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Very old UPS still ticking after minor repair

Below is a picture of the front panel of the 3U UPS I’ve been using for my home office computers since about 1996. The main part of the panel has been repainted twice, but the ‘dwm’ (my initials) was done with a Sharpie when I bought the UPS. At the time, this was just used to distinguish it from my wife’s UPS in the same rack.

It lacks modern communication (it only has an oddly-pinned DB9 connector for communication). This is a drawback that will eventually trigger a replacement. However, I like the 3U form factor, since it makes the thermals more reasonable than a 2U unit without being loud. A single 90mm fan is in the rear, and I don’t think I’ve ever heard it since it’s normally in a rack under my desks. It’s also just been super reliable. Until recently…

Due to the lack of good diagnostic communication, the LEDs on the front panel have to be interpreted using the manual (I have a PDF copy). For the last couple of months, once in a while it would show one of two diagnostics after a power blip. One indicating low battery, one indicating ‘main relay failure’. If I cycled it off and on, the issue would sometimes toggle, sometimes repeat, and usually go away after I reduced the load.

Figuring it was worth a shot, I bought new batteries before digging in. Once I had the old batteries out, sure enough they were completely dead. As in 0V across the series (should be 48V). Hmm, they’re brand-name that I’ve used many times for replacement, that usually last 3.5 to 5 years. These were less than 2 years old.

I taped the new batteries together as usual to make a pack, then installed them. I then powered the UPS and heard arcing inside. Oh no! I unplugged it from the mains.

I removed the UPS from the rack and removed the top. Nothing appeared to be cooked, and no detectable scent of magic smoke. So I turned off the lights in the room, plugged it back into the mains and turned it on. During its self-test… arcing at the connection to the negative end of the series of batteries.

The issue was a loose fast-on connector. The female side had opened up over the years, presumably from the many battery swaps this unit has seen. I squished it with some Knipex pliers to make it tight again and reinstalled. I reran my testing, with no arcing and no overheating when running a 75% load (using a convenient multi-setting portable electric heater I find handy for such things) on and off battery. I didn’t leave it on battery for long since I don’t want to drain the new batteries, but I think it’s good to go.

Here’s a picture of the inside. Doesn’t look too bad for being nearly 30 years old!

I like the fact that the relays have clear housings. I was able to watch all of them operate, with no visible arcing or stickiness. One of my fears was that one of them was welded or intermittently sticking from contact material transfer, which would’ve required removing the main board, finding suitable replacement relays, and a decent amount of desoldering and soldering work.

I suspect this might be the last time I replace the batteries in this unit. I like the Eaton 5P UPS units I have elsewhere, especially since they have USB connections that work with NUT (Network UPS Tools). Replacing this old UPS with a 5P1500RT would not be a bad thing, and it would free up space to put a 1U Raspberry Pi rack in my office cabinet like the one I have in one of the basement racks. It would also homogenize my UPSes, which would be convenient from a monitoring perspective.

Kind of funny that Best Power, the company that made my old UPS, was eventually bought by Eaton, who is my preferred UPS maker today. Best Power made great stuff, and I’ve been very happy with my Eaton UPSes. I bought several Best Power UPSes back in the day based on a recommendation from a coworker (David Bolen at ANS), but this is the only one I still use and it’s been in continuous 24-hour use for decades. There are advantages to the lack of things like a backlit LCD screen: longevity.

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Office furniture: end tables for the window seat

I completed some end tables for the window seat. Same basic construction as the window seat: solid oak and dowel joinery. The tops have plywood support for the porcelain inserts. The feet are delrin, bolted on with countersunk 5/16″ stainless steel bolts going into threaded inserts in the legs.

Each end table can be latched to the window seat with draw latches that are installed on the underside of the top. When latched, they are VERY stable, basically making the window seat and end tables one large contiguous surface.

I am still waiting for more brown CableDrops from blueLounge, but the intent is to have a Lightning cable and USB-C cable readily accessible at each end of the bench. These run to chargers on the wall beneath the end tables. Right now I only have 20W chargers there, good for tablets or phones. If ever needed, I can swap in beefier chargers for laptops.

I still haven’t ordered a cushion for the window seat.

