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• Building the X-Axis, Pt. 2

  Sebastian Lenartowicz • 12/10/2014 at 02:07 • 0 comments

  So now the X-axis has another rail. Well, that's great, but there's nothing to move along it yet, which makes it useless.

  To build the sliding element for the rail, I started with this large bit of plastic, which came from a plotter that someone had already dismantled and looted (no new steppers or long rails for me). I used a jigsaw to cut out the bit marked with Sharpie in the bottom left, with the idea that I would use the protruding cylindrical bit as a second slider on the new rail.

  Before I started doing anything with that part, though, I have to modify the existing carriage to accomodate it (something it was ill-equipped to do). I started by cutting some protruding bits of plastic off the bottom of it, to make attaching the second slider easier. I then continued by drilling some bolt-holes through the part of the carriage that stands up at 90 degrees to the travel angle (the intent was to mount the bit I cut from the plotter to this).

  After cutting it to the right size (I just rough-cut it from the plotter end-cap), I realized that the best way to mount the new piece was to use some long M4 bolts, with a couple of nuts between the protruding element and the slider acting as standoffs (because the protruding element has an uneven surface, mounting it directly wouldn't work very well, and I wouldn't be able to do a good enough sanding job to make it work because it's made of ABS and would melt rather than grinding).

  When that was done and started moving, I realized that the carriage wasn't capable of moving along the entire rail length because of the protruding bit that held the secondary rail on, and this was costing me about 1 1/2" of my travel distance. To remedy this, I ground down the part that held the second rail to make it much smaller, and cut a matching wedge out of the cylinder (which is hollow), so that the carriage could travel the entire rail.

  The end result of all of this isn't pretty, and still wobbles around a bit if I put some force on it, but slides straight and smooth (especially with some lubrication) and will likely do until I'm able to print a replacement for it when I get this printer up and running. Finishing this means that the X-axis carriage is basically done, and can be set aside until it comes time to mount it to the Z-axis.

  Oh, and the final product looks like this:

  The plan in the end is to mount the extruder to the bit that sticks out, and cut off any excess on an as-needs basis (though I'm hoping to avoid having it stick out too far, so it won't cut into the Z-axis travel distance).

• Building the X-Axis, Pt. 1

  Sebastian Lenartowicz • 12/08/2014 at 00:06 • 0 comments

  I decided to start off the build in earnest by building the X-axis, because I felt like that was one of the components that needed the most work. The basis for the X-axis is the print head carriage off of a B+W inkjet fax machine, with a total travel distance of about 9 inches. Because of its previous function, it needed some major modification before being ready to be put to use in a 3D printer. The first, and biggest, problem is the wobble in the print head itself - the way it's designed, it uses only a single rail and the force of gravity to keep it stable and on target relative to the paper. This is unacceptably error-prone when it's being used for a 3D printer (as it will be moving around in more than one axis, and might jerk around and move off-target as it's being adjusted in the Z-axis).

  To remedy this, I decided to add a second rail and a slider for it, to keep everything stable without relying on gravity.

  Before starting to work on the rail, I removed several protruding bits of metal that might catch on things or cause problems when the printer is finally in operation.
  

  To mount the rail, I started by drilling out one of the pre-existing holes in the carriage frame (which had a matching hole on the far end along a straight path) to make it a little wider (it was 5mm before, and 6mm after). This was to accomodate a smooth rod that I extracted from a broken HP office laser printer (of uncertain model number) of roughly the right length.

  The two images show the hole before and after. I also ground off that little bit of metal next to it and sanded it down, so the slider will be easier to make and have a longer travel length.

  The next step was to cut threads into the rod, using an M6 die and some WD-40 as cutting oil (I didn't have anything better lying around). 3 nuts later, and I had a second rail (though no slider for it yet). I finished off by cutting the rail to length (so it wouldn't be sticking out) and sanding off some of the pointy edges I created while removing the protruding bits before.

  The end result looks like this:

  The next step is to make the slider, which I'm going to be cutting out of a large piece of plastic that once formed the end cap of a plotter (large-format printer), which I couldn't salvage any interesting parts from because someone got to them before I did.
  

• Getting Started

  Sebastian Lenartowicz • 11/25/2014 at 04:52 • 0 comments

  So I got this crazy notion into my head that I'll build a 3D printer from scrap parts. Well, that's great, but what next?

  I started by collecting some scrap from my university's junk pile. They throw out a ton of e-waste, both functional and not, and I pulled out some components that might form a decent base for a scrapyard 3D printer.

  My current design premise is based loosely on the RepRap Mendel, with XZ being paired and Y on its own.

  For the Z axis, I'm using this large carriage (left), salvaged from a (non-functional) IBM Wheelwriter electronic typewriter. It's more robustly built than either of my other two carriages, and has a geartrain attached to the stepper with a nice high ratio, so even if (as I suspect) the stepper turns out to have a high angle/step, I shouldn't have too many issues. As a plus, it's also got a nice long travel distance. The metal frame is very stiff, and the two rods should ensure that it moves smoothly and stays straight, even when it's loaded down with the X-axis components.

  The X axis takes a similar tack, but this time it's the carriage off an inkjet fax machine (right), and it's a lot lighter than the massive typewriter components. It has a shorter travel distance than the Z or Y axes, but I figure the light weight is worth the tradeoff. My one possible concern is that the datasheet for the stepper lists it as having an angle change of 7.5 degrees/step, though whether that will be an issue remains to be seen.

  Both the typewriter and the fax machine carriage components will need some modification before I can use them to build the printer (mostly cutting away unnecessary protruding elements), but I will be keeping their basic structures intact because they are relatively stiff and strong.
  

  Finally, the Y-axis will be built from this: a dismantled Epson flatbed scanner (left). This model has a high maximum scan resolution, which leads me to believe that the stepper will be relatively precise. The current idea is to use brackets and bolts to mount the bed to the scan head (which has been completely dismantled, with only the plastic housing left behind). The scan head itself runs using a stepper and timing belt on one side (left in the picture) and a small wheel on a raised plastic ridge on the other. Whether the motor will be able to hold up to the rigors of 3D printing remains to be seen. And, yes, that is a hole in the bottom, cut when my design idea was for an XYZ-together printer (I was going to mount the extruder on the scan head). Now I figure it'll save some weight and make it a bit easier to see what I'm working on when I'm building it.

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