Hardening your Prusa i3 3D printer

I believe the current and original design of the Prusa i3 3D printer has a lot of areas that need improvement.  It seems the printer serves a great purpose of teaching you about Fluid Deposition Modelling (FDM) printers, but as a printer in itself, it leaves a lot to be desired.  They should have called it “The Trial and Error Printer.”

If you make the mistake, as I did, of building your printer out of lexan or acrylic, you’re going to have a lot of problems.  Additionally, if you buy some random set of printed parts off ebay for your printer’s structural members, you’re going to have even more problems.

All in all, it is a wonderful  stepping stone to the next printer project, but in itself, I would not call it a production class machine that you can rely on day in and day out.  No, sadly, those cost a few more bennies.

Here are some pictures of what I have done to harden my machine so it prints more precisely.  Note, I’m not calling it reliable, or precise, but “more precise” than a vanilla kit machine.

My first priority was to stabilize the platform and frame.  I made a bad choice in using the 6mm acrylic frame.  But I’m stuck with it for now.  So I am doing the best I can with it.

I dug out a piece of 18×24 MDF for the base.  I set the printer about in the middle and marked the places where the frame had zip tie holes and drilled through the board.  I ended up using zip ties for the time being, but reality is, a screw and nut will be a more permanent solution.

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Next on my list was the X axis carriage.  I reduced the bearing count from four to three, and re-arranged it so the two bearings are oriented on the top where the two belt ends connect to the carriage.  Though not scientific at all, my theory was that this was a better arrangement to control wobble on the X axis carriage.

 

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The next big area of improvement, especially when using printed bushings, is to constrain the bearing sleeves on the X axis.  The combination of ABS and HIPS here causes too much slip.  So I used M3x6 screws as a set screw.  I drilled a hole in the side of the X Motor carriage bearing sleeve using a 2.78 mm (7/64) drill bit.20150530_103421I then followed suit on the right side X Axis Idler.  Additionally, pictured above and below you can see a set screw that holds the Z axis nuts in place.  These are important because these nuts come unseated easily.

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Next thing I wanted to do, but didn’t get around to it until now, is to get rid of the silly zip ties on the bed that hold the bearings in place.  I finally got these half printed before something happened and oh well I used them anyway.  These greatly minimize the wobble of the bed that is caused by the zip bearings rotating in their seat.  The zip ties do not constrain it enough.

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Lastly, I used dry lube that you can get at a quality bike shop.  This is the lube we use on chains to keep dust from collecting on the chain.  Apply a thin coat with a foam brush to all your rods and move your axis all the way from one end to the other several times.

20150530_105020Now you should have a fairly stable and solid Prusa i3 printer.  There are still yet more tweaks to be done to this project-disguised-as-a-printer.

 

High resolution closeup of 3D Printer quality

Here are some high res photos of things I’ve printed, or attempted to print.

These were printed at .2mm layer height, green is ABS, red is HIPS.

Some of these are duds.  They either didn’t finish or didn’t make the cut.

This is a set of bushings I was printing.  These are duds because I had the wrong infill setting and you can see the dimples on the middle one’s side…

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Some more bushings that didn’t survive.  Not the printer’s fault, I just had to tweak yet another setting…

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This dragon was printing very nicely, albeit a few holes that I haven’t quite figured out, but then in the end, this green filament is very blobby and caused the print to fail. I’ve given up on this filament because of this issue.  It was Shaxon from Fry’s Electronics.

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Here is a hollow block I printed by accident.  I had left the infill set to zero for a previous print, and this is what I came out with.

The interesting part is the excellent bridging.  Look into the hollow block and you can see the bottom of the top, where it bridged. Also, you can see the layering on the sides and how nice and even they were.  I don’t see any banding either…

 

 

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3D Printing Bed Adhesion challenges

The difficulty with printing plastics using an FDM 3D printer is getting them to stick to the bed for the entire duration of the print.  There a lot of different common wisdoms that you will read about on the internet, and here is one more!

I’ve used ABS Juice for ABS, Blue tape for PLA, Glue stick, etc.  But Now I’ve found the ONE SIZE FITS ALL sticky stuff!  It’s Elmers Carpenter’s Wood Glue!

I diluted it in a mason jar, I didn’t really measure it, so you can just wing it.  Make it runny is all I can say.  Then apply it with a sponge brush.  Now all of my different filament materials including Nylon, PLA, ABS and HIPS stick to the bed!  They grip the glue very well, and I have no warping!  Check the pics!

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In fact, it stuck so well, it pulled the lettering off the blue painter’s tape 🙂

The line you see in the plastic is where the two parts of painter’s tape joined together on the bed.

 

3D Printing Aria the Dragon

My most challenging print so far.

Up to now I’ve been printing parts for additional printers.  Thought I would tackle something majestic.

I love dragons.  Here is Aria The Dragon from thingiverse.com

But So far she doesn’t look that great.

dragon1dragon2I’m trying to figure out the right settings for her.  I’d like to print at .1 or .2 mm layer height.

The above was printed with Repetier Host using Cura slicing.

So, I figured out why it was so bad… Printing too fast.

Rectangular infill, 50% speed, .3mm layer.

Retraction enabled, 2mm
1.6mm shell (4 shells @.4mm nozzle size)
.8 top/bottom
15 % infill – grid

I cancelled the print because something snagged and the Y axis skipped.

After several attempts, I decided to slow the print way down using the Feedrate setting in Repetier host.  I set this down to 25% in a desperate attempt to get a quality print out.  I was pleasantly amazed when I woke up this morning to find this on my printer….

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While not perfect, it is definitely getting close!

Settings so far:

.3mm layer
No raft or brim
Shell thickness: 1.6mm (4 shells @ .4 mm nozzle)
Top/Bottom thickness:  .8mm
Infill overlap: 5%
Infill type: Concentric lines
Solid Top/Bottom
Retraction @ 40mm/s 2mm distance
Temps: 230/90
Material: Bright green ABS

The interesting thing about this ABS, I had terrible luck with it before. It would warp and banana like crazy, and I pretty much labelled it “junk.”

But after I modified my el-cheapo Jhead hot end, everything I print now prints great!