Wednesday, July 30, 2014

This 3D Printer is Fully Operational

At the end of last week I received a replacement heater cartridge from the printer manufacturer for the second extruder hot end, which up until now had not been functioning.  They threw in a spare as well, which I thought was nice.  

Anyway, I disassembled the extruder assembly, removed the defective heater cartridge, and replaced it.  Since the new cartridge had new wires associated with it, I had to redo all the wire routing as well.  A bit of a pain, but not too bad.  In the process of reassembling the extruder assembly I discovered why I had been having trouble getting the vertical bolt in the extruder assembly to thread.  Looks like it wasn't really a problem with the nut not being held tightly enough in place, but more a problem with the bolt itself.  I replaced the original (top) with a spare (bottom), and it screwed in with very little difficulty.  Looks like the original had some threads stripped.  Whether it came that way and I didn't notice or the stripping was the result of all the fiddling I did trying to get it to tighten, I can't say.  


So with the extruder assembly reassembled and the two hot ends carefully leveled relative to each other, I was finally able to do the dual-extruder calibration.  This prints a series of squares with each extruder.  By identifying the one where the two colors are right on top of each other, you can adjust the relative positioning setting in the firmware.


One thing I noticed while doing this is that dual extruder printing is not a trivial exercise.  When an extruder is hot but not being actively used, it tends to ooze a little filament.  This is a big problem when both extruders are hot but only one is being used.  The ooze from the unused extruder ends up sticking to the build where it's not supposed to, messing up the print.  

A little research uncovered this video that explains the issues and potential solutions nicely.  It also has a cool lesson on what you can do with a new flexible filament type called Ninjaflex.  Check it out.  I ordered a spool, and will be trying it out over the next few weeks.

As a last step in setting up the printer, I cut some glass from a cheap picture frame I bought at Michael's.  I now have this laid on top of the heated bed, so I shouldn't have to worry any more about the possibility that the bed is gradually being warped by the shrinkage of the plastic as it cools.

In addition to ordering some Ninjaflex, I also ordered some ABS.  So we'll soon see how the printer deals with different filament types.  I'm also strongly thinking about buying my own filament extruder  so that I can make my own (and supply it to friends and school), but not sure when I'll have time to get to it.





Monday, July 28, 2014

What I like about the Felix 3.0

A few things that I really like about this 3D printer:

(1) The display unit allows printing without being connected to a computer.  All the initial printing I did was using the USB connection to drive the printer directly from my laptop.  This was kind of a pain, as the laptop was then tethered to the printer for the (fairly lengthy) duration of the print.  Now that I have the contrast set properly on the display unit, I can put the GCODE on to a micro-SD card and start the print up without connecting the computer.  Very convenient.

(2) Upgradability.  People who bought earlier versions of this printer were able to download and print their own upgrades, or order just the necessary parts.  I figure things will be changing rapidly in this field, and hope that with this printer I can stay near the front edge of the home printer field with relatively little further investment.  I also liked that there were standard printable accessories on the web site, and user-contributed improvements.  Shown below is an improved Z-axis limit sensor fine adjustment device.




(3) Openness.  It's using all open source software.  Repetier Host, Skeinforge, Slic3er, etc.  No proprietary filament needed, just standard 1.75 mm PLA or ABS.  

(4) Design.  More and more I'm coming to appreciate the design of the printer.  With the version 3.0 the manufacturers have really worked out a lot of the design kinks from the earlier versions, and have replaced the previous printed parts with mass produced injection molded versions.  The solid metal frame  seems very sturdy and provides a large build area.  The hot ends also seem pretty reliable.  Of course, I don't have a lot of different comparison points, but I'm pretty satisfied with what I've got.

Finally, I'm really glad that I opted for the kit and built this thing myself.  I think if I had bought it preassembled I'd be a lot more timid with it, but since I put the whole thing together I have a lot of confidence that I should be able to fix anything that goes wrong with it.





Thingiverse Prints

Looking for fun and useful things to print, I went to Thingiverse.  Found several files for iPhone bike mounts, from which I chose this one:  http://www.thingiverse.com/thing:350389.


My first try for this was printed horizontally, and ended up as a support material disaster.  Way too much of it, and way to hard to remove.  It did motivate me to investigate the Skeinforge slicer settings, however.  The Repetier Host "Help" wasn't particularly helpful at all, but I did eventually find this page with decent explanations of what the myriad options actually do.

