Category: Oddities

Who’d’a thunk it?

Bulk Ink Delivery

Now, I’m a big fan of continuous ink supply systems for desktop printers and buy ink by the pint, but these folks put me to shame…

US Ink Delivery Truck

It’s delivering ink to the Southern Dutchess News plant in Wappingers Falls.

2011-01-30
ATX Power Supply Dual +12 V Outputs: Fakery Thereof
I wondered if the Thing-O-Matic would benefit from having its two high-current heaters on a separate +12 V supply than the DC Extruder, after finding that the heaters dragged the +12 V output down by nearly half a volt.

A bit of rummaging turned up a suitable ATX supply with a data plate that might justifiably lead one to believe that the supply provides separate +12 V outputs:

Turbolink ATX-CW420W power supply data plate

There’s no indication which of the four connectors might use +12V1 and +12V2, but, being that sort of guy, I applied an ohmmeter to the various yellow wires and found they were all exactly 0.0 Ω apart.

Huh.

So I opened the Warranty Void If Seal Removed top cover and found this situation:

ATX with fake dual 12 V supplies

Nota bene:
- All the yellow wires terminate in the same solder blob below the PCB
- Two incoming wires got neatly spliced together in mid-air, despite having free holes in the PCB
This may not come as much of a shock: they lie…

Perhaps if you spend more money on your supply, it’ll actually live up to the data plate specs. Then, again, perhaps you’ll just be spending more money.

And, if you swap in a fancy supply for the MBI-stock one, it might not make much difference at all. I suspect the various power levels and current capacities have pretty much the same degree of integrity…
2011-01-25
Unexpected Midnight Visitor

That post reminded me of an incident at my parents’ house, long after I’d moved out and many years ago.

For context, the Ancestral Home is a three-story brick pile dating back to the late 1800s, with nonstandard bricks and much thicker walls than you’d expect, with plaster-on-lathe interior finishing and really nice wood trim. It’s on the southwest corner of the Hummelstown PA town square, where Main Street tapers down to two lanes.

They were awakened around midnight by a mighty crash downstairs and found this in the front room:

Interior View

It seems a westbound van, traveling at what’s tautologically called “a high rate of speed”, swerved across Main Street, tripped on the curb, plowed down a concrete planter, and spanked the front corner of the house pretty hard:

Front View

The driver wasn’t thrown clear, but a whole pile of crap fell out as they were extracting him.

Outside View

Even in the days before air bags, this one was a total loss:

Aftermath – The Van

IIRC, the charge came down DWI but I vaguely recall he somehow wriggled out of that.

The building was never quite the same thereafter, either: those plaster walls were never meant to take a direct hit.

The pix are more horribly discolored satin-finish pages from the Family Album. One could do better color correction if one really had to, but …

2011-01-04

Cabin Fever Tchotchke: Engraved Dog Tag

Once again I’m planning to attend the Cabin Fever Expo in York; my shop assistant says this year she won’t barf in the kitchen sink Thursday evening just before bedtime…

If I’m going to haul a Sherline CNC setup that far and spend all day talking machining, I must have some tchotchkes / swag to talk about. We figured a small plastic dog tag with relevant URLs would be appropriate.

I modeled the tag after my father’s WWII tag, including the mysterious notch. The rounded ends actually have three curves: two small fairing arcs blend the sides into the end cap.

The G-Code routine figures out all the coordinates and suchlike from some basic physical measurements & guesstimates, so tweaking the geometery is pretty straightforward. There was a blizzard going on while I wrote it: a fine day to spend indoors hacking code.

My assistant fired up Inkscape, laid out the text, figured out how to coerce G-Code out of Inkscape using the cnc-club.ru extension, then aligned it properly with the center of the chain hole as the origin on the right side. My routine calls the text G-Code file as a subroutine.

The extension’s header and footer files wrap EMC2’s SUB / ENDSUB syntactic sugar around the main file. The default files include an M2 that kills off the program; took a while to track that one down.

