Heater errors on a MakerBot Replicator 2

We have a MakerBot in our office and use it for all sorts of prints. Since we first got the MakerBot has been giving us random errors.

Sometimes the extruder would stop extruding with no error showing up. A firm press on the filament would usually get it extruding again.

After that happened a few times we couldn’t get it to extrude at all. Taking apart the extruder head showed me that the problem was the knurled bolt. The knurled bolt was clogged and caked with ground up pla dust. A tooth brush got rid of most of the dust but wasn’t getting deep enough into the teeth. I had to use an Exacto knife and clean out each tooth manually.

Then the MakerBot continued to have the intermittent extruder errors. I reached out to MakerBot support and they pointed me to two things. The thermocouple may be damaged or the heater is damage.

What was happening is the temperature was dropping in the extruder, the pla would freeze in the nozzle and the knurled bolt would chew on the pla. The dust and cake knurled bolt was from the pla being chewed on.

The support guys at MakerBot realized this problem and sent me a new thermocouple and a new heater cartridge.

Replacing them both showed me that the previous thermocouple was bent sharply. The thermocouple was giving intermittent temperature readings.

Here is the error that I was getting on the MakerBot.

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Now look at the culprit that was ruining my prints.

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I’m printing again now. Working with MakerBot support was alright but took too long to get a response. I only wish MakerBot had a support phone number.

3D Printed Cookie Cutters

A while back a friend of mine was talking about her baking job. Turns out that there are uses for 3D Printing in baking: cookie cutters

I found a quick method to printing cookie cutters. I like this method because it shows the power of using a configurable slicing engine.

I started with a logo, a rough shape of a bakers head. In sketchup you can import images to then model on top of. I traced the head, gave it some thickness and exported the .stl. I now had a model that was basically the shape of the cookie I wanted.

Making it into a cookie cutter meant changing some settings. In Slic3r, the settings were changed to:

Infill: 0
Top layers:  0
Bottom layers: 0
Perimeters: 3

What this leaves you with is just the few shells of perimeters, leaving you a perfect cookie cutter.

There are many designs for cookie cutters on Thingiverse. Try printing a few out. Eat some cookies, they are great after a long day of printing.

Here are some that I printed out.

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3D Printed Disk Sander

I’ve recently been working on a project that involves many laser cut parts that for some reason weren’t fitting very well. I was spending too much time sanding things down by hand and decided to do something about it. I printed out a disk sander attachment for my drill.

The disk sander uses a bolt as the shaft that you clamp your drill too. The bolt I used was 6/32 machine screw about 2.5 inches long. Its set through the center of the sanding disk. The head of the bolt is recessed into the disk so that the sanding plane is smooth.

Attaching the sand paper only needs a little bit of Elmers Glue-All. Just cut a disk of sand paper as close as you can get to the size of the disk.

The printer settings I used were:

  • Layer Height: .4mm
  • Infill: .4
  • Perimeters: 3
  • Top and bottom layers : 4

These settings gave me a pretty strong print which let it stand up to the drill quite well. Good luck sanding for yourself. Let me know how this worked out for you

Hands Off with Leap Motion

I got to visit a Leap Motion Developer Meetup In NYC. I was really impressed with the Leap Motion technology. Apparently it works like a kinect but for your desktop. The detector is very responsive and doesn’t have any obvious lag. Its great technology and I can’t wait to have them become more widespread.

Use Filament to substitute bolts in your 3D designs, weld plastic with your extruder

Many designs I’ve found online seem to not take full advantage of the 3D printer. If you have a machine that can make anything, why are you resorting to using bolts in your design. I think if 3D printing is to become a common household tool, then more things should be designed to only use the products of 3D printing.

A while ago I realized that I could use a piece of filament as a substitute for a bolt in my designs. The way I seal the filament into the piece is by extruding extra plastic from the extruder manually. Extruding manually while moving the piece underneath works pretty well, but it won’t be as pretty as the rest of the print. I find that there are many trace hairs of plastic that get stuck to the print head. It’s probably a good idea to clean off the print head after using it to weld 2 pieces of plastic together.

Ok, so the real reason for doing this. This is secretly part 1 and 2 of 507 Mechanical Movements.

Getting PLA to stick to your Printrbot build platform with Hairspray or ABS juice

I was having a ton of trouble with PLA. It never wanted to stick to my build platform when I started working with it. I started searching online for solutions and I found a few.

The two best solutions I found were to use either hairspray or ABS juice. The recommended brand of hairspray is Aquanet Super Ultra Hold. You’ll know your brand of hairspray is working well if it makes the build bed tacky after you apply it. Here is some more information about hairspray : http://www.thingiverse.com/thing:28787

The second best I found was to use ABS juice. ABS juice is a mixture of 9 parts acetone with 1 part ABS. Its not a problem if you add more ABS into the acetone, it’ll stay at the bottom and be mush. The acetone dissolves the ABS and stays in solution. When you apply that acetone it’ll leave a thin layer of ABS on the build platform for your material to stick to. It works, but the acetone will slowly eat away at your Kapton tape as you apply more and more. I’m not looking forward to replacing the Kapton tape, so I’ll stick with the hairspray.

Good luck with your PLA prints.

3D Printed Crossbow

I was given the challenge to make something that will shoot, and make it fully printable. I settled on making a printable crossbow. In the 3rd century to make a crossbow required a team of skilled artisans and weeks of time. I figured using 21st century technology I should be able to do about the same in about a day.

The bow design was basically designed by eye by what looked good. I choose the 2mm wall thickness for it after a few test prints of strips at different thicknesses. The 2mm wall thickeness gave me what looked to be the best flexibility and durability.

