Month: February 2014

I spent most of today trying to figure out how to get large prints in ABS to complete without curling up in the corners and ruining the print. Here’s the stack of LCD faceplate attempts that I produced.

The first attempt used the same settings as the calibration cube, but after about an hour it had curled enough in two corners that it was clear it wasn’t going to complete in a useful state. The second through fourth prints were attempts to print with the printer set to faster speeds to see if it would be able to keep ahead of the curl. Turned out no, and I had to bump the temperature up by a good bit to keep it from randomly jamming because it was trying to push plastic through the nozzle at about the same speed that the plastic was melting. The last prints I started playing with infill settings – it’s not a structural piece so the default of .4 infill is probably way overkill. I also had to slow down the travel time because it skipped steps a couple times.

The successful print was with .1 infill, a 1 mm brim, and the travel speed limited to 200 mm/s (down from a high of 500 mm/s). It still took over half an hour to print and there was slight curling in one corner (I’ll try increasing the brim next time to see if that’s actually what was helping). I think I’m going to need a proper heated chamber to print large pieces of ABS (luckily most of what I want to do in ABS is small pieces), so I might start trying to work with PLA tomorrow even though it’s not recommended for the E3d hotend I have.

The banding I was getting last night turned out to be from one of the threaded rods being bent. The design prevents it from pushing the extruder back and forth so I didn’t expect it to be a problem, but as it turned it was raising/lowering the end of the X-axis from where it should have been. I don’t think I quite have it perfect yet, but it’s much better. I also smoothed out the motion of the Z-axis while I had the rods removed so now I shouldn’t have any binding.

Also, because I recorded it, here’s a video of a short print from start to finish:

Against all odds my first print was a success (using ABS even):

That’s after everything cooled down a bit, you can faintly see the traces on the bed where the pieces were before they popped loose (due to the bed shrinking as it cooled at a different rate than the plastic) and I moved them. It’s decidedly not a perfect print (horizontal banding, some spots where the perimeter pulled apart between layers, some waviness on one corner where I’m guessing the layer started), but considering the ambient temperature in my living room is 18C I’m surprised I got a successful print on my first try.

Interestingly, the quality of this piece is actually good enough for the first couple things I was planning to print so I may do some printing before I dive into further calibration.

As promised, here are pictures of the build process:

Entire kit laid out on my project table.

Base frame assembled

Upright frame assembled/installed

X-axis assembled

Z-axis installed

X carriage/belt installed

Y-axis/bed installed

Electronics installed (but not wired)

Extruder installed

Wiring complete (including endstops)

LCD installed and working

Testing the extruder

Bonus/reward for scrolling this far, video of my first print:

Infill layers
More infill

See this piece:

That’s the heater cartridge that I burned out today. It turns out the heater will burn out if the temperature sensor isn’t well-connected thermally to allow the temperature to be controlled quickly. As best as I can figure my hotend is a mix of the new thermistor but not the latest heater block, which means there wasn’t a hole for plugging in the thermistor I got such that the end would be against metal. I didn’t realize the heater could be burned out if you’re not careful so I just inserted the thermistor in the through-hole on the far side of the block from the heater and stuffed some aluminum foil in the other end of the hole. That got me valid temperature readings, but they lagged the actual heater temperature by a bit too much: when I set the target temp to 300C to tighten the nozzle (so thermal contraction would form the seal between parts) the heater worked intermittently for a brief while and gave out.

I’ve since taken my dremel tool and embiggened (I’m sure it’s a word) the hole for the smaller thermistor so mine will fit, but I didn’t have a bit the exact right size so it’s a bit loose. I’m planning to essentially glue it in with thermal paste (which was suggested in the first place) before I tape it down. I also paid an absurd amount to have a new heater cartridge overnighted so I should have that Friday afternoon.

On the bright side, I can now upload firmware and the printer seems to be working properly mechanically. I was even able to extrude a small amount of plastic before I realized the heater wasn’t heating any more:

The fact that I could still push plastic through easily so long after the heater had apparently shut off is a pretty good indication that it well surpassed the 300C I had targeted.

The one thing I have left that I may be able to work on is the firmware: the lcd is attached and displays data, but I haven’t been able to access the menu I thought it offered (there’s a button and a knob for input). It’s entirely possible that there’s more to it than just turning on the “display” flag in the firmware so I’ll be looking for that tomorrow night.