Tuesday, September 30, 2014

Curtain Ring Stops

I learned a long time ago, that having cool toys (like my 3D printer) goes over much better when I can make practical stuff for around the house.

So my very first real project was to print some curtain ring stops. Our curtains have grommets to hold them on a rod, but the stop at the end of the curtain rod is slightly smaller than the hole in the grommet. From time to time, the curtain pops off the end of the rod. This doesn't bother me, I'm 6'-4" tall (1.93m for those metricized folks) and I just reach up and put it back on. My wife, not being nearly as tall curses every time the curtain comes off the end.

It takes about 12 minutes to print one disk (about 50mm diam and , so I ganged them up and 3mm thick) and printed 4 at a time.

Here's what the disk looks like when screwed onto the end cap:
and what it looks like when installed:
I've ordered some silver filament to print the disks for the living areas, and will use the white ones (I ordered black, white and blue filament with my printer) in my wife's sewing studio.

The disks are a fairly simple geometry, so I decided to model them using OpenSCAD:
translate([0, 0, 0]) {
 difference() {
  cylinder(h=3, r=25, center=true);
  cylinder(h=3, r=2.5, center=true);

translate([60, 0, 0]) {
 difference() {
  cylinder(h=3, r=25, center=true);
  cylinder(h=3, r=2.5, center=true);

translate([0, 60, 0]) {
 difference() {
  cylinder(h=3, r=25, center=true);
  cylinder(h=3, r=2.5, center=true);

translate([0, 60, 0]) {
 difference() {
  cylinder(h=3, r=25, center=true);
  cylinder(h=3, r=2.5, center=true);
Next time I'll learn how to do for loops instead of copy/paste.

Wednesday, September 24, 2014

Bukito - First Print

So I got the bed trammed, and all of the limit switches checked out. Time to print!

For the first print, I decided to print  the Bukito Tram G-Code

Here's a video that shows it just after I started the first print. It places 4 beads around the outside of the table, and you can examine these to see how well you've trammed things.

Here's another video that shows the cylinders being printed.

And one showing the extruder screw.

My photo of the finished print:
and another from above:
A bit of closeup showing some of the fine threads on the inside of the cylinders:
A ruler to give some scale:
And finally, a closeup of the side of the cylinder:

Tuesday, September 23, 2014

XV-11 Lidar

I picked up a nifty little XV-11 Lidar Controller and bought a broken Neato XV-11 for $28 on eBay.

When I got the XV-11 it appeared to be well and truly dead. The batteries were fully charged, but the LCD wouldn't turn on. Which was fine. All I wanted was the Lidar sensor.

I disassembled the XV-11 and got the sensor off. Connecting the motor to 5v made it go round, and providing 5v on the appropriate line gave me the following on the serial port.

Piccolo Laser Distance Scanner
Copyright (c) 2009-2011 Neato Robotics, Inc.
All Rights Reserved

Loader V2.5.15295
CPU F2802x/c001
Serial WTD10713AA-0240567
LastCal [5371726C]
Runtime V2.6.15295
#Spin...3 ESCs or BREAK to abort...
and a bunch of binary data if I spin the turret by hand.

I got the Lidar Controller today and hooked it up:
and it seems to work. I tried running the Visual Test and was able to get this output:

which is my office (about 12 feet x 20 feet).

Very cool.

This should be useable on my indoor platform that I'm putting together.

Bukito - Assembled

My Bukito 3D Printer showed up in the mail today. This was also a KickStarter. It's only about 9 months late, but it looks like it was worth the wait.

It came as a kit, and took about 3 hours to put together. Now to level the table and do a first print (maybe tomorrow - time to go to bed now).

The build volume is about 5" x 6" x 6" which should be fine for most of the stuff I want to do. I figured I'd start small and then once I'm comfortable with a 3D printer, and know what I like and dislike, I can invest in a bigger printer.

I just discovered Nick Lievendag's blog and it will be interesting to see how his evaluations turn out (for consideration in buying a larger printer).

Saturday, September 20, 2014

Argentum - Swapping stepper motor direction

The Argentum has a nifty calibration routine where you stick the head in the middle, and then it figures out which way the steppers are wired up by which limit switches are hit.

However, their algorithim is still a big buggy. The calibration routine seemed to work fine when the head was in the middle (no limit switches activated), but had some issues if it started with one of the X-axis switches acivated:
Upgrading the firmware from the 0.12 version that came with the printer to 0.14 seems to have resolved that. However, I discovered an issue if you tried to calibrate while the head was in the home position (Y limit switch activtated):
When it starts out and the limit switch is activated, then it tries moving very slowly for a short period of time, since it doesn't know which way the head is moving (towards or away from the limit switch). However, since I had previously done a calibration (which it remembers), it should have tried to do its initial move away from the switch rather than towards it.

Since I didn't like the noises the machine was making while this happens, I decided to swap the direction of the Y axis. These are bipolar steppers being used, so you only need to swap the wires on one of the two coils to get the stepper to go in the other direction.

Here's a photo of my Y-axis connector, as it arrived:
The Argentum came with a nice little screwdriver package, that included a variety of 1/8" bits. The torx T3 bit was small enough to fit through the rectangular hole in the housing and depress the metal tab which allows the wire to be released. Here's what the clip looks like once its outside of the housing:

Once the metal tab is flattened, you can start to pull the wire out. I did this with the yellow wire, and then the blue wire. Once both wires are started, you can pull completely out of the housing, swap them and reinsert:
 Make sure you insert both wires far enough that the metal tab re-engage to keep them in the housing.

Now the y axis moves in the opposite direction, and calibration routine works properly even when starting from the home position.

Argentum - First Print

I signed up for the Ex1 Kickstarter (now called Argentum) and it arrived about a week ago.

The kit came as mostly laser cut acrylic parts, which was fairly straight forward to put together. The instructions are fairly detailed.

Here's a photo once it was assembled enough to test the electronics:

There is a simple starter circuit that you can print, so I tried to print it:
Hmm. That doesn't look very good. Only the ascorbic cartridge was outputting anything. I tried removing the ascorbic cartridge and got nothing, and I tried swapping silvr cartridges and got nothing. So I figured I must have screwed up the cabling some where. There are 4 cables with about 20 pins each that drive the print heads, and I had managed to swap the 2 for the silver cartridge.
This is what it looked like after fixing the cables. This was just one layer. You need to print 3 or 4 layers to get enough silver down to reduce the resistance.
Here it is after 4 layers:

And a closeup:

I also took a short video of it while it was printing the 4th layer:

With 4 layers, each trace had a resistance of about 1.5 ohms. Here's the first circuit:
Notice that the color of the traces has changed. After printing 4 layers, you rinse the circuit under water, which removes the small remaining traces of nitric acid, There is an additive in the ascorbic which prevents the silver from balling up and leaves it as tiny particles. The additive is water soluble, and once its removed, then the remaining sliver starts a sintering proess (at room temperature), which furthere reduces the resistance, and cause the color to change from dark gray to light gray.

When you print on FR4, you can heat the whole thing up to about 300C and apparently, the silver will become almost white. I'll post further photos once I get a circuit printed on FR4.

Here's the first circuit working:

In this case, the components weren't soldered down, but are being held down with tape which is conductive in only one axis (the thin axis in this case). They call it z-axis tape.

I put the outer shell of the printer on and this is the finished printer:
I still have to go though the alignment process, and I'll try printing a circuit on FR4.