Well, the beast is finished, but not without some hand wringing…I had to redo some of the z-axis as it was too tight for the servo. Turned out that some superglue had bound the lock nut to the bushing in the MDF, so a little brute force to undo and re-setting did the trick. I also took a needle file and smoothed out the holes in the z-axis carrier so it was smooth traveling up the guide rods. Silly me also put some of the bottom supports in the base the wrong way round so the guide holes for the wires were on the opposite side of the machine…no big deal really as I just drilled some others on the other side… There’s a forum over on the MakeSmith site for all of us Beta-testers putting the machine together and the issues we face and solve (eventually!). That’s one of the great things about projects like these, and Open Source Hardware in general, there’s plenty of like-minded and helpful souls out there with good advice. One such person posted a really ingenious way to smooth the travel of the carriers on the guide rods and that proved very useful. Pulling the rods out one end with everything in place and using a drill to rotate them to help smooth the guide holes really helped get everything working smoothly for me…a great tip! Here is the completed CNC with a dremel in place…

I’m running this with a Mac and the Ground Control software has a few issues at the moment, most notably random crashes that disconnect the arduino from the computer. Bug reports have been filed, but until the software is a little more stable, then I think cutting anything too complicated may have to wait..There’s also a small issue with the other servo’s jittering a tiny amount whilst another axis moves…not sure what’s going on there, but again I await comment from Bar/Tom on the forum who seem to be on-top of answering everyone’s questions!

Here’s a small video of the machine in action doing a few simple movements (apologies for the somewhat amateurish camera work…).

CNC Snippet

Well, I’ve had some time to start putting this kit together and it hasn’t been without a few frustrations…The body is laser cut MDF and the instructional videos (on youtube) are good and reasonably clear. For the most part, construction has been without major hiccups. It pays to put things together without the glue first to check alignment/fit etc then go back with the adhesive. Gluing the acrylic drive parts together took an alarming amount of superglue to actually get it to stick…The only significant issue i’ve encountered is that the steel rod guides can prove tight against the guide holes in the MDF, especially I’ve found for the Z-axis tool holder..even though the rods were inserted into the tool holder and ends whilst everything was glued, they still managed to setup a tiny bit out of line….several minutes of manually sliding it up and down has loosened it up a lot, but until I fire up the servo then I won’t know if it’s sufficient to prevent binding and hence vertical accuracy…Also the cuts on the threaded rod have proved poor so a little dressing with some small files is necessary before you can get a good thread for the locknut etc…

The main body frame was pretty straightforward and the movable bed is nice and ‘loose’ on it’s guides so shouldn’t prove a problem once in motion (Due to a minor ‘repair’ to the Z axis assembly, I started putting the other parts together out of order…the horror!).

You’ll note from the picture that it’s all controlled from an Arduino compatible driver board with a custom power control header for the CNC. At the front you can also see one of the servos which is attached to the threaded rod via an acrylic toothed gear and ‘socket’…we’ll see how well that holds up after some use. The degree of rod rotation (and hence board movement) is provided by a magnetic sensor at the end of the threaded rod (see picture below, there’s a magnet glued to end of the locknut)…

So far, I’m really enjoying putting this together, and there isn’t much left to finish it….then the fun starts as I try and figure out how to drive it from my Mac….The creators, Tom and Bar have come up with a really neat piece of open source kit!