Category: Tips

Tips learned from experience building a MakerBot

Oh, OpenSCAD…

One of things I really like about OpenSCAD is how anything I make in it is guaranteed to be manifold.  It’s a solid modeler and by manipulating, adding, and subtracting solids – I should always end up with another solid.  I exported two of the parts necessary for a Pez Powered Disc Shooter only to discover that OpenSCAD refused to compile one of the parts – because that part had some polygons with an incorrect winding order.  Mind, I had no problems exporting the part in the first place – but importing it back?  Nope.

Oh, OpenSCAD, is our love affair over so soon?

Design idea – printable calipers

There are plenty of lasercut calipers on Thingiverse.  I suppose the problem with a 3D printable caliper is getting the accuracy down.

However, why not take the accuracy out of the equation?  It should be simple enough to create a printable little caliper that has a thin slot for inserting a printable paper ruler.  The easiest way to achieve the thin slot would be to make the calipers out of two separate pieces that fit together.   Then the calipers could be designed to have a little window for viewing the sliding edge of the calipers against the paper ruler.

Yes, you could print one of the business card ones on cardstock, but why not just print a durable plastic one if you can?

I’m so giddy!

I can’t wait for OpenSCAD to finish rendering this new object I’ve fashioned out of a DXF file!

Toolpath was basically:

  • Inkscape importing PNG image
  • Convert image to SVG, reduce colors, simplify lines
  • Export to DXF
  • Incorporate extruded DXF into design

It will be mine.  Oh, yes, it will be mine. 12

 

  1. The precious. [↩]
  2. That’s a red herring.  It’s clearly a Doctor Who themed object. [↩]

What’s the best toolpath for SVG to OpenSCAD?

While I have one selfish motive for wanting a reliable toolpath for going from an SVG to OpenSCAD, I’d also like to do a tutorial on this. 1 2.

  • I can export an SVG from Inkscape to a DXF.
  • I can import that same DXF into OpenSCAD.
  • I can’t render the DXF or extrude it into a solid.

I just can’t seem to make OpenSCAD make heads or tails of that DXF.  Is this a problem with the DXF files produced by Inkscape?  A little bit of Googling tells me that Inkscape v0.48 (the one I’m using) exports in DXF R13 format which includes features that are not well supported by OpenSCAD.  My attempts at finding plugins that will successfully allow Inkscape to expert to DXF R12 format have not been fruitful.

  1. 3D Models with OpenSCAD on Make uses a toolpath that isn’t available in my version of Inkscape
  2. DXF R12 exporter, didn’t work for me
  3. DXF R12 exporter, didn’t work for me either
  4. Yet another DXF R12 exporter that did not work for me
  5. Link suggesting that something called “pstoedit” might be helpful in converting SVG’s to DXF R12’s.
  6. From Photo to Inkscape to DXF to OpenSCAD to MakerBot to Costume Jewelry is an excellent tutorial on the exact toolpath I would like to get working

After MUCH fiddling around I have discovered that the only DXF exporting plugin I can get to work is the one called “Better DXF Output”, NOT to be confused with “Better Better DXF Output.”  Unfortunately, I’ve installed so many of these little plugins I no longer recall exactly which combination of them might actually be working for me.  I’ll do a little investigation and post a short tutorial on how it’s worked for me.

Edit: I’m 85% certain this is the plugin that worked for me.  http://www.bobcookdev.com/inkscape/inkscape-dxf.html

  1. Selfish as in I already have an idea for how I would use this knowledge to make something cool. [↩]
  2. What could it be?  Hint:  It’s related to something that rhymes with “Doctor Who” [↩]

Pick me! Pick me!

Okay, I’ve gotten the clearance from Pattywac to join in the United We Stand team design challenge.  Although I voluntarily take myself out of the running from every challenge, I love participating.  They’re just too much damn fun.  :)

I never participate in the judging on these things – but it would look a little odd to have me be both someone who blogs about something and a guy who is the subject of the blog post.  Blogging here at MakerBlock.com, I happily post about anything that comes to mind, even if it is ridiculously self-indulgent.  However, I really don’t want the posts at MakerBot to be about me – I want them to be about the awesome stuff people are doing in the DIY 3D printing community.

The potentially ethical problem I faced with this most recent challenge is that as a team design challenge, I wouldn’t want to disqualify an entire team of people just because I was on it. 1  So, my proposal to MakerBot and Pattywac was that as part of any team, I would agree to forgo any winnings of any kind. 2  This was acceptable to both.

