by makeme

Archive for October, 2011|Monthly archive page

A 3D Printer Under $250

In Uncategorized on 23, Oct, 2011 at 22:22

All the coolest gadgets are too darned expensive; especially when they’re brand new. 3D printers are no exception.

Even the dramatic reduction in price that the open source hardware movement has managed to produce only brings 3D printers down to just over $500. That’s amazing compared to the commercial options (which start at $10,000) but it’s just not good enough.

I think the goal should be $250. That’s right around the pro-sumer line so anything under it is legitimately obtainable for the average person. You don’t have to worry about how much profit you can generate with the thing when it’s cheap enough.

A printer that cheap could become a practical option for STEM education. It would be a good introduction even if it didn’t have impressive performance.

Based on some research it looks like that price point is obtainable, in theory, today.

The most expensive part is always the electronics. Well, eMAKERshop sells sanguinololu electronics, fully assembled (and flashed), with the pololu drivers, for $125. They also sell a mechanical endstop kit for $10. Nema 17 stepper motors are around $15 from Kysan (4 of those). A 12v 5a power supply goes for around $10 on Amazon. That’s the majority of the electronics right there for about $200.

Now we just need to build the frame and linear motion systems. A 1/4″ x 2′ x 4′ piece of pine plywood can be about $10. Home Depot lists 16″ keyboard sliders for about $15 (3 of those). Assuming you could make the printer out of cabinet supplies, that’s about $55. If the extruder could be made out of a bolt with some nichrome wire (old school I know) it wouldn’t add much to the total, which is now around $255.

There are some crucial assumptions in there like a dirt-simple extruder and no need for timing belts. At any rate I think this demonstrates that the idea isn’t as far fetched as it might at first appear. A big piece of the puzzle will be getting around the need for metal pieces, printed pieces, and laser-cut pieces.

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Insane 3D Print Resolution

In Uncategorized on 16, Oct, 2011 at 14:31

You know how professional 3D printers start at $10,000 and then work their way up to $100,000 or more? Yeah…that’s probably going to change soon.

Dave Durant posted a long series of examples of how the latest generation of open-source 3D printer software and hardware is quickly outstripping our ability to challenge it. His post is well worth reading through, so I’m just going to highlight one point.

He linked to this post in which Jordan Miller put one of the newest Ultimaker prints under a microscope.
LowerMag_WithFingerAndScaleBar_162pixelsPerMillimeter

That thing on the left, kind of hard to identify…that’s a finger. Or, rather, those are the little ridges that make a fingerprint. Yeah. The average layer height in that print is 0.074mm (74 microns).

I just want to remind the reader that resolution was achieved on a printer that’s not only around $1600 but also open-source, so the software and hardware designs are available for free.

Dave has another example of a print by Paul Candler that uses 0.02mm (20 microns) layers (two perimeter layers for each infill layer). For comparison, the Stratasys UPrint can do 0.25 or 0.33mm. It costs $20,000.

If you want an Ultimaker (you should by now) you can even win one for free.

 

 

 

 

 

Lower Entry Barriers For 3D Printing

In Uncategorized on 12, Oct, 2011 at 22:36

The basic technology required to make a 3D printer work isn’t particularly groundbreaking, so it’s nice to see a brand new design as opposed to yet another copy. Origo is a project (company?) started by Artur Tchoukanov and Joris Peels with the goal of producing an $800 mass-produced 3D printer specifically for kids. It looks like they’re planning on using a double swing arm for the X Y motion, which greatly simplifies the physical construction, lowering the cost. They are also integrating the software so that kids can design things in 3DTin and then have their creations automatically printed. Also, a recycler, but I doubt that idea will work.

