Repairable machines is a timelab project, located in Ghent, Belgium
SEPTEMBER 10th 2011 - VERSION 1.08:
We are currently publlishing version 1.08 of our machine.
It now features an anti-backlash system on the Y-axis, greatly improving accuracy. Our last machine achieves <0.2mm, take a look here for examples of what we made on it.
-added a strap to fix the power supply in place
-extended the belt tensioners in block B to run through both front and back panel of this block, reinforcing the block.
-removed superfluous holes from block A
-tighened the dimensions of the clamp on block Z
-extended the bottom panels of block E up to the front end of the block.
You can find images of our presentation at Pixelache, Helsinki on Flickr.
JANUARI 27th: Milling a contour into a 4mm sheet of plywood.
We're trying out CAD.PY, in search of a more novice-friendly control software.
CAD.PY allows you to import a black and white bitmap, and mill away everything in black. I like it.
Hard to get it properly set up though, and little reference on it online; A good help is http://www.fablab.nl/articles/2008/09/24/installeren-van-cad-py
MARCH 14 2011: You can find images of our presentation at Pixelache, Helsinki on Flickr.
JANUARI 27th 2011: We're starting work on the documentation for the miniCNC, with the help of intern Merel.
OCTOBER 10th 2010: The latest prototype can be seen in the exhibition in Kortrijk "Yes, we're Open" from the 8th to 25th of October.
We got most of the kinks out of the machine and proceeded to our first real milling test. Quite happy with it, though we needed some superglue to fix the Y-motor to its gear. We need a redesign of that gear wheel and some better mechanical connection. Otherwise it's coming together quite well.
This one is still powered with an old PC power supply, I went shopping for a smaller form-factor 3A power supply which will fit inside the back X-box.
TO DO LIST:
-make the design a bit larger, so we can achieve the originally intended milling surface
-redesign the Y-motor gear attachment
-integrate a small form-factor power supply
-try alternate stepper drivers instead of the Makerbot industries package
MODIFICATIONS SINCE LAST UPDATE:
-the double x-axis rods are now connected via a belt and are driven by a single, more powerful motor.
-the Y-motor is now linked up via gear wheels (see below)
-the steel U-frames have been abandoned for now in favor of an open ground plate. This has the advantage that both X- and Y-motors and linkage are accessible without disassembling the machine. Though I really liked the look of the heavy steel frame, this accessibility makes a huge difference in ease-of-maintenance and upgradeability.
-Z-block and Y-block have been modified so they can be removed from the machine without disassembling the entire machine.
-replaced the large, sturdy bearings on the Z-block with the same smaller, more tight-fitting ones we used on the Y-blocks.
Redesigned the Y-block. Because we wanted to keep the height of the machine minimal, the Y-motor had very little space to connect to the M8-rod. (image on the left) The motor is now moved to the side and connected via lasercut gearwheels. This has the added advantage that a gear reduction can be put in later. Really like this solution.
We tried printing the gear. It would be less brittle than the acrylic lasercut one, and easier to attach to the motor, but it tends to bend by heat deformation. Waiting fo our heated build platform on the Makerbot before we try that again
We replaced the small Dremel-extension thingy with a full-sized Dremel, as the little thing had too much backlash.
We also ordered a small 12V rotary tool from Proxxon. This could then potentially run on the same power supply as the electronics, eliminating the need for a second power cord for the Dremel.
Designed & printed the motor couplings & axis endstops on our Makerbots.
We've assembled an alpha-version of the miniCNC. We now also have spare parts, so we can stop cannibalising previous prototypes when working on a new one. We also added a 'base station' for easy mounting of smaller objects for milling.
ISSUES & PROBLEMS:
-we can't replace the z-axis or the z-motor without disassembling the entire machine. The next version should have a z-assembly that can be disassembled:opened up.
-the double X-screws are giving us headaches. When one motor loses steps, the Y-bridge gets skewed. We're currently running the 2 motors on 1 stepper driver. Everybody agrees this is a bad idea. We want to keep the 2 motors, but add a belt between the 2 screws.
-the electronics are Makerbot stepper drivers & motherboard. They're now simple placed on the side, but we intend to integrate them in the space between the 2 X-motors. They do take up much space though; the Pololu stepper drivers are much smaller.