Gas station without pumps

2019 September 30

Thirty-ninth weight progress report

This post is yet another weight progress report, continuing the previous one, part of a long series since I started in January 2015.

My weight is almost the same as a year ago, showing a steady increase since classes ended. This does not bode well for my retirement years.

The pattern for this summer looks the same as for last summer—I’m going to have to try to drop my weight this fall, and not wait until January.

I’ve been exercising more this summer than last year, cycling up the hill to work out at the OPERS Wellness Center about three times a week. I’ve been averaging 3.77 miles/day for August and September. That exercise does not seem to have affected my weight gain, though. I like to kid myself that the exercise has increased my lean body mass while reducing the fat, but one look at my waist disabuses me of that notion.

I think that being home and having available food at all times makes a bigger difference than exercise in failing to control my weight (I say, having just eaten a chocolate-chip cookie my wife baked this afternoon). Not only are the way too many chocoloate-chip cookies in the house, but my son and I will be baking a big batch of Shakespeare shortbread cookies tomorrow, also, though we’ll be giving most of them away on the bus trip up to Ashland for the Oregon Shakespeare Festival.

2019 September 24

Fall philosophy sing-ups

Filed under: Uncategorized — gasstationwithoutpumps @ 12:05
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A couple weeks ago, I got an announcement of “Fall Philosophy Sing-Ups” through the mailing list for the umbrella school my son used to homeschool with.  Although I realized it was just a transposition typo (Sign⇒Sing), I thought the concept amusing enough to point out to my wife, who immediately thought of Monty Python’s Bruces’ Philosophers Song:

Unfortunately for the students, the description of the course did not sound like nearly as much fun.

2019 September 19

Printed 3DBenchy

Filed under: Uncategorized — gasstationwithoutpumps @ 13:32
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One of the standard test pieces for 3D printers is 3DBenchy, a design with several somewhat difficult features created by (licensed CC-4.0-By-No).  I finally got around to printing it earlier this week on my Monoprice Delta Mini using Hatchbox Gold PLA with a layer height of 0.07mm and the 0.4mm brass nozzle that came with the printer. It took 4 hours and 25 minutes to print at that resolution.

I’ve been trying to figure out how to get Cura 4.2 to dump the entire settings used to generate the Gcode, but I’ve been unable to do that—it seems to record only the differences from the standard settings. So far the best I’ve been able to do is to extract settings from the output G-code:

;Filament used: 3.85238m
;Layer height: 0.07
;Generated with Cura_SteamEngine 4.2.0

M82 ;absolute extrusion mode
G21;(metric values)
G90;(absolute positioning)
M82;(set extruder to absolute mode)
M107;(start with the fan off)
G29 P5 Z0.3 V4; (Level the bed with 5x5 array)
G1 X55 Y0 Z5 F3000;(Move to the outside of the bed.)
G92 E0;(reset extrusion distance)
G1 E5 F500;(Prime.)
G92 E0;(zero the extruded length)
G1 Z0;(Down to printing height.)
G2 X0 Y55 I-55 J0 E20 F2000;(Draw a priming arc.)
G92 E0;(zero the extruded length)

adhesion_type = none
build_volume_temperature = 0
default_material_bed_temperature = 50
layer_height = 0.07
layer_height_0 = 0.14
material_bed_temperature = 40
material_bed_temperature_layer_0 = 50

alternate_extra_perimeter = True
brim_width = 3
cool_min_layer_time = 3
fill_outline_gaps = True
infill_sparse_density = 25
line_width = 0.35
material_initial_print_temperature = 195
optimize_wall_printing_order = True
top_bottom_thickness = 0.42
xy_offset_layer_0 = -0.05
zig_zaggify_infill = True

That is enough to recreate the settings in Cura 4.2, but if the default values change in later versions of Cura, I won’t know which to reset. Some of these settings are irrelevant, also, as the brim_width doesn’t matter since I didn’t use a brim, for example.

Print speed is the default 60mm/s with walls and top/bottom at the default 30 mm/s and travel at the default 120mm/s.

I chose to print at 0.07mm (70 µm), since I read somewhere that multiples of that thickness are best for the Monoprice Delta Mini.

Bottom view shows the shiny surface from using a glass plate with hairspray as an adhesive.

The top surface looks pretty clean, but stringing can be seen from the stern and between the uprights of the wheelhouse.

The top view looks pretty good from this angle also, but some blobbing can be seen inside the bow.

The port bow shows smooth sides, but some stringing on the hawsepipes and poor bridging at the top of front window of the bridge.