So, are you interested in collaborating on this design challenge?  I’d be especially interested in getting collaborative help on any of my existing projects, going from my highest interest3 to lower interest4 :

  1. Clockwork spider5
  2. Open source disc shooter
  3. A printable clock that actually keeps time
  4. A sonic screwdriver
  5. A dalek that can rotate it’s head, roll, and move it’s gun, eyestalk, and plunger6
  6. A better Voltron
  7. A puzzle box
  1. And, really, having me on your team is hindrance enough. [↩]
  2. I just want to feel included! [↩]
  3. #1 [↩]
  4. #7 [↩]
  5. I’ve already had input and help from Dna on this [↩]
  6. Mad props to innovationbylayers for the existing dalek on Thingiverse [↩]

Confluence

With my MK6 disassembled1 and work projects stacking up, I tend to become more prolific in writing and designing. 2

Whenever my ‘bot is in need of repair, my mind goes back to all of the projects and things I keep meaning to print…  but never find the time for.  I also think back to design problems I was having… and sometimes come up with solutions!

Take, for instance, the puzzle box from The Mummy.  I’ve been meaning to get back to this for more than six months.  Well, an idea for a way to make it spring open just occurred to me.  I could put another octagon shaped box inside of the puzzle box and a flatish spring underneath it, squished between the two boxes.  If the top of the box is released, the spring would force the inner box up – and against the lid components and the entire lid open.  It would also potentially work well with little spring loaded pins just under each of the lid pieces.  I’m thinking something like a piece of filament forced upwards by the spring from a retractable ball point pen.  Or, if your spring was good enough, the spring could be under just one of the lid pieces – with the other lid pieces laying on top of it.  As that one pieces is forced up, it could force the others out.

Without the benefit of my printer running, I’m also putting a few extra brain cells3 on my clockwork spider project.  I was inspired by several things recently.  First is the video of how a mechanical clock works I had posted earlier.  As you’ll recall from Skimbal’s Rubber Band Gear Mechanism/Engine, a wound spring engine will want to expend all of its energy all at once.

That video describing the inner workings of a clock demonstrates a little regular that only lets it unwind a little bit at a time, so it can expend its energy over a longer time period.  Secondly was Erik’s pick-n-place tape feeder.  This design uses an interesting spring/gear/ratchet wheel.  Skip to 1:25 for a demonstration of the mechanism in question.

Now, in the instance of Erik’s device, it is the ratchet that moves back and forth – rather than the wheel turning at a constant rate.  However, this gave me an idea.  It should be feasible to create a similar spring/ratchet combination to prevent a wound device from expelling it’s energy at once.  Last, but by no means least, is Dna’s rubber band ratchet engine designed to power a clockwork spider.

In pondering my attempt at an open source disc launcher, I’ve been trying to think of the best way to pull back the spring.  If the firing pin/slider is going to be powered by a rubber band, it’s going to need to be a decently sturdy mechanism.  I keep thinking back to a rack and pinion set up.  There could be a notch in the bottom of the firing pin/slider, a peg in the flat side of a rack, and a small gear run off of a big gear, with the trigger on the big gear.

What else?  Um, I think the tank by mraiser could make a good platform for a larger clockwork spider.  Also, I would like to see a version of the tank that’s run off of clockwork/gears/regulators/rubber band/springs.

  1. More on this later [↩]
  2. I didn’t say better, mind. [↩]
  3. Both of them! [↩]

ProfileMaker Version 2.0 is coming!

A few cosmetic details to work out yet…  but I’m almost ready to launch the second version of my ProfileMaker.  I released the first version late last night.

I’d like to think that I’ve increased the number of options while still keeping a slim and intuitive user interface.  I would really appreciate any comments, criticisms, or questions you may have.

ProfileMaker thoughts…

Looking at Dave’s Profileinator seems really well suited to a stepper extruder.  However, he also suggests adding a “Flow Fudge Factor.”  I just use this set to 1.0, so I’m not sure if I’m using it correctly.

Flow Fudge Factor: I have to enter 1.0 into the flow rate to get 2.0 RPMs on the extruder.. I got tired of doing this math so I added flow fudge factor and set it to 0.5. This doesn’t change the volume calculations – it just modifies the flow rate on the table. If you have a MK4/MK5 extruder with a DC motor, start this at 127.5 to get the PWM value to use

In any case, it looks like by multiplying it by 127.5 you can get the required flowrate for a DC motor.  In printing with a DC motor, I never wanted to drop the speed below 255, because the DC motor had such a small range of speeds.  I could print between about 230 – 255.  Given this, I can understand why so many others, probably using a DC motor, would rather pick their flowrate as 255 and then determine the proper feedrates.