I ended up going to Craft->Raft and changing "Support Flow Rate" from 1.0 to 0.7.  This should mean thinner support material that is easier to remove.  I also tried printing vertically, with both exterior and interior support.


Much less material this way, and it came off pretty easily.  One of the interesting things about this print was that the overhang on the bridge-shaped part that fits over the handle bar came out pretty well without any real support. A few threads of filament sagged significantly, but the print recovered and by the time it reached the top you would never have known there was a problem.  The surfaces where I had to remove the support material do look a bit rough, though.  Maybe time to switch to ABS and try sanding or acetone to get a nicer finish.


When I went to mount this on my bike, I found I didn't have the right size zip ties handy.  That got me to thinking: maybe I could print zip ties.  Turns out you can find zip tie designs on Thingiverse, but they don't print well in PLA, as it is too brittle.  My test print worked, but promptly broke after a little bending.  Maybe I'll get some Ninjaflex and try again.


Another thing I found on Thingiverse was a design for a baseball stand.  Kai (my son) had brought back some souvenir baseballs from his trip back east to visit his grandmother, so I thought I could print him out something personalized to put them on.  Unfortunately the thingiverse contributor did not upload the CAD source files, so I had to redesign the stand from scratch in order to customize the text.  

This ended up being surprisingly easy, taking only 6 lines of code (counting by semicolons):

use<Write.scad>

difference(){
union(){
cylinder(h=10, r=25,$fa=3);
translate([-20,-45,0])
cube([40,30,10]);
}
cylinder(h=10, r=20);
translate([0,0,8])
cylinder(h=2,r1=20,r2=22,$fa=3);
translate([-20,-45,0])
rotate([30,0,0])
cube([40,30,10]);
translate([0,-35,0])
writecube("Orioles",[0,0,0],[40, 30, 10],face="top", t=8,h=7);
translate([0,0,5])
writecylinder("Camden Yards Summer 2014",[0,0,0],25,25,center=true,west=180);
}




Printed one for Camden Yards, and two for Fenway Park:




One more Thingiverse print, made for my daughter.  Took this arm band to work to show off, and everyone thought it was way cool, especially that the whole thing was printed as one interlocking piece.  Check out the instructable video.







Thursday, July 10, 2014

Home-printed toolbox

Here's the home-printed version of the toolbox.  The print quality was about the same as the Makerbot, with one noticeable improvement: no sag in the lid corner. 




I printed the box portion with supports, and it ended up putting buttresses on both the inside and outside.  The outside ones came off pretty nicely, but as you can see from this photo I had trouble removing the inside one.  I'm going to have to look at the SFact slicer settings to see if I can control the supports a bit better.  Another thing you can see in the photo below is the internal honeycomb structure of the automatically generated infill.  This avoids wasting material while maintaining structural strength.  



The time required for this print was about the same as for the Makerbot, maybe an hour and a half for the box and a half hour for the lid.


Thursday, July 3, 2014

Lists

Things I've bought in support of this ridiculous (but fun!) 3D printer:


  1. Set of metric allen wrenches
  2. Set of socket wrenches
  3. Wire stripper
  4. Metal ruler with 1/2 mm markings
  5. Grounding strap
  6. Soldering iron
  7. Soldering tool set
  8. Solder
  9. Exacto knife
  10. Heat shrink
  11. Suction-cup clamp
  12. LED magnifying glass
  13. Two 1kg spools of PLA filament
  14. Cordless Dremel tool
  15. Dust cover
  16. Glass cutter
  17. Sewing machine oil (for cutter)
  18. Glass pane (from picture frame)
  19. Hair spray
  20. Denatured alcohol solution glass cleaner
  21. Micro SD card
  22. Gloves
Things I've used that I already had
  1. Assorted screw drivers, large and small
  2. Needle-nose pliers
  3. Adjustable wrench
  4. Multimeter
  5. Teflon spray lube
  6. Hammer
  7. Wire cutters
  8. Spatula
  9. Calipers (borrowed)
  10. Dental mirror
Things I had to get to assemble the printer that weren't in the kit