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Office furniture: customizing a store-bought wastebasket

I bought a wastebasket that caught my eye at The Container Store while I was there for bamboo drawer organizers. I took a picture of it while I was in the parking lot.

I knew I would need to use bags with it, but when I got home and put a bag in it, I felt it looked like ass. I wanted to hide the bag inside, and also hide the bag flap around the rim. So I lined the inside with some scrap 1/4″ oak plywood I had on hand, and made a drop-on collar out of solid oak to hold the bag in place and hide the flap.

The recess was intentional, so I could create a lid. I wanted a flat lid so that the wastebasket could be used as a tiny table (say for holding a book or my iPad when I doze off on the new window seat). I went with solid 3/4″ oak I had on hand (leftovers from one of the rolling drawer cabinets). I used finger holes instead of a handle, to keep it flat.

After stain and polyurethane, I wound up with this.

In hindsight, I could’ve just built the whole thing from oak scraps I have. But the store-bought wastebasket was the inspiration, and I’m very happy with the result.

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Office furniture: window seat/bench gains a drawer and fans

I recently installed the 3U fan panel in the window seat. It’s powered via a Kasa smart plug, so I can turn it on/off via HomeKit (usually using Siri). It’s quiet, but does a nice job. However, it came with ball bearing fans which I know will get loud over time. I’ll replace them with Noctua fans when they get loud enough to be annoying.

I also built and installed a wide wood drawer on 100 lb. drawer slides. I’m using it to store office miscellany. It has built-in finger-jointed dividers, but I also added some bamboo organizers from The Container Store.

I still need to order a cushion from rofielty.com. In the meantime I’m working on end tables to butt against the window seat.

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Office furniture: under-desk rack

I recently realized that I never posted pictures of the completed under-desk rack.

Hiding under the desks, where it normally lives.

I guess I never posted about what’s going on in this rack. There are two ethernet switches, a Ubiquiti US24 and a Ubiquity 16XG. They’re connected via a pair of 10G fiber connections with LACP. The 16XG is also connected to the 16XG in the basement via a pair of 10G fiber connections with LACP. I use the copper 10G connections in the 16XG in the under-desk rack for Mac Studios and a Threadripper 3960X Linux workstation in my office. I use the US24 for CalDigit docks (for wired laptop connectivity), Raspberry Pis, etc. There’s a patch panel for each switch that passes through to parallel patch panels in the rear. This lets me keep the cabling in the front super-clean (just short patch cables).

There’s a Middle Atlantic 3U fan panel in the rear, exhausting air. There’s an ancient Best Power UPS in the bottom that just keeps on working (with battery replacements every 3 or 4 years). There’s a Furman PDU in the top with pull-out LED lights.

It’s on casters, and can be rolled out easily to gain some work space (more than shown here). The top insert is porcelain, the same as the rolling drawer cabinets.

There is a lot of ventilation in the front door. The front window is scratch-resistant polycarbonate, but the door box is vented on all 4 sides. There are two layers of stainless steel mesh in the vents. One is coarse for strength, the other is fine to keep pet hair and dust bunnies out. The inspiration here came from a pie cooling cabinet in an old bakery I used to visit. The air flow in this cabinet is front-to-back, for the components and the CloudPlate.

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More office furniture: a second rolling drawer cabinet

This was mostly a duplicate of a similar cabinet I had already built. And I already had built the shell, but not the top or the base. It’s taller than the first, to allow for some shelf space. I finished it recently. No in-progress pictures or even nice pictures. 🙂 But it has 21U of rack space. 19U is consumed with old Middle Atlantic TD drawers. 1U is consumed by an old rack mount PDU. The drawers are much deeper front-to-back than the PDU. Hence 1U below the PDU is a blank, which allows space for wall warts to be plugged into the PDU. The shelves are on shelf pins, so it’s easy to get to the outlets on the PDU by pulling out the lower shelf. Having the PDU here let me mount my Lutron and Hue hubs on the wall next to the Unifi in-wall HD WiFi access point. The access point is powered via PoE, but the Lutron and Hue hubs use wall warts. The Hue hub lets me control the Hue table lamps and the Hue bulbs in the floor lamps in the den via HomeKit. The Lutron hub lets me control the recessed lighting via HomeKit. I have Lutron stuff elsewhere in the house, and all of it currently uses this hub for HomeKit control (usually via Siri).

