Category Archives: DIY

Singer no. 42 Cabinet Swing-Arm

Posted on 2013-12-22 by pappp

One of my previous posts about my Singer attracted an email conversation with another owner about the swing-arm mechanism on the no. 42 cabinet. Unfortunately, the end-of-semester insanity struck before the matter was settled, and I am still unsatisfied with what I’ve been able to figure out.

Now that I’ve had a bit of time, I pulled apart my mechanism and took photos, shared below. I’m reasonably certain that if the mechanism is complete and correct, the arm will automatically deploy when the leaf is lifted. Unfortunately, I’m also quite sure that the pieces I do have are inadequate to support that functionality, and I can only guess what the other bits might be.

The larger diameter end of the part I do have matches the diameter of the holes in the hinge, and the smaller-diameter end matches the hole through the swing arm and base.
My best guess is that there are several objects similar to the pictured pin, one of which protrudes below the table into the catch hole of the swing arm through the holes in the hinge mechanism, springloaded “up” such that it retracts when the leaf is out, and is depressed by something protruding from the hinge-hole in the leaf pinning the arm when closed. The pictures sent by the other owner show what looks like the end of a similar pin protruding into the bracket, but it does not extend any where near far enough to retain the arm.

Posted partly in the hopes that my pictures will help other folks with their cabinets, but also if anyone with a no. 42, especially if it has a working swing-arm mechanism or parts that are not pictured, sees this I’d love some more information about how they’re supposed to go together.

Posted in DIY, General, Objects | Tagged , , , | 7 Comments

chdk-ptp PKGBUILD

Posted on 2013-11-10 by pappp

In another episode of fixing things for the Cameras as Computing Systems class I’m taking, I made a PKGBUILD that apparently correctly builds and installs chdk-ptp on Archlinux systems. Chdk-ptp is a tethered-control application for Canon cameras running CHDK, that hooks a variety of custom extensions to the ptp protocol. Their build system is a little lackluster, is missing things like an install rule, and requires a helper script be installed to do some path munging before running the binary, but the documentation is good enough to sort it out, and the program itself seems to work. My package depends on iup-all-bin from the AUR which also provides the cd dependency (not marked in its provides array, though there isn’t an official package to conflict with). I tried to use the built-from-source AUR packages for cd (Seriously, who thought that was a good name for a piece of software?) and iup, but iup was giving me a hassle and the chdk-ptp documentation suggests the binary distribution will be less trouble anyway.

The PKGBUILD format has changed a bit since I was last making my own- I like most of the changes in terms of clarity and modularity, but it does require a bit of re-learning. It also means I have a couple of pet packages that probably need attention.

The build is a little janky so despite it passing through namcap with only one expected warning, I don’t want to put it in the AUR until I’ve tested it enough to be reasonably sure it works as intended. I expect I will get around to that eventually.

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Makergear M2 Heated Bed Issue

Posted on 2013-10-04 by pappp

There was a problem with the Lab’s Makergear M2 recently that is worth writing up.

Last weekend, we had it off site for a demo event for a group of highschoolers interested in engineering and medicine, which included assembling samples of these printable articulated hands that Dr. Dietz designed. (Semi-related: I’ve watched him do it, and continue to be mystified how he does things like this in OpenSCAD). We printed some models live, but on the last print of the trip it made a burning plastic smell. Not the usual, pleasing corn-syurp-y PLA-at-work smell, but acrid recently-deceased-electronics smell. We couldn’t locate the problem, and everything was working, so we assumed filament impurity and moved on.

M2RAMBO39530Melted

The next day, the bed stopped heating. Probing around with a DMM indicated the board was fine but the wire harness was not (A thank you to the Ultimachine folks for putting proper test points on the outputs). A bit of googling turned up this thread implicating the quick release screw terminal block that connects the bed leads to the board. Sure enough, upon yanking the connector free, the removable wire-side portion was a melted mass.

39530Melt

The existing connector is a Molex 39533-2002 rear-entry, two lead “Eurostyle” connector. Interestingly, Makergear and/or Ultimachine (Makergear buys and installs RAMBO Boards) used straight-through 5.08mm (200mil, but usually talked about in metric) quick release connectors – screws on the top, wires enter from the right – for the other MOSFET outputs, but a rear-entry (screws on the left, wires enter from the top) for the bed heat. This seemed odd since the side of the little laser-cut enclosure the RAMBO board lives in obscures the screw heads, but the reasoning will become clear. When I was poking at it to see if I could figure out what went wrong, I noticed the threads on the melted side were all but stripped out, but I don’t know if that was a cause or a symptom.

