The ORD Bot's New Clothes

My hackerspace's laser cutter has recently come online after extensive repairs, and it's now the go-to tool for everything, because nerds love lasers.  Also because, for a group of people used to often waiting at least an hour to get a basic design manufactured on a 3D printer, the concept of getting something out of the laser cutter within five minutes is irresistible.

I too have jumped on this convenient bandwagon, and decided to make my printer's build plate, LCD display mount and fan mount (to cool the RAMPS board) out of laser cut acrylic.

Step one was meticulously measuring up the ORD Bot and designing the pieces.  I used SketchUp, which is one of the most user-friendly free CAD programs out there.  I've designed one piece in SketchUp before, but that was a while ago so I had to learn the basics all over again.  I actually think designing for a laser cutter is a great way to start with CAD, because the designs are 2D.  So you can get used to how a 3D design interface works, how to pan and zoom around your design, how to make sure you're drawing your shapes on the correct plane, etc. without the added complexity of three dimensions.

I ended up using two of my three designs - the fan mount needs a bit of extra work.  Here are my SketchUp models for the build plate and LCD mount:

I then exported the models as DXF files and opened those in CamBam, where I smoothed out some rough edges and created a file that could be used to plot a toolpath for the laser cutter.

As you can see the designs aren't complex, but they had to be millimetre perfect to be able to fit onto the ORD Bot, which has pre-cut mounting holes.  So I was delighted and extremely proud of myself when the finished products ended up fitting really well:

Build plate

Since I won't be using a heating element, which would usually go between the blue anodised aluminium plate and the actual build surface, I suspended the build plate on nylon spacers.  This will give me room to clip baking paper to the acrylic surface, for better food safety.

LCD mount

The LCD mount fitted a bit differently than I anticipated.  I designed it to be fastened to the ORD Bot's back plate with four bolts for extra security when the entire machine starts vibrating with the force of five stepper motors.  In the end I had to move the mount up a little to fit it around the Makerslide frame, so it's only fastened with two bolts.  It seems secure for now, but I'll keep an eye on it when I start using the printer.

I've also fitted the endstops on my Z and Y axis, using mounts made by a kind hackerspace colleague.  I decided to use mechanical endstops because they're simpler than the optical or magnetic options.  If one of the axes should reach its limit, it will hit the metal switch and stop the print, like so:

The endstop mount for the X axis needs redesigning, so more on that - and the redesigned fan mount - later.

Baby's First Steps

It's been a while since I last posted, but that doesn't mean nothing has been happening. I've finished connecting the wiring for the stepper motors, and am currently in the process of sourcing bearings, bolts and tubing so I can assemble my extruder and its carriage. I've also got some STL files for 3D-printable endstop mounts, which I'll get around to printing and testing at some point... Because this is all unfamiliar I'm taking things slowly at the moment.

Since all the motors are hooked up now, I connected the printer to a power supply last week (with supervision of course). The good news is that all the motors are in working order, yay! Here's a very short video of my printer's first movements:

Like most babies' first steps, hers were jerky and hesitant. Unfortunately this is at least partly because the threaded rods on the z axis aren't 100% straight - it's such a slight bowing that a human can barely see it, but it's more than enough to upset a robot. After a bit of oiling things started to run more smoothly, but needless to say I'll be keeping an eye on this.

Obviously there are a few things on the go right now.  I'll report back when something else interesting happens :p