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.

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.

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 ;-)

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:

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. 

Testing the printer

Last weekend I was able to get through almost all the steps to my first print.  Here were some of the stumbling blocks:

• Remember the knob for the display?  In my last post I said it looked like I needed to clear out some support material.  Well, it looks like I was just supposed to shove it on.  When I cleared out all the support material, there was no way to fasten the knob on.  No big deal, though.  I can just print a new one when I get the printer working.

• I was able to get the X, Y, and Z axes moving just fine under manual electric control.  The Z axis was a bit squeaky at first, but I used some teflon lubricant and now the noise is gone.

• In the first (manual, non-electric) leveling step, it's kind of hard to visually estimate the distance between the hot end tip and the build plate.  Then when I got to the fine adjustment stage I had difficulty getting the two hot ends exactly level.

• The final step before doing the first test print was to heat up the hot ends and extrude some filament under manual control.  The instructions talk about adjusting the tensioning bolt to get it tight, but not too tight.  Too tight can cause a clogged extruder.  I fiddled with this for a while, but couldn't get the extruder wheel to grab the filament.  

At this point I was thinking that between the difficulty leveling the hot ends vs. each other and the difficulty getting the filament to grab, I should take a second look at the extruder assembly.  When putting it together, we had trouble with a couple of vertical bolts that didn't seem to be grabbing with the nuts inside the assembly.  So I removed the outer fan and took a look.  Sure enough, one of the nuts had grabbed, but the other had just been pushed aside in its slot.

As a reminder, this is how those nuts were inserted into the assembly...

Here's what it looks like from the side, with the nuts flat.  They are supposed to be pinched enough in their slots so that they won't turn, and you can thread the bolt through to firmly fasten the extruder assembly onto the X-axis shuttle.

Here's what I found when I looked at that from the bottom.  The one on the right threaded just fine, but the one on the left wouldn't.  I sent a copy of this photo to the manufacturer, and they agreed that the plastic part on the left was defective.  The cutout for the nut should be a symmetric half-circle.  Probably the missing material there was why the nut wouldn't stay in place.  They are sending me a replacement part, but it hasn't arrived yet.  I did get one other suggestion from the discussion boards; use a thick nut instead of a thin one.  I was able to find thick M4 nuts at Home Depot without any difficulty, and will substitute them when the new part comes.

Last night I also was able to resolve the extrusion issue.  I just had to tighten the tension bolt a little more than I had initially been comfortable with.  

When the replacement part comes, I should be able to get the two hot ends level and be good to go for the test print.  Just a little longer!

Finishing the build

My friend Bill Hegarty from work came over again today, and together we finished building the printer with around 5 hours of work.  It was relatively straightforward work, which Bill gets most of the credit for.  Really a one-person job for the most part.  We did encounter a few minor problems, though:

• When attaching the kapton sticker to the build plate, a speck of metal (FOD!) somehow got onto the plate and created a dimple.  We peeled the sticker back a bit, removed the speck, and proceeded onward.  I think getting a very flat surface is very important on that step.
• We had not labeled the fan wire ends (wasn't called out in the instructions that we were supposed to), so when we got to the point of connecting them up, we weren't sure which was which.  The solution was to grab a 3V CR2032 battery and test to see which wires made which fans move when connected.  This worked well, and we were quickly able to establish which fan was which.
• There was a step missing for inserting flat nuts into their slots in the power supply case, so when we went to close the power supply up, there was nothing for the bolts to screw into.  This was easily corrected.
• The instructions say that the board is sensitive to ESD (electrostatic discharge), but I didn't have a good grounding station.  Our solution was to plug in the power supply (establishing a ground) and then clip my grounding strap to one of the power supply screws.  I hope this worked.   Of course we were careful to make sure the power switch was off!
• The 3D-printed knob for the display didn't have an opening for insertion on either side!  Looks like there is support material that needs to be cleaned out.

See below for a picture of the wired-up board.  Again, Bill gets the credit for doing most of this.  My count was 57 wires to be attached.

Front and back pictures of the assembled printer:

Me and Bill posing with the completed printer:

When the job was done, there was still a fair amount of leftover material

In particular, there was a thermistor that was unused.  I think this is a spare in case one of the hot-end thermistors dies.  A few of the pieces are clearly intended for the filament spool and cleaning accessories to be added later (I have to print the main parts).

Tonight I finished annotating my PDF copy of the assembly manual and uploaded it to the support board.  Also ordered a couple of kilos of PLA filament from Amazon.  Tomorrow I will start going through the User's Guide and see if I can do my first print!

More iterations on the toolbox

So while I've been working on the 3D printer kit at home, I've continued to play with the 3D printers at work.  Here's my design for a toolbox with a lid that actually opens and closes.  It uses a dimpled hinge concept.  The trick is that there has to be enough flexibility in the end pieces to insert the lid, but without breaking it.

The first try didn't work at all, as I couldn't get the hinge in without breaking the hinge side pieces.  So I modified the design a bit, putting a slot into one of the side pieces as shown below:

This worked better, but with the 4 cm base box length I still ended up bending the end piece and breaking it off.  So I scaled up by 1.5x.  Rationally, one knows that 2x length yields 8x volume, but  I think the picture below really dramatically illustrates what a big difference that makes.  The 1.5x box is huge compared to the original.  But you can see that the right-hand hinge edge still ends up getting bent by the insertion process.

Thickening up the hinge end pieces a bit seems to do the trick, though, and the final version snapsin and works just great.

This was printed in ABS on a Makerbot 2x we have at work.  It has a dual extruder and heated bed, just like my Felix 3.0.  It will be interesting to compare print quality.  A problem did show up with the printing process; one corner sags substantially.

The guy who is responsible for the printer thinks it's sagging because the Kapton tape on the print bed is getting worn, affecting the adhesion of the initial layer.  People on the Felix support boards have talked about similar issues, including deformation of the build plate due to printing of large objects.  The boards didn't explain why the deformation occurs, but I'm thinking it is happening because ABS shrinks a bit while it cools; since it shrinks while still stuck to the build plate it can exert a bowing force.  Even a little deformation can ruin the leveling of the plate and affect the print quality.  One possible fix that is talked about on the boards is using a (cheap) glass plate clipped to the build plate instead of a Kapton covering.

As a final note, here's a photo of the prototype we did up for our Matlab competition's trophy.  This was printed from Shapeways.com using their color sandstone option.  The membrane surface is the Mathworks logo, and was created in Matlab and exported directly to a 3D-printable file.  The final version will be bigger, with some writing in the flat square part.  Holding this thing in your hand really brings home the amazing potential of this technology.