MakerBot Industries

Parametric Tardis by Gossamer

If there’s something that’s even better than a regular TARDIS, it’s a parametric OpenSCAD TARDIS. ¹  In the true spirit of Thingiverse, the designer Gossamer, shared their designs and source code.  Doing so allowed other users to join in, offer suggestions, and Gossamer immediately updated the TARDIS code to incorporate these improvements.

Here are two OpenSCAD pro-tips:

• Best Programming Practices.  OpenSCAD for Windows tends to freak out when you don’t add a leading “0″ to a decimal.  By adding writing “0.5″ rather than “.5″ you can ensure compatibility across platforms.  Thanks Bluemetal!
• Too Many Elements.  Sometimes OpenSCAD will complain that there are too many elements.  You’ll see this happen a lot more when you’ve got some “for loops” or lots of nested functions. By adding “render()” before a group of code, you force OpenSCAD to render and cache that group of code.  Each successive render will be a lot quicker. Thanks Tbuser!

What other OpenSCAD tips do you have to share?

Parametric Tardis by Gossamer

None of the Tardises on here were quite what I was looking for, so i decided to make one myself. I tried to make it as parametric as possible, but you'll still find some things, such as the depth of the face impression, that are static. I'm working on an accompanying insert that will light up the light on top from the inside, I'll add that as a derivative as it develops. Let me know if you find any parameters that aren't scaling/re-sizing properly. EDIT: Per suggestions from Bluemetal and Tbuser I've added leading 0s to my decimal values and added render() to the face module, so it will now compile(F5) properly.

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1. And, goodness knows, I feel compelled to blog anything Doctor Who related. [↩]

I’ve been using a 1/16″ aluminum build surface on my Thing-O-Matic for weeks, with really good results. Now you can buy an aluminum platform from Makerbot, and cover it with wide Kapton tape for the ultimate build surface. I’ve been using this combination on my Cupcake CNC for a while, and it is great: parts adhere really well and there is no warping. (Top tip: wipe the platform with acetone before printing for even better adhesion.)

However, this poses a challenge: sometimes parts stick to the platform so well that it can take a real effort, and a lot of force, to get them off. On the Cupcake, I would just detach the build platform and lever the piece loose. However, on the Thing-O-Matic, the platform is fixed, and you end up applying a lot of force to the X&Y platform as you try to release the piece.

One solution is to just double up the aluminum plate, and hold it on with bulldog clips, as described here. However, I went for a quicker solution in the short term.

Wing nut holding heated build platform for easy removal

I just put M3 wing nuts on the bolts holding the platform (you only really need 4, one on each corner, not 6). When I’m done printing, I can just detach the HBP connector (power off first!) and quickly unscrew the wing nuts. This allows for easy access to the printed piece from all sides, plus I can apply quite a bit of force without affecting the structure of the Thing-O-Matic.

At some point, I’d love to see a quick release mechanism for the Thing-O-Matic platform, like this one, but for now this is really saving me a lot of time and effort.

When putting together my Thing-O-Matic, first with a Mk5 extruder and then a Mk6+, a perpetual source of frustration was attaching the thermocouple to the thermal block. It seemed like tightening the nut would rotate it, and it would come loose. Moreover, more than once the stresses of assembling and disassembling the extruder would loosen it as well.

Fortunately, there is a simple solution:

Mk6+ heater block with groove for thermocouple

I used a Dremel tool with a diamond grinding bit to make a groove in the side of the heater block, where the thermocouple fits. It grips the thermocouple wire as the nut is tightened, and prevents it from rotating loose. With this simple change, I can always get the thermocouple installed on the first try, and it feels really solid.

Sometimes you need to manually edit or delete a Skeinforge profile. The built-in profiles are stored with ReplicatorG in its installation directory, but the user-created profiles are in a hidden file within the user’s home directory. On Mac OS X, if you want to edit these profiles directly, say to edit the start.gcode file, it can be awkward to find and open the right directory. Fortunately, there is a simple way to access it, with no hacking or trickery required! Here’s how it’s done:

First, make a new Finder window. It should open in your user directory. Then, go to the Go menu in the Finder, and choose the Go To Folder… option.

Then, enter the name of the folder where ReplicatorG stores all the user stuff, which is usually “.replicatorg”:

And voilà, the folder opens up!