The header file:

O<dogtagtext> SUB

And the matching footer file:

O<dogtagtext> ENDSUB

The Inkscape-to-gcode instructions come out with absolute coordinates relative to the origin you define when you create the layout. The nested loops in my wrapper slap a G55 coordinate offset atop each label in turn, then call the subroutine.

The result is pretty slick:

I carved out that proof-of-concept label atop double-sided adhesive tape, but peeling off the goo is a real pain; a 2×3 array will be much worse. I’d rather do that than figure out how to clamp the fool things to the sacrificial plate, though.

The engraving is 0.2 mm deep with a Dremel 30 degree tool. My shop assistant describes it as “disturbing” the acrylic, not actually engraving a channel. This isn’t entirely a Bad Thing, as the font isn’t quite a stick font and the outline of each character mushes together. We must fiddle with the font a bit more; she favors a boldified OCR-A look.

Some lessons:

The Kate G-Code syntax highlighter isn’t down with EMC2’s dialect
Be very sure you touch off the workpiece origin in G54, not G55
Xylene doesn’t bother acrylic and works fine on tape adhesive
Symlinks aimed across an NFS link work fine in ~/emc2/nc_files/
That 2×3 array may be too big for the Sherline’s tooling plate
Tool length probing FTW!

The G-Code:

(Cabin Fever 2011 Dogtag)
(Ed Nisley - KE4ZNU - December 2010)
(Origin at center of chain hole near right side)
(Stock held down with double-stick tape)

(--------------------)
(Flow Control)

#<_DoText>      = 1
#<_DoDrill>     = 1
#<_DoMill>      = 1

( Sizes and Shapes)

(-- Tag array layout)

#<_NumTagsX>    = 3                         (number of tags along X axis)
#<_NumTagsY>    = 2                         ( ... Y axis)

#<_TagSpaceX>   = 60                        (center-to-center along X axis)
#<_TagSpaceY>   = 35                        ( ... Y axis)

(-- Tag Dimensions)

#<_TagSizeX>    = 50.8                      (2.0 inches in WWII!)
#<_TagSizeY>    = 28.6                      (1-1/8 inches)
#<_TagSizeZ>    = 2.0

#<_HoleOffsetX> = 4.0                       (hole center to right-side tag edge)

#<_NotchSizeX>      = 3.5                   (locating notch depth from far left edge)
#<_NotchCtrY>       = 5.0                   (locating notch from Y=0)

#<_NotchAngleBot>   = 30                    (lower angle in notch)
#<_NotchAngleTop>   = 45                    (upper angle in notch)

(-- Fairing Curve Dimensions as offsets from end arc center)

#<_EndFairR>    = [0.68 * #<_TagSizeY>]
#<_CornerFairR> = [0.25 * #<_TagSizeY>]

#<_PCRadius>    = [#<_EndFairR> - #<_CornerFairR>]
#<_PCY>         = [[#<_TagSizeY> / 2] - #<_CornerFairR>]
#<_PCTheta>     = ASIN [#<_PCY> / #<_PCRadius>]
#<_PCX>         = [#<_PCRadius> * COS [#<_PCTheta>]]

#<_P1Y>         = [#<_TagSizeY> / 2]                    (top / bottom endpoint)
#<_P1X>         = #<_PCX>

#<_P2X>         = [#<_EndFairR> * COS [#<_PCTheta>]]
#<_P2Y>         = [#<_EndFairR> * SIN [#<_PCTheta>]]

(-- Tooling)

#<_TraverseZ>   = 1.0                       (safe clearance above workpiece)

#<_DrillDia>    = 3.2                       (drill for hole and notch)
#<_DrillNum>    = 1                         ( ... tool number)
#<_DrillRadius> = [#<_DrillDia> / 2]
#<_DrillFeed>   = 200                       (drill feed for holes)
#<_DrillRPM>    = 3000

