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.

Tag: Improvements

Making the world a better place, one piece at a time

  • MakerGear M2: PETG Filament Indentations

    Running some PETG filament through the M2’s new V4 extruder drive produced nice indentations from the drive gear:

    PETG filament indentations - front view
    PETG filament indentations – front view

    The square-looking indentation at the far left came from having the filament sit unmoving for an hour or so. There’s a smaller indentation to the left of that from a partially engaged gear tooth.

    The side view:

    PETG filament indentations - side view
    PETG filament indentations – side view

    That’s with the adjusting screw cranked 1/2 turn inward from what felt like first contact.

    It’s an M4 screw with 0.7 mm pitch, so each turn moves the extruder pressure arm 0.35 mm. However, the bearing actually pressing the filament against the drive gear is 1/3 of the distance from the fulcrum to the screw:

    M2 V4 Filament Drive - front view
    M2 V4 Filament Drive – front view

    Sooooo the bearing should move more-or-less 1/3 as far as the screw, modulo the arm bending, the fulcrum not actually being a pivot, and suchlike: 0.35 mm at the screw should push the gear 0.1 mm into the filament.

    Squinting at the filament through a measuring magnifier says the indentations are 0.30 mm deep, which means the screw moved 1.0 mm after the actual “first contact” with the filament. That’s not surprising: PETG filament seems soft and easily indented, the force required to dent the filament doesn’t amount to much, plus there’s plenty of mechanical advantage from my fingers through the screwdriver to the filament.

    Turning the screw another half turn certainly won’t mash the drive gear teeth another 0.1 mm into the filament, though, because the force increases dramatically as the dent goes deeper into the filament.

    Compare that to PLA filament through the V3 extruder, back in the day:

    M2 extruder - filament embossing
    M2 extruder – filament embossing

    Looks more or less the same to me, but there’s no way to tell at this late date.

    That blue tube anchors the filament guide and keeps the whole affair from thrashing around as the extruder zips back & forth along the X axis.

  • MakerGear M2: 24 V Fans

    My M2 dates back to early 2013 and arrived with a 12 V platform power brick and a 19 V brick for everything else. I replaced the platform with a hotrod version, used a DC-DC SSR to control the high-current path, drove it from a 48 V brick dialed back to 40 V, and left the 19 V brick alone.

    Recent M2s use a single 24 V brick for everything, including the motors and V4 hot end, so I decided to ditch the 19 V supply when I installed the new hot end. The stock 12 V fans depended on PWM to reduce the 19 V supply to something tolerable, but, with 24 V ball bearing fans being cheap & readily available, I replaced all three.

    I bashed a pair of angled brackets from a random heatsink fin to hold the extruder & platform fans together:

    M2 V4 Extruder - 24 V fans
    M2 V4 Extruder – 24 V fans

    All of that hangs from the single screw in the lower left corner of the upper fan, which has worked well enough and never given any trouble, despite my misgivings.

    They’re much quieter than the original fans, perhaps as a result of operating at their rated voltage without PWM trickery. In theory, the fan mounted horizontally in the electronics box should survive longer with ball bearings, but the original sintered-bearing fan didn’t complain too much.

  • MakerGear M2: Under-Gantry LED Lighting Clip

    The V4 hot end reduced the clearance under the X-axis gantry to the point where a bight of wire from the white LED panels drooped onto the platform during homing. A bit of snipping, drilling, and filing produced a clip from the same steel strap that’s holding the Z-axis switch cable against the gantry:

    M2 Gantry - LED wire clip
    M2 Gantry – LED wire clip

    That was easy…

  • MakerGear M2: V4 Nozzle vs. Re-Relocated Z-axis Switch

    Mounting the Z-axis platform switch on the X gantry to sense the actual platform position worked perfectly with the original MakerGear V3 hot end, at least after I relocated the switch a bit further from the balance point. It does require moving the nozzle off the platform before homing the Z axis, for the obvious reason:

    M2 Z-min switch - center gantry - in action
    M2 Z-min switch – center gantry – in action

    The smaller MakerGear V4 hot end uses a completely different mount that puts the nozzle higher than the switch lever:

    M2 V4 hot end vs platform Z switch
    M2 V4 hot end vs platform Z switch

    The clearances were close enough to rule out plastic, so I bandsawed some 33 mil (1/32 inch) brass shim stock and drilled holes in the appropriate spots:

    Brass switch bracket - drilling
    Brass switch bracket – drilling

    After discovering the blindingly obvious fact that you can’t heat brass sheets clamped to a steel vise enough to melt silver solder, I padded the brass with cardboard insulation and tried again:

    Brass switch bracket - clamped for soldering
    Brass switch bracket – clamped for soldering

    The cardboard charred and burned and stank up the shop, but held everything in alignment long enough:

    Brass switch bracket - soldered
    Brass switch bracket – soldered

    A bit of file & sandpaper work shined it up just fine, then I slotted the lower mounting holes enough to accommodate 2-56 nuts between the gantry and the bracket:

    Brass switch bracket - mounted - front view
    Brass switch bracket – mounted – front view

    Yeah, I could tap 2-56 holes into the brass sheet, but let’s be reasonable: two turns does not a secure fitting make.

