Tag Archives: Heck

A new design and an old problem

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I don’t have killer 3D modeling skills – but am able to build a reasonable model using Sketchup.  It may be closed-source, but it’s got a fantastic UI.  (Heck, Apple has made an entire business model out of this proposition).

I’m trying to design a printable nut and bolt – and have a pretty good design.  The diameter of the threads on the bolt is almost 1cm, so it’s pretty large.  Constructing spirals manually is a real pain, so I used a plugin/script for generating the internal and external helixes.  (Helixi?)

The difficulty with Sketchup is that it’s not really a 3D modeling program – it’s a sketching program that makes really good looking images and reasonably good 3D models.  The problem is that it doesn’t really check to make sure triangles are properly oriented, sides are facing the way they should be, or that it is manifold.  Oh, and when the model is small it will start making little holes in your object.

There are plugins for exporting Sketchup files to STL files, but either due to a flaw in Sketchup or the plugins, they results are not as good as what you would find in other programs.  The end result is that to get a really good STL out of Sketchup I have to design in Sketchup, export as a 3DS model, import into Blender or NetFabb, fix it up, and then export back to a fixed STL.

If you’ve got a better way for transmuting a Sketchup file into a reliable STL, please let me know!

Remounted extruder controller board

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Tony’s recent comment to my post about my alternate extruder controller board mount really deserves its own post.  Tony’s comment was:

That’s a pretty logical place for it. Other than needing some more wiring, I wonder why they didn’t design it that way? I wonder if it might introduce some EMI noise?

I’m about 95% sure I know why they designed the extruder mount on the extruder itself rather than the side of the ‘bot.  As designed the entire extruder is completely modular.  You could swap in a brand new extruder assembly in about 30 seconds (four bolts, one ethernet cable).  Heck, if you had a second Z stage and extruder you could probably swap in a new extruder in 15 seconds (one ethernet cable, swap Z stage).  They’ve said from the beginning they wanted their system to be totally modular and hackable – and that it is.

I haven’t noticed any symptoms of EMI noise on my prints.  In fact, I’m getting some really great prints with my current Skienforge settings.  I have a little blobbing and stringing – but I suspect that could be fixed with some attention to oozebane etc.

There are a few really great things about my setup:

  1. More modularity. A totally new extruder (let’s say dedicated to PLA or a different color ABS) would not require a second extruder board.  This means with a printstruder and printed dinos (I’m still refining those designs) you could have a totally modular extruder for about $65 worth of hardware rather than $175 ($125 plastruder kit + $50 extruder controller board).
  2. Visibility. I can easily see what’s going inside the extruder and whether the idler wheel is moving – without lines on the idler wheel.
  3. Less work. It’s one less thing to take off the extruder when I need to do any kind of work on the extruder.  It’s not much time, but it is still a benefit.
  4. Ergonomics. My ‘bot is sitting on a surface about 5 feet off the ground.  Having the motherboard rotated 90 degrees counter clockwise allows me to front-load the SD card.  This is easier for me because of the surface height, but I also had to do it because otherwise the side mounted extruder board would have blocked the SD card slot.  Frankly, I would rotate the motherboard even if the extruder isn’t side-mounted.
  5. Centrality. This keeps all of the electronics all in one spot and makes inter-board cabling slightly easier. 1
  6. Less movement. I doubt moving the extruder board around on the Z stage would ever cause a problem – but it certainly won’t when it is side-mounted.

However, this setup isn’t perfect:

  1. Less modularity. One could argue that having the extruder board side-mounted decreases the modularity of the system.
    1. Counterpoint: That said, if you already have an entire second extruder complete with extruder board, there’s nothing stopping you from swapping it in as easily.
  2. More wires. I now have six wires2 running to the extruder board.  Disconnecting/reconnecting six wires is more work than disconnecting/reconnecting one ethernet cable.
    1. Counterpoint: In just about any circumstance where you are disassembling your extruder you’re going to need to disconnect those six wires anyhow.
    2. Counterpoint: I picked up a six pin male/female connecter set the other day.  Once I clip the wires I can again have a plug-n-play extruder without needing to fiddle with screw based connectors or with the extruder board in the way.
  3. More maintenance. Those same six wires need to be maintained/wrangled instead of one ethernet cable.
    1. Counterpoint: As you can see from the pictures I’m using the little blue twist-ties that came with the ethernet cables to essentially bundle the wires together.  I just wind the twist tie around the bundle and compress it to form a tight coil.  Works really well with several of these placed at intervals.  Clean and still flexible.
  4. Shielding. There is less shielding on the six thing wires versus one large ethernet cable.
    1. Counterpoint: This has not been an issue for me.
  5. EMI noise. I’ve never had problems which I would attribute to EMI noise from wiring, but I suppose it is possible.
  6. More work. It is slightly more work to put the extra holes in the side of the bot to allow the motherboard to be mounted 90 degrees counter-clockwise and mount the extruder board on the side.
    1. Counterpoint: Perhaps 5 minutes of work total?
  7. Z stage blockage. My extruder board is attached by only three bolts because one of them interfered with the Z stage.
    1. Counterpoint: This just isn’t that much of an issue, especially with the extruder board remaining stationary.

Overall, I find the benefits far outweigh any problems that side-mounting the extruder might cause.

  1. But, as you can see from the prior post, not much neater. [↩]
  2. Two each for the thermistor, nichrome, and extruder motor. [↩]

C is for Catalyst

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I purchased the MakerBot Deluxe Cupcake CNC kit – which came with plenty of tools and TONS of plastic.  The Deluxe kit came with things that you’ll need to operate your MakerBot such as the USB2TTL cable, power supply, and ethernet cables.

However, the wrenches and hex keys could be reused to build another ‘bot.  Parts printed up on a MakerBot could be used to print several very useful, and sometimes expensive, parts for another MakerBot.  The plastruder toolhead is $125.00 without the circuit board.  If you could print up the dinos, printstruder, idler wheel, and insulating retainer ring, you’re replacing all of the lasercut acrylic parts ($50.00 at MakerBot).  A persistent person could even replace all of the plastic spacers, wooden or plastic pulleys, the various wooden holders (Z rod caps, Z stage guides, X end rod caps), and probably even the  entire Y stage with printed parts. 1

Heck, if you had all of those parts you would basically just need a box in which to install them all.

Hmmm.  Anyone feel like designing a printable Y stage?

  1. In fairness, the Y stage would have to be printed up in several pieces due to size limitations. [↩]

Patience grasshopper

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Patience grasshopper, patience

Patience grasshopper, patience

Recent posts to the MakerBot Operators group show some people’s frustrations with this growing company. 1  Yes, they’re out of stock of electronics and other parts, but they’re also doing their best to crank out as many kits as possible.

Overall, I’d rather have them churning out robot kits than keeping spare parts in stock.  The plans for all of the electronics are open and free – you could have someone else fabricate them or build them yourself.  Still others have started up businesses selling lots of replacement parts and even upgrade kits.

We might be impatient for our kits, but they’re literally devoting their weekends and free time to getting these kits to us.  In fact, it’s their feverish dream to get a MakerBot kit into your hands.  You’re just not going to get this kind of devotion and service anywhere else.

I have one piece of advice if you’re waiting for your kit to arrive or replacement parts to be back in stock:  start designing stuff right now.  You already know what you want to build.  Just create a library of things you want to churn out.  Upload them to Thingiverse, get feedback modify, and improve them.  Heck, improve designs posted by others.

Your kit will be here before you know it and you’ll be happily (and woozily) sniffing ABS fumes too.  :)

  1. Photo courtesy of changhg [↩]

MakerBot, Mendel, Mendel-Mini Build Areas

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Owning a MakerBot, I’m not even sure why someone would need something to print pieces much larger than the MakerBot build area.  Printing something as large as just the maximum build volume of a MakerBot would take ages.

While the official longest print logged on the Makerbot website is Zach’s Disney head, clocking in at 2 hours and 45 minutes, I’ve read about people printing for up to 8 continuous hours.  If the build volume for a Mendel is 4.3 times that of a Makerbot, it would take more than 34 hours to fill that build area.

When you’re printing a door hook in 15 minutes, it doesn’t pay to drive to the hardware store.  When it takes 34 hours to print a big plastic brick, you’re better off driving to the gas station, filling up your tank, driving to McDonald’s, filling out an application, working an hour, quitting and demanding your paycheck, driving to the hardware store, buying a single brick, and then driving back home.  I figure that kind of silliness would only take half a day or so.  Heck, with 34 hours, you could do this at least six times over.