#<_MillDia>     = 3.2                       (mill for outline)
#<_MillNum>     = 1                         ( ... tool number)
#<_MillRadius> = [#<_MillDia> / 2]
#<_MillFeed>    = 150                       (tool feed for outlines)
#<_MillRPM>     = 5000

#<_TextDia>     = 0.1                       (engraving tool)
#<_TextNum>     = 1
#<_TextFeed>    = 600                       (tool feed for engraving)
#<_TextRPM>     = 10000

(-- Useful calculated values)

#<_TagRightX>   = #<_HoleOffsetX>           (extreme limits of tag in X)
#<_TagLeftX>    = [#<_TagRightX> - #<_TagSizeX>]

#<_EndFairRtX>  = [#<_TagRightX> - #<_EndFairR>]
#<_EndFairLfX>  = [#<_TagLeftX> + #<_EndFairR>]

#<_NotchCtrX>   = [#<_TagLeftX> + #<_NotchSizeX> - #<_DrillRadius>]

(--------------------)
(--------------------)
( Initialize first tool length at probe switch)
(    Assumes G59.3 is still in machine units, returns in G54)
( ** Must set these constants to match G20 / G21 condition!)

#<_Probe_Speed>     = 400            (set for something sensible in mm or inch)
#<_Probe_Retract>   =   1            (ditto)

O<Probe_Tool> SUB

G49                     (clear tool length compensation)
G30                     (move above probe switch)
G59.3                   (coord system 9)

G38.2 Z0 F#<_Probe_Speed>           (trip switch on the way down)

G0 Z[#5063 + #<_Probe_Retract>]     (back off the switch)

G38.2 Z0 F[#<_Probe_Speed> / 10]    (trip switch slowly)

#<_ToolZ> = #5063                    (save new tool length)

G43.1 Z[#<_ToolZ> - #<_ToolRefZ>]    (set new length)

G54                     (coord system 0)
G30                     (return to safe level)

O<Probe_Tool> ENDSUB

(-------------------)
(-- Initialize first tool length at probe switch)

O<Probe_Init> SUB

#<_ToolRefZ> = 0.0      (set up for first call)

O<Probe_Tool> CALL

#<_ToolRefZ> = #5063    (save trip point)

G43.1 Z0                (tool entered at Z=0, so set it there)

O<Probe_Init> ENDSUB

(--------------------)
(Start machining)

G40 G49 G54 G80 G90 G94 G97 G98     (reset many things)

G21                                 (metric!)

(msg,Verify G30.1 position in G54 above tool change switch)
M0
(msg,Verify XYZ=0 touched off at left front tag hole center on surface)
M0

O<Probe_Init> CALL
T0 M6                           (clear the probe tool)

(-- Engrave Text)

O<DoText> IF [#<_DoText>]

(msg,Insert engraving tool)
T#<_TextNum> M6         (load engraving tool)
O<Probe_Tool> CALL

F#<_TextFeed>
S#<_TextRPM>

(debug,Set spindle to #<_TextRPM>)
M0

G0 X0 Y0                (get safely to first tag)
G0 Z#<_TraverseZ>       (to working level)

G10 L20 P2 X0 Y0 Z#<_TraverseZ>         (set G55 origin to 0,0 at this point)
G55                                     (activate G55 coordinates)

O3000 REPEAT [#<_NumTagsX>]

O3100 REPEAT [#<_NumTagsY>]

O<dogtagtext> CALL

G0 X0 Y0
G10 L20 P2 Y[0 - #<_TagSpaceY>]         (set Y orgin relative to next tag in +Y direction)

O3100 ENDREPEAT

G10 L20 P2 X[0 - #<_TagSpaceX>] Y[[#<_NumTagsY> - 1] * #<_TagSpaceY>] (next to +X, Y to front)

O3000 ENDREPEAT

G54                                     (bail out of G55 coordinates)

(-- Drill holes)

