I've been designing a magnifier light and one of the parts I thought I'd 3D print. It's right on the limits of size that the Robox can manage but it just fits onto the bed. I started a test print to check the sizes and it seems to be correct. I did however increase the speed and layer thickness and that meant that the edges went quite wavy. I'll give this another go when I've got some time as I believe it could be a very long print job although I think a few model changes and adjusting a couple of settings could improve print time.


Challenge Print

I also gave the temple challenge print another go. This time I simply loaded it up with the Normal settings and printed. I think that the needle valves really help with this kind of model as you could see them in action as each of the slender columns was built up. As it reached the point nearing the top of the arches the model seemed a little unstable but these were knitted together successfully in the next couple of layers. However I'd say that was a feature of the model rather than the printer. If you had problems you could reduce the speed of the print and that should help.

2015-02-20 22.52.12.jpg2015-02-20 23.45.12.jpg


Software update

Whilst on the CEL Robox forum, I spotted that the 1.1 version of Automaker was shipped with the auto-update turned off so I needed to download the latest 1.1.2 manually. I noticed improvements described for filament load and eject, I've not had any issues with those with this model, the preproduction one was quite tricky in that regard. There is also an update to the pre-print purge to ensure that the nozzles are clean before printing, I've not actually had any issues with that step. The door open was giving me some issues with the production printer but seems to be a bit softer with this software update and now reliably unlocks.




As mentioned in my original plan of action, I hoped to print some gears as part of my road test. There's a couple of reasons for this. It should test out the accuracy of the printer with fine detail. It should also check it's ability to print small and thin things without warping.


Given that I'd already had some success with OpenSCAD I decided to continue using it for this test.

I found a Parametric Involute Bevel and Spur Gears script by Greg Frost but I could not work out how to use it. Luckily there was also Spur Gear Fitter Script by Cliff L. Biffle which uses that library to "fit" gears together. I tweeked that to space the gears slightly and generated the above image and an STL file for the printer.






The print was scaled to 25% giving a large gear of approx 20 mm and a small gear of 8 mm, it should be possible to get OpenSCAD to print out the sizes so I'll do that for next time.


My first attempt at printing was a fail in that it did not stick to the bed. I removed the failed prints and gave the bed a wipe down with a rub. For good measure I also moved the gears to a different part of the bed. I also changed the print speed to 50%. This did not help. I checked all the settings and it was at this point that I spotted that my white filament had been ABS not PLA all along.


I tried again in the middle of the bed at fine resolution and normal speed, I also added a large brim to the print. This seemed to work a lot better with the gears sticking to the bed although there seemed to be some curling up at the edges. The print completed without error and I waited for the bed to cool before removing it. The brim broke off easily so the gears should be good to clean up. The over all shape of the teeth and the inner holes is very well reproduced. However when we look at the gears from the side the results are not so good. There is significant distortion in the teeth shape rendering it unusable as a gear. I've not bothered with scanning this one as you can tell all you need from the photos.


I hope to get some advice for how to print better gears and I'm wondering if a bounding wall might help keep cooling consistent.