September 9th, 2013
Knowing how crucial the z-axis calibration and alignment is, I focused on that today. I manually rotated the z-axis rods to get even pressure on all of the z-axis v-rail wheels. I then brought the z-axis down to where the #1 nozzle touched the blue painter’s tape. I used this at my point of reference in adjusting the heated bed to ensure it was perfectly level with the x-axis. This required moving the various axis’ and adjusting the 4 corners to ensure it was even all the way around. Here is a good source for aligning the z-axis on an Ord Bot.
Once I had that straight, I saw that the #2 nozzle was a bit higher off the base plate meaning adjustments were due. I ended up partially disassembling the #1 nozzle and adjusting it to be even (up and down) with the #2 nozzle using my recently leveled heated bed as a reference.
I went ahead and re-adjusted my z-axis home offset (see the video above) and printed another test cube. It had a little peeling at the bottom, but the top was fine. This lead me to bring the z-axis home a little farther down. I decided to also try a calibration print using the #2 extruder with 0 infill. I let it print up about half way. This gave me an edge to check the extrusion thickness/flow.
I was pretty happy with the results, but may adjust the setting later as needed.
I then went on to try a dual-extrusion test print. I am using Repetier-Host with the integrated Slic3r for my single-extrusion printing, so I followed this guide to get started. I chose this neat little dual-color traffic cone as my test object.
My first run showed me how far off my “eye-ball” numbers were when setting the offset in Slic3r (I was off my about 1.25mm). Taking that datapoint, I modified those settings and tried it again.
The end result was great! I saw that the two extruder offsets are still a little off (maybe .25mm or so), so I will make that adjustment and try again. I also had a bit of oozing from the dormant extruder despite setting retraction for both at 4mm. I will continue to play with those settings as well. Once I am happy with the offsets, I will put them in the firmware, so that I can use other applications without having to enter them again. I plan to post data and/or screenshots of all of my settings once I fine tune them as well. I will also post a summary walk-through of the printer and its components.
I must say, this was a fun and rewarding project. I found that finding the right source for parts and supplies makes building a 3D printer much cheaper than buying one pre-made.
Either a spool of SainSmart ABS filament to print parts with or buy pre-printed parts on eBay $34
SainSmart 3D Printer Kit (comes with all of the main electronic components and LOTS of extras) $206
Some extra lengths of 22AWG stranded wires (about 50 to 100 feet) $7
A few lengths of 14AWG or 16AWG stranded wire for connecting the heated bed $4
A single or dual extruder (assembled or kit) from eBay $130
An Ord Bot Hadron mechanical frame with stepper motors from eBay $450
1 foot or so of ⅛” diameter heat shrink $1
1 foot or so of ¼” diameter heat shrink $1
Plenty of zip ties (4” long works) $3
Plastic cable shielding $6
PTFE tubing (5/32 outer diameter, 3/32 inner diameter) $3
1/16” thick scrap sheet metal $3
IN540 MOSFET (for fan control) $1
1N4001 diode, 1KΩ resistor, 6.8KΩ resistor $1
Cost: $850 (these sell online for $1500)
Soldering/Hot Air Gun station (like the Saike 852D+)
Allen wrench set
¼” drive Socket set
Phillips and flat tip screw driver set
5mm X 0.8 tap (optional)
3mm tap (optional)
Carpenter’s square (for aligning the Ord Bot frame)