I bought most of my Middle Atlantic drawers about 25 years ago. The price has nearly tripled since that time, so I’m glad I bought so many of them way back when. They were originally in two of my server racks and a pair of MDV-R12 cabinets. I’ve been repurposing them for years. They’re durable, they happily hold more weight than I’ll ever need to put in them, I can reconfigure as desired, and they look good to me. This cabinet has two 5U drawers with locks, a 4U drawer, a 3U drawer and a 2U drawer.

Below is the other cabinet that I mostly duplicated. This one was finished in July 2022 while I was still working on the floor (hadn’t finished the shoe moulding). It’s now on the opposite side of the French doors.

Both of these cabinets are on casters, so I can move them as needed. Both are solid oak with porcelain inserts in the top that are intentionally just taller than the wood frame. So when I slide something a bit off the porcelain, it doesn’t scar the wood frame.

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More office furniture: a bench

I’ve been working on a bench for the home office. I wanted something big enough for a short person like me to be able to lie down on (say while waiting for a make -j4 buildworld to finish on FreeBSD on slow hardware), and strong enough to outlive me and a now young oak tree to replace the wood I used.

I also wanted a little bit more drawer space. As is my penchant, I’m using Middle Atlantic TD rack mount drawers (all of my office furniture is sized to accommodate 19″ rack mounted gear). However, the bench spans the only HVAC register in the room (in the floor), and the combination of the position of the register and the width of the window bay meant that I could only put drawers in one side. For now I’m only occupying 5U of the 8U rack space, because I suspect I’m going to want a 3U fan panel to assist the HVAC when summer arrives.

The bench will be getting a cushion, of course. It is solid oak, with the base constructed of 4×4 legs and 2×4 stretchers. The top is 1 3/8″ thick oak butcher block (a workbench top), which I framed with 1×2 oak. It’s 61.5″ wide and 25.5″ deep. The height was dictated by the window sill; I didn’t want to block access to the handle in the lower window sash.

The feet are 1″ thick Delrin, bolted to the bottom of the oak legs via countersunk 5/16″-18 stainless countersunk bolts that thread into threaded inserts installed in the oak. I rough cut the Delrin, then mill the countersinks on the drill press. I then mark for the inserts in the oak.

I then drill the holes for the inserts and install them.

I then bolt the foot to the leg.

I then use a flush cutting bit on my trim router to make the feet match the leg, then run a roundover bit on the edges. Delrin/acetal machines like butter, even with woodworking tools. I use 1″ thick Delrin/acetal for heavy furniture feet, since it allows me to countersink the 5/16″-18 bolt heads more than 1/4″ (zero chance of the bolt heads contacting a floor for the next 75 years), while still having a lot of Delrin/acetal grabbed by the bolts. It’s not cheap, but it is fantastic for this application. If this were going on a wood floor I’d round over the countersink edges, but it’s going to live on porcelain so there’s no need. When I first used these kind of feet on the desks, I used 4 bolts. But 2 is plenty.

I have more than once considered UHMW instead, mostly for the cost saving. But it doesn’t machine quite as nicely, and it’s also not terribly dimensionally stable over temperature and humidity. Of course, neither is wood, but oak sealed with shellac and polyurethane doesn’t move much. And importantly, all of the weight is sitting on the feet. I don’t want them to squish over time. My desks are REALLY heavy, but the feet have held up beautifully. Honestly, if your design affords it, I can heartily recommended Delrin/acetal for feet. But even if you don’t use Delrin/acetal… replaceable feet are awesome. Here they’re on square oak 4x4s, but Delrin/acetal is also easy to lathe if your leg ends are round.

The top also has threaded inserts in the bottom, and the base pieces bolt to the top via countersunk 5/16″-18 bolts through the stretchers from underneath. The next picture shows one of the bolts (washer not shown) threaded into one of the inserts, and an insert installed into the bottom of the top.

The next picture shows the deeply countersunk holes in one of the top stretchers (the bench is upside down here). This is from before I glued and doweled the base pieces together.