O<DoDrill> IF [#<_DoDrill>]

T0 M6
(msg,Insert drill)
T#<_DrillNum> M6
O<Probe_Tool> CALL

F#<_DrillFeed>
S#<_DrillRPM>

#<_DrillZ> = [0 - #<_TagSizeZ> - #<_DrillRadius>]

(debug,Set spindle to #<_DrillRPM>)
M0

G0 X0 Y0                (get safely to first tag)
G0 Z#<_TraverseZ>       (to working level)

#<IndexX> = 0
O1000 DO

#<IndexY> = 0
O1100 DO

#<TagOriginX> = [#<IndexX> * #<_TagSpaceX>]
#<TagOriginY> = [#<IndexY> * #<_TagSpaceY>]

G81 X#<TagOriginX> Y#<TagOriginY> Z#<_DrillZ> R#<_TraverseZ>
G81 X[#<TagOriginX> + #<_NotchCtrX>] Y[#<TagOriginY> + #<_NotchCtrY>] Z#<_DrillZ> R#<_TraverseZ>

#<IndexY> = [#<IndexY> + 1]
O1100 WHILE [#<IndexY> LT #<_NumTagsY>]

#<IndexX> = [#<IndexX> + 1]
O1000 WHILE [#<IndexX> LT #<_NumTagsX>]

G30     (go home)

O<DoDrill> ENDIF

(-- Machine outlines)

O<DoMill> IF [#<_DoMill>]

T0 M6                   (eject drill)
(msg,Insert end mill)
T#<_MillNum> M6         (load mill)
O<Probe_Tool> CALL

F#<_MillFeed>
S#<_MillRPM>

(debug,Set spindle to #<_MillRPM>)
M0

G0 X0 Y0                (get safely to first tag)
G0 Z#<_TraverseZ>       (to working level)

G10 L20 P2 X0 Y0 Z#<_TraverseZ>         (set G55 origin to 0,0 at this point)
G55                                     (activate G55 coordinates)

O2000 REPEAT [#<_NumTagsX>]

O2100 REPEAT [#<_NumTagsY>]

G0 X[#<_NotchCtrX>] Y[#<_NotchCtrY>]     (get to center of notch hole)
G0 Z[0 - #<_TagSizeZ>]                      (down to cutting level)

G91                                         (relative coordinate for notch cutting)
G1 X[0 - #<_NotchSizeX>] Y[0 -  #<_NotchSizeX> * TAN [#<_NotchAngleBot>]]
G1 X[0 + #<_NotchSizeX>] Y[0 +  #<_NotchSizeX> * TAN [#<_NotchAngleBot>]]
G1 X[0 - #<_NotchSizeX>] Y[0 +  #<_NotchSizeX> * TAN [#<_NotchAngleTop>]]
G90                                         (back to abs coords)

G42.1 D#<_MillDia>                          (cutter comp to right)
G1 X[#<_TagLeftX>] Y0                       (comp entry move to tip of left endcap)

G3 X[#<_EndFairLfX> - #<_P2X>] Y[0 - #<_P2Y>] I[#<_EndFairR>] J0    (left endcap front half)

G3 X[#<_EndFairLfX> - #<_P1X>] Y[0 - #<_P1Y>] I[#<_P2X> - #<_PCX>] J[#<_P2Y> - #<_PCY>]

G1 X[#<_EndFairRtX> + #<_P1X>]                                      (front edge)

G3 X[#<_EndFairRtX> + #<_P2X>] Y[0 - #<_P2Y>] I0 J[#<_CornerFairR>]

G3 X[#<_EndFairRtX> + #<_P2X>] Y[#<_P2Y>] I[0 - #<_P2X>] J[#<_P2Y>]    (right endcap)

G3 X[#<_EndFairRtX> + #<_P1X>] Y[#<_P1Y>] I[#<_PCX> - #<_P2X>] J[#<_PCY> - #<_P2Y>]