    Here’s why a plastic bracket wouldn’t work:

    Brass switch bracket - side view
    Brass switch bracket – side view

    That’s with the V4 hot end aligned per instructions, although I may rotate it 1/4 turn clockwise at some point. Note that there’s no filament going in the top, as I did all this before firing that devil up for the first time.

    The switch lever had enough free travel that the platform would hit the bottom of the X axis linear slide screws before activating the switch, but lowering the switch would put the lever below the nozzle. I added a 15 mil brass shim to the lever and it’s all good:

    Brass switch bracket - lever shim detail
    Brass switch bracket – lever shim detail

    Admittedly, the lever rests a bit less than 1.000 mm above the nozzle, but we’ll see how much trouble that causes.

    The switch trips 2.0 mm above the nozzle, so the new startup G-Code looks like this:

    ;-- Slic3r Start G-Code for M2 starts --
;  Ed Nisley KE4NZU - 2015-03-01
;  Makergear V4 hot end
; Z-min switch at platform, must move nozzle to X=135 to clear
M140 S[first_layer_bed_temperature]	; start bed heating
G90				; absolute coordinates
G21				; millimeters
M83				; relative extrusion distance
G92 Z0			; set Z to zero, wherever it might be now
G1 Z10 F1000	; move platform downward to clear nozzle; may crash at bottom
G28 Y0			; home Y to clear plate, origin in middle
G92 Y-127
G28 X0			; home X, origin in middle
G92 X-100
G1 X130 Y0 F30000	; move off platform to right side, center Y
G28 Z0			; home Z to platform switch, with measured offset
G92 Z-2.00
G0 Z2.0			; get air under switch
G0 Y-127 F10000	; set up for priming, zig around corner
G0 X0			;  center X
G0 Y-125.0		; just over platform edge
G0 Z0 F500	; exactly at platform
M109 S[first_layer_temperature]	; set extruder temperature and wait
M190 S[first_layer_bed_temperature]	; wait for bed to finish heating
G1 E20 F300		; prime to get pressure, generate blob on edge
G0 Y-123		; shear off blob
G1 X15 F20000	; jerk away from blob, move over surface
G4 P500			; pause to attach
G1 X45 F500		; slowly smear snot to clear nozzle
G1 Z1.0 F2000	; clear bed for travel
;-- Slic3r Start G-Code ends --

    The prime-and-wipe section accommodates gooey PETG, although that will require more attention.

  • Netgear GS308 Wall Mount

    A Netgear GS308 gigabit switch replaced an older 100 Mb/s switch below the living room window across from my desk:

    Netgear switch mounted
    Netgear switch mounted

    Of course, the mounting slots in the new switch didn’t match those in the old switch. A scrap of plastic sheet serves as a space transformer:

    Netgear switch backplate
    Netgear switch backplate

    The odd-looking knife plows a furrow in the plastic, after which you capture the sheet between two flat surfaces and snap it along the scribe. Faster / easier / more accurate / less exciting than bandsawing, cleans up with quick swipes from an edge deburring tool, not much can go wrong.

    The top holes are 3/16 inch for the existing mounting screws. The center holes are tapped 6-32 with nuts to hold them in place.

    A block of closed-cell foam behind the sheet holds it vertical so I can just barely see the activity LEDs at each port from my desk.

    Yes, I scrubbed the sheet before mounting it…

    Memo to Self: put the screw holes slightly higher, so they’re properly centered after sliding the case into position. Otherwise, you must cut another slice off the top of the sheet before mounting it.

  • ID3 Tagging Audio Book Files

    For whatever reason, the audio books we get at the library sale generally don’t have CDDB database entries, so I fill in the appropriate values by hand. Weirdly, some individual CDs within a single book do have entries, which confuses the process (well, me) no end unless I notice it first; I’ve turned off auto-lookup to make that problem Go Away. Perhaps a different database would help, but I don’t do this nearly often enough to care that much.

    Given that:

    • Mary plays the tracks sequentially from start to finish
    • The tracks don’t correspond to book divisions
    • She doesn’t care about the details

    I concluded a simple track naming convention that sorts in ascending alphabetic order would suffice.

