It’s been a while since I’ve posted anything… Since being in the new house, tinkering with my 3D printer has absorbed roughly 75% of my free time. Although I got my printer and kit-form (with oh-so-useful hidden instructions written in Chinese), I was fully expecting some work to be involved. But I wasn’t expecting the learning curve I found! See these failed test prints…
3D printing is a wonderful and interesting new technology, but it is not consumer-ready by any stretch of the imagination. If you decide to invest in a 3D printer, prepare to learn everything about how it works. And if you’re not willing to spend many hours tweaking, learning, and failing repeatedly, I recommend not buying a printer. Just order 3D printed objects from a maker online if you desperately need something.
I faced several issues on my journey to reliable prints (and they could still be improved), but below you’ll find my essential setup tips.
My first major mistake was the nozzle settings in my slicing software (I personally use slic3r, and have been more than happy with it). Where my printer was a kit, that was bought for me, with all the writing in Chinese, I was a bit stuck for details. I used the default settings in slic3r to begin with, which assumed a 0.5mm nozzle. With a smaller nozzle than that, it ended up pushing more filament through the extruder than it should, expecting more plastic to be extruded than was actually possible. Huge clogs in the hot end, a weird knocking sound coming from the extruder motor (a sound that will revisit us later) and no PLA being laid down whatsoever. With a bit of trial and error, and some caliper measurements, I discovered I had a 0.3mm nozzle. A change in the slic3r settings, and most clogging issues were gone.
After getting the nozzle settings dialed in, my prints started flowing a lot better than expected. I’d set up some test prints, leave them running but I’d return to find them stopped halfway through, with the machine still moving around, and the horrific clicking coming from the extruder motor once more. A bit of investigation, and I discovered that if I had enough slack on the filament it would be fine, and would only stop printing when it ran out of slack. The obvious issue was that the stepper was not pulling strong enough to turn the filament spool, causing it to lock up and make the hideous clicking sound which eternally haunts my soul. To resolve this, I had to tweak the power output of the stepper driver to give it some more oomph. In my case this was done by simple turning a screw on the driver board. You can get out the multimeter, and do some maths to find the required value, but trial and error is quicker. You turn it up (when the printer is powered down), and hear if the clicking is stopped. With the extra power, this can make the extruder motor run hot to the touch (which can cause other issues if that heat reaches the filament), in which case you turn it down a bit and try again. After about an hour of playing I got the sweet spot where the motor is only a little warm, but there’s no clicking and the motor has enough torque to turn the filament spool on the holder.
Steps/mm Firmware Settings
With the above issues resolved, printing was finally getting there. I’d run a test print, and it would go from start to finish without intervention, laying plastic the whole time. However it was “thin” – the walls weren’t solid, there seemed to be strange gaps between some of the layers – generally just not right. I found the resolution within the firmware settings. To make permanent changes to settings in firmware, I needed to get the Arduino IDE and a copy of the Marlin firmware the printers main board runs on. Luckily, both of these things are freely available on the internet. The Marlin firmware source files include many files to control the operation of the printer, but the key is Configuration.h – where you can tailor the firmware to your machine. One of the key settings to help it run across many different styles of is the steps/mm settings – for each axis of movement (and the extruder itself), you can specify how many stepper motor steps result in motion of a single millimeter – this needs to be changed to take into account different stepper motors or gearing systems. The key issue I had was in my extruder settings – the steps were way off. I got out the calipers, and using pronterface on my computer I told the extruder to push out 30mm of filament. Once done, the caliper measurement showed only 22.7mm of filament had gone through! No wonder nothing had substance, it was pushing nowhere near as much plastic as expected! A quick bit of maths – (Expected Movement distance / firmware E-steps setting) * Measured movement distance – and I had the correct step/mm figure. I put that into the Marlin code, recompiled and flashed my driver board, then redid the test. This time I measured 29.7mm of filament pushed through. Considering I had asked for 30mm, that was pretty close! I re ran the calibration and maths a few times, and eventually zeroed in on the perfect number. Now it is pushing the correct amount of filament, everything is working fine!
Now, these 3 steps got me from extreme frustration, to a functioning printer. I recommend the above for anyone having issues with a new cheapo printer.
Of course I have had other frustrations, but those are specific stories for other times!