The left part of the base is doweled and glued (Titebond III) together, as is the right leg assembly. It looked like this after assembly.

The bench is heavy even without the drawers (I’d guess about 75 pounds), but the Delrin feet allow the bench to glide easily on the porcelain floor when desired.

I am one of those people that likes really solid bench seating and bedding. Something that doesn’t flex or squeak, at all. And doesn’t move unintentionally but can be moved easily as needed. And can be disassembled/reassembled should it need to be carted up/down stairs. And fits the intended space exactly.

Objectives met.

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Building custom desks: the first one is done!

First desk done before room is done.

In every failure is an opportunity: a learning experience. Patience and persistence lead to success. That’s basically the story of my desk saga.

This saga started a long time ago, with haggling over what would be appropriate aesthetically versus what I can’t live without in a home work space. Honey, I love you so much for making so many compromises. And for letting me crowd the room a bit so we can each have a desk in this room and work alongside each other. And for choosing and buying the wool rug and pad we’ll have in there!

There’s a big upside to the approaching end of this saga: we’re getting some fairly nice custom matching desks for the home office. Made from scratch by me, from my detailed SketchUp drawings all the way to final assembly and finishing. Solid oak and polished PEI 5 porcelain touch surfaces, solid oak structure, acetal wear surfaces (the feet). Each desk breaks down into 4 very strong pieces. The top has eight threaded inserts for recessed bolts in the base pieces that hold the top to the base pieces. Each of the base side assemblies connect to the rear base assembly with 2 guide pins and flanged leaded bronze bushings for alignment and 3 long stainless recessed hex head bolts from the side assembly into dowel nuts in the rear base assembly.

Two power strips are mounted to the bottom of the top in the rear (plenty of room for those pesky wall warts and 18 total outlets).

The desks are substantial. I can sit on them. I can stand on them. They’re heavy, yet they’re not difficult to move due to the acetal feet and porcelain floor. They’re a good size: the tops are 70″ long by 36″ deep. They don’t scream ‘computer desk’ except for the over-bridges (which aren’t attached to the desks and are hence ‘optional’). No cable grommets. Easily repurposed as a large reading desk or craft desk.

This whole experience was a gamble. While I trust my ability to build things, I had no luck finding any stories about someone using very large porcelain tile in a desk top. I’m sure I’m not the first one to do something like this; I just wasn’t able to find anything.

This made for some guesswork with what I needed to do in order to bring the odds of cracking the porcelain to an acceptable low. I’m very familiar with porcelain flooring deflection requirements, but this isn’t a floor; the static load is low, and the dynamic load is very low. And there are tradeoffs for weight, total thickness, space for support, etc.

The porcelain is very dimensionally stable. The water absorption rate is minuscule at .5%, and it’s very dimensionally stable versus temperature. The solid oak, on the other hand, will contract and expand a bit with changes in humidity and temperature. And the plywood is between the solid oak and the porcelain in terms of dimensional stability.

I didn’t want cement board (weight, thickness). I didn’t trust Ditra here, mainly the bond to the substrate. Floors don’t get inverted, but a desktop could when breaking it down to move.

I wound up with 1.25″ of total plywood thickness under the porcelain: 1/2″ BCX plywood glued and screwed to 3/4″ oak plywood. The porcelain is adhered to the BCX plywood with SikaBond construction adhesive. It retains some flexibility when fully cured, which allows the wood to expand and contract but not lose bond with the porcelain. The frame of the top is 1″ thick solid oak pieces, glued and doweled together as a full assembly before gluing and screwing it to the top of the 3/4″ oak plywood (edging the 1/2″ BCX plywood and standing proud of it to allow the porcelain insert with adhesive). The porcelain is intentionally recessed a little bit; if I spill my coffee on the porcelain, it’ll mostly be contained on the desk. The edges of the 3/4″ oak plywood are concealed with 3/4″ x 3/4″ solid oak pieces that are glued and 18-gauge nailed to the 1″ oak frame. Hence the total top thickness is 1.75″.

