The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

Author: Ed

  • Unit Pricing Obfuscation: Nothing Exceeds Like Excess!

    Walmart Tissue Unit Prices
    Walmart Tissue Unit Prices

    What with this being allergy season, my ladies blew through our tissue stockpile in short order and it’s time to reload. Give that we’re just blowing our noses it in, deluxe-edition tissue paper isn’t a priority, but these Wal-Mart unit-price stickers are not nearly as helpful as they could be…

    Hints:

    • The second label is for a shrink-wrapped block of three boxes.
    • The bottom label is for a name-brand tissue that’s unit-priced per sheet.

    Exercises:

    • Which container has the least expensive sheets?
    • The most expensive?
    • Is the 3-pack more or less expensive than a 1-pack?

    Essay: why do you think Wal-Mart does this?

    More unit pricing grumbling.

  • Continuous Flow Inkjet: Tank Topoff

    Just topped off the tanks again…

    • Yellow: 30 ml
    • Light Cyan: 20 ml
    • Cyan: 27 ml
    • Light Magenta: 22 ml
    • Magenta: 30 ml
    • Black: 30 ml

    Back in February I added 40 ml to the Black tank.

    The odd numbers are what was left in the bottom of the bottles

    Memo to Self: That’s about 8 oz = 250 ml of each color and 500 ml of Black since getting the printer in late Dec 2007. Figuring OEM ink at $2/ml: $3500. Current bulk ink cost is on the order of $20/bottle: $140. The continuous ink system was about $50 back then and $100 now.

    The backstory.

  • Chipmunk on High Alert

    The chipmunks are busy cleaning up all the maple seeds from the driveway, but, being chipmunks, they like to stay near a safe spot.

    The absolute best spot to watch for danger seems to be the 4-inch PVC pipe I attached to the garage downspouts: you can see out, but when a threat appears you can run up the downspout!

    [Update: the Cooper’s Hawk just swooped on a red squirrel, missed, and landed on the patio railing as the rodent vanished up the pipe.]

    Chipmunk peering from drainpipe
    Chipmunk peering from drainpipe

  • Sherline Tool Table

    Having recently converted to EMC 2.4 and switched the tool table to the new format, I took the opportunity to add a few useful drills.

    Low numbers are random end mills & suchlike. Number drills run from 100 to 180, and I’ll add more as I need ’em. Fraction drills run from 201 through 264, although it’s highly unlikely I’ll ever fit a 64/64-inch drill in a chuck that also fits in the Sherline spindle.

    All the Z lengths are exactly 1, because I now have a tool length probe that is absolutely wonderful.

    In practice, I use the tool table mostly to tell Axis how to draw the tool cylinder in the backplot, because I feed in most diameters directly in the G-Code. The Axis “manual toolchanger” routine prompt will now serve as a mnemonic for the actual size, but I write the G-Code to emit a (debug, #Drill_Size) message for clarity.

    The  Sherline.ini file references the tool table with the line:

     TOOL_TABLE = Sherline.tbl

    Herewith, Sherline.tbl:

    ; Common end mills
T1 P1 Z1 D0.1225    ; 1/8
T2 P2 Z1 D0.1535    ; 5/32
T3 P3 Z1 D0.187        ; 3/16
T4 P4 Z1 D0.25        ; 1/4
T5 P5 Z1 D0.3122    ; 5/16
T6 P6 Z1 D0.374        ; 3/8
T7 P7 Z1 D0.4374    ; 7/16
T8 P8 Z1 D0.4720    ; 1/2
T20 P20 Z1 D0.09787 ;  2 mm
; Number drills
T107 P107 Z1 D0.201 ;  7     5.11    10-32 clear
T109 P109 Z1 D0.196 ;  9     4.98    10-32 clear
T118 P118 Z1 D0.170 ; 18     4.32     8-32 clear
T121 P121 Z1 D0.159 ; 21     4.04    10-32 tap
T127 P127 Z1 D0.144 ; 27     3.66     6-32 clear
T129 P129 Z1 D0.136 ; 29     3.45     8-32 tap
T136 P136 Z1 D0.107 ; 36     2.72     6-32 tap
T132 P132 Z1 D0.116 ; 32     2.95     4-40 clear
T143 P143 Z1 D0.089 ; 43     2.26     4-40 tap
T141 P141 Z1 D0.096    ; 41     2.44     2-56 clear
T148 P148 Z1 D0.076 ; 48     1.93     1-72 clear
T150 P150 Z1 D0.070    ; 50     1.78     2-56 tap 0-80 clear
T152 P152 Z1 D0.064 ; 52     1.63     0-80 clear
T153 P153 Z1 D0.060 ; 53     1.52     1-72 tap
; Letter drills
T203 P203 Z1 D0.047 ;  3/64     1.2     0-80 tap

    It turns out that the tool table has an undocumented limit of 50-some-odd entries, at least in EMC2 2.4.1. That puts the kibosh on my plans to add a bunch of entries to cover all the drill sizes Eagle might require for a PCB. More on that in a while …

  • Monthly Aphorism: On Cleaning

    • If you have to move it to clean behind it, don’t move it.

    Dad knew that most dirt wasn’t particularly harmful, so he didn’t worry about it. If you had occasion to move something for whatever reason, that was the appropriate time to break out the vacuum cleaner (or shovel) and deal with whatever you find, but there was never a reason to go looking for trouble.

    Of course, I feel the same way. Equally of course, this drives my esteemed wife crazy…

  • New Tires for the Van: Overtightened Lug Nuts

    The shop spec says the lug nut torque shall be 104 newton·meter or an equally odd 77 lb·ft. Let’s not get into quibbles about the differences between lb·ft and ft·lb here, OK?

    Anyhow, based on the wildly differing and grossly excessive tire pressures left by the guys who installed the new tires, I figured the lug nuts would be over-torqued… as, indeed, they were. My bending-beam torque wrench goes up to 140 n·m and didn’t even come close to breaking those puppies loose.

    So I deployed a manly breaker bar and applied most of my weight to the far end. A back of the envelope guesstimate says they were well over 200 n·m, with a few grunt outliers.

    Yes, the breakaway torque can be higher than the tightening torque, but they were far beyond even that level.

    Lubed the threads, tightened to spec, and it’s all good. I’ll check them next week just to be sure, but sheesh if we had to fix a flat on the road, it would have gotten ugly.

  • Do You Feel Lucky Today?

    Drugs by Nostrum
    Drugs by Nostrum

    Just got a new shipment of dope from our usual mail-order med supplier. The new dope comes in a livid red capsule, a disconcerting change from the previous green.

    So, being an educated and somewhat wary consumer, I check the label to see what’s new. It seems my supplier is dealing from a new manufacturer!

    Hitherto, I’d only encountered the word nostrum in phrases preceded by words like quack. The dictionary definition, at least for some values of dictionary, seems to back that up:

    Noun

    Nevertheless, Nostrum Pharmaceuticals appears to be a legit concern.

    There’s a reason why big companies spend all that money to come up with names that are equally meaningless in all known languages…