Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Mary has been quilting up a storm lately and wanted a larger surface to handle a bed-sized quilt. A table in the basement was big enough, but she wanted a larger flat surface around the sewing machine adjacent to the table.
I converted the typing return (*) from her upstairs desk into a table, then cut a piece of aluminum-clad 1-inch foam insulation board to fit. It’s 4 feet long, a convenient length to cut from the 4×8-foot insulation board, and slightly narrower than the typing return. Cutting it required a long X-Acto knife blade, but a really sharp utility knife would work as well.
Some stainless-steel tape finished off the edges. The tape itself is lethally sharp-edged, but it’s perfectly harmless if you do a good job of smoothing it against the foam board…
A pair of closed-cell rigid foam blocks held one end of the board at the proper height around the sewing machine, while a pair of cutoffs from the wood pile were just the right thickness & length to extend under the other end. It turns out that precise height isn’t nearly as vital as we expected; close enough is fine.
I cannibalized a pair of table-saw feed roller stands for this project; they had just the right height adjustment and shape to support the typing return and the foam board.
The end result aligns the surface of the sewing machine with both the top of the table and the surface of the foam board. The quilt slides easily over the whole affair and doesn’t bunch up like it did before. Success!
Foam support blocks
(*) A “typing return” is the little table that sticks out from a desk, upon which you put a typewriter, back in the day when typewriters ruled the land. Nowadays, she uses it for her sewing machine, which normally lives at her desk, because there’s no practical way to type at right angles to one’s desk.
That’s the sort of item you can’t do web searches for, because all the terms are so heavily overloaded. Give it a try; you’ll find one or two useful hits. There’s a difference between syntax and semantics; we’re not in the semantic web yet by long yardage.
I don’t do any fancy 3D milling, so it takes a lot of Z-axis backlash to get my attention. While setting up for some circuit-board drilling, I finally noticed that the backlash far exceeded even my slovenly specs: something like 20 mils.
The Z-axis backlash adjusting nut on the saddle was as snug as it usually is. Heaving on the saddle, though, pulled it up & down and moved the handwheel on the top of the Z-axis motor.
Ah-ha! That says the leadscrew itself is moving, which shouldn’t be possible because it’s captured at the bearings in the stepper motor mount.
Some tedious disassembly later, the top picture shows the Z-axis leadscrew and motor mount, with the nut obviously too far away from the lower ball bearing housing. The nut was finger-loose and I moved it while extracting the leadscrew; it’s supposed to be snug against the bearing in normal operation.
The solution is a drop of Loctite, which should be applied to the canonical “clean and dry” threads. Hosing this part of the leadscrew down with solvents isn’t a good idea, because you don’t want any inside the lower bearing in the motor mount, so I spent some Quality Shop Time spinning the threads against a (dry) rag, running the nut to the other end (all of a few millimeters), and repeating until most of the oil was gone.
Properly adjusted nut
Sherline documents how to assemble & install the motor mounts, so there’s not much mystery involved. I loosened the preload nut until the housing spun freely on the shaft, then tightened it a teensy bit; the housing still spun freely and there’s no detectable end play.
Reinstallation requires putting the motor mount at the same spot on the Z-axis column as before. I moved the saddle to the top of the column, ran the leadscrew into the saddle nut, and then tightened the motor mount screws. That allows the mount to move to suit the saddle nut’s position, rather than going through the tedious saddle alignment process I mentioned as part of the gib adjustment.
It’s all good… call it 3 mils of backlash on all three axes.
Memo to Self: It’s possible to run the Z-axis backlash adjusting nut off the top of the leadscrew thread, then re-engage it without removing the motor mount. The trick is to hold the anti-backlash nut firmly against the saddle nut while turning the leadscrew to engage the thread. Remember that it’s a left-hand thread…
Mary picked up a rather well-used wooden-dowel clothes drying rack at a tag sale for essentially nothing; one of the dowels was missing. That’s easy enough to fix, as I have a stash of dowels from what seems to be another rack of the same type on my wood stockpile…
Of course, those dowels are just an inch or two shorter than needed.
So…
Turn down the ends of two dowels to 0.29″ x 3/4″ to fit the holes in the support struts
Sand a small taper on the ends
Pull the staples, insert the longer dowel and mash the staple back in place
Eyeball the length of the other dowel, hacksaw to fit, install similarly
Find a length of brass tubing that slips over the dowels
Cut some heat stink shrink tubing to fit
Spliced dowels
I used urethane adhesive, because it expands as it cures and will fill the gaps inside the brass tubing. The heat stink tubing is just for nice… although it does make for a rather stunning contrast to the aged wood dowels, I’ll agree.
