Month: November 2014

Breaking the Rules

Radioshack failed me this evening: they don’t sell micro usb jacks, and when it came down to it they sell the plugs but not the jacks for the smaller variants of barrel power connectors. They do sell 1/8″ mono headphone jacks and plugs, and as far as I could find that was the smallest plug/jack combination I could get (prioritizing small for the jack).

For context: a while back I got some of this stuff with the intent of making heated gloves or at least hand/wrist warmers. It was cold enough this week to make me think about that project again, but I need a power source.

Micro usb seemed like a great idea: if I’m at a computer I can plug it in there (probably for low current, but it shouldn’t be all that cold if I’m sitting at a computer), or I could use my car phone charger (don’t know the current, but it would be better than nothing), and for a portable solution I could cut the end off a usb cable and wire it to a battery (I certainly have enough usb cables…). I’m seriously considering ordering micro usb plugs from sparkfun, but I think I’ll need a more final solution including something to mount the plug to for it to last. In the meantime, headphone jacks will have to do.

Along with my headphone jacks I bought a sacrificial usb extension cord to modify (extension so I would have a usb female plug to make a usb battery pack out of if I ever feel the need). Here’s the completed modification:
Soldered together

And the successful results:
Success!

I’m fairly certain that it’s a bad idea to have power run to this type of plug (hence the post title) because:

  • it’s easy to short across two exposed and side-by-side contacts
  • what happens if you pump 5V DC into a headphone jack?

At any rate, this is intended to be a temporary solution while I’m prototyping this. Ideally I’ll find a better solution and order parts at some point.

I didn’t actually measure it, but my laptop put out enough current to very noticeably warm a 6-8 inch length of the heat tape. That means I’ve got all the pieces I need to make this work, next step is to figure out how to either 3d print or sew a glove to wire for heat.

Polar Vortex

Monday morning when I left my house it was in the upper 60s (I probably left home around 9:45) and I considered not wearing a coat (totally didn’t check the weather). When I left work I was rather glad to have a coat because it was in the teens and snowing. Because it had been warm earlier in the day the roads were icy with snow that had melted and refrozen. I saw a snow plow on my way home, but I think it was just spreading grit because the snow wasn’t building up and still hasn’t really accumulated tonight (Thursday).
Snowscape

Monday night may have been the warmest temperature I’ve been out in since temperatures dropped. Tonight when I left work my car had a hard time starting (even with a battery that was new last spring), so when I got home I wasn’t surprised to see that the temperature was negative.

Filament Drying

The bin I designed to keep my filament dry worked fine until mid-summer when I switched filaments (which involves taking the lid off the bin) multiple times on a humid/rainy day when I had the windows open. I’m guessing that overwhelmed the silica gel cannister, and ever since that day I’ve had trouble printing with ABS.

I knew nylon was sensitive to moisture, especially after the first time I left the nylon hooked to the printer for a while and got steam out of the nozzle for the first layer or two of the print when I used it next. I didn’t realize ABS would have similar issues until today when I once again tried to print ABS and had issues. When I paused the print it kept oozing filament (similar to but not nearly as extreme as nylon did) and when I listened closely I could hear the faint sizzling of water vaporizing. I looked it up and sure enough, ABS, nylon, and even PLA are listed as having issues with moisture, and it was a relatively wet summer here (bigger issue is that I just opened the windows for the breeze rather than turn on the AC).

A quick Google search revealed that one way to dry filament is to stick it in the oven for a while hot enough to vaporize water. Google also told me that ABS softens at around 100 C and PLA softens at more like 60 C, so I’m not drying my PLA and 100 C is about the hottest I should put ABS in for. That all sounded great so I stuck my two spools of ABS (and the nylon) in the oven to dry, along with the silica gel canister to reset it’s moisture absorbing capabilities.

Issue: the spools are black, so they absorb heat quickly, and they couldn’t take the heat:
Melted Spool

Fifteen minutes later when I checked on it none of the filament had softened (I’ve heard tales of people fusing an entire spool of filament together, which makes it unusable for printing), but all three spools had softened and the largest was melted to the oven rack. I dropped the temperature a bit but left it all to heat for another hour or two.

After all that, there was no difference whatsoever in terms of bed adhesion. I spent the better part of the afternoon working on it and I’m not entirely sure what made the difference: the last round of changes included changing my z-offset, windexing the glass build plate (having previously just been scraping it clean with a glass scraper), and mixing up and applied cold a new batch of abs juice using fresh filament instead of failed print bits.

Finally, after several months of not getting good results from ABS:
Keychains

The first try (right) I should have stopped when it became clear that the first layer adhesion wasn’t good enough, but I was so happy to get even that much that I let it go so I could see how the letters came out. The second one included a slightly modified design: there’s a one layer thick block to anchor all the parts that tried to curl.