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Printrbot Jr 3D printer

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See all my TinkerCad objects

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18 August 2013 - I've ordered a 3D printer

I've ordered a Printrbot Jr kitset, during the end-off-run sale for the version 1 Printrbot Jr. Printrbot are scaling back their kits and are focusing more on ready-to-go printers.

It uses standard 1.75mm PLA.


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3 September 2013 - It's arrived: Building with Adam


Unboxing

Instructions

Tada!

First part of the base completed.

After Adam was in bed, I carried on.

End of day 1.

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4 September 2013 - More building


Next day - completed the print platform (x axis).

The y axis and print nozzle mounting.

Y axis in place.

After school Adam was keen to get building again.

Almost done.

Completed!

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7 September 2013 - Computer talks to printer

Finally got Repetier software talking to the printer.

Issues I struck:

1. The Printrbot Getting Started Guide is a little too minimal. I had to trawl the forums for info/clarification that's missing.

2. When I plugged the power in the Guide says "the fan should start". I thought - oh, that's a clever simple way for the Printrboard to signal to the user that it's boot OK and is alive. But no. The fan it's referring to is the one in the large computer power supply that comes with other Printrbots. The Jr comes with a small laptop power supply that gets hot, but has no fan.

So it took me a while to realise the printer is on but doesn't indicate to the user in any way that it's on. There is a green LED on the Printrboard - but that's hidden inside the box.

3. The Repetier software does not fit well on small/old 1024 x 768 pixel laptop screens in size. The manual control sub-window needs more space - so it has slider bars - which I didn't notice for ages. The effect of that was that the critical OK button was hidden. Again - it took me ages to work out why the software seemed to connect but the manual controls didn't do anything. Ya, gotta hit the OK button to start talking to the printer.

4. I inserted the wedge that holds the z-axes end stop adjustment bolt in the wrong way 'round. So the bolt currently does not poke down into the hole. I'll need to pull it out and flip it over.

Now that I've got the computer talking to the printer I can work through the calibration phase.

To do:

  • flip x-axes end top bolt wedge. DONE
  • set up the end stops correctly. DONE
  • set the software print area limits. DONE
  • get a sheet of glass for the printer bed. DONE
  • add 3 layers of blue painter tape to the printer bed. DONE
  • level the bed. DONE
  • test print. DONE
  • add a voltmeter. DONE
  • add better belt tensioning levers. DONE
  • add LED around extruder to illuminate the build DONE
  • replace z-axis threaded rod with metric
  • add a heated bed?

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11 September 2013 - Calibration and first prints

I drilled another hole in the x-axes end top bolt wedge to position the bolt in the right place.

I discovered the Y axes is inverted, so plugged the Y motor connector into the Printrboard the other way round. That worked. Worth watching: How to get your Printerbot Jr working.

Added a 155 x 155mm glass bed (4mm glass with polished edges), then two layers of blue painters top of that. A glass bed is supposed to be flatter than the plywood and less likely to warp.

I added some bike chain oil to the Z axes rod.

I ended up with a print area of: X=135, Y=135, Z=80

Leveled the bed. I starting from the center (with the Z at "0"), then doing the X axes, then the Y, then checked all over.


Ready for action.

My first print:


I hadn't set the Slic3r config correctly

Second print:


Much better - got most of the settings as rcommended in the Printrbod Guide.

Third print:


Mesmerising.


Now we're looking pretty good. The base is a bit wonky - but I suspect that's to be expected with no heated platform (yet).

As soon as we had it off the bed Adam was tidying it up. Notice there's a piece of real Lego plugged on top - it works!

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My first Tinkercad design printed

I created my first design - a box that is 130 x 130 x 80mm - which is the largest my printer can do at the moment, with 0.5mm thick walls - which might be the thinnest my printer can do).

Tinkercad is a web browser based 3D object design tool. Very simple, and perfect for beginners like me.

And here's how the print turned out:


My first design - printed.
  • One of the corners lifted because my blue painters tape wasn't stuck down hard enough.
  • The walls are a little bit bowed - possibly because the fan was too wimpy to cool the plastic before the next pass?
  • 0.5mm wall thickness is a single bead of plastic.
  • 0.5mm Is not strong enough to resist separation between layers if handled roughly.
  • 0.5mm is opaque.

Print in progress.

I was pretty happy with that print. Learned a bit more.


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My first useful object: shower head bracket

I've printed a shower head bracket to replace the bit of velcro that had been used to hold it in place. The orginal plastic bracket broke off years ago.

First I designed a 5mm high version in Tinkercad, then print it and tested it in situ to see if it would fit.

The design has two pieces which were printed in the configuration that they would fit together when installed. I tried using a 0.25 mm gap between the pieces to create seperation between the two pieces - but the result was fused together. Turns out a 0.5mm gap works fine.

Once I'd sorted that out I printed the final design.


Final Tinkercad design.

And then printed it. Here it is installed.


New shower head bracket installed and working.

The pink colour is not ideal. I'm still working my way through the test role that came with the printer.

If the bracket breaks with use I'll add another 1mm to the wall thickness. I like designs that use the minimum of material to work effectively - so hopefully this'll be strong enough.

Next project: cupboard handles for Adams draws. I wasn't thinking something that Lego could plug in to on the front.


Suggestion for optimizing Lego prints:

... reducing the extrusion width works--i.e. by making thinner threads of plastic, the slicing operation is better at handling the case when an area is narrower than the extrusion width. In Slic3r you can change it in the "Advanced" tab, under "Extrusion width".

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Useful object: tricycle pedals

A while ago we inherited two tricycles - each with one pedal missing. I shifted both to one trike, then designed and printed these:

Tinkercad pedal left Tinkercad pedal right

Two pedals printed.

The pedals on the trike.

You can download the STL files from Tinckercad.com: left and right

They each took me 1 hr 35 mins to print on my Printrbot Jr and used just over 9200 mm of 1.75 PLA (about NZ$4 each in plastic).



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Miscellaneous observations

I'm now using just one layer of blue painters tape. If I'm doing a small object I'll only use one or two strips in the glass.

Large flat based objects really need fresh tape - otherwise the corners will peel up as the print progresses - which mean I end up with a curved bottom. In some cases that's quite nice.

I can keep printing on the blue painters tape if I move each new object to print on a different part of the bed.

I seem to have a 2 degree skew in my x-y axes. It's most noticeable in square bottomed objects. I'll need to trawl the forums to find a good solution.

The second role of PLA I have seems to have slightly different melting characteristics. It seems to "string" between moves more. I think I need to play with the extruder extration parameter a bit more. I'm printing at 187 degress. Need to do even more temperature experiments. I suspect each PLA source will have different characteristics.

I need a "new PLA characteristics discovery procedure".


23 Oct 2013 - ordered a 1kg role of "natural" and "grey" from China. The grey stuff was great, the "natural" was much lower quality (was thicker and less consistent, specially if not very dry).

19 Jan 2016 - Ordered a 1kg role of black 1.75mm PLA from http://www.makershop.co.nz/


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Email me with any questions


Page last modified on 19 January 2016 at 11:36 PM