M2RAMBO39533

Since it is a standard connector, the (apparently intact) board side will mate with any two-position 3953x part. We found an ebay listing for five 39533-2002 for about $8 shipped, which are compatible and straight-through. Sadly, ebay is usually cheaper and faster than dealing with an electronics vendor if you only need one thing. The replacement seems to work fine, but clearly the original was a rear-entry model to keep the wires from being pressed against the side of the case. The M2’s wire harness is definitely its weak point; two of three serious intervention-requiring stoppages have been related to the bundle headed up to the bed/Y assembly.

The general lesson is to keep an eye on your screw terminals, especially if they are carrying current. I recall replacing the (non-quick-release) bed heater screw terminals on Collexion’s Makerbot ToM after a meltdown not long ago, so there is clearly a general issue with running that much current through screw terminals (several of the common crimped connectors would likely be superior in most ways). Since it came up (and since it is intuition-defying and I’ve heard a lot of people who should know better get it wrong) I’ll close with a reminder that you should not tin your wires before placing them in screw connectors – I know I’ve read this in a standard, research-backed source from ISO or NASA or somesuch, but I can’t find it right now.

ADDENDUM: It cooked two more of the same connector, then we discovered that the SD card connector was a little lose, and apparently causing a ground problem. It hasn’t cooked another connector since, and the bed heats faster than it was, so strong evidence that that was the root cause.

Posted in DIY, Electronics, General, Objects | Tagged , , | 3 Comments

As a quick “look at me being a good citizen,” a “class projects sometimes do have positive externalities,” and so that I have a convenient pointer/local copy, I just touched up the script for building a GCC 4.5 toolchain suitable … Continue reading →

Posted on 2013-10-01 by pappp | Leave a comment

Udisks2 Misfeature Fix

Posted on 2013-08-25 by pappp

Apparently David Zeuthen committed a patch back in February (appears in udisks2 >= 2.0.91, afik) that lets you single-point (or selectively) switch Udisks2 back to the nice, sane, predictable “Removable drives mount to /media” behavior instead of the asinine “Drives are owned by some user who happens to be logged in at a local session at the time they are plugged, mounted to /run/media/$USER/$LABEL, and ACL’d to that user” nonsense that has been a near-constant source of inconvenience lately. I’m surprised it took me this long to find it.

Following these instructions, all you have to do is create a Udev rule (ie. /etc/udev/rules.d/99-correct-media-mount-point.rules) with the line ENV{ID_FS_USAGE}=="filesystem|other|crypto", ENV{UDISKS_FILESYSTEM_SHARED}="1", and storage mounts to /media/$LABEL (You may want to leave out crypto, it actually makes sense for encrypted volumes to be obscured from other users like that) with no funky ACLs by default.

No more tedious user,noauto,nofail fstab entries on all my machines, for all my frequently-used discs to prevent that behavior! Hurrah!

Posted in Computers, DIY, General | Tagged , | 3 Comments

Singer 201-2 Restoration

Posted on 2013-07-18 by pappp

My 1947 Singer 201-2, S/N AH040755

I wrote about this machine once before a few years ago, but only brought it down to Lexington to work on it at the beginning of July. I’ve had a delightful time cleaning restoring it over the last couple weeks, and just wanted to post some pictures and musings. I did have it correctly identified before – it is a 1947 Singer 201-2, in good mechanical and OK cosmetic condition. The machine’s story from the family has settled on it being my great grandmother’s machine down the matrilineal line, but I don’t know if they were the original owner, or what exactly has happened to it over the last couple decades. My grandmother noted that she remembered her mother doing upholstery work on it, and my mother remembers using it as a child, and it was in my grandmother’s basement three years ago. Descriptions follow pictures below.
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Posted in DIY, General, Objects | Tagged , , , | 21 Comments

N109 Thinkpad AC Adapters

Posted on 2013-06-16 by pappp

N109-6

Since I’ve been documenting failure modes in electronics, another tale of electronic woe regarding N109 type knockoff Lenovo 90W AC adapters. I have a couple T series ThinkPads, which conveniently all use the same 20V 90W supplies with the same connector. I noticed that the stress relief on one of my AC adapters was wearing, so, having had a streak of good luck buying various direct-from-China products, I bought a knockoff replacement adapter that way.
I would suggest that you don’t want do that.
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Thrunite T10 Repair

