Rack mounting test equipment

[Tony_G]

Hi All,

I recently decided to clean up the home workshop and put some of my test gear into a rack (instead of sitting on the bench or shelf) but I've never done this before so I thought I'd ask for the insight of the forum.

My concern is whether or not I need some form of shelf or rail for this gear to sit on - For example I have 4 fairly heavy items (8663A Sig Gen, 8902A Measuring Receiver, 5440B/AF DC Calibrator, 5200A AC Calibrator) - These are all in the 50-100lb range I think (i.e. bloody heavy).

Looking at their manuals though, it seems that the rack mounting kits are all just done on the front - With the weight of these things, this seems wildly optimistic w.r.t the rack not bending or the mounts breaking.

Anyone have any feedback on this? I bought several rack rail kits to provide a 'shelf' but the mounting of the rails gets in the way of the equipment rack mounts so I don't think they can be used together.

Thoughts/comments/suggestions?

Thanks,

TonyG

[MosherIV]

Hi

19" rack equipment usually have multiple mounting options.

You are right, if the equipment is too heavy, just the front mounting is not enough. Usually, there are some kind of rail which bolts to front and back of the rack is used and there are side bars which will sit on top of the rail and bolt to the side of the equipment.
Fancy rails may use slide bearing but expect these to be expensive.
I think most of them are propitiatory to each piece of equipment, ie there is not standard mounting on the side of the equipment that I am aware of.

Another option is a tray which bolt to both front and back of the rack.

FYI I have mostly seen computer rack equipment.

[edpalmer42]

Many 'rack-mount' devices (e.g. computer servers) require slides that are supported at both the front and back.  Even though they have mounting ears at the front, they warn that you can't use those by themselves in a normal rack.  So you need a cabinet that has rails at the front and back to bolt the slides to.  Then the servers slide in on ball bearing rollers.

OTOH, I have a large, heavy HP power supply.  I noticed that the monster transformer is mounted right at the front of the unit, as far forward as they could possibly put it.  This means that most of the weight on the mounting bolts is going to be straight down rather than twisting.  Four or six mounting bolts on a normal rack would have no trouble with that.

Instead of shopping for a standard rack, you might want to look for a computer cabinet so that you can handle both types of equipment.  You could then use slides or use a piece of plywood with angle brackets to create a shelf to rest the equipment on.

Ed

[Quiggers]

I've used rack shelves in the past, but you need the rear rail to support them, I bought  mine from maplin and the rack strip with the 90^o slots to support the rear of the shelf.

[Tony_G]

Thanks all - I bought some of these Navepoint adjustable rack shelve rails - They do a good job in supporting the gear but they get in the way of the rack mounts at the front.

I looked at some proper Agilent racks and they have an additional mounting slot on the inside of the rack rail (which must be the 90 degree slot that Quiggers refers to). It looks like I'm going to need to find something to modify the front rail in my cabinet to that I can still use the OEM rack mount gear.

TonyG

[ManateeMafia]

I currently have three racks of gear and the biggest issue, next to weight, is air flow. Some manufacturers draw the air from the rear but it comes out on the sides. You will need to consider top mounted fans unless the racks have perforated side covers.

My heaviest items include a HP8566A and a Fluke 5440B. The 8566A is pretty heavy and I have added a rear cross support in addition to a rail on each side plus a front support. It has shifted a bit so I made sure there was a good gap between it and the shelf below it.
I don't want sliders as they are not really necessary. I used them in the military for doing calibrations from the top but this is typically not needed for most gear.

Just look for rack support brackets and add any flanges to your test equipment. The front and rear supports can be made or bought. They also come in handy if you need to relocate a rear connector to an access panel. It will also be important to note how the flange screws and nuts are attached to the rack chassis. Mine are in channels and have the ability to move up and down. Other racks  have the nuts fitted in a square hole and are pretty secure.

[Tony_G]

Thanks - I'm using a 4 pole open rack (no sides or top) - I think I might just be able to put some square tube stock in at the front and attached the shelves to that - This would clear up the front holes for the rack mount attachments only.

TonyG

[Berni]

Some time ago i moved all my big equipment in to a rack and it went pretty well. Im using a full sized 75cm deep Compaq 42U rack with side panels and doors that sits on caster wheels for easily moving it despite it weighing over a quarter of a metric ton.

Its not full of equipment but it probably already has over 100kg worth of stuff in it. Some of the heavy items being a HP 8566B boat anchor spectrum analyzer and a Gigatronics 7100 synthesizer along with a few hefty rack mount PSUs. To mount it all in i mostly used rack shelf's that screw to both the front and back rail then simply put the equipment on the shelf. The big ass synthesizer is mounted on server sliding rails, and since those are pretty strong you can easily set another piece of equipment on top like it was another shelf. (I can post a photo when i get home)

The shelves and sliding rails i got with the rack when i bought it used off a guy. Also i don't have rack mount kits for all my equipment and as you said just using the front to bolt it in is a bit precarious.