The view from the stern shows bad stringing for the rear window. The 0.1mm writing on the stern is barely legible with angled lighting (not really with this flash).

The starboard view shows bad stringing between the uprights of the bridge and some blobbing on the back of the bridge, as well as some layer marks near the top of the arch.

Many of the calibration checks (measured/ideal) are hard to do with calipers, because there are not well-defined measurement points or other parts of the print interfere with placement of the calipers. I skipped some measurements entirely as impossible to measure with the calipers.
roof length 22.9mm/23mm
chimney cap diameter 6.4mm/7mm
depth of chimney hole 11mm/11mm (hard to measure accurately)
chimney inside diameter 2.4mm/3mm (hard to measure accurately)
length 60mm/60mm (hard to measure accurately)
width 29mm/30mm (hard to measure accurately)
height 48.2mm/48mm
box height 15.65mm/15.5mm
box width 11.8mm/12mm
box inside width 7.8mm/8mm
box depth 9.1mm/9mm
box length 10.75mm/10.81mm
hawsepipe diameter 3.95mm/4mm
front window width 9.95mm/10.5mm
rear window outer diameter 11.35mm/12mm (horizontally)
rear window inner diameter 8.9mm/9mm

The z-heights look about 0.5% too big and the x-y dimensions about 2% small (though I don’t trust the measurements—I’d want to use a rectangular block for re-calibrating).

I think that the biggest problem is stringing, which may be fixable by increasing the retraction, though bridging at the top of the front window is also flawed. Retraction is enabled and is the default 6.5mm @ 25mm/s.

I’ll be asking for advice on the 3D-printing subreddit, since asking for help on Benchy prints seems to be common there.

2019 September 17

Spacers for electric outlet box

Filed under: Uncategorized — gasstationwithoutpumps @ 12:34
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Yesterday I printed some functional (rather than decorative) parts. The problem I was addressing was one that had been bothering me in a low-key way for several years—an electrical outlet in the living room that was wobbly. The problem started when I had the front wall insulated. Because the wall is self-formed concrete, sheets of foam insulation were added on the inside of the wall, sheet rock put over the insulation, and then a skim coat of plaster added to match the original texturing of the walls. The outlet box for the electrical outlet was now rather deeply recessed in the wall, and the carpenters move the outlet forward by using longer screws.

Unfortunately the spacers they used to hold the outlet in the new position were not real spacers, but plastic wall anchors, which did not hold the outlet firmly in the right place—they were relying on the strength of the plastic wall plate to hold the outlet forward. This was never very secure, and this summer the wall plate broke while plugging in an extension cord, so I decided to print some properly sized spacers to hold the outlet securely in place.

I turned off the power and measured the spacing needed with the depth gauge of my calipers, as well as measuring the room available for the spacer. I printed two spacers that were 13mm long and replaced the outlet, only to find out that outlet was still too deep in the wall for the new cover plate to be screwed to the outlet. I tried measuring how much further out the outlet needed to be (estimated at 9mm) and printed a pair of 22mm long spacers.

These are the 13mm and 22mm spacers that ended up being extra. The ears on the spacer are not necessary—I put them on to match the outlet, to make alignment easer, as the hole was initially not centered vertically. I later changed the design so that the hole was centered, so the orientation is now irrelevant and a simple rectangular spacer would suffice. The parts are printed with 0.14mm layers in Hatchbox Gold PLA, with 25% infill.

On the first attempt to print a pair of 22mm spacers, one printed fine, but the other ended up with a long trail of tangled spaghetti after printing halfway just fine. Reprinting just one 22mm spacer failed again, this time with a blobby mess. The problem, however, was clear—the print had gotten detached from the baseplate and was moved around by the printhead. Using some hairspray on the bed increased the adhesion enough that it printed fine, without needing to add a brim.

These two prints were supposed to be 22mm spacers. The one on the right was printed at the same time as one of the successful prints, and the one on the left was an attempt to reprint just one spacer. For both, the failure was insufficient adhesion to the glass bed—I fixed the problem by using hairspray to increase the adhesion.

When I put the 22mm spacers in place, the outlet stuck out too far (my measuring skills clearly need some improvement). The outlet stuck out much more on the bottom than on the top, so I put on the cover plate and measured the clearance from the wall on both the top and the bottom. I decided that I could use the smaller 13mm spacer on top, but I would need an 18mm spacer on the bottom. After printing an 18mm spacer, I assembled the outlet once more, and everything fit perfectly, with the cover plate flush against the wall as desired.

