Delving deeper into 3D

Been concentrating quite a bit recently on the 3D printer. It is a really interesting learning curve, although it has its fair share of frustrations!

So long as you are able to work out what goes wrong when it does, so you can learn and improve (technique, settings, components etc) then it is a valuable experience. The technology (at least the very low cost machines) is still pretty rudamentary, and needs constant massaging to get results. In saying that, successful prints are rewarding- fascinating to watch the process, and what is produceable is quite amazing.

Not sure how my ratio of success to failure is going – I’d probably be lucky for it to be 1:1, but as I refine things, that will continue to improve.

The first major problem I had to deal with was bed adhesion (and that can still rear its ugly head!) If the print dislodges from the bed, then it gets pushed around by the printer head, attaches (and melts) to the printer head, or at the very least is no longer where the printer things it should be, so the printer tries unsuccessfully to print in mid air. Great if you wanted a birds nest!

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The birds nest, and the dog turd. Neither were what I was aiming for.

I’ve pretty much resolved the bed adhesion (mostly). The original aluminium bed is now gone, and in its place is very flat, thick tempered glass (actually some Ikea glass shelves). A regular wipe with a gluestick is sufficient for really good bed adhesion.

Why I bought the Rigidbot (RB) kit, and not a preassembled model? So I knew how it was built, and can disassemble, fix and rebuild easily, knowing how it all goes together.

A recent example:

Printing was going pretty well, but over time it was becoming increasingly obvious that there was a leak in the filament path, allowing molten filament to escape, run over the outside of the nozzle and drip into the print.

Next, I was starting to get significant shifts during the print, which is obviously not ignorable.

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It got to the point that the printer jammed during the print, I’m guessing on a significant glob of plastic. Not sure what caused the shifts, but one problem at a time, and maybe the second would resolve itself.

I have a dual head, so went to upgrade the second nozzle to the correct hotend (got two types in the box, and installed the wrong ones, thus the leaks that were developing I assume).

Managed that, but then the printer would not work- gave an error about a extruder not being available. Turns out that even though I was careful, and it looked fine, the thermister was dead anyway. At the same time on the working head, one of the wires pulled out from the connector for the heater.

There was so much solidified plastic ooze, nothing could be unscrewed- not the thermister, not the heater, nozzle, even the retaining bolt.

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Step 1
Tested the thermister by unplugging it. Got the same error (which just going offscreen said mintemp) (the thermister allows the printer controller to determine printer head temp. Normally around 200C for PLA plastic)

Tested again, but this time shorting out the two pins. Same error, but this time max temp. Ok, pretty sure the problem is the thermister.

Step 2
Reflashed the RB to make it a single extruder unit. That way I could fire it up enough to bring the heater online.

Step 3
While holding the heater wire in place, got the head up to 200C, and loosened the retaining bolt, and just nudged the thermister so it was a bit loose (remembering it is still providing current temp feedback on the active head)

Step 4
Turned off the RB, and while still hot, undid the thermister fully.

Step 5
Rebuilt the RB head to a single head setup using each of the still functional parts.

Fired it up, tested, and we are back and working.

So much easier having built the unit from a kit, this was a relatively easy evolution.

Lots of other lessons learned, such as what happens when the filament tangles on the reel 8 hours into a 10 hour print.

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Interesting though, it does show the internal fill structure that the slicer program creates. This is currently set at 10%.

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However, despite the myriad of failure mechanisms, there are also many successes.

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Next step is to rebuild the printer head with a better extruder and a better hotend. After that, well, we’ll see how the next changes work and what develops (or fails!)

A lot at this stage is printing for printing’s sake, as each one provides valuable lessons. Once that is nailed down, project design and 3D modeling will be next, as well as post printing treatment- smoothing prints with vapour baths.

Don’t worry, it won’t dominate the woodworking, but anything interesting, challenging and stimulating is going to get my attention! In the long run, it will be able to complement other shed operations.

3 Responses

  1. Stue,
    Keep up the articles on your 3D printing, I find it very interesting.
    Regards
    Frank

    • Will do!

    • Keep an eye out for the next edition of ManSpace. Just sent through a 2500 word article on 3D printing which may be of interest.

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