[zlymex]

I have 4 racks of test gear(2 not shown), they come with 4 boards/plates for each rack that can support 5440B(plus a 5450A) at ease.

[Tony_G]

Thanks Zlymex - Who made your cabinets? The problem I'm having is finding ones that have those holes for the support brackets - Yours have the square holes on the front of the rail and then a bit behind that another set of square holes that can hold the support bars/shelves - I'm only finding racks online that have the holes in the front.

TonyG

[SoundTech-LG]

Hope yer' racks look better than these... 



http://www.cepro.com/photo/readers_share_14_horrifying_wiring_messes_before_and_after/0/hdmi

[Berni]

That is a nice rack you got there (no pun intended). I sense a bit of a volt nut there.

Here are some photos of mine. In the photo from the back you can see how it is all put together. Only 2 precis of equipment are actually rack mounted, the rest basically just sits on pretty sturdy metal shelves. I also included a photo from the back to better show how its put together.

In case anyone is wondering what the equipment is(top to bottom):
Hantek HDG2012 Arb Function gen 20MHz (I regret buying this piece of crap)
Agilent E3610A Linear PSU 15V 3A
HP 8082A Pulse generator 250MHz, 1ns rise time
Agilent 66332A Dynamic measurement DC source 20V 5A
Agilent 6032A PSU 60V 50A 1kW
HP 8566B Spectrum analyzer 100Hz to 22GHz
Compaq keyboard tray(useful as a pullout table)
HP 6624A System PSU 4 channel
Gigatronics 7100 RF Synthesizer 10MHz to 20GHz

[zlymex]

Thanks Zlymex - Who made your cabinets? The problem I'm having is finding ones that have those holes for the support brackets - Yours have the square holes on the front of the rail and then a bit behind that another set of square holes that can hold the support bars/shelves - I'm only finding racks online that have the holes in the front.

TonyG

There are several type of racks in the electronic store where I live, I just choose the type suitable for me(right height, right depth, no door). They only got samples so that I had to place order and wait for few days. But I can also make some slight custom requirements.

Edit: my rack is very similar internally as Berni's especially looking from the back.

[Berni]

You might want to look trough craigslist or ebay or similar for any old server racks that fit your requirements. The sort of rack i got costs about a grand new while i picked it up used from a guy for 100€ in pretty good shape. Apart from a scratch here or there all it needed was a bit of a clean with a pressure washer outside. If you are lucky you might also get a few shelves, server rails, power bars, mains cables etc still left inside. Those shelves alone can easily cost more brand new than what i paid for the whole rack.

Also basic 60cm deep rack is enough for all the usual test gear as the 60cm are the internal dimensions of the largest thing that can be slotted in, not the outside dimensions.

[Tony_G]

Great suggestion - I was looking at eBay but the freight charges were killing it (often doubling the price) - Didn't think of checking Craigslist.

Thanks for this - Appreciate it.

TonyG

[Berni]

Great suggestion - I was looking at eBay but the freight charges were killing it (often doubling the price) - Didn't think of checking Craigslist.

Thanks for this - Appreciate it.

TonyG

Yeah personal pickup is the only option you have. Not only are full sized racks very big they are also heavy as heck. So heavy in fact that such a rack has to have all the doors and panels taken off to leave a bare frame in order to make it light enough for a average person to lift and move. Just one side panel tends to weigh about 35kg. With everything on it such a rack could weigh from about 70 kg  to  over 150 kg. Also keep in mind any narrow flights of stairs as the frame is usually a solid welded together cuboid. Also mind the wide racks that have extra width to provide air flow up the sides, those are too wide to fit trough a regular door. If you ever want to move it once its in the room getting one with caster wheels under it is also a good idea (I find it very useful to be able to pull it away from the wall to access the back when wiring up stuff).

So yeah you better have a trailer for your car and in my case i had to drive about 110km one way to get it as i couldn't find anyone closer.

[GreyWoolfe]

Berni is right on the money.  My ham radio club needed a new rack for our main VHF repeater system.  We found a deal at a fifth of the price new-$300, including the keys to lock it.  We had to pick it up with a truck and trailer.  It then had to go into the communications room on top of the hospital where the repeater is located.  It was easy to get it to the top floor through the freight elevator.  We then had to manhandle it up 2 flights of stairs with a bend half way up of course.  Then we had to get the doors and sides off to lift it over a landing, through double doors and down a landing, both with handrails to get it into the room.  That truly was as much fun as you want to have in any given day.