    Asunder auto-fills the fields after the first CD. After a bit of manual wrestling to extract an error-filled track, I had a directory full of MP3 files with informative, albeit slightly redundant, names:

    1901-01 - Track 01.mp3

    Alas, the ID3 fields apply to a single music CD, with track numbers and names within a single album and no notion of a multi-CD set. I use the “year” field as a CD sequence number; it must be a four-digit year and, seeing as how Asunder defaults to 1900, the first CD becomes 1901.

    So the following fields apply:

    • Genre: “Audio Book” (for v2 tags) or Speech (v1 tag = 101)
    • Artist: author
    • Album: book title
    • Year: 19 + CD number within set as 1901
    • Track Name = CD number + track number as “D:01 T:01”

    But the real gotcha is that the Most Favorite MP3 Player (remember MP3 players?) recognizes only ID3 v1 tags and Asunder writes only ID3 v2 tags.

    Fortunately, the id3v2 utility can do this thing. Rather than screw around selecting each file, extracting the v2 tags, doing something horrible involving bash or sed or awk or whatever, and ramming the results into v1 tags, I just fed in the appropriate number of CDs and more than enough tracks, then ignored any errors concerning missing files.

    Firing a Bash cannon broadside:

    for d in {01..15} ; do id3v2 -1 -a "Who Wrote It" -A "The Book Title" -y 19$d -g Speech 19${d}* ; done
for d in {01..15} ; do for t in {01..15} ; do id3v2 -1 -t "D:${d} T:$t" -T $t 19${d}-${t}* ; done ; done
for d in {01..15} ; do for t in {01..15} ; do id3v2 -2 -t "D:${d} T:$t" -T $t 19${d}-${t}* ; done ; done

    The last line tightens up the title name tag in v2 format to fit the MP3 player’s teeny display. The next time around, I should remove the “Track” text from the file name for consistency.

    And then it just worked…

  • Dell U2711 Monitor vs. Displayport Cable

    Part of the flailing about while working around the Ubuntu video driver update glitch included blindly swapping a Displayport cable, which triggered another failure after everything settled down: the (empty) DVD drive’s activity light remained dimly lit with the PC off and both monitors in power-save mode. Unplugging the PC’s power cord extinguished all the internal LEDs on the system board, but left the drive light shining the same dim green. Disconnecting the USB cables to the monitors (they both have USB hubs) had no effect. Unplugging the monitors extinguished the LED after a bit. Unplugging one of the Displayport cables turned it off instantly, which was a clue that took a while to recognize.

    Worse, the landscape monitor, a year-old Dell U2711, now refused to wake up from power-save mode during boot, even when it was the only monitor connected to the PC. Searching with an assortment of relevant keywords produced several interesting results, including a lengthy Dell support forum thread, all suggesting a deeper and surprisingly longstanding problem with Displayport connections on big Dell monitors.

    I knew most of the remedies weren’t relevant, because this failure happened while the BIOS felt around to identify the monitors: not a driver issue (not in effect yet), not a Windows issue (fer shure!), not a Linux issue, and not a BIOS configuration issue (nothing changed, plus Dell doesn’t allow much configuration).

    It turns out that the original pair of Displayport cables bore Amphenol logos on the connector shells and cable. One of the replacements was a Genuine eBay cable from halfway around the planet, bearing no markings of any sort. Given the hints in those search hits, I discovered that the Amphenol-branded cables did not carry pin 20 between the connectors, but the eBay cables did: just a little something extra from eBay!

    Installing the two Amphenol cables extinguished the DVD drive light by preventing the monitor standby power from backfeeding the PC through the video card and the monitor woke up correctly on the next two boots. Whether that will permanently cure the startup problem remains to be seen, as it was somewhat intermittent with the wrong cable and the forum threads suggest that the monitor will continue to work for a while before failing again.

    While pondering all that, I severed the pin 20 connection in one of the eBay cables, just to have a different cable in hand. This diagram from the Wikipedia article, with pin 20 highlighted, shows it sitting under the longer blank section above one of the keys:

    DisplayPort Connector - pin 20 highlight
    DisplayPort Connector – pin 20 highlight

    The connector shell has snap latches that succumb to gentle prying with a razor knife, revealing the hot-melt-glue potted interior, with the orange wire snaking away from pin 20 at the top of the other side:

    DP connector - latch side
    DP connector – latch side

    One snip, a bit of prying to extract the end from the glue, and it’s ready to be buttoned up again:

    DP connector - pin 20 wire cut
    DP connector – pin 20 wire cut

    Both Amphenol cables and the modified eBay cable now have labels noting that they do not connect pin 20. We’ll see if that makes any difference…