Elephant - top layer

Further Adventures in 3D Printing


Our 3D printer has not had much use lately. The main reason for this is we have simply been too busy with other things. However, we recently received a new sample of masking tape for the print bed, and we thought this was as good an excuse as any to dust off the 3D printer and start printing off some more stuff.

If you have read our previous blog post on 3D printing, you may have seen our previous attempts have been a little hit and miss, but in general, the results have been excellent. In the past, we have suffered from the prints warping and lifting slightly off the print bed, so we were determined to get to the bottom of why this was happening and to try and find a solution. Here is how we got on.

Having received our new sample of masking tape, we were keen to have a go at printing off some new ideas. For a start, however, we thought we would check that everything was working as it should by printing off some old favourites like our unicorn and elephant. Unfortunately, our first attempts with the new tape did not turn out at all well, and we found that all our prints simply refused to adhere to the tape. Even ones like the elephant had issues which had previously caused us no problem at all.

The image below shows the results of one particular attempt where the print lifted from the print bed and formed a sticky mess under the extruder.

Initial attempt

Initial attempt

We had a bit more investigation to do.

The first thing we tried was to move the printer to a more stable platform, as the table which we were using was a little on the wobbly side. However, this made little or no difference.

Since we had run out of our old masking tape, there was no way of checking whether or not the new tape sample was the cause of our problems. Also, since we had waited so long to receive our new sample of masking tape, we did not want to wait for another different sample.

We did think that it was perhaps worth trying a different type of tape to see if this might work. The only thing that we had readily available in a decent width was some Gorilla tape, so we thought it might be worth a try. However, although we did find that the prints adhered well to the Gorilla tape (probably due to the initial layer effectively being melted into the tape itself), this caused a problem with the surface of the tape remaining stuck to the print when the print was removed from the print bed. This can be seen from the image below:

Gorilla tape print

Gorilla tape print

If we were going to make any progress with what we had available, we needed to go back to basics.

One of the things that we had noticed when printing the elephant (the GCode for which we had received with our 3D printer) was that the print head cooling fan was on from the very start of the print. However, with the other prints that we had tried, we noticed that the fan only came on after the first 2 layers had been printed. We were fairly confident that this would make a difference, as previously our elephants printed better than all our other print attempts. However, there was something else that we needed to do also, as we were now finding, with our new sample of masking tape, that even our elephants would not adhere to the print bed.

Something that had been suggested to us some time back was that it might be worth rubbing down the print bed with some form of alcohol to ensure that there were no greasy residues which might prevent our prints from adhering properly. Luckily, we had relatively easy access to 250ml bottles of Isopropyl alcohol, so we got hold of a bottle and some paper towels and tried cleaning the surface of the print bed, and also the layer of tape that we placed onto the print bed. The result made quite a difference to our first attempt at printing an elephant, and we think that it was one of the best things we had managed to print.

Elelphant - base layer

Elephant – base layer

Elelphant - top layer

Elephant – top layer

Satisfied that our newfound knowledge was helping to improve the quality of our printed elephant, we decided to investigate further how to ensure that the fan would be running at the start of our other prints. This meant digging into some of the more expert settings within our slicing program, Cura.

You can access the expert settings within Cura using the ‘Open expert settings’ dropdown from the ‘Expert’ menu. Pressing Control-E also provides a shortcut to the expert settings. Within the expert settings, there is a ‘Cool’ section, where one of the settings is ‘Fan full on at height (mm)’. We had this set at 0.5mm. We reasoned that by changing this value from 0.5mm to 0.0mm, it should cause the fan to turn on from the very start of the print.

Examining the resulting GCode showed that a GCode of ‘M107’ was replaced with a GCode of ‘M106 S255’. We decided to try this with our printed unicorn, and, sure enough, we found that changing this setting had the desired result of causing the print head cooling fan to come on right from the beginning of the print, and this provided much better print bed adhesion.

Pleased with the progress we were making, we decided to investigate some more options within the Cura slicing program. One of the other issues that we had had with our printed unicorn was that the rear end of the unicorn was not printing very well because there was no support for areas that were not in contact with the print bed. We had noticed that there was a ‘Support type’ option under the basic settings within Cura. For the prints that we had done, we had opted for a setting of ‘None’; i.e., no support. We thought we would have a go at printing one with a support type setting of ‘Everywhere’. The trade-off for this setting was that the print would take an additional 7 minutes; however, the finished result was well worth the extra time, as can be seen in the image below:

Unicorns

Unicorns

The unicorn on the right was printed with no support, whereas the one on the left had a support type setting of ‘Everywhere’. This causes the print areas not in contact with the print bed to be supported using a small platform, which can simply be snapped or cut off once the print is complete.

One final thing we wanted to do was to ensure that the print head would always automatically go to the home position before starting the print. We found that this was just a matter of adding the GCode line ‘G28’ (Move to origin/home) before the ‘G29’ (Probe bed) GCode line in the ‘start.gcode’ on the ‘Start/End-GCode’ tab within Cura.

Following these final tweaks, we are finding that the majority of our prints are coming out far better than our previous attempts. Going forward, we will continue to try out new things and carefully monitor our results, and we will be sure to let you know of any discoveries we make along the way.