2019 September 14

About halfway through my 6-month break

Filed under: Uncategorized — gasstationwithoutpumps @ 22:52
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In Grading done!, I posted a to-do list for the six months I have off until I start teaching again in January.  I’m now three months into that period, so I thought I would revisit the list:

  • Review senior portfolios for about 50 graduating seniors. DONE
  • Rewrite the Applied Analog Electronics textbook.  I have about 161 to-do notes left in the book from teaching the last two quarters—some from student comments, some from observations made while grading. I’m down to 70 to-do notes, so I’m a little ahead of schedule.  If I can maintain an average of one note removed per day, I’ll be done by Nov 24.  I’ve been wondering whether I should release an interim version of the book, with the additions and corrections so far, for anyone who need the book for fall quarter or fall semester.  I’ve not had enough sales to indicate that any class but mine has ever adopted the book, but if even one or two readers would benefit from a September edition before the December one, I could do another release.
  • Read the Student Evaluation of Teaching forms for both quarters and think about how to improve the class based on them.  This will probably require a beer or two, as I know that some of the students really hated the class (based on anonymous comments on Piazza).  I’ll wait on that until my stress level has gone down a bit, or I won’t be receptive to even the good ideas. I still haven’t done this—I should do it soon, as it could affect some of the book rewrites.
  • Design a senior project involving testing hearing aids—perhaps contacting faculty at the hearing-aid research center at DTU.  Maybe visit DTU in Copenhagen? I’ve not done anything about this, and it is looking unlikely.
  • Visit my dad in Boulder. DONE  (I’ll probably want to visit him again, but I’m not sure when.)
  • Get a new range hood installed (I promised this to my wife last summer). No progress.  I have a range hood selected, but installing it will require professional help, so I haven’t ordered it yet.
  • Get a new refrigerator (the old one is rusty and the interior light doesn’t work) No progress. I found a couple of refrigerators that would fit the space, but haven’t ordered anything.
  • Get a new desktop computer and monitor—perhaps a Mac mini? No progress. I’ve been using the “MacBook Air (11-inch, Early 2014)” machine that I use for lecturing from, even though one of the touchpad switches is broken.
  • Remove the ivy and blackberry vines in the backyard (that is a never-ending project, as the vines have covered about 50′ by 20′ to almost head height) I cleared a small area, and I’ve been keeping it clear, but it is only a tiny piece of the area that needs clearing.
  • Clean solar panels Not done yet, but something I could tackle tomorrow.  It has been really hot lately, so getting wet from using the hose and a squeegee on a 20′ pole does not sound bad.
  • Fix my desk lamp (the one I made)—the copper tubing has suffered from metal fatigue, partly as a result of the cat playing with it and bending it over.  I’m trying to decide between remaking the copper supports (out of copper tubing again) or soldering on copper pieces to splint the fatigued part. No progress.
  • Mow the front lawn (easy! I can do it in an hour or two next weekend) I’ve mowed the front lawn a few times this summer.  It doesn’t look great (the “grass” consists of many different species of weeds), but it is not as bad as in June.
  • Mow the back lawn (probably impossible) Still seems impossible, but I should at least blaze a path back to the compost heap.
  • Sort all my old screws, bolts, and nuts by size and put them in accessible storage boxes. No progress.
  • Clear the breakfast-room floor of electronics, magazines, catalogs, … that have accumulated while I was grading. I’ve done this a couple of times this summer.  Stuff keeps re-accumulating, though. I’ll probably do it once more before my trip to the Oregon Shakespeare Festival, so my wife can have a clean breakfast room while I’m away.  (She has work and can’t go up to Ashland, so I’m going with my son.)
  • Clear the bedroom floor of hardware, books, magazines, and stuff that has accumulated over the last decade.  But where will I put it all? No progress
  • Replace the soap dishes in the bathroom (I like the design of one that has cracked, but I can’t find another like it). No progress.
  • Hire someone to haul the truck load of debris on my driveway to the dump. I’ve added more to the pile, but not hired anyone yet.  This is way overdue.
  • Get an architect to design wheelchair access to my house (I don’t need it, and hope I never will, but I’d rather it were in place before I need it). No progress.
  • Get a new gate designed, built, and installed on the driveway.  The old one rotted away, so I’m thinking of going with concrete pillars and a steel gate this time, instead of redwood. No progress.
  • Clean solar panels. Why was this on the list twice?  I’ll be lucky to get it done once!
  • Clear leaves, twigs, and dirt out of gutters. No progress.
  • Install path lights, if I can find any that look decent. I bought some cheap solar path lights from American Science and Surplus, but they were a waste of money (even if not much money). My wife decided that they looked awful and they only stay lit for about an hour after sunset, so they are neither decorative nor functional.
  • Get my annual eye exam (6 months overdue). DONE
  • Get a physical therapist or sports-medicine specialist to advise me how to run without exacerbating my hip osteoarthritis. I had one appointment with a physical therapist, but I did not find his advice very useful. He basically suggested not running, gave me some stretching exercises, and chatted with his assistants—not a particularly valuable half-hour session for over $500. I have started working with a personal trainer at UCSC, for $24–30 an hour ($24 is the price for the 3-session intro package with a student trainer, $30 is the price for single sessions, with discounts down to $27 if you buy 10 sessions).  I’m doing the personal training once a week, with two other workout sessions a week on my own.
  • Join a gym and learn to use fitness equipment (for example, I’d like to learn to run on a tilted treadmill, so that I can do a stress echocardiogram test without fearing for my balance). I’ve got a membership at the UCSC gym, for $$22.84/month (going up in October).  I can’t use payroll deduction, because I don’t get a paycheck while on unpaid leave of absence. The gym has not been too busy during the summer, but if it gets super busy when the students come back, then I might discontinue the membership.