Your Skeinforge profiles will be in the folder labelled sf_xx_profiles, where xx is the version number. The start.gcode and end.gcode files are in the folder “alterations” within each of the profiles, and can be edited with TextEdit, or any other text editor. The “profiles” folder within each profile contains the settings for each individual module within Skeinforge. You can edit them directly if you are brave, or more practically, just copy the profiles to back them up or move them to another machine.¹

1. This trick works great when using ReplicatorG 24 and earlier. Stay tuned — or take a peek at the beta early — to take advantage of the new “Locate” button in the Skeinforge window when you “Generate G-Code”: automates this for you. [↩]

Tricks for measuring with a digital caliper

A digital caliper is one of the most useful accessories to a 3D printer.  With a caliper in hand you can ensure you’re going to end up with accurate replacement or upgrade parts.  Some Skeinforge guides even suggest using calipers to assist in calibrating your printer.  The guys over at Buildlog.net have put together a short guide with some tips and tricks for using your digital calipers.

Clamp solutions for friendless tinkerers

This post could also be entitled “How to build an Automated Build Platform if you have no friends.”  There are a lot of assembly steps that would be a lot easier if you have a second pair of hands or special clamps for holding things.  If you’re like me you have neither. 

1. If you don’t have a set of special clamps for holding parts in place, you can wrap a rubber band around the handles of a pair of pliers.  This will make it grip tight enough to hold small parts steady. (Pictured above)
2. If you don’t have a second set of hands for holding little pieces down, you could just use a small piece of tape to keep them in place.  This seemed to work out pretty well for me. (Pictured above)
3. I have some really long heavy gauge twist-tie like wires.  Sometimes I will twist them around parts in order to position them easily.  With this project I found it easiest to wrap the motor wires around a roll of blue painter’s tape so that the ends stuck off about an inch or so.  Doing this kept the wire weighted down and leads positioned so that I could easily tin them.
4. It’s important that you gently press down on the small resistor and capacitor as you solder them down on the one side.  If you don’t, the small parts will actually shift as the solder melts.¹
5. I used my utility knife in place of the exacto/razor knife for all steps requiring a knife.  I’d suggest being super careful no matter what you use.
6. When soldering the second lead of the thermistor, it would be better to cut the small piece of wire to just barely overlap with the lead for the thermistor.  When you attach the lasercut top to the automated build platform, there’s a large cutout that will accommodate the bumps left from the soldered parts – so they won’t be squished flat against the lasercut top.  If you trim the small piece of wire, there will be less of a bump between the circuit board and the lasercut top, allowing the platform to be slightly more level.
7. If you are assembling the belt without a friend, it’s pretty easy to take a longer piece of kapton tape (say 30mm or so) and tape both ends to a table or other clean surface.  Then you can easily lay the belt on it without getting anything tangled.
8. A word of warning – I followed the directions pretty closely and ended up with a belt that looked exactly like the belt shown in the step that says, “Bend the creases to remove them. Your result should look like this.”  However, in the next step it appears the belt is in a mirrored position.  I doubt this makes a difference in its operation, so I forged ahead with the rest of the build.
9. When assembling the rollers I found it easiest to put a piece of folded cardboard on the ground, brace the metal shaft against the cardboard, and force the rubber tube down onto it.
10. When assembling the cables, it took me a few minutes to understand how the blade worked with the plastic housing.  I thought I was supposed to press down with the blade as I yanked on the wire.  In reality, it’s a lot easier.  You just press down into the hole in the plastic housing.  When you do, you’ll end up folding a small metal tab downwards.  That metal tab is what keeps the wires from sliding out.  So, once the tabs are pressed in, set down your blade, and the leads will just slide out easily.
11. Before assembling any lasercut parts, I would wipe down all the wooden parts with a paper towel.  They’re fresh out of a laser cutter, so there’s a small amount of ash on the edges.  A quick wipe will mean your parts aren’t going to be all smudgy later.
12. I didn’t see where in the assembly instructions sandpaper was required.  It is useful to have around never the less. 

What is up with the T slots?

However, I noticed one very odd thing while assembling my automated build platform.  I’ve come to appreciate MakerBot designs for not wasting material, making the best use of space, and just being overall elegant and streamlined.  When I was done assembling my automated build platform, I had four nuts and four bolts left over.  I also noticed that even though the automated build platform was secured to the Y platform using five small magnets² , the underside of the build platform has four T-slots that are completely unused!³

What’s that about?

1. I wanted to see what would happen if I didn’t hold them down and this is exactly what happened.  All I had to do to fix it was re-melt the solder with my soldering iron and press gently on the part. [↩]
2. Indicated roughly by the yellow dots above. [↩]
3. Indicated by the red arrows above. [↩]