ShapeOko Kit (completed)

I recently purchased on of the early pre-order ShapeOko mechanical CNC kits. I'd been thinking of attempting to build a CNC machine myself for a while, but the price and quality of the ShapeOko project convinced me to try this first.



7/3/12


The kit itself came very well packed and organized. With all the parts neatly organized in individual bags, it was easy to put the mill together in less than a day. I found the only somewhat tricky element to be the instructions, but spending a little time looking through the ShapeOko wiki was enough to figure out what was going on. For stepper motor control I used the GrblShield, which was simple to connect to and run. My software stack consists of Autodesk Inventor Student (dxf or 3d file)->CamBam(free 40 use trial)->GCodeSender. Unfortunately, I was too excited about getting it working to think about taking picures of the assembly.

Obviously, the combination of a not-very-stiff pen mount and incorrectly-set-z-axis-height created some problems on the above "Hello World!" picture. Since then I've spent some time playing with feed rates and other variables to make things run faster and more smoothly. For my cutting tests I have been using a Dremel rotary tool on high speed with a 1/8" standard wood drill bit. So far I have tried cutting foam, soft wood, hard wood, and acrylic with varying levels of success. What has become most clear is that finding the correct feed rate for each material is critical for a good cut and finish. I have also recognized that a standard drill bit will not function very well as an end mill. I've put in an order for a couple of proper end mills so that I can soon begin to cut things for real. My ultimate goal is to cut 1/4" aluminum plates with this mill. I think that this will be entirely possible with some more practice and better bits.

Test cutting a riser for Metal Scooter out of some wood

Overall, I am very impressed with the ShapeOko CNC mill. Its design seems really well thought out and rigid, and the hobbyist community oriented aspect of the project is also very cool.  It is amazing that a highly funtional and legitimate miniature CNC machine can cost less than $350. I am excited to begin putting it to use for real parts and projects.

6/5/13

I've recently had the time to make a number of modifications to my ShapeOko CNC router. While the original kit worked well on softer materials, it quickly became frustrating to deal with aluminum milling. To minimize flex across the X axis and the limited torque of the Dremel spindle, the ShapeOko had to run at painfully slow feed rates and small depth increments. This meant that even small parts required hours of time standing at the machine, manually spraying lubricant and monitoring progress. Even with those conditions, the tolerances were not as accurate as I would have liked.

I started out by designing and welding a "cage" to permanently house the ShapeOko in. The thinking was to cover it in panels of clear acrylic to prevent the clouds of sawdust that came with routing wood. It also allows the baseplate to be removable and provides space to put a drip tray below the mill if I decide to use lubricant when cutting metal.

It is pretty obvious that this frame is not based on the standard ShapeOko dimensions. The size reflects the new expansions made to the Y-axis to increase it to 1000 mm.  I chose to paint it blue just to create some bright contrast against the red ShapeOko. The extended bar visible on the  top of the frame in the picture is not a mistake, but instead where I intended to mount a new electronics box.

Instead of sitting on top of the workbench waiting to be shorted out by metal shavings, the Arduino+Grbl Shield and 24 volt power supply now have a home inside a new box. The connections run to four male connectors mounted on the box. The mystery fourth connector is for the new stepper I am installing across the X-axis to run a duel motor setup. This will reduce wobble that previously came with having an unpowered side of the Y axis.

More clearly visible here are the two fans and buttons that were installed. The power switch runs between the power supply and the Grbl board, it does not turn the power supply on or off. Also included are two new 12 volt fans run in series to help provide some extra cooling to the stepper drivers. Finally, the essential reset switch was also brought out to the front.

Here is the frame with the box mounted. It turns out I overestimated the strength of the ABS RadioShack project box, and assumed that two bolts through the top would be sufficient to hold it on. With the weight of the power supply, however, the entire box flexed to a point where it wouldn't even close. The solution was a piece of square steel tubing added along the inside top of the box to help it retain its shape. The steppers were wired to the box with 4 conductor wire from McMaster-Carr and female 4 pin connectors.

Visible here is another upgrade I made to improve rigidity. The secondary piece of MakerSlide across the X-axis probably isn't strictly necessary, but I figured it couldn't hurt.

The final change was the switch from a Dremel tool to the Dewalt DW660. The router seems to have some decent power, and I have supplemented it with a variable speed control and laser tachometer so that I can actually start to record some cutting data. All parts of the new ShapeOko setup seem to be working well at this point, and I will probably update with more details after I get the chance to make a few test cuts.