Today I completed the mechanical assembly of the Tantillus. It turns out that the normal nema17 kysan steppers are indeed too large. I have some others on order which should hopefully be here tomorrow. I’m going to use the ramps 1.2 that is currently on my prusa1. That one already has an sdramps on it and the headers on it for the LCD. The 1.75 bowden adapter looks like its going to work. We’ll see once I get started. I did need to reprint one part today, but that is pretty minor. I’m currently debating on swapping the printed lm8uus out for real ones, but I’m still on the fence. Tomorrow I’ll get the ramps 1.2 installed and the hot end wired up.
The stock tantillus uses 3mm filament in a bowden configuration. Since I don’t use 3mm, I wanted to adapt it to 1.75mm. I’m using a #8 nut rather than a 1/4″ nut that the ptfe tube threads into. So that I wouldn’t have to change the design, I build a 1/4 shell nut that wraps the #8. See the pics below:
Tonight I managed to get the x/y-axis and the carriage for the tantillus assembled. Next I’ll add the gears and the fishing line. Maybe tomorrow I’ll make it to the extruder body. I still need to adapt the bowden setup to 1.75, so it may take a few days. If all goes well, the printer will be up and going by the weekend!!!!
I’ve always used tilted fans pointing at the extruder, but wanted to get more precise with my cooling. This helps to improve the print quality because it can cool the PLA very quickly after it exits the nozzle. For my QU-BD extruders, I designed my first duct which used a 40mm fan and a very narrow chamber. Having the fan tilted at such an angle inhibited quite a bit of airflow. To remedy the situation, I ordered a blower (squirrel cage) type fan. I picked 4 of these up off of ebay. I’ve switched back to my MG nozzles because I have a lot of printing to get done for upcoming builds. I built two fan ducts. One of which blows directly on one side of the nozzle which is similar to what I have typically done, but a bit more focused. The second picture has a circular fan duct that I just designed. I still need to adapt the circular duct to the long duct, but that should not be much of an issue. I did a rudimentary test and am very impressed with the result. I can’t wait to try it out!
I’m finally getting to what I would call a stable/predictable state with the QU-BD extruders. Certain parts would allow the flow rate to drop which in turn caused the plastic to bake in the nozzle. I moved up to a .4 nozzle to help it a bit. Now its working beautifully as you can see below.
So I’ve been struggling to get one particular part to print while many others did with the QU-BD extruders. After numerous tests and tweaks, I discovered that when the flow is very low, the PLA hardens in the filament tube. While it sounds simple, this was one hell of a revelation. Now I can print without issue. The prints come out beautiful. The trick for this part was to use a .28 layer height instead of a .2. I print at 212C at 80mm/s. I’m going to build a calculator to determine the min flow rate in a gcode file, but its working. More to come later. Check out the quality
I’ve been tuning the QU-BD extruders to get them to be more reliable. What I’ve found is that they are extremely sensitive to temperature swings. I’ve made a temperature table for Marlin based on the supplied information by QU-BD. Here it is for reference.
#if (THERMISTORHEATER_0 == 61) || (THERMISTORHEATER_1 == 61) || (THERMISTORHEATER_2 == 61) || (THERMISTORBED == 61) // QU-BD
// Thermistor lookup table for Marlin
// ./createTemperatureLookup.py –rp=4700 –t1=25.0:100000.0 –t2=150.0:1783.0 –t3=250.0:232.0 –num-temps=36
const short temptable_61[][2] PROGMEM = {
{187, 350},
{212, 340},
{241, 330},
{275, 320},
{314, 310},
{361, 300},
{417, 290},
{483, 280},
{562, 270},
{657, 260},
{770, 250},
{907, 240},
{1073, 230},
{1275, 220},
{1519, 210},
{1816, 200},
{2177, 190},
{2613, 180},
{3138, 170},
{3766, 160},
{4506, 150},
{5364, 140},
{6339, 130},
{7416, 120},
{8567, 110},
{9751, 100},
{10918, 90},
{12016, 80},
{13002, 70},
{13845, 60},
{14536, 50},
{15078, 40},
{15487, 30},
{15784, 20},
{15994, 10},
{16137, 0}
};
#endif
The results of my current print at 212C are below.