I love the desk. It’s super strong and rigid. It has enough mass to avoid monitor shaking. It accommodates the Mac Studio exactly as I intended. My keyboard, trackpad and wrist rest fit under the shelf in the over-bridge. The porcelain should be impervious to my watch bands, writing instruments, coffee spills and sweating cold drink rings.

It’s also satisfying to have gone all the way from this detailed SketchUp drawing I created from scratch:

Desk design in SketchUp.
Lots of fasteners in desk design in SketchUp; dowels, pocket holes, steel guide pins into leaded bronze bushings, threaded inserts, stainless steel bolts into dowel nuts, wood screws.

To a completed desk and overbridge.

Mac Studio on one of the desks I created from scratch.
Mac Studio on the first desk I completed.

I am coming from a Middle Atlantic ELUR 84″ wide edit center desk. I’ve had it for ages. Functionally it’s been great. Aesthetically, not so much. MDF with laminate top and edged with plastic. It’s too big for the den where I want two desks, and definitely too ugly. There was a time that it spoke to me, at the right price, for my work desk. That time has passed.

However, I did take a tiny bit of inspiration from the ELUR. The distance between the side leg assemblies is similar. As is the ability to disassemble the desk (though my fastening is much more robust). The over-bridge height is about the same.

But I wanted a spot to hide away my keyboard, trackpad and wrist rest and didn’t want racks in front of me. I wanted natural looking materials. I wanted a very durable but aesthetically pleasing top surface. I wanted the over-bridge to be optional. I wanted something I could scoot on the floor without damaging the floor or the desk. And I wanted sort of a materials theme to this room. The floor is wood-look porcelain. The walls, built-ins and french doors are wood. So despite the desk porcelain being very different than the floor porcelain, the desk follows the theme: oak and porcelain.

One of the great things about being a ‘maker’ as a hobby instead of as a professional: build what you want or need, on your own timeline, with your own budget for time and money. And today we’re sort of in a golden age for makers thanks to the widespread availability of information, from how to use free or inexpensive CAD software to how to use various power tools to ordering custom machined parts online to how to get started and advance with 3D printing.

In the case of these desks I created, the ability to create detailed SketchUp drawings was very valuable; even the pocket holes are in the drawings. This gave me the reference I needed when I finally started the build. When you’re doing this in your precious ‘spare’ time, it could take many months to complete. A week of workdays between time to spend on woodworking generally erases memories of measurements, etc. And in my particular case, the ‘engineering’ part of the desk creation is as much if not more fun than the actual assembly. There are more opportunities to be creative at no cost other than time and the electricity to run the computer hosting the drawing software. I spent a LOT of time on the drawings, tweaking and refactoring until I had something I was confident would meet all of my desires. Doing this, and being able to drop the desk model into a model of the room with the other furniture I created, was very powerful and very satisfying.

It’s probably worth noting that all of my revisions are in one of my repositories. Which makes it kinda fun to see what I did over time.

This post is too long. The gist: big effort, but I’m really happy with the result. The same is true for the under-desk rack (I’ll post about that later) and the first of two rolling drawer cabinets (I’ll post about those later too).

There are various random pictures of the desk(s) during construction and completed here:

Desk photos

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Making my own office furniture: part 8

I haven’t posted a furniture update in a while…

Desk #2 has been done for a while now. It’s in the den. I love it. I’m not using it yet, because I need Desk #1 to be done before I migrate my office to the den. But every time I walk by that room, I wind up walking in there to see the completed desk and run my hands over the porcelain and oak.

The base of Desk #1 has been done for a long time. It was done before I started Desk #2, but I wound up completing desk #2 before returning to work on Desk #1.

I’m now in the process of building the top for Desk #1. The base has been done for a long time. Tonight I routed the final edge of the top and flipped the top upside down on the bench. I then assembled the base on top of it so I can mark the bottom of the top for the threaded inserts. As a reminder, the desk breaks down into 4 pieces. Threaded inserts and bolts hole the top to the base, and the 3 parts of the base are connected via long bolts into dowel nuts and aligned via guide pins into bronze flanged bushings.

I’ll post something outside of this thread about what I think about these new custom desks.

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Making my own office furniture: part 7

I bought 11/32″ plywood at Home Depot and another quart of Minwax satin wipe-on polyurethane at Menard’s.

