Tuesday, 28 June 2016

Upgrading the Micro Kossel round 2

     So, after the last time I upgraded the Micro, I did some motion testing and found that the new effector was trading increased print height for build radius, in other words it was limiting prints to half of the physical build plate with a slightly taller maximum height. I decided to see if I could do better. Starting with the E3D Lite6 Documentation, I imported the STL of the original effector into my favourite 3D modeling program and designed a new effector that raised the heatsink above the effector and supported nozzle cooling fans.

Micro Kossel with upgraded raised effector
     Designing this new effector was far from simple, my first steps were basically creating a digital mock-up of the Lite6 and it's fan ducting along with removing the center holes from the mesh for the effector platform, took about 2 days of work and research to finish that part. Next was deciding where to put the nozzle fans and not interfere with the motion mechanics. My basic idea was to place the fans at the top of the hot-end, tilted about 30 degrees down from horizontal, and with the nozzle just below the bottom of the effector.

Effector version 1 with one fan installed for testing
     As you can see, not the best design, mainly because I forgot to allow for the wiring harness! That gap near the front is my attempt to correct the issue with a wood chisel, not particularly effective and not something I'd do again.
     For my second iteration, I decided to move the effector so it's just above the wiring, basically made it shorter, the design work was fairly quick this time, so I printed version 2 the next day.

Effector V2
Version 1 (left) and Version 2 (right)

Effector V2 with fans and Kapton tape
V2 with hot-end half installed

Hot-End clamp with mounting screws

For the non-printed parts I'm using a pair of 3010 box fans with 2 of the corners cut off, 6 M3x20mm screws, and 2 M3x10mm screws.

V2 with hot-end fully clamped

     This solved the wiring issue, so I proceeded to install the rest of the components, only to find that the fans protruded too far from the effector and jammed against the rod arms, not much of an improvement over the 'tuna can' effector. So back to the drawing board for version 3.

Version 2 (Left) and Version 3 (Right)

     For Version 3, I moved the fans upwards so they are fully above the hot-end and rotated them 180 degrees so the lowest edge is pointing inwards towards the Bowden tube, not outwards. As you'll probably notice, the v3 prototype's fan mounts are a bit rough around the edges, that's because my Mini Kossel was being glitchy about printing V3, just some kinked filament, so I cut the fan mounts off the V1 and epoxyed them to the incomplete V3 print.

V3 with Hot-end installed

Version 3 fully assembled

     All that remained was to attach the rod-arms and test the range of motion, the V3 design allows the effector to practically touch the drive belts without issue, and adds a full 5 cm to the maximum build height, bringing the maximum build volume up to a 13 cm diameter by 11 cm high cylinder.

You can find the stls for the raised effector here: Body Clamp
Non-printed parts:
2 3010 case fans with 2 corners removed (see photos above)
2 M3x10mm screws for the hot-end clamp
6 M3x20mm screws for mounting the fans and hot-end clamp

Tuesday, 21 June 2016

3D printing around the house

So I was looking around and realized that I've done a few 3D designs that I'd forgotten about because they're simple everyday objects, so I thought I'd share a couple of them.

Temperature knob on kitchen oven
Tea jar lid
First up is the temperature knob on the kitchen oven. This one is a good example of 3D design being used to replace a unavailable part on old equipment. What isn't visible in the photo is that the control shaft, the metal bar that the knob is mounted on, snapped from fatigue about 0.5 cm behind the faceplate, so I photographed the damaged area, measured the cross section of the rod and it's hole, and combined that with the style of the remaining knobs to create the replacement in the photo. It's glued in place with 5 minute epoxy (Lepage brand I think), and has been working perfectly for about 4-5 months at this point.

The other one is a simple replacement lid for a jar we use to store tea bags, the original ceramic one broke when it got dropped on the floor. Design wise, this one was quite simple to create, I simply measured the diameter of the mouth of the jar along with the width of the lip around it, and used those to create a cylinder with the same diameter as a starting point. The rest was simply making a shape that looked like a nice handle and about 4 hours of 3D printing.

Saturday, 11 June 2016

Project: Vein Finder

For the past 2 weeks I've had a side project going and now it's ready to share. I call it Project: Vein Finder.
Project: Vein Finder powered and ready
If you're wondering what a vein finder is, it's a specialized flashlight used by medical professionals to locate veins under the skin when starting i.v. lines or giving injections.
Vein Finder prototype ready for testing
Basic operation is fairly simple, flip the switch to turn it on and hold it about 6 inch above the section of skin you're searching for veins, the red light acts as a highlighter for veins and makes it easier to see them.
Vein Finder Parts with LEDs installed
 The parts list is fairly simple, 6 620-680 nanometer 5-6000 millicandela LEDs, 6 51 Ohm 1/4 watt resistors, a 2 position switch (SPST Rocker in this case), a holder for 2 'AA' batteries, 2 'AA' 1.5 volt batteries, and some dark colour 3D printer filament.
Electronics installed and ready for initial testing
Tools needed are a 3D printer, a decent multi-meter, needle nose pliers, wirestripers, and elecrical tape to insulate the internal connections. The internal circuit is fairly simple, just connect the positive lead from the battery holder to the switch, switch to the positive leads of the LEDs in parallel, negative leads of the LEDs to a 51 Ohm resistor independently, and finally connect the resistors to the negative lead of the battery holder.
Vein Finder with cover for forward electronics installed

LED testing after electrical assembly

Here's the source files for the 3D printed shell: Project: Vein Finder Shell

Sunday, 5 June 2016

Upgrading the Micro Kossel

I've been doing some upgrades to the Micro Kossel lately, aiming to improve the print quality and since PLA prints best when cooled immediately below the hot-end, I remixed a raised effector to fit the E3D Lite6 hot-end and installed the result:
Micro Kossel with new effector

Assembly is fairly straightforward, main non-printed parts needed are 6 M3x10mm screws, 4-8 M3x20mm screws, and 2 3010 case fans (Example):
Effector parts
3010 fans installed with 4 M3x20 screws

After installing the fans on the effector platform, the next step was to disassemble the old effector from the Micro's frame and mount the hot-end in the new one.
Hot-End half installed, fan on the right is for heat-sink cooling
Alignment of heat-sink
new effector installed and ready to print

After all the mechanical assembly was finished, the last step was to connect the new fans to the control board's connector block (D9 on Ramps 1.4 with the Micros default firmware) and start printing.