G1 X[#<_EndFairLfX> - #<_P1X>]                                      (rear edge)

G3 X[#<_EndFairLfX> - #<_P2X>] Y[#<_P2Y>] I0 J[0 - #<_CornerFairR>]

G3 X[#<_EndFairLfX> - #<_P2X>] Y[0 - #<_P2Y>] I[#<_P2X>] J[0 - #<_P2Y>]    (left endcap complete)

G0 Z#<_TraverseZ>

G40

G0 X0 Y0
G10 L20 P2 Y[0 - #<_TagSpaceY>]         (set Y orgin relative to next tag in +Y direction)

O2100 ENDREPEAT

G10 L20 P2 X[0 - #<_TagSpaceX>] Y[[#<_NumTagsY> - 1] * #<_TagSpaceY>] (next to +X, Y to front)

O2000 ENDREPEAT

G54                                     (bail out of G55 coordinates)

G30         (go home)

O<DoMill> ENDIF

M2

The doodles leading to the equations:

We’ll see you there!

2011-01-02

Bugged ATX Supply

I intend to use an ATX power supply as a cheap source of bulk +12 V and +5 V power for the resistors on those heatsinks. I have a 250 W box on the shelf (harvested from a dead donor PC) that seemed ideal; they run more efficiently with higher loads and I only need 150-ish W.

Being that type of guy, I opened it up to see what’s inside…

Damaged ATX Supply

Huh. Looks like some small creature of the night immolated itself down there in the lower left corner, tucked against the transformer. There’s nothing more than black goo and charred filaments left over, with green-blue corrosion creeping up the resistor lead.

Or maybe it’s actually toxic snot from the manufacturing line. Hard to say at this point.

The power supply tester says the juice comes out fine & dandy, so I might use the thing after trying to get the gunk out.

2010-12-29
Buckle Up For Safety

Windshield head strikes

Y’know how some folks say they don’t wear a seat belt because they want to be thrown free in a crash? Here’s how that works in actual practice.

The air bag fires as the front bumper begins to deform and your body rises off the seat. Because you’re not belted in, the bag boosts your upper torso against the roof liner, bounces your head off the sunshade and bezel, then feeds you directly into the windshield glass.

Laminated glass doesn’t disintegrate, so your skull probably won’t completely penetrate the windshield. You’ll lose some scalp, though, as you slide down the crumbling glass and wedge above the dashboard.

Even if you survive a broken neck, the ensuing brain trauma means you won’t be the same person ever again.

News flash: massive brain trauma does not make you a better person.

Before laminated windshield glass became mandatory, your head would completely penetrate the windshield. Here’s what happened in 1937, from the incomparably grisly — And Sudden Death by J. C. Furnas:

Safety Glass Windshields

I read one of the many Reader’s Digest editions of that article during my formative years. Probably the one in October 1967, if a bit of Google-fu serves me right. You can’t get reprints of it from RD any longer, it seems.

However, unbelievably, while I was composing this post, I checked eBay and found a typewritten copy of the article, signed by Furnas, with 38 minutes remaining in the auction. I was the only bidder: for nine bucks (delivered) it’s mine.

Most likely it’s a publicity / fundraising copy, because the handwritten notation on the first page reads:

With best
regards to
[name]
J. C. Furnas
Oct 20, 1947

Those SUVs reside in the junkyard along the Dutchess Rail Trail near Creek Road, where I might get a new seat to rebuild my comfy office chair this spring.

2010-12-17
Cold Solder Joint

Found this inside a friend’s dead USB memory stick:

Cold solder joint in USB memory

The leads come from a teeny 12 MHz crystal. The solder blob on the other side looked just fine, but you simply can’t tell by looking.

As it turned out, the stick was dead for some other reason: the Flash memory controller chip got hot when the stick was drawing power. Resoldering all the joints had no effect, which wasn’t surprising.

I suspect a killer static discharge or some such calamity.

2010-12-16