When printing this bow I set Slic3r to infill the material in a concentric pattern. What this did is made the flexible in the dimensions I needed it also helped with the trigger. The bow was printed with the handle side up and with support material. The part under the trigger needed support material.

The trigger design stumped me for a while. I was originally going to steal some design from google images. All of the designs I found had far too many moving parts. I wanted the bow to be simple and not have much assembly. After drawing every trigger out, I figured I can just use the plastic as a spring, which worked great.

You can download the model here : http://www.thingiverse.com/thing:60343

Adjustable Focus 3D Printed Liquid Filled Lens

A while ago I saw a TED talk about adjustable glasses. I wanted to build my own. This could eventually be used for eye glasses that are printed out or for a telescope or a microscope.

The biggest problem with this is making a seal that doesn’t leak around a plastic film. There were several designs I went through to get to the hexagonal pattern that I eventually published. Using the circular mating plates for the film never gave me a good seal all the way around. It turned out that since the printer doesn’t print thin lines accurately all the way around the circle, that the grooves in the plates wouldn’t ever mate up properly.

With the hexagonal parts I found that the groves printed out more reliably and mated much better. Still not perfect since it leaks, but a little RTV or Weldit can solve that problem.

 

Experiments using Acetone Vapor to smooth 3d printed objects

I found a hackaday post on smoothing out the rough edges on 3D prints and thought I should experiment for myself.

I wanted to try out how the smoothing would effect different kinds of prints. I found a tall statue , a shotglass skull, and a twisting heart box.

I collected all of the items that I’d need according to the video. The items where

  1. Acetone
  2. Wire hanger
  3. Bottom of a soda can 
  4. Glass jar with lid
  5. Printrbot

I set my Printrbot to 110c through Pronterface. Every few minutes I monitored the temperature with an infrared temperature sensor to make sure the bed is at the right temperature. While waiting for the bed to get to temperature I poured out about one tablespoon of nail polish remover into the glass jar. When the heated bed was at the right temperature I put the jar on for it to heat up.

The jar I was using started to form condensation of acetone on the walls in about a minute. It took about 5 minutes for the condensation to be forming from the top of the jar. In hindsight, I should have waited for the vapor to fill the whole jar before I put in the first model.

The first model I used was the statue from thingiverse : http://www.thingiverse.com/thing:26317

I took the model out every few minutes, you can see the progress in the gallery bellow.

 

I next experimented with a heart shape box from thingivers: http://www.thingiverse.com/thing:900

With the heartshape box I wanted to see how it would slide after being treated. My results were disappointing with this. It did not become glossy and smooth, it didn’t get the beautiful clear coat of abs as a shell. It basically only got a little shinier. I’m not sure why this model didn’t have any real results from the acetone. Even after this 15 minute trial, I went back later at night and left the box in the chamber for an hour, still no difference. I think there is something else going on here that makes a model be effected by the acetone treatment.

 

Finally I wanted to test out the skull shotglass: http://www.thingiverse.com/thing:38282

The skull shotglass had good results from 15 minutes of treatment. The face and back of the skull became very shiny. There was no loss of detail that I can tell from the face. The entire exterior of the plastic feels completely smooth almost as if it was injection molded. The top side of the skull has  more of a shine then the bottom, which is telling me the acetone vapor is dropping from the top onto the skull. The whole skull somehow feels more solid, if you tap it, it gives you a satisfying thunk. The inside of the shotglass is a similar surface to the surface on the heart box, it also has the same results as the heartbox. The inside is basically the same, no real differences. I wonder what process is going on preventing these smooth curved surfaces from being effected. Here is the skull after 15 minutes.

The vapor treatment worked really well with 2 of my models. I’m still unsure as to why it didn’t work well on the heart box.

Acetone Vapor bath

Printing with support material on the Printrbot Plus with Pronterface and Slic3r

Skull shotglass being printed

Skull shotglass being printed

3D printing with support material increases the kinds of objects you can print. Usually when designing the concern is to print parts without overhangs. This was a problem, so I started experimenting with support material. I’m using Printrun and Slic3r 0.9.8 for printing. The change to get support material is in the configuration file in the standalone version of Slic3r.

Open Slic3r and go to the Print Settings tab. Open the Support material settings. In the Support Material page is a checkbox for “Generate support material”, click it and when you slice now, it will generate it for you. Lets have a look at the settings.

Overhang threshold: Slic3r checks for the overhang angle, if the angle your printing out is higher then this number then it will print support material under it. The default is 0 but should be changed under some situations. Keeping a low support angle isn’t necessary, many printers can print 15-20 degrees without any issues of over hangs. It is beneficial to keep a low support angle if the part your printing is very small, since it will help prevent warping.

Pattern: Rectilinear will give you single extrusion wide walls at the default of 2.5mm spacing. This is convenient because you can pull it all out in one strip.

Pattern: Honeycomb will give you a honey comb pattern. This works better with more organic shapes.

Pattern spacing: Slic3r sets the default at 2.5 mm. Setting the spacing lower is going to use more support material and make it harder to remove afterward. Adjust this if your overhangs are close to 90 degrees and its a small piece.

Pattern angle: Pattern angle adjusts the rotation of the pattern of the support material. Sometimes the pattern will have a flat wall that is close to a wall in your model, making it nearly impossible to remove cleanly. If your slice is having interference issues with your support material then rotate the angle to an angle you likely do not have in your model .

The two models I used are:

  • Small overhang test: http://www.thingiverse.com/thing:16503
  • Pointed Teeth Skull shotglass : http://www.thingiverse.com/thing:38282