Jeff Epler's blog

1 January 2019, 18:56 UTC

Qidi Tech I


I bought this 3D printer in the fall of 2017, though they were already calling it the "2018" model. It's a fully enclosed, dual hotend printer which is a knockoff of the Flashforge, which in turn is a knockoff of the Makerbot.

Initially, I didn't blog about this printer because I was kinda disappointed with it. It takes up a lot more desk space, spools are a pain to mount and unmount, and I initially didn't have much luck with larger prints, ABS adhesion, or dual material printing, which were three major things that I had hoped to do with the printer.

More recently I started pretty obsessively reading about the Genuine Prusa i3 MK3 with MMU2, and trying to justify the purchase. In the process, I had to admit to myself that maybe I needed to give those three major bullet points another try, either to satisfy myself that it couldn't be done, or to finally meet my goals.

Happily, I think I met my goals, and I feel much happier about this printer than I ever did in the first year of owning it. And as a bonus, I am also successfully printing flex filament on it!

First, I had found that the Z height of the two nozzles never quite matched. I was very reluctant to mess with their alignment, because it is supposed to be set at the factory. However, I eventually discovered that it was my own problem all along: I had failed to fully tighten one of the screws which attaches the hotend assembly to the X carriage, which accounted for at least 90% of the Z height mismatch of the two nozzles. I still have minor problems in vase mode if the unused nozzle brushes the print in progress, so things aren't perfect, but they're really quite a lot better.

Second, I went through the bed leveling process by using the "look at filament after it's been laid down" method, instead of the "try putting a sheet of paper under the nozzle" method. I had the nozzles way too close to the bed, and now my first layer problems were resolved. At this point, PLA and PETG both printed marvelously.

I took a detour from using Cura to Slicer PE (part of the obsessive googling about Prusa I3) and learned a few tricks, such as making the first layer line width substantially wider for better adhesion; and had some modest success with dual extrusion printing. When I returned to Cura, I found I could apply these ideas. With respect to dual extrusion printing, I found that turning OFF a bunch of Cura features gave me better results: There's no need for a priming tower when you have two hotends (vs the prusa style with multiple extruders and a single hotend), and eliminating or reducing the temperature changes for the "not currently used" nozzle actually reduced stray wisps of filament. HOWEVER, when you do this it's important that the layer time not be too long, and that both filaments are used throughout the print, so that heat creep doesn't have a chance to clog a nozzle. I did in fact get a clog this way, but fixed it easily by replacing the PTFE lining. (and, contrary to my fears, this seems to have left the Z alignment of the two nozzles just as good as before. So now I have some Micro Swiss replacement nozzles on order, because I think these are pretty worn by now)

I have also had good luck simply using different material types as support materials (e.g., PLA for PETG and ABS, and PETG for PLA), for manual (solvent-free) removal.

Finally, I printed a couple of parts for the extruders that claimed to improve printing of flexible filament. While I hadn't tried any before, I've had some luck printing with a roll of what I think is TPU (and also one non-serious jam). This includes printing a combined PLA-TPU object.

I've just started dabbling with ABS Juice as a bed adhesive, but after a couple of prints I realize I need to switch to Kapton or glass to use it, if I don't want painter's tape permanently embedded in my prints. It has given a couple of ABS prints with perfect first layer adhesion that I would not have had without it, though.

Is this a great printer? Arguably, no, you shouldn't have to do a year of fiddling with a printer before you can get great prints and use all its capabilities. Am I feeling better about this printer than ever before? Yes, I feel like I've leveled up in terms of successful printing with it.

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1 January 2019, 15:51 UTC

Five Years of Prius (2013) Fuel Efficiency


Year Miles MPG Gal
2014 7546.8 44.4 170
2015 7333.6 43.9 167
2016 9368.8 44.8 209
2017 9936.2 45.1 220
2018 8853.6 42.0 210

Our total distance travelled was lower this year, mostly because our longest driving trip was taken in a rental car. The fuel economy was quite a bit lower, probably because the longer trip we did take was in the mountains of colorado, and a long climbing drive can be pretty awful for efficiency. The car also had its tires replaced this year, and the new tires may not reach the same level of low rolling resistance. Finally, it might be the case that an aging traction battery is affecting performance. Frankly, I'm disappointed with the numbers for the year.

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18 November 2018, 20:59 UTC

Codeword TESTAMENT COBALT


Files sealed under codeword TESTAMENT COBALT reveal an unusual cooperative mission between the Laundry and civilian law enforcement, beginning as early as 2009.

