Archive for April, 2013

Printing printers

Monday, April 29th, 2013

I bought a printrbot LC kit about a month ago. I had been toying with the idea for a long time, but was spurred on by seeing a 3d printed cat toy that a friend made and realizing that there are relatively inexpensive printer options ($500-600) out there today. At that price it is relatively easy to justify; if my only options were the $2k monstrosities from MakerBot then I would have never purchased one.

So far I've been having a lot of fun and am very happy with my printrbot LC, which I would highly recommend. I occasionally wish that I had purchased the LC+ rather than the LC (200 mm vs. 150 mm of travel along each axis) but it hasn't been a significant issue so far.

You need a reasonable amount of mechanical, electrical and computer skills for assembly and setup. CAD experience is also helpful for designing things. My wife thinks I'm crazy and would never build one herself. You can buy preassembled printers, but there's something to be said for knowing how it all fits together so that you can tear it apart to make modifications and debug issues.

There are a few absolutely essential upgrades:

  • fan, fan mount and three-point bed leveling system. The fan addresses PLA oozing and makes bridging work incredibly well. The leveling system is necessary to get good consistent adhesion. All three of these things are included in the LC v2 (currently shipping) whereas I had to purchase them after the fact.
  • glass bed and clips. I separately purchased the 0.125" x 6" x 6" piece of borosilicate glass from McMaster-Carr to use as my bed. The glass is rigid, hard and chemically inert so easy to clean, and provides good adhesion to PLA. The first thing that I printed (after Mr. Jaws of course!) was a set of clips for holding the glass in place. I taped the glass to the PCB heater for this print, and there was a noticeably amount of sliding around.
  • wall-mounted filament spool holder. I mounted a toilet paper holder onto the wall in my room and it is absolutely perfect for holding a 1 kg spool of filament. It is a much better option that the lasercut spool coaster and spool options from printrbot in that the spool can never slide off yet rotates easily.
  • filament guide. I'd also highly recommend replacing the built-in wooden idler latch with one that has a built-in filament guide. My extruder used to occasionally skip if the incoming filament angle was off-axis; the built-in guide solves this problem.

The glass clips have worked quite well, although the combination of the clips and the leveling bed design effectively reduce my y-range from 150 mm to 110 mm. I will probably design modified clips in the near future.

Adhesion between PLA and the glass bed has generally not been an issue. I've printed with natural, red, black and white PLA to date. Only the black PLA has sub-par adhesion, requiring that the glass is squeaky clean and that both the extruder and bed are hotter than normal (e.g. 185/60C typically, 210C/65C for black filament). 1 kg of PLA costs about $30. I've purchased spools from from printrbot, Amazon and 3D Printer Hub and haven't had any issues.

Regarding extruder temperature, I'd recommend running M303 to automatically tune your PID settings if you have a printrboard with Marlin firmware. I use a set of 5 mm calibration cubes and a frog to check print quality whenever I've modified anything.

One other tip - rather than trying to fine tune the z-limit screw, I've found that using the "Z offset" parameter in Slic3r is much easier way to adjust the degree of first layer squishing. This does not affect the need for the bed to be level, just removes the need to mechanically fine tune any constant offsets. For leveling, I follow the standard procedure of putting a sheet of paper between the extruder tip and bed and adjusting the thumbscrews on the bed to yield a constant and light amount of rubbing between the paper and tip across the bed.

I've come across a lot of useful links. Here are some of the better ones that I'd recommend checking out: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

Here's a video of my printer chugging away:

On biking to work

Sunday, April 14th, 2013

I've been biking to work for almost a year, so wanted to share some of the things that I've learned.

Route: I live about 5 miles from work. About half of the route is on an off-street paved trail, a quarter is on nice roads (residential, business parks) and the last quarter is on a busy 35 mph road with a marked bike lane. The biking layer on Google Maps is a key tool for scouting out a route, although I'd recommend using Street View to confirm that all of the roads are bike-friendly before trying them (e.g. Central Expressway is marked as bike friendly).

Showers: I sweat a lot. In the summer after a run it looks like I also hopped in a pool. So having a shower at work was absolutely critical for me. Your mileage will vary depending on how easily you sweat and if you wear a backpack, but having a shower and changing room at work is an important consideration.

Panniers: I bought a pair of Ortlieb panniers a few years ago, which was a fantastic investment. Compared with a backpack they are waterproof, can carry much more weight and volume, and keep your back dry (see showers above).

Lighting: I have four lights: two attached to my helmet using velcro and two attached to my bike. The front light on my helmet is a 2W LED beast so that I can see on the pitch black trail at night while the other three lights are generic bike lights. The front light on my helmet also serves as a headlamp when we go backpacking. Maybe the most important part of the lighting setup is a good set of rechargeable batteries. Eneloop is the best option here by far and puts NiMH to shame. Any charger will work; I have this one and it works great.

Clothes: I usually wear the same clothes I would go on a run in; shorts and a synthetic short or long-sleeve t-shirt. If it's cold, I have a dayglo windbreaker and gloves in addition to a headband that keeps my ears warm under the helmet. If it's really cold then I pull out the balaclava and as a bonus get to scare people.

Other gear: I have a set of plastic fenders for winter, although it's about time to take them off for the summer. They aren't my favorite things in the world, but they do their job. I also don't have them mounted perfectly so they interfere slightly with the operation of my back brake, which is why I'm eager to take them off for the year. Also, clipless pedals are a must and make biking in general so much more enjoyable.

Safety: I've never had any issues with cars even though I bike home in the dark about six months out of the year. This is probably due to the combination of my dayglo jacket, four lights and I'm on a car-free trail for about half of the trip. My main issue has been biking with slippery conditions when it's rainy and I've had three relatively minor solo accidents. All three accidents were on one region of the trail and caused by slippery road markings (two accidents) or biking too fast down a wooden bridge (my bad).

That's about it. So remember - lots of lights, Eneloop batteries and panniers.