And it’s all good!
(Use it up, wear it out, repair it, wear it out again, then save the pieces because they’ll come in handy for something else.)
This Philips LumiLED app note gives some specs on automotive lighting. The one we bikies all tend to ignore is the surface area: greater than 37.5 square centimeters for rear combination stop-turn fixtures. Call it a scant 4 inches in diameter. You’ve never seen a bike light that large, have you?
LED combo tail stop light
Maybe the right thing to do is start with a street-legal truck light and build some electronics around it. This is a 4 inch diameter, 44 LED rear light with both taillight and brake light terminals. At 12 V, the taillight draws 10 mA and the brake light is 250 mA. Got it from Gemplers with a recent order, but they’re certainly not the optimum supplier if that’s all you’re buying.
Obviously, it’s unreasonable to run a 3 watt taillight on a bike, as the most recent crop of single-LED killer headlights are merely a watt or three. Battery life remains a problem.
At 10% duty cycle the brake LEDs would average 300 mW. That might be roughly comparable to the running lights on some cars these days.
With the taillight constantly energized and the brake flashing at 4 Hz, it’d be 120 + 0.5 * 300 = 270 mW.
That’s more reasonable. With a 50% efficient upconverter to 12 V, that’s half a watt. Start with 4 AA cells, triple the voltage, draw 100 mA, runtime is 1500 / 100 = 15 hours. Good enough.
And it ought to be attention-getting enough for anybody! The only trouble will be fitting the damn thing on the back of the bike; fortunately, ‘bents have plenty of room behind the seat, so maybe attaching it below the top seat rail will work.
Memo to Self: The rear reflector must be something like 3 inches in diameter, too. We ignore that spec, too.
As mentioned there, removing a water heater anode rod generally requires considerable, umm, persuasion. I used a 12-point socket wrench, as I didn’t have a 1-1/16″ impact wrench on hand. Now I do…
The first pic shows the head in front of the two sockets; the 6-point socket on the right will do a much better job of not ruining the anode rod bolt head because it grips along the entire length of all six sides.
Now, in general, you don’t care about ruining the head, because the rod’s pretty much not going to be there by the time you remember to check it. What you do not want: the wrench rips the corners off the head before loosening the thread.
Goobered anode rod headGoobered anode rod head – side view
The thread on this anode rod was in great shape (I’d wrapped it in Teflon tape the last time it was out), but it was still firmly jammed in place. These pix show what the 12-point socket did to the bolt head during the beatdown.
Bottom line: right now, while you’re thinking about it, buy yourself the nice 6-point 1-1/16-inch impact socket you’ll need to extract the anode rod from your water heater. If you don’t already have a honkin’ big breaker bar, get one of those, too; this is no job for a sissy 3/4″-drive ratchet wrench.
The real problem is holding the water heater in place while you beat on the breaker bar. I have yet to see a good solution.
Offset Tank – 2009
That husky 6-point socket isn’t going to fit into the stupidly offset hole in the top of the water heater, even after applying the nibbling tool to get the 12-point socket in place, but that’s in the nature of fine tuning…
Removing a water heater element is no big deal: apply the appropriate socket (1-1/2 inch for this heater) to the hex head and turn it out. The trouble comes during installation, when you must hold that long rod exactly horizontal inside the tank, gripping the electrical fittings inside a narrow access port amid all the insulation.
My fingers can’t hold the element horizontal and twist it at the same time, so I made a tool: cross-threading the heating element and goobering the threads in the tank port is not an option!
Improvised heating element installation tool
A 32 mm socket just cleared the square blue electrical insulation block and butted against the 1-1/2 inch hex head. Because the block is square and the socket is hex, it was a pretty loose fit, but this was the right general idea.
I put a layer of masking tape on the inside of the socket and covered the electrical connections on the element.
Then I mixed up a batch of Bondo auto-body repair epoxy, buttered up the end of the heating element, and gooshed it into the socket. The Bondo filled in the gaps between hex and square, turning the wrench into a custom-fit tool that firmly gripped the heating element.
Reinstalled heating element
A brief pause for Bondo curing, pop an extension into the socket to use as a handle, return to the water heater, and screw that sucker right in place. Worked like a charm!
