This the rail I used: http://openbuildspartstore.com/v-slot-linear-rail/

Cuts for a 12″x12″ heated Bed

20×40 Rails
A. Legs x4 = 515MM (2x1500mm)
B.Horizontals x4 = 440MM (2x1000mm)
C. Top Beams x2 = 450MM (1x1000mm)
D. Base Beams x2= 430MM (1x1000mm)
E. Bed supports x2= 395MM (1/2 x 1500mm)
F. XY Slider x1 = 464MM (1/2 x 1500mm)

20×60 Rails
G. Z Slider = 428MM (1x500mm)

Z Lead Screw x2= 400mm

While I enjoy using my 3d printer there’s one chore that I hate doing over and over again. Leveling my print bed and adjusting the print height!
I even have an auto bed leveling setup with an inductive probe, but I still find it necessary to tweak the height of the bed to get the perfect first layer on my prints. I’m often switching nozzles or changing filament types and tweaking my bed height is such a pain.

Well, I’ve found the solution! I’ve created a new command in Marlin that allows me to tweak the bed height and I can even save the setting for future prints.

The new command is M116.

M116

To add this command to Marlin, you must add the code snippet below to the file Marlin_main.cpp and upload to your 3d printer( I added it after the command gcode_M115() )


/*
M116 Tweak Z setting (positive values raise the bed)
*/
inline void gcode_M116() {
float origPosition;
origPosition = current_position[Z_AXIS];
float tweak_step=0;
if (code_seen('Z')) tweak_step = code_value();
destination[Z_AXIS] = origPosition+tweak_step;
zprobe_zoffset+=tweak_step;
prepare_move(); // this will also set_current_to_destination

st_synchronize(); // This will reset Z readout to original value after moving Z the tweak distance
float v = current_position[2] = origPosition;
sync_plan_position();
}


This command will raise the bed by 0.1mm when you send the command “M116 Z-0.1″ and to lower the bed 0.1mm by sending “M116 Z0.1″. It will adjust the bed height, but it will then set the Z height value to whatever it was before you adjusted the bed, so it is fine to run this command in the middle of a print.

To add these commands to your control panel in Simplify3d go to Tools>Firmware>Macros tab and copy from the image below. (Add M500 to the end of each macro if you want these tweaks saved after resetting your printer)

For convenience I added these commands to my Simplify3d machine control panel, and now my first layer headaches are gone!

The original C-Bot printer design uses little plastic ramps that cause the bolt to press towards the rail as you tighten the bolt, this can work in general but doesn’t allow you fine control of how tightly the wheels are pressing on the rail that they are sliding along. If the wheel is too tight you get too much friction and the bar doesn’t roll smoothly. Too loose and you introduce slop and vibration during your 3d prints.

To allow for more precise adjustment I’ve started using 6mm eccentric spacers from OpenBuilds Part store, these work because the center hole is drilled offset from center and allows you to adjust how tightly each wheel rests against your V-rail by rotating the spacer with a small wrench. You only need the eccentric spacer on one side of each axis carriage, so for my printer each assembly has four wheels and I only use two eccentric spacers, one each for the top two wheels. This modification is fairly cheap, the most difficult part is printing out new parts that have the proper opening for the new spacer.

I’ve only modified the X-carriage and Y-carriage so far but I’m very pleased with the results. The rail seems to roll much more freely but without any slop. I will eventually modify the Z axis as well.

Files are here!

C-bot plates modified for eccentric spacers

I wanted to add some lighting to my 3d printer so that I could see the status of the bed heating and to shed some light on the build platform.

I went with these RGB strip lights from Amazon.com, they can be driven by a 12v power source and have a convenient adhesive backing which makes it easy to mount anywhere. Also make sure you order non-waterproof led lights since they cost less… unless you plan to 3d print in the rain.

Here’s a link to the RGB light strip I used:
http://amzn.to/1GMLXTC

I also needed 2 T0-220 Mosfets to allow the Rumba board to control the led lights without getting zapped. The pwm pins on an arduino can only handle a maximum current of 40ma, using mosfets is necessary since the LEDs can draw more current than that.

Here’s a link to the type of Mosfets that I used:

http://amzn.to/1Gw51mK

Wiring instructions for connecting the mosfets between your Rumba board and the led strip can be found here:
https://learn.adafruit.com/rgb-led-strips/usage

I used only 14″ of the RGB LEDs and I have plenty leftover for other projects. I mounted the LED strip using the adhesive already mounted on the back of the strip.

To modify my Marlin firmware I followed the instructions on this page here:

https://ultimaker.com/en/community/view/7204-rgb-led-strips-control

The hard part for me was finding which pins I could use on the RUMBA board and what their pin numbers were. I ended up plugging the power lead of the RGB LED strip into the + side of HE2 and the RGB Green wire to the – side of HE2 on the RUMBA. The pin number for HE2 is “4”. The HE2 port already has a MOSFET on it so no need for extra wiring there.

The other two pwm pins you can use on the RUMBA are on the expansion port called EXP3 and are pins 5 and 6. Look at the image below and realize the EXP3 port is ONLY the two rows of 7 pins on the left and does NOT include the two pins under the label “12V”. This confused me at first and I was connecting to the wrong pins.

Where to find the extra pwm pins!

When I enter M420 S0 and send it to the printer the LED strip pulses through all the colors of the rainbow, and it looks pretty cool!

Now that I had my LED lights wired up and able to be activated with Gcode commands, I now wanted it to gradually change from yellow to red as my build platform heated up. To do this I modified my Marlin_main.cpp with the following snippet of code. I modified the function gcode_M190() with the lines in bold below.

inline void gcode_M190() {
LCD_MESSAGEPGM(MSG_BED_HEATING);
no_wait_for_cooling = code_seen('S');
if (no_wait_for_cooling || code_seen('R'))
setTargetBed(code_value());

The first step I took in building my Core Bot was printing out all the parts for the machine. I was fortunate that my friend was traveling for 3 weeks and lent me his Makerbot Replicator 1 so that I could start print all the pieces I needed to build the printer. My family was mesmerized by the new machine and loved watching it print out new pieces day after day.

I’ve been dabbling in 3d printing at work for the past year and now I’m addicted. I have two friends who own 3d printers and I’m constantly impressed with the many different creative projects they create with them, everything from bird houses to artistic sculptures to belt buckles! You can see much of this work at my friend Eric Pavey’s blog . I began researching 3d printers to buy based on my experience using a Makerbot Replicator 2x. I wanted a printer with a cubic foot build volume, heated bed, dual extrusion capability and a light weight print head to prevent “ringing” artifacts on my prints. I found a printer that met these criteria in the Fusion F306 printer but I wasn’t prepared to spend the $3900 price. While searching for an alternative I came across Carl Feniak’s C-bot project which had all the features I wanted for around $1000, the only catch was that I had to build it myself! Thus my Journey began building what I like to call “Core Bot”. I will document the process I went through building the printer so that others can benefit from my experience.

I’m a 3d technical artist and I have been working in video games for the past decade. I’m currently working at the incredible Activision studio –  Sledgehammer Games. Sledgehammer created  Call Of Duty Modern Warfare 3 and we are working hard to make more of the best games on the planet.  Please check out my demo reel on Vimeo if you want to know what being a tech artist entails.

Mason Sheffield Tech Art Demo Reel 2012 from Mason Sheffield on Vimeo.