To quote the former Senior Auditor, it's "fractal contingency plans all the way down". TESTAMENT COBALT was another such contingency plan, one of many directed at establishing permanent human presence on parallel planets Earth. As a secondary goal, it would create a cadre of grateful youth and young adults who were bound to the Laundry by minor Geases without being on-the-books Laundry staff.

In the late 1990s, when relations between the OPA and the Laundry were on relatively good footing, the Laundry received a list of what we now know were second-tier sites from ABJAD SURVEY: Generally, parallel earths which were capable of supporting unprotected plant and animal life, but due to variations in fundamental constants could not support silicon-based computer techonlogy. Even then, the OPA was so dependent on digital technology that they deemed such worlds useless for their own needs.

The next lucky break (pun intended) occurred during the human exploration phase of the EDEN (Escaping DEmons Nextdoor) project when an unlucky team member suffered a compound fracture due to a fall. The team medic quickly discovered that the particular fundamental constants in this universe left all opioid painkillers totally ineffective. Subsequent to the team's emergency return, debriefing revealed that a third team member who had successfully concealed her prescription painkiller addiction up to that point had felt her addictive cravings disappear upon arrival on the the parallel now designated TESTAMENT COBALT 2007a. After a specific testing protocol was instituted, further TESTAMENT COBALT parallels were identified (TC2007b-f, TC2008g-w and TC2009x-ai)

From these pieces, an enterprising member of the Laundry formed their plan for an unusual diversion/drug addiction reabilitation program. In conjunction with a few friendly law enforcement officers in Avon and Somerset, the program got off the ground in small numbers at first, but at its peak there were apparently hundreds of participants per site on at least 8 TESTAMENT COBALT sites.

For participants, the benefits were clear: no criminal record, and a complete recovery from chemical addiction after just a few weeks in a rural area without social media or internet. In return, participants agreed to not disclose the details of the TESTAMENT COBALT sites and enrolled in what was termed a voluntary national service program—until age 35, they could be called up in time of emergency to serve the country. Both clauses were enforced by minor geas upon acceptance of the contract.

This clause was activated by Senior Auditor Dr. Armstrong in 2014 during the events of The Delirium Brief. Within moments, some 28,000 program participants disappeared from this Earth, returned to their TESTAMENT COBALT parallel worlds. Then, using the thaumic energy of approximately 33% of those worlds' native plant, animal, and sea life, a hyperspatial isolation ("hyperstop") grid with a duration of up to a gigasecond was kicked off, sealing them away from the rest of the multiverse. It's up to them to survive and thrive while restricted to an agrarian level of technology.

We can only hope that when the first of these grids collapses in 2050, TESTAMENT COBALT subjects and their descendants will rejoin a local multiverse that is once again habitable by the sort of life that once lived here on Earth.

"We fight on so that something that remembers being human might survive" — S.A. Armstrong

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22 October 2018, 20:57 UTC

Codeword BISON ZENITH


This is a work of fiction, channeling Charlie Stross and his Laundry Files series. I made it after we started hearing rumors that Intel has cancelled their next generation process too... BISON ZENITH confirmed

Connect the dots:

Internal Intel memos from as early as 2008 confirm a skunkworks plan to develop metamaterials—a "superlens"—rather than pursue techniques like EUV for post-14nm process nodes. The "superlens" was supposed to be able to focus normal UV light onto sub-wavelength regions, impossible for traditional optics and even according to the predictions of quantum physics.

FOIA requests show hundreds of chartered flights yearly from the NSA's Utah Data Center to the Chandler Municipal Airport, just 3 miles from Intel's Fab 42 just outside Phoenix Arizona, starting in 2012 and continuing until April 2018.

The uncanny resemblance of Chandler's Cottonwood and Sun Lakes golf course developments to class D and F warding glyphs; and the unusually strict anti-occult and anti-religious symbol rules in the HOA covenants. (This would have been for the safety of the subdivision's occupants; at such short range even as innocuous a religious symbol as a "marshmallow peep" would burst into flame within the area of the glyph itself)

Results from ABJAD SURVEY show that in near-habitable parallels, the most frequent parameter variation that prohibits the survival of an earth biosphere is in the parameter 'c', the speed of light. Variations as small as 3% prevent pollinators from locating flowers, but even variations of 27% are short-term survivable by adult humans, given proper personal protection.

The unexplained hour of localized daytime darkness in Chandler AZ on 4/18/18; initially reported as a "terror attack", there were no direct casualties (just road accidents). The official NTSB report states that the crashed Cessna 680 on arrival from Salt Lake City had no one on board.


Our conjecture:

When the Black Chamber shows up with credentials thst say "NSA" and promises you access to an out of this world process for creating integrated circuits, you need to take that phrase literally. But of course in the first two decades of the century, there was no awareness of this in the general public. And if you were on the inside, you would authorize such activities as a matter of course.

