In my previous post from this 3D Printing Beginner Series I was still in the situation where some things (Emmets Gear Bearing in particular) just refused to print.
Larger curvier objects still seemed to print well, but small intricate details where extrusion speed slowed down usually resulted in extrusion stopping.
This week I feel much closer to solving this issue, after seeking some expert advice from Andy and Whitney from the 3D Printing Today Podcast.
Suspect MakerWare Setting Defaults
For starters, they told me that the default settings in MakerWare (the software shipped with the 3D MakerBot printers) are not good. 230 degrees for PLA is simply too hot in most cases.
This will result in heat creep, where the cool end of the extruder becomes too warm and pushing the PLA filament though the thermal barrier tube is like pushing string though a tube, it’s not going to happen and can only end in a jam occurring.
Too high a temperature can cook the PLA too. Remember PLA is organic (often made from corn starch or sugar cane) so in theory it can litterally cook, changing it’s state for ever and rendering it useless.
More experimentation shows that I have more successful intricate prints when printing from cold and the printer’s been off for a while.
I have still had a few really good prints this week, like my Cuddling Cats, which I sprayed with the new copper paint. I love this stuff by the way and can highly recommend it. Especially sprayed thin on green PLA, as ageing weathered copper turns a greeny blue over time anyway, so this looks awesome.
Anyway, I’ve had a few other failed prints too, such as the Celtic Skull which would have been my biggest print yet, with my biggest so far being the larger version of the cuddling cats.
Based on what I’ve learned I think that slow extrusion speeds when printing intricate parts causes heat creep, which in turn ends in a PLA jam in the extruder. Unloading and loading the filament again always clears the issue and I can print well again.
What this all means is that I’m printing quite a bit cooler and speeding up the extrusion and the overall print time so hopefully the PLA is less likely to become soft in the cool end of the extruder and jam it.
Wish me luck, the print is half way though right now and looking good so far…
Mini Wireless Camera and a Desk Fan
For my birthday last year my girlfriend brought me a mini wireless camera for use in bird nesting boxes. Well, as the birds have refused to nest in my garden, until this year when it was too late to fit it, I have used it as a Cat Cam in the garden and a Mouse Cam in the garage.
It’s pretty useful, because now I can keep an eye on the printer from my living room. It also has sound so I can listen for the dreaded extruder stepper motor click, meaning we have a filament blockage. If nothing else, I can simply see when the print is finished.
You can buy these cameras from various places but mine was from SpyCameraCCTV.com. I’m not affiliated with these in any way, but I believe if you use Welcome as promo code you can still get 10% off.
Another piece of equipment I tried this week was a desk fan, to try to cool the Replicator 2 a little in this hot UK weather we’re seeing at the moment. That didn’t really work, so my cat has now adopted that to keep her cool instead. Well I did steal her camera 🙂
He asked me if I’d try it so I used the plain case I downloaded from MakerBots Thingiverse, dragged it into Tinkercad and cut out three letters for her name. Luckily it’s a very short Chinese name so this was easy.
The first attempt failed because I didn’t level the build plate beforehand so it warped a little at one end. After a quick levelling of the build plate it worked great and they were very happy with it.
Finally, I just popped into the office (I’m writing this outside in the sun) to check on the gear bearing print and it very nearly printed! It stopped extruding for a few layers in the middle then carried on printing the rest, so hasn’t quite made it, but it’s given me confidence that I might be along the right lines with the “extrusion speed/heat creep” theory.
I’ll let it cool and then try an even thicker layer height and even faster speed. The finish won’t be such high quality but at least it might work. I’ll also search online for a cool end fan upgrade as this might help a lot.
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