New 8pre USB too wide to fit standard 19" rack

[Tzakuk]

Has anyone else experienced this trouble? I have removed and re-installed the rack ears, thinking they might snug in closer to the unit, but that did not help. My SKB rack is in good shape, not bent, all other units fit just fine. I put a framing square on my 8pre, and it measures 19-1/16" I am afraid I will have to mod the rack ears to make it fit. Just wondering if I am alone in this...

[Shooshie]

I had to modify my rack for the 896mk3.

Apparently MOTU has changed manufacturers or something, and nobody bothered to check the dimensions.

Shooshie

[mikehalloran]

Oooops!

[bayswater]

Yes, all my MOTU units, audio and MIDI, have been slightly larger than other items in my racks. I've had to jam them in, or make slight modes.

[MIDI Life Crisis]

I guess some people like bigger racks than others. This bird has quite a rack...

[James Steele]

I had to modify my rack for the 896mk3.

Apparently MOTU has changed manufacturers or something, and nobody bothered to check the dimensions.

Shooshie

That seems like a pretty major "whoopsie!"

[Tzakuk]

MOTU has agreed to send me another set of rack ears. They "don’t expect this to make much of a difference - however, best of luck"

In the mean time, I have taken a flat file and modified the ears to fit.

[mikehalloran]

There are many theories as to how 19" became the arbitrary standard. It probably goes back to Bell Labs and AT&T.

Any Navy engineer will tell you, however, that a 19" rack was the maximum width you could fit down the corridor of a submarine. I live near Moffet Field and worked a half mile from the Westinghouse nuclear sub facility and used to make deliveries to both. If it came up in conversation that I also worked in radio or recording, I always got the question, "Hey, I bet you don't know why a rack is 19", do you?"

[bayswater]

There are many theories as to how 19" became the arbitrary standard. It probably goes back to Bell Labs and AT&T.

Any Navy engineer will tell you, however, that a 19" rack was the maximum width you could fit down the corridor of a submarine. I live near Moffet Field and worked a half mile from the Westinghouse nuclear sub facility and used to make deliveries to both. If it came up in conversation that I also worked in radio or recording, I always got the question, "Hey, I bet you don't know why a rack is 19", do you?"

"The 19-inch rack format [in telecom] with rack-units of 1.75 inches and holes tapped for 10-24 screws with alternating spacings of 1.25 inches and 0.5 inch was an established standard by 1934."
G. Robt. Mezger (W2BLL), The Relay Rack in Amateur Construction, QST Vol. 18 (1934), American Radio Relay League.

[James Steele]

"The 19-inch rack format [in telecom] with rack-units of 1.75 inches and holes tapped for 10-24 screws with alternating spacings of 1.25 inches and 0.5 inch was an established standard by 1934."
G. Robt. Mezger (W2BLL), The Relay Rack in Amateur Construction, QST Vol. 18 (1934), American Radio Relay League.

So not much older than the NTSC television standard, which was slowed down to 30fps to 29.97 to add color at one point. The joke was NTSC stands for Never Twice the Same Color.

[Shooshie]

There are many theories as to how 19" became the arbitrary standard. It probably goes back to Bell Labs and AT&T.

Any Navy engineer will tell you, however, that a 19" rack was the maximum width you could fit down the corridor of a submarine. I live near Moffet Field and worked a half mile from the Westinghouse nuclear sub facility and used to make deliveries to both. If it came up in conversation that I also worked in radio or recording, I always got the question, "Hey, I bet you don't know why a rack is 19", do you?"

"The 19-inch rack format [in telecom] with rack-units of 1.75 inches and holes tapped for 10-24 screws with alternating spacings of 1.25 inches and 0.5 inch was an established standard by 1934."
G. Robt. Mezger (W2BLL), The Relay Rack in Amateur Construction, QST Vol. 18 (1934), American Radio Relay League.

Now wouldn't it be funny to learn that submarine corridors were sized to fit 19" electronic gear, and not vice-versa? I wonder which standard came first.

I measured my rack gear with three different rules, just to be sure that I didn't make a mistake when I built this desk. Across the ears, every one of them measures exactly 19," including a telco patch bay by ADC. (non musical device)

This new MOTU 896mk3 is exactly 19 ⅛" wide. I don't know about you guys, but to me ⅛" is a HUGE error in stuff with tolerances so precise as electronic gear, which has adhered to this standard for 80 years now. I thought it might be metric or something, but it doesn't come close to any even metric number. The box is 1/16" taller than other 2-space units. The 1296 in the picture is 3.45" tall, while the 896mk3 is 3.52" tall. That was what forced me to alter the rack by chipping out its shape in the support pegs between units.

At the same time, MOTU is not prone to mistakes of this kind. I've always found there to be underlying logic to everything they do even if it goes against the grain of conventional wisdom, so I wonder if there is a story behind this. Surely it's not just because some engineer forgot to measure twice. On the other hand, the ears are attached to the box with allen screws, and there appears to be some play in them. That was surely unintentional. But the height? I don't know. I think they goofed.

On my work desk there are cabinet doors on either side of the rack which do not allow even an extra sixteenth of an inch, much less an eighth. Maybe I was overzealous with exactitude, when I should have been allowing for things like this. There's always something that eventually changes and doesn't fit when you try to standardize everything. I've built other desks to match various computers so that they could be rolled away and out of sight when not in use, and never did two models in a row fit those spaces. I always tore them out and rebuilt them as shelves, putting the computers below the desk. Now I just let them sit on an open platform and don't try to contain them at all. I know, I know... this is more info than anyone here needs or wants to hear. But it's personal experience for any who might be planning a desk: don't build it to fit any kind of gear exactly. When it goes out, the replacement will be a different size.

Here are some pics to show you what I'm talking about:



Then solution to the width was to allow it to overlap the other box.


Spacer pegs had to be resized for it to fit. That chipped-away peg in between the boxes is what I'm talking about:


Shooshie

[Tzakuk]

Very interesting stuff Mike.

Thank you Shooshie. I have also built several cases and cabinets, and I have never had any issues until now. That being said, the case in question here is an SKB molded 6U; it should not be a problem. Also, you may well be correct, submarine bulkheads were likely designed to accommodate 19" racks.

I have some pics. I will add them when I get a chance to upload them.

[rainmaker]

I also had to modify my rack when trying to mount two 2408 mkIII's on too of each other. They are too tall and the pre drilled racks screw holes in my standard rack rails didn't line up correctly inside the Motu screw holes very well.