03-25-2015, 01:07 AM
Thanks to Barry for the inspiration. Thingiverse Files
Davinci 1 to MK8 Carriage
03-25-2015, 02:23 AM
Updated carriage for better heater clearance
03-25-2015, 03:01 AM
Awesome!! Thanks for creating this.
On a side note on my mk8 extruder mod has some serious issues. I have some heating issues, specifically unloading the filament. I think I need better quality quick connects.
But more concerning is when loading the filament it looks like the gear is going in the wrong direction, almost like it's trying to unload the filament.
03-25-2015, 03:28 AM
You can swap wire sets to reverse the rotation. You should have two sets of wires on your stepper.
On my stepper its
red + / black -
green + / blue -
Copied from the stepper wiki
Motor moving the wrong direction
To get the motor moving in the right direction, is actually does matter which coil is which and what the polarity of the coils are. However, if they're wrong, the motor just turns the wrong way, it's easy to fix that by swapping wires. Pick one the following to reverse the stepper's direction:
Switching the polarity of either (one) coil, like changing ABCD to BACD or ABCD to ABDC.
Swapping the coils, like changing ABCD to CDAB.
Stepper direction can also be reversed in the firmware.
Plugging the plug in backwards (in case your electronics' plugs allow that). This swaps the coils, and reverses both coil A and coil B. Thus the effect is to change the direction 3 times, which gives a net effect the same as changing the direction once. Only few electronics allow that, because you have to figure the right way not once, but each time you connect the stepper.
03-25-2015, 03:40 AM
Another thing to look at is how much spring pressure the filament idler wheel has on it. My first MK8 had an issue with the screw that pushes down on the tension spring. I had to grind off over half of the screw head to relieve spring pressure enough so the filament idler wheel wasn't smashed into the filament gear. You should be able to push a piece of filament, by hand, through the extruder gear and idler pulley easily. You will feel the teeth on the filament as you push and there should be small teeth marks left in the filament. If you are binding the wheels because the spring pressure is too much, this might explain your overheating issue.
If I can find the pictures I took of my MK8 tensioner mod I will post them.
03-25-2015, 04:35 AM
Here are the pictures of the tensioner mod I had to make on my first MK8. My latest MK8 does not have this issue.
03-25-2015, 12:40 PM
Thanks you guys!! Good information. I'll take a stab at this tonight. I am also going to test the voltage coming from one of a suspected problematic heater line. I am using wiring from a broken DaVinci I bought online so I have no idea if the wiring had any issues previously.
03-25-2015, 06:06 PM
This is a dumb question. But is it a bad idea to solder the heating wires? I don't know if they get hot or if they could melt the solder.
03-25-2015, 09:45 PM
The direction of the stepper needs to be changed. If using repetier firmware there is a setting for inverting the direction. Otherwise the wires need to be cut and swapped.
Several have soldered the heater wires. The problem with the original plug was it isn't the right size. I heats up because of the resistance.
03-26-2015, 01:31 AM
I found out my what my problems were. I don't think the stepper had any problem because I was using it on my davinci extruder without any problems.
The MK8 extruder I bought has a loose connection on the heating wire right near the hotend. I though it was my side of things since the extruder was supposedly new. So I soldered the heating wires and powered it up and had the same problem with the heater not working on the unload state. I did the old wiggling of wires to see if temps changed and found the loose connection near the hotend. I think not only is one heater wire loose but also the thermo wire because not only was the heat increasing, the temp reading started jumping all over the place. I'm not sure if this is worth fixing since it's near the hotend and I bought this new.
03-26-2015, 02:15 AM
Is it easy to replace the heating wire in the mk8 hotend? It looks like the wires go into some sort of hard puddy epoxy. How would you insert a wire into that.
03-26-2015, 11:15 AM
Never mind I figured it out. I actually was successful in taking one of the working heater wires and cutting it in half. Then removed the bad wire completely from the solid metal wire that gets hot. I then fed the wire I cut into the brass looking attachment that holds the solid metal wire and the heater wire. Turned the machine on and problem solved. One! More issue still with stepper motor direction.
Could I just reverse the plug that goes into the stepper? I think I might sand the plastic extrusion down so it fits
03-28-2015, 02:10 AM
I got my mk8 up and running. Is your carriage available on thingiverse?
03-28-2015, 10:48 PM
Cool thanks. I have been having some weird print issues with my mk8. The abs looks really rough and gobby. It also creates this weird gobby line in this print I started.
04-01-2015, 01:35 PM
Hey Chris, the greeetech extruders are fake chinese remakes. I didn't know this so I am getting a makergeek mk9. Everything is compatible except the fan, and I am trying to see if I need an extra set up for the thermocouple to work