'm going to re-fit the drives inside my off-site USB backup cases.

The other idea is to find rubber hose that has a 5/32" inside diameter and make washers out of that by cutting it into bits.

Update#2: I installed a drive into the USB enclosure last night using (4) rubber gaskets and (1) 3/8" long 6-32 machine screw per hole last night and I have a few observations:

1) You'll need to use something sticky to hold the (3) gaskets in place over the hard drive mounting holes (I used electrical tape which is best) because as you lower the drive into the USB enclosure, there's no way to re-position the washers if they fall out of place.

2) The USB drive didn't have mounting holes, it had mounting "slots". This means that the rubber washers are going to twist and contort (and the 3/16" inner diameter washers would have been a nightmare). You may need to get some very thin metal washers to give the rubber washers a firm foundation.

3) Using (4) rubber gaskets on each mount point is probably over-kill, although it was necessary due to the length of the 3/8" machine screws that I used. If I used something shorter, like a 1/4" machine screw, I could have gotten away with just (2) rubber gaskets (maybe only 1 between the mounting bracket and the drive).

posted by Wuphon's at 4:22 PM