3d printing

3d printer, day 2

I’m Jason Firth.

I apologize in advance for the photos. No idea why they came out so bad.

Last time, I talked a bit about setting up my new 3d printer, an FLSUN Delta Kossel. The first day consisted of fighting with the firmware that was set up without any limits, and with some seriously wonky default settings.

I was able to complete my first 3d print, a ring from thingiverse, and then moved onto my second 3d print, a ball valve I designed:


Unfortunately, it didn’t print very well, and after printing successfully once, I wasn’t able to get it to print at all again.

I still had a few problems. The head wanted to dig into the bed. I tried to tape some magazine stock to the bed to protect the head and I tried to calibrate the bed that way, but that was a pretty poor solution. What I discovered is that there were a few problems with what I was trying.

The unit came with leveling springs, and the instructions on YouTube suggested I install them. This turned out to be a bad idea, because the nozzle contains a spring as well,and the two were fighting each other. I took out the spring, and because I’m concerned about the heated bed touching a bunch of plastic, I took one of the spare square bolts and used it as a spacer:


Next, I wasn’t happy with the auto calibration. The entire unit shook dramatically as it auto calibrated because of the huge amount of force needed to overcome the spring. I looked at the head and realized I didn’t have *one* adjustment, I had *two*. The silver set screw that set where the button releases, and the black set screw that set the spring tension:


I realized I’d have to calibrate the nozzle before I could run a printer calibration.

First, I loosened the silver screw until I heard the switch click, then I tightened it slowly until I heard it click again. I pressed the nozzle to prove the switch was actuating properly, because a couple times I just tightened it until I heard it click again but it didn’t reset with nozzle movement.

Second, I loosened the black set screw until the switch opened, then tightened it back up until I heard the switch close again.

After calibrating the print head, I was getting much better calibrations that didn’t shake the unit so badly.

Finally, to deal with the print head jamming itself into the print bed, I discovered a setting called Z-offset. I was able to change the z-offset from the unit faceplate.

First I went to the control menu:


Then the motion menu:


and Finally set the Z-offset:


I figured out the z-offset by setting my height (I used the faceplate in the prepare menu, but you could easily use Repetier to do it from your computer) lower and lower, until I couldn’t slide a piece of paper under the nozzle anymore. I set the Z-offset to the number of mm.

The final improvement I made was to place a fan near the bed. The unit has a fan built onto the nozzle, but this didn’t seem like a bad idea.

I was finally able to consistently make successful prints. Early on, I designed and built these clips so we can screw our undercabinet lighting to the cabinets:


And by the end of the day I had printed a spool holder I designed:


I was really happy how this one turned out. Not so happy about how the picture turned out, mind you. No promises how it will hold up once I place a 1kg spool on it instead of the smaller provided spool.

A few things I’ve discovered in a day of printing:

Don’t waste time trying to save material. A 1kg spool of filament has about 330m of filament. All the designs I’ve been printing use less than 10m of filament.

You see a lot of prints that look like they’re really substantial, but they might not be. The prints might be completely hollow inside. The above print has a 5% infill, so very little inside.

Shell thickness is your friend. I printed a tube with a 0.5mm shell thickness, and it was a great demo, but very quickly broke. I printed with 1mm shell thickness, and everything was much more substantial and is holding up much better. Given the choice between infill and shell thickness, I’ll choose shell thickness every time.

I didn’t need a raft or anything once I had the printer well calibrated. Suddenly the bottoms of my print were good by themselves.

Even though professional designers using molded plastic might use voids to conserve material, that seems to be a really bad idea here. I created an earlier spool holder that used a thick column with voids, and it was a really complicated print — it was constantly retracting and spooling out and ended up being really messy.

Today’s prints pushed the limits of a 40mm radius print bed, so I spent some time doing some tests. I figure I can safely print to 70mm without the print head or arms contacting anything, so I increased the print radius to 70mm in the marlin source code and re-uploaded.

I had a calibration error I couldn’t figure out — my Y axis was off, but only my Y axis. A post on the marlin forums suggested moving to the latest, so I moved to the nightly and re-uploaded. That worked perfectly. After upgrading, the printer calibrated happily and I’m ready for more printing tomorrow.

Because I don’t want someone like me to have to deal with the annoyance that was my first day, I took the configuration headers and submitted them to the marlin project for entry into the examples file.

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