The "superlens" technology is better understood as a pair of back to back gates, leading to a region of the multiverse with the a 'c' value about 70% below nominal. This would allow a UV process that supported the 17nm node in our physics to scale down to the 5nm mode, allowing Intel to maintain its worldwide process advantage for a decade or more.

Black Chamber produced the superlenses at the Utah Data Center and hand delivered them to Intel staff who were unaware of just what they were handling. The gates were presumably designed with a half life of around a week, based on the frequency of flights. This plan went fine, until something happened on the 4/18 flight. Did containment of the gates fail during the flight, or was it a part of a defection plan or a convert operation by one of our adversaries?

In any case, Intel never did ship a post-14nm part from the Chandler fabrication facility.

Editor's note: Strictly speaking, 'c' is not a parameter, since it is not one of the fundamental dimensionless constants. Technically, I should say 'ɑ'. But since the effect we're interested in pertains to the speed of light, it is clearer to express things in these terms. Remember, in atomic units 'ɑ = 1/c'.

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22 October 2018, 20:16 UTC

Codeword BISON MERIDIAN


I wrote this a few months ago when this story was making the rounds. This is a work of fiction, channeling Charlie Stross and his Laundry Files series. I might make a little follow-up now that there are rumors that Intel has cancelled their next generation process too... BISON ZENITH confirmed

Many later historians claim that it was the reports of atypical neuropathy in staff at GlobalFoundries labs that tipped off the Black Chamber to the dangers of extreme nanoscale lithography. The earliest reports, of course, said nothing about the US Occult Service's involvement; instead there were just bland mutterings about "business opportunities" and "emerging high-growth markets" to explain the (now decade-long) shuttering of an entire wing of the Santa Cara facility.

The second cover story was floated when the first leaks related BISON MERIDIAN were posted to the SCP Foundation wiki. In this version, not directly contradicted by anything in the public record, semiconductor chips manufactured with EUV Lithography produced produced silicon clumps of a particular size that allowed them to escape environmental filters and cross the blood-brain barrier into facility staff, leading to the reported symptoms.

It was actually the animal sacrifices, reported by a Black Chamber asset on the custodial staff, that first tipped off the authorities. In typical Chamber fashion, everyone who might have been involved in the sacrifices was rounded up and "debriefed" (and so what if the subjects never again have full sensation on their tongues and the bottoms of their feet?).

According to an unredacted BISON MERIDIAN folio obtained by the author, the Black Chamber's found that sub-10nm lithography techniques had inadvertently created a summoning grid for what one subverted researcher worshipped as "Otvor Bog" (literally "God of the Aperture", though possibly also a play on the English-language phrase "God of the Gaps"). Unlike most extradimensional incursions, which are information-theoretic in nature, the semiconductor wafer actually extrudes the body of Otvor Bog, albeit just a 16x16mm section of it at a rate of around 4ml/day.

This author cannot help but connect this evidence to the codewords BISON NADIR and BISON ZENITH which have also appeared in redacted reports; to the continued delays in Intel's next-generation lithography process; and to TSMC's apparent success in this region, together with rumors of the "black safes" throughout that facility. The author has been unable to confirm reports that the "shuttered" GF buildings have continued to draw power from the electric grid at a rate that far exceeds the requirements of a few energy lights and environmental monitoring devices.



One final tidbit from BISON MERIDIAN: As the primary atomic constituents of an Otvor Bog type incursion are oxygen, hydrogen, silicon, and nitrogen, (and no carbon) SIDE EYE (basilisk sidearm) is not an effective countermeasure.

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28 July 2018, 13:19 UTC

GPSDO: An attempt that is too simple


Since I have all the components—a GPS timesource, a voltage controlled OCXO, and a microcontroller with some DACs—I thought I'd try to make a simple GPS Disiplined Oscillator.

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24 July 2018, 2:18 UTC

keyestudio gps shield as frequency counter


Superficially similar to the elecrow GPS shield at the time of writing it's available from ebay for around $20.

I chose this model because it has a ublox GPS module and a header with signals marked "GP" and "EX". EX should be external interrupt, and it opens the possibility of a simple GPS-disciplined frequency counter.

It comes with a small antenna, short cable. One of those godawful laptop style connectors, and no provision for directly soldering a better one. Sigh.

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15 July 2018, 15:59 UTC

Fun with frequency

26 March 2018, 23:51 UTC

Fuzz-testing CircuitPython

17 February 2018, 17:31 UTC

Watch Repairs

6 August 2017, 2:26 UTC

poc: Python OCE Composer

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