    I have been doing mainly upper-body exercises at the gym, but I’ve also been practicing running on the treadmill.  I just noticed today, though, that I’ve been training at the wrong pace.  What I’ve been doing is upping either the incline or the pace every 30 seconds until I can’t take the pace any more, but I’ve been keeping the numeric values of the %incline and mph roughly the same—starting at 5mph at 5% slope and gradually increasing to around 7.5 mph at 7% or 7.5% slope.  But the stress test I took in December had me stopping at 4.3mph and 10% slope.  So I should probably be working at a slower pace and greater slope (maybe aiming for 5mph and 15% slope).

    The Bruce protocol calls for 3.4mph and 14% slope in stage 3, but that would not get me to my maximum heart rate.  I think I can manage stage 5 of the Bruce protocol (5mph at 18% slope, 14 METs) for a short while, because I can sometimes sustain 14 METs for 30 seconds (7.5mph at 7% slope), but I’ve not tested myself at a slower pace and higher slope.  One problem I have is that the protocol (both the Bruce protocol and the modified one my cardiologist used) calls for a long time at an awkward pace that is between a brisk walking pace (4mph) and a slow jog (6mph).

    I’ll probably switch my treadmill training to staying at 5mph and just increasing the incline by 1% every 30 seconds.  That will help me feel balanced on the treadmill, even at the awkward pace, which was the main limiting factor for me last December.  I do know that the test was stopped well below my maximum heart rate, as I’ve been routinely seeing heart rate over 170bpm on the treadmill, and the cardiologist had me stop at 163bpm last December.

  • Repaint the garage door (scrape, sand, prime, paint) No progress.
  • Paint the book room door. No progress.
  • Fix or replace garage-door opener. No progress.
  • Spot sand and apply Danish oil to wood floor where old finish has worn away. No progress.
  • Do some robotics—perhaps continuing work on the bot I started for the mechatronics class, perhaps a balance bot, perhaps making a board for precisely positioning the gear motors that I have, perhaps a drawbot, perhaps a true digital clock with mechanical digits. No progress.
  • Find something useful to make with my 3D printer. I don’t know whether I’ve found anything useful, but I have done some fun 3D printing this summer.
  • Do some weaving—I’ve not woven in over a decade, but I still have a lot of yarn and looms taking up a big chunk of the house. No progress.
  • Figure out what charities (or political organizations) to give more money to. My wife and I sat down and made a list of charities to give to this year, and came up with amounts to give.  I’ve only written a couple of the checks so far, but I’ll do more in the next couple of months.  I’ll probably want to take some money out of my 
  • Look for something interesting to do with other people once I retire (most of my hobbies are solitary). No progress.
  • Brew a batch of mead (I’ve not made any since the Loma Prieta earthquake in 1989). No progress.
  • Improve documentation for PteroDAQ. No progress.  More important is to move PteroDAQ out of the Mercurial repository on BitBucket, since Atlassian is trying to get rid of all their Mercurial customers.
  • Port PteroDAQ to new processors? No progress.
  • Temperature-compensated VCO. No progress.
  • VCO using one op amp and one FET (is it even possible?) No progress.
  • Torque-measuring rig for small gear motors.  Both stall torque and torque vs. speed. No progress.

So, as expected, most of the possible summer projects have shown no progress.

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