David C.'s CNC Router

Dave C.'s CNC Router

It's a good time to update on another builder. Dave C. is building his CNC Router with patience and method. He is equipped with some nice tools to make sure the form and mechanics are perfect. When he first told me he was working with these power tools, I was very jealous and I wanted some fancy power tools for myself.

Dave's CNC machine is another alteration in the works. The bed of the CNC machine is stiffened by steel. He is using cross dowels for all of the connections. The rails are mechanically fastened to the rail support pieces. And he is using some motors bought about 6 months ago which have a bit less torque, which I am very eager to see run.

At first look, it is apparent that he has widened the z-axis rail support for a wider cutter mount and maybe for a larger cutter. This also has the potential to stiffen the z-axis side to side. You can also see the use of cross dowels for the connections. They look very neat, and he will benefit with higher strength at these connections.

He was egging me on earlier to create a jig for the dowel nuts, but he was able to come up with one himself. As you can see on the left, he made a jig out of two pieces of MDF glued at a right angle and two holes spaced perfectly in the middle of the thicknes of the board. Align the hole along the same line on the board, and you have a guide that will assist in making a flawless intersection.

The bed of the CNC router is starting to come together in this photo. He chose not to reinforce the bed with MDF. He decided that steel would serve as the reinforcement by using steel angles for the rails and the same angles in the underside of the bed for further reinforcement.

Getting ready for painting. I wish I had painted the pieces early on.

Shown here is the z-axis assembly put together and painted. Blue is a nice color and works well with the aluminum color.

Since I haven't shown a solution for fastening the rails to the MDF, Dave took it on as a well thought-out project. First, he picked up this screw mechanism that is usually found in cheap bookshelves and desks. We have all come across this piece before. It's called a cam nut. It mates with a torque type cylindrical mechanism that creates more force by turning it over the head of the screw.

With a little modification, the screw can be adapted for use with the rail. Since the fastener did not come with machine thread, he used a lathe and turned the existing thread down to form 8-32 thread.

The rail is then drilled and tapped to receive the fastener. If the end of the fastener sticks out of the rail edge, it can easily be filed down.

The finished product of the rail adhering to the MDF.

Dave also wanted a bit more stability with the linear slide bearings. This is a good way to do it. This method will restrict the slide bearing from moving laterally in and out of the groove. He simply drills a hole in the middle of the bearing assembly and drills another hole through the MDF shown in the next image, and fastens it with a standard screw and nut.

Showing progress with the gantry put together around the bed. This, in my view, is the part of the build that really shows a lot of progress.

Testing the motor, coupler drive train on the z-axis. He purchased the lovejoy couplers from my site and couldn't wait to try it out.

The motor mounts will be made of rectangular aluminum stock. This will be an interesting experiment.

After cutting the stock to a length that will properly house a motor, he drills holes for the mounting screws and the shaft. The coupler will be positioned within the mount.