Before we get started, a disclaimer: The stock Tevo hotend is NOT (despite their claims) designed for ABS temps, and while you *can* technically run ABS on the machine, the PTFE tube goes down into the hotend, which releases toxic fumes, and melts/scorches the end of the PTFE tube causing it to deform and either pinch the filament too much or draw back from the hotend, leaving a small gap which can lead to a clog. Print with ABS temps at your own risk! (I did, I’m alive still!)
Ok, onwards and upwards!
First, check that your coldend fan is on a constant 12v supply. It should turn on to full speed when you turn the machine on, and never change speeds. If you adjust the cooling in software and it fluctuates speeds or changes during printing, or does not start cooling until the print starts, OR until the first layer/s are done, then you have it plugged into the *part* cooling fan’s power. You should have it wired into the same sockets that the 12v supply for mainboard is in.
Second. There’s a good chance that the capacitive sensor is shot. It should only have a range of a few millimeters, to begin with, but it’s possible that due to your overheating problems, it’s fried. If it reliably detects the aluminum build plate when you try to trigger it manually, then you have a mounting issue. Possibly, because of your heating, it’s slipping or shifting. The default configuration of the sensor mount places it over the vents from the heat sink on your coldend, which caused some issues with blocking air flow with mine, though not to your degree. One of my first prints was a mount with a slider and retainer screw, which you can find on Thingiverse, which I cut some holes in in Fusion 360 to allow venting. Heating/cooling of the coldend may also be why your heatbreak is slipping. Check that the grub screws aren’t stripped and that they hold well when cold, then (after solving your cooling fan issues) torque them down a bit when the machine is hot (carefully!).
Make sure that you tighten your nozzle up against your coldbreak tube, with about 0.10mm of PTFE tube sticking out of the coldbreak which will be squished back into the coldbreak when you snug the nozzle. The nozzle should, once properly seated, have about a millimeter of gap between the heatblock and the hex head of the nozzle. Heat the machine and tighten again (again, carefully!).
Now, the difficult bit… the liner of the heated bed is crap. Mine came off almost immediately. I scrapped all of it off and replaced it with glass and hairspray, which was very much superior. Better adhesion, better first layer texture (It’s smooth as silk), and a removable bed, to boot! I use dollar store 8x10 picture frame glass, so if it breaks I can replace it easily. Only problem; the capacitive sensor can’t read through the glass. You’ll have to manually level your bed, which most 3DPrinting gurus swear by, anyway, or upgrade to BLTouch.
Assuming you can solve the heat transfer issues, upgrade to a *Real* BLTouch, ASAP. If heating is still an issue, you should go for the E3D v6 first, as it’ll probably solve all your current heating issues and more that you haven’t encountered yet.
Hope this helps!
-Corbald