More 3D printers, particularly cheaper ones, is great. However, I would like to see the cost and complexity drop even farther. Here are some ideas for how that might happen:

  • The printer itself shouldn’t require powerful or precise tools.
The Thing-O-Matic achieves precision with laser cutters, the Mendel achieves precision with another 3D printer, and they both use special steel rods. The designs depend on expensive and difficult-to-maintain manufacturing tools.
I think it’s possible to avoid the use of things like laser cutters, precision ground steel rod, and pre-existing 3D printers. Anything that’s going to be expected to recreate precise movements is going to need some precision parts and assembly, but that’s almost entirely about the layout. For example, instead of laser cut parts one could print a template on a desktop printer, attach it to the wood, and cut/drill by following the guide. The typical solution to linear motion is some kind of bearing riding on precision rod, but some things like aluminum angle and drawer sliders are nearly as precise while being far cheaper.
The real barrier to entry, however, are the precision manufacturing tools. You CAN download the blueprints for a Thing-O-Matic, but they are specifically designed to be produced on a laser cutter. For example, the T-slots aren’t something you can accurately reproduce on your own. Likewise, while you CAN download the parts files for the Mendel, good luck carving them. “Many of the mendel parts are quite difficult to make from wood, and could do with a re-design. They are all created with 3d printing in mind, so there is no consideration for access to internal spaces, or grain or any of the other things to keep in mind when working in wood.” Designs with these requirements create a speedbump which sucks down money, time or luck. Instead, the goal could be for the printer design to require nothing more than a hand saw (cuts) and an electric drill (holes).
  • It doesn’t actually need a .5mm nozzle.
Creating sub-millimeter holes is kind of a problem. The only really reliable way to do it is to put the nozzle blank and drill bit into a lathe. If you allow the nozzle diameter to rise you start to run into pre-manufactured components like needles. Or, at a minimum, things like 1/32th (.8mm) drill bits that are cheaper and easier to obtain than .5mm bits (at least in the States). Even 1/16th (1.6mm) bits would be small enough to do something useful (probably equate to a 2.7mm wide track) and are pretty much free.
More importantly, moving up to something like a 1/16th bit wouldn’t require any special tools to use. Even holding a sub-millimeter bit requires a special tool. A 1/16th will fit into a standard drill chuck. Sure, you CAN get sub-millimeter bits that have expanded shafts, but that’s starting to raise the barriers again as people need to special order them and they can’t be easily replaced.
  • Make each part do more than one job.
The Mendel (and derivatives) is a good example of not doing this. As great a design as it is, there are metal rods being used for the structure and then different metal rods being used for the linear motion. Using the frame material for linear motion would create more synergy (do you have your innovation Bingo card?).
  • Simplify the positioning system.
The reason 3D printers tend to use linear motion is that it’s really simple to program for. 3D files record things in XYZ Cartesian coordinates, so it’s just a matter of calculating the steps. That’s great for the programmers, but not so great for the mechanical engineers. They have to figure out how to create a 3-axis linear motion system on the cheap. Switching to something more like the Origo (a double swing arm) would make the bot a lot easier to build. All you’d have to do is slap a couple arms onto the shafts of a couple motors. The programming would be more complex, and maybe the motors would be more expensive, but the physical construction would be much simpler.
  • Reduce the number of electronic components.
Electronics are expensive, even when you build them yourself. The electronics package is around 1/4 of the cost of a Thing-O-Matic, for example. It might be possible to create a “board on a chip” design inside a Field Programmable Gate Array (FPGA) that would literally do ALL the calculations. It could even replace the stepper boards. FPGA’s, instead of running software, are reconfigurable hardware. You program their logic gates and then they just do what they do. They have hundreds of I/O ports, allowing all the windings of the stepper motors and all of the sensors and all of the heaters to be controlled directly by the FPGA (via some form of amplification). Also, and this is important, they are truly parallel. If something needs to happen on one I/O pin it doesn’t have to wait for the software to get to that part, it just goes in and right back out.
FPGAs aren’t exactly main stream, and there aren’t any open-source solutions yet, but you can get the software you need to program them for free (just sign up for a license). I’m not sure how many gates you would need to replace an Arduino and four Pololus, but seeing as how you could do it with a single chip it’s worth looking in to.
  • Why not design things without a computer?
Origo is on the right track in terms of making it easier for people (kids) to design the 3D models that 3D printers construct. Why not make it even easier? OpenSCAD, a program that has already proven itself in the open-source 3D printing world, already has support for generating 3D models directly from 2D pictures.

openscad 2D to 3D

With just colored lines and some labels OpenSCAD can generate a water-tight 3D model. Kids (anyone) could use crayons or colored pencils to draw a blueprint of their design, scan it, and have it start printing automatically.