Server rack modifications - strong enough?

Question

Question: Can I modify this rack and have the result still strong enough to hold the content?

I have a server rack made from Steel. However it is 1980's old and doesn't quite conform to modern standards. To rack up some new devices, it needs modification and I'm not sure if this is a good idea.

I've mocked up the post at https://www.tinkercad.com/embed/7CJmNpPJF3S but it doesn't really help.

The rack was from a Data General computer from the 1980s. However there are no active components left so it is not a valuable antique computer.

Problem is that I need to fit some rails for (more) modern equipment, and they look like this:

This is a 1RU rail kit for a Supermicro server, front and rear showing how they will not sit correctly.

Same photos, but showing a Dell SAN. To get the most volume possible, modern equipment uses that space outside the "box"

Additionally, the modern rails are longer, so won't collapse short enough to reach the rear supports.

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WEIGHTS

Each server weighs about 15 kilograms, and the SAN is easily 40 kilograms per unit and there are three units. I also have two hefty APC UPSs to fit, which will be 50+ kilograms each.

Total weight is about 250 kg, say 300 kg for misc and rounding. That's 660 pounds total.

Top of the rear rail (excuse the kit please)

Lower half of same rear rail. You can see the "extensions" I bolted in years ago to fit the previous HP server's rails.

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PLAN

I'm thinking of emptying the rack, and taking a grinder + cutoff wheel to it.

1. the rear vertical rail will be cut off completely, and relocated so its further back in the rack. I lack welding kit, so will drill and bolt the verticals to the horizontals where they cross. That is only Four Bolts per side, which may not be sufficient.

2. At the front, I intend on cutting off most of the rear flange to create clearance for rails.

Of course cuts will be ground smooth, and then bare surfaces will be primed and painted with a matching colour.

Answer 1

Completed! That was both fun and terrifying at the same time. Any questions please ask.

0. Confirmed that I had cutoff wheels for my little grinder, and any other required gear. We were in Level 4 lockdown, which prompted me to get-on-with-it.
1. Shutdown servers, and stripped out everything in the way, both around and in rack.
2. I used a 100mm cutoff wheel to cut through 7 welds holding each vertical bar.
   
   Rear vertical support removed.
   For "reasons" the three switches were left running in-place, with their rears supported by a black nylon strap. Also notice the live power cables taped out of the way so they wouldn't swing into the cutting area.
3. I then trimmed the inner flange on the front posts.
   
   Left side was easier, the sparks were flying down, but on the right side the sparks went up because the grinder wouldn't fit in the other way.
   I left the top and bottom 12RU in place and removed the inner flange in the middle 24RU.
4. Swap from cutoff wheel to grinding wheel and deburr all the cut edges. Wire slivers were easily removed and vaccuumed later.
5. The posts were cleaned up too. The flange was left in place for added strength, but I swapped the sides so it was no longer in the way.
6. Posts were measured and drilled with four x 7mm holes. That's all that would line up with anything, and is the sketchiest part of this rack.
7. 
   Drilled holes were deburred, weld was ground flat, and all bare metal was primed with zinc spray paint.
8. Rear rails installed with 4x 1/4" UNC HT bolts per side.
9. Server rails were installed using bolts if required, or simply clicking home.
   Dell rails are very very good, Supermicro rails are not.
10. After that, its all about cabling nicely.

All in all, its now beastly heavy and rolls like a loaded truck. I have no fear of gravity-induced problems.

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Downsides? I missed a weld and managed to cut clean through the corner of one side rail. Fortunately its on the side near the wall.

I also can't get blue paint at this time because lockdown, but I did have everything else to hand.

Finally, grinding metal is dirty. Very dirty, and the dust likes to stick to your shoes and be tracked inside. Not recommended.