how to tell the difference between "rev A" vs "rev B" supermicro rack rails?

BLinux

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I mostly have a bunch of "rev B" supermicro rack mount rails. I recently got a system with inner rails only that are not labeled "rev B", but when I looked closer, they are 1mm thicker than the "rev B" rails I have. I'm assuming these are the "rev A" rails perhaps? If so, how do I identify the outer rails that match with these inner rails? Specific part number? any other visual indicators?
 

Patrick

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I usually look for Rev B stickers/ markings. I am not smart enough to tell you. I do know that all of the newer systems are Rev B.
 

BLinux

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I usually look for Rev B stickers/ markings. I am not smart enough to tell you. I do know that all of the newer systems are Rev B.
thanks.

yeah, i think i have what are "rev A" inner rails. i'm trying to figure out how to buy the matching outer rails. i know what the "rev B" stuff looks like, but not the "rev A".
 

ww2planes1

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I recently ordered an SM846 system off ebay, and when I got it, it came with mismatched rails (Rev B inners and Rev A outers), so I had to try and figure out which rails were which as well (and then convince the seller to send me a matching set of inner rails, which they ultimately did). My Rev A outer rails have no markings on them what-so-ever to indicate what Rev or even what Part Number they are. I did some google image searching and I guess that Rev B rails are typically marked on the outside edge of the extension slide, near the front. There should be a sticker there saying "Rev B". The inner rails are correspondingly marked on the inside of the rail near the back, so that when you're about to push the inner and outer rails together, both stickers should be plainly visible. If you see two Rev B stickers, you've got Rev B rails. If you see no stickers, you've got Rev A rails (or Rev B rails that someone peeled the sticker off).

I think the main difference between the rails that makes them incompatible is the height. I measured mine and got:
Rev A Inner - ~40.6mm tall
Rev B Inner - ~39.24 mm tall
Rev A Outer - ~39.4mm to the inside of the ball bearings.

The hole pattern on the inner rails differ slightly from Rev A to Rev B, but I don't think it affects the function or how it attaches to the chassis.

This is for the 2U/3U MCP-290-00053-0N "yellow label" 26.5" rail kit.
 

BLinux

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hey thanks for the reply! that's good information. However, how does a "rev A" inner rail at 40.6mm fit into a "rev A" outer rail that only has 39.4mm?

the short of it is that "rev A" outer rails don't have a "rev B" sticker, but there's still a chance that it's a "rev B" with the sticker removed? I need to take another look, but out of the dozen or so rail sets I have, that all fit on "rev B" inner rails, none of them have a "rev B" sticker on the outer rail... but I'll take another look to double check.
 

ww2planes1

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An artifact of how I took my measurements. The inner rail has grooves that the ball bearings go into, and I measured to the outside of the inner rail, but on the outer rail, I measured the distance between the ball bearings:

+------------------+ - I measured the inner rail to the outside of the groove
)________________( - ASCII art inner rail

|o________________o| - ASCII art outer rail
+--------------+ - I measured the outer rail to the inside of the ball bearings

The distance between the bearings is necessarily smaller than the total width of the inner rail because otherwise the inner rail wouldn't stay in. BTW, I used a set of calipers to measure these, not sure if you'd be able to tell with just a tape measure.

To be honest, I'm new into this, I just ordered my first SuperMicro case a few weeks ago, so I am FAR from the authority. Additionally, I only have one set of rails to play with, so I don't know how other rail model numbers work. I just did some google image searching and looked on ebay to try and figure out if there were identifying marks. For the inner rails, you can usually see the "Rev B" sticker. For the outer rails, I found a product image on Newegg here: SUPERMICRO MCP-290-00058-0N Short Rail Set - Newegg.com that shows a similar "Rev B" sticker at the end of the rails. Those are the exact rails I have, but I'm assuming SM is consistent.

I've also seen rails sold that have a white, circular "B1" sticker on them. I assume this also indicates a Rev B outer rail (see this ebay listing here for an example: Supermicro W-778-B-0 W-778-A-0 Repon Rack Mount Telescopic Outer/Inner Rail Kit | eBay)

So, a very long answer to your question, but, if it's got stickers, I think it's a Rev B. If it doesn't, I think it's a Rev A. (again, I'm basing this off about two weeks of experience, a bit of google searching, and exactly one set of SM rails, so I may be wrong). Out of curiosity, do you know exactly which part these Rev A inners came from? Are they the 26" long rails, or are they shorter?