There’s a flexible gasket sealing the element to the tank port and I gave the element a few degrees more twist when I tightened it up, so the insulation block isn’t neatly aligned.
Getting the socket off wasn’t too difficult: twist to the side, pull, and the Bondo pops off the masking tape. Peel the tape off the element and it looks pretty much like it did before. The Bondo fell out of the socket when the element came out, so that was easy enough.
I was busy getting the water heat back in action and didn’t take any detailed pix, but I think you get the idea…
While draining the water heater tank, I extracted the anode rod. Well, that was the plan; it took longer to drain the tank than I expected and much longer to get the anode rod out.
The anode rod is basically an aluminum cylinder around a steel-wire core, attached to a steel bolt that screws into the top of the water heater. It has a 1-1/16″ hex head that calls for a rather large socket.
You can see one problem right away: the anode rod’s head is offset in its opening atop the water heater, making it essentially impossible to get an ordinary 1-1/16″ socket onto the thing. No, they didn’t mis-punch the hole… notice that the cold water inlet nipple is offset in its opening. The hot-water nipple is offset, too, just in case you were wondering.
Why is that? Well, the one thing that isn’t offset is the temperature & pressure relief valve on the right-front side of the tank. It seems when Whirlpool’s engineers were tasked with adding more insulation to the shell to get a better efficiency rating, they forgot that T&P valves don’t have arbitrarily long stems. Thus, the inner tank is offset within the shell so the T&P valve can reach outside.
Of course, that means the insulation is thinner on the right-front than the left-rear, you can’t extract the anode rod, and the inlet & outlet nipples rub against the top cover, but so what?
Offset Tank – 2003
The photo is of the Whirlpool water heater I just installed, but it’s identical to this one installed back in 2002 and another installed in 2001 (the one that recently failed). They haven’t seen fit to correct the holes in the top cover in the last seven or eight years:
This on a $400 water heater. “Made with pride in the USA”, indeed.
Anyway, when I installed the heater, I applied a nibbling tool to the top cover and gnawed an opening sufficient to get the socket in and the anode rod out. When I checked the rod in 2004 (after two years), it was corroding, but that’s the way it’s supposed to be: it’s working!
Missing Anode Rod
The recommended inspection interval is three years, but I admit I let it slide for five, based on what I saw earlier. Well, this time the anode rod was well and truly stuck. I eventually clicked an 18-inch breaker bar into the socket and wailed on the end with a two-pound hammer; after far more beating that I really liked, the bolt head loosened and the whole affair unscrewed easily and came out without further protest.
Behold, there’s no rod attached to the head!
I used a 12-point socket for this operation, but I have a six-point impact socket arriving shortly ($0.99 from eBay, plus $2 shipping). A 6-pointer has the advantage of applying force along the sides of the hex head, rather than just the vertices, which reduces the risk of stripping the head. Been there, done that, you’d think I’d learn from my experience, but I needed to get that thing out so I could proceed with the sediment extraction.
[Update: More about why you really want a 6-point socket there.]
There was an ominous clank inside the tank while I was massaging the breaker bar with the hammer. Peering down inside the tank through the rod hole, I spy the remains of the rod standing against the lower heating element, atop the expected pile of sediment in the bottom which is clogging the piddly little drain valve. It’s like looking into the Titanic’s dining room through a rivet hole.
Turns out that the rod had broken off quite some time earlier. After better than an hour of laparoscopic surgery through the lower heating element port, I finally extracted the rod: it was bent double, which means it had been standing upright for a while and eventually folded over. The long section to the right is actually two rod cores folded against each other; the far right end has a neat U-bend.
Corroded anode rod core
OK, I shouldn’t have left it slide for that long…
So it goes. Leaving the rod across the heating element seems like a Bad Thing, plus I should get the rest of the sediment out of the bottom. That’ll be easier if I can flush the tank through the lower element’s port.
I picked up a new magnesium rod at JD Johnson, a local plumbing outlet, for $28. That’s far less than at Water Heater Rescue, an invaluable source of information on the subject. The rod is 36 inches long, half a foot less than the 42 inch original, but that’s close enough; given the limited headroom, it’s easier to get into the tank.
Removing the lower heating element requires a 1-1/2″ socket and the courage to cut back the insulation packed into the element port. More on that tomorrow…
The Smell of Molten Projects in the Morning 