Posted on 2013-06-07 by pappp

T10Bodymd

The Thrunite T10 light I’ve been carrying failed to come on when I reached for it the other day. It wasn’t a dead battery, and, yesterday, I determined that the 24mo warranty offers free repair contingent on you paying for shipping to and from Shenzhen, China, which comes out similar to the purchase price. I like my little T10, so this evening, I decided to fix it myself.

tl;dr: If you have a T10 die on you, it is likely to be the negative contact spring in the bottom of the body corroding/moving. Try cleaning and/or re-seating it.
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Posted in DIY, Electronics, General, Objects | Tagged , | 3 Comments

Attempts at Embedding News Discussion

Posted on 2013-05-22 by pappp

Following up my previous post, I’ve tried a couple configurations for replacing the news discussion features that Google has been slowly making worse for years, and am less than satisfied with all of them. The two most promising so far are:

TTRSS Published feed through FeedWordPress
TTRSSFWP
This generates individual posts from the items in the published feed, in whatever form the interaction between the feed and the WP template generates. It gets all the desired content up, and in principle it provides a local comment scheme.

It is, however, extremely noisy compared to the other content I put up, without clearly delineating itself from original content. WordPress can be configured with alternate post types, and per-type display , but that is a level fucking about with PHP and CSS that I’m not willing to engage in unless I absolutely have to. Part of the noise problem is that it doesn’t behave terribly well with snippeting: FeedWordPress faithfully reposts all of whatever came down the feed, and what I would really like is the full note, followed by the link and a short description. While the tools are present to filter and massage the feed, it would take a nontrivial bit of parsing around inside the feed content to produce full notes and limited-length blurbs. Google Plus’s “unbecoming addiction to abbreviation,” as a friend put it, as well as the inflammatory, misleading headline issues at HN and Reddit have made me aware that clumsy truncation is not really acceptable.

A substantially larger problem is that, despite setting all the appropriate options for local comments, FeedWordPress stubbornly refuses to do anything other than pass the comment link through to the original source. Since borrowing WP’s comment system is the primary reason the news-as-posts model seemed appealing, this is not acceptable. There is a four-month-old unanswered bug report (admittedly, a crappy bug report in broken English) about the issue, but that was all I came up with.

This was the one I was most hopeful for being a drop-in solution, but it clearly would take a substantial amount of the sort of web front-end work I don’t enjoy to make it work well

TTRSS Published feed through HungryFEED
TTRSSHF

This just gives an unobtrusive feed of notes and headlines in any container your WP theme supports. Pretty nice as a “Look at these interesting things” sort of mechanism, and makes a nice way of advertising that you have a news feed available, but has absolutely no facility for local discussion. It delineates the content better, but lacks the discussion and history features I would like.

If I decide I need to get off of Google’s services, either because the services become too unsuitable or the parent company does something too horrible, I’ll look around again. Setting up a custom post type (easy), with custom display properties (straightforward but unpleasant), a segregable output feed (trivial), and working comments (??) to auto-post TTRSS’s Published feed into using a mechanism like the FeedWordPress solution above would not be horrible, and would support all the desired functionality, but isn’t something I’m currently willing to do “just because.”

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Replicating Reader Sharing with TTRSS and WordPress

Posted on 2013-05-22 by pappp

I was shit-talking Google Plus’ utility as a replacement for Reader’s social features, and realized I think I actually can do at least as well with my existing infrastructure. I’m not immediately planning to switch, because Plus offers convenience and discovery for others, but I wanted to try it, so there will likely be some spurious posts appearing [and disappearing] shortly. I suspect most of my readership consumes their internet through a feed reader, so this post exists as documentation.

For the interested: TTRSS has a publish mechanism, which creates a custom RSS feed of any article you mark published, along with whatever note you have attached to it with the built in annotation system. It even allows for non-feed content to be shared. There are various WordPress plugins that can embed an RSS feed (HungryFeed,EmbedRSS) or import an RSS feed as a post type (FeedWordPress).
Embedding as custom posts gives both distinction and a comment system, and it is a universal interfaces (can read from web, subscribe via RSS ,etc.). There is even social discovery support built in should such a thing take off.

If this experiment works really well, I might even talk myself into using it before Google gives me another reason.

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