  1. Replacement optical sensor after pins broke
  2. Longer screws w/nuts for fastening one of the sensors
  3. Thicker M4 nuts for extruder assembly
Things I've printed so far
  1. Thin-walled test objects 
  2. Objects for filament spooling mechanism: 3 triangular doodads & 1 support arm
  3. Filament dust-cleaning attachment
  4. Tweezer holder (mounts on printer frame)
  5. Replacement knob for display  (the one delivered with the kit had issues)
  6. Parts for improved Z-axis leveling device, posted on forum by a Felix user
  7. Mini engraved and embossed memento toolbox, in 2 pieces (my design!)
Issues I've overcome

  1. Broken pins on one of the 3 optical sensors (broke due to excessive bending during wire-routing attempts, ordered replacement sensor)
  2. Too short screws for mounting one of the optical sensors (replaced with longer)
  3. Non-grabbing bolts on extruder assembly (used thicker nuts)
  4. Forgot to label fan wires (used battery to identify which was which)
  5. Extruder not grabbing filament (adjusted tension)
  6. Adhesion difficulties (hair spray)
  7. Uneven extruder hot-end tips (fiddling)
  8. Blank display unit (adjusted contrast with potentiometer)
  9. Confusing display knob inadvertently rendered useless (reprinted)
Issues remaining 

  1. Second extruder not heating properly; shows open circuit when tested with multimeter
  2. How to deal with jealousy of all my friends ;-)

Wednesday, July 2, 2014

First Prints

I've made substantial progress since my last post, and have printed a number of objects.  Here's how I got there.

First off, the picture I showed in my last post didn't really represent a defective part at all.  The missing piece of plastic didn't really have anything to do with whether the nuts would stay in place or not.  I disassembled the extruder assembly, put in the thicker nuts, and that seemed to do the trick.  Leveling the two heads was still a difficult proposition, though.  I had to alternate tightening the horizontal bolts going through the fan with the vertical ones holding the assembly onto the cart, but eventually I managed to get the thing pretty even.  Here's a photo of my first test print:


Came out pretty nicely, I thought.  One of the things the manual said to look for were gaps in the layers, and I did see some of those (more visible with the black filament I switched to later):



The solution to this was to tighten the tension on the extruder.  Counterintuitively, you have to turn the tension bolt counterclockwise to tighten the tension.  Not catching on to that may have been the source of my initial extrusion problems.

I had some issues with adhesion in a few of the early prints, but using a raft seemed to help with that. Here are some photos of me printing out the accessories:



Notice that the piece on the left has a lot of support material.  I had trouble getting that off.  I tried using a Dremel tool to cut it away, but all it ended up doing was melting the plastic, which made getting the support material off much more difficult.  I did get it off eventually, and the part -while not pretty any more - did function.  Those parts are for the spool support, which assembles like this



The two bearings are supplied with the kit and press into the printed parts.  Here's a video of the support arm (the bottom piece) printing:

video


Here's what it's supposed to look like when assembled:



Another printed part holds a couple of felt pads.  The filament goes through these pads in order to clean off any dust stuck to the fiber so that it can't get into the extruder and cause a clog.  You can see it in this picture of the fully assembled printer, complete with accessories mounted.  



However, you may notice that there's only one spool in the picture.  When I tried to run the second extruder, I couldn't get it to heat up.  At first I thought it was a problem with the thermistor, but some resistance measurements with a multimeter make it look more like the heater is what's not working.  I've posted to the support forum to get suggestions on what to do about that.

The display is also not working.  It lights up, but only with a blank blue screen.  We'll see what the forum has to say about that as well.  I'm wondering a bit if these could be my fault: ESD damage due to lack of a proper ground while handling, or maybe from moving the X axis too rapidly by hand while demonstrating the motion to my daughter.  But I don't think either of those scenarios is super-likely, as everything else is working fine.

You may also notice the can of hair spray in the background of the photo.  I was having some adhesion problems, so I did some googling to see what solutions were out there.  The two most often recommended solutions were hair spray and painter's tape.  The hair spray seems to work pretty well for me, creating a tacky film on the kapton tape that I can easily clean off later with a denatured alcohol solution.  

I had another adhesion problem resulting from the second extruder.  It was pushing up the layers that the first extruder had laid down.  After a couple failed prints I rechecked the distance between the extruder nozzle and the print bed, and found that the second extruder was no longer level with the first.  It was a bit lower, which explained why it was contacting the filament laid down by the first extruder.  After releveling the two, everything worked fine and I was able to print out my own copy of the toolbox I had designed with OpenSCAD a while back.  Looks like I'll have to periodically check the leveling to make sure it doesn't slip again.