The plywood will be used as underlayment for the porcelain tiles inset in the top of the under-desk rack cabinet. I cut it to size, checked the fitment, and marked it for screws. It will be screwed and glued (TiteBond III) to the existing plywood of the top.

The tiles in the top are 17+7/8″ square. I’m using one whole one and one that I cut to 8+1/4″ width tonight on the tile saw. I slightly beveled the edge after cutting. The plan is to use Loctite PL Premium MAX to adhere the tiles to the underlayment. This isn’t a floor, and in fact in its intended use it will never have anything on top of it. But if we ever decide we don’t want it to live under the desks, it will make a nice robust top. The tiles are PEI 4, which should far outlive me for a table top. I like porcelain table tops, since they’re impervious to water and heat. If they’re PEI 4 or PEI 5 porcelain, they’re also nearly impossible to scratch. Easy to clean, sanitary, etc. I’m not going to use epoxy grout here, but that’s an option when desired.

I think this cabinet is quite nice for it’s intended purpose. I went a little overboard in the mix of materials and the front door design, but that’s the advantage of designing and building your own stuff from raw materials and parts. You can take your time and get exactly what you want, without compromising in areas that matter to you.

Looking back at this, there’s an unconventional mix of materials and components in this cabinet design. It’s a computer rack designed for a specific set of gear arranged in a particular manner, so it has rack rails front and rear. It has casters. Neither of those are unconventional. But then the cabinet itself is made of edge-glued solid oak panels (not steel, not MDF). It has a skirt to hide the casters. It has a very unconventional front door, to show the gear in a subdued manner (tinted scratch-resistant polycarbonate) and vent from the sides, top and bottom of the door. The door has solid brass butler tray hinges. It has marine grade solid brass hold down latches to hold it shut. It has a guide pin and leaded bronze bushing to make it self-center every time it’s closed. The ventilation holes are covered with filters inspired by an antique pie safe I saw in a bakery 20 years ago. The bottom of the inside is covered with a piece of UHMW so it’ll be easy to get my UPS in and out without using rack slides. The top is porcelain framed in solid oak.

You can’t go out and buy this kind of thing at a store. You could commission it, but given the amount of time I spent on the design in SketchUp, it’d be expensive. But you can build it. It requires patience, persistence, and multiple skills (and tools). But that last part… we learn by doing. If you’re not afraid to fail, you can build just about anything. And as a software engineer, I really appreciate the fact that I can spend no money on materials until I have the design nearly completed in a 3D drawing on my computer. The execution of the design just follows the drawing.

The desks I’m building follow a similar pattern. The Delrin (acetal) feet aren’t typical. Nor is the porcelain top (I couldn’t find anything on Google with respect to building a desk with an inset porcelain slab). Nor is the combination of joinery I used (dowels, pocket holes, guide pins and leaded bronze bushings, dowel nuts with long bolts, threaded inserts).

Porcelain tiles of the size I’m using are relatively new here in the U.S., and given that I’m not running stringers under the top, could be considered ‘risky’. But my fear has been allayed by handling the tiles. Despite the fact that they’re 60″ long and 30″ wide but only 6.5mm thick, I’ve not broken one just carrying them around like pieces of plywood. And they will flex a bit without cracking. I do have suction cups for placing them, but I haven’t needed them for general handling. And it’s desk tops, not workbenches. I won’t be hammering on them, nor putting a ton of weight on them. There’s 1.25″ of plywood underneath, and 1″ thick solid oak bordering. The top will be on a very strong base. I don’t think the porcelain is going to crack on me. And it’s sanitary, PEI 5 (nearly scratchproof), impervious to any fluids I’d have on my desk (coffee, water, juice), and easy to clean. It looks like polished marble but it’s manmade (didn’t require carving up the planet). It can’t be dented by writing instruments. It won’t be bothered when I spill candle wax on it. My watchbands won’t scratch it. It doesn’t care about sweat, and in fact it’s a comfortably cool surface to rest your forearms on. I can adhere things to it (cable guides, phone dock, etc.) and later remove them with no damage whatsoever.

Risky? Perhaps. But from risks come rewards and learning experiences.