Movable Bed CNC machine 6

At this juncture, I had to consolidate what I had available and decide what kind of design of the cnc machine I wanted to build. Most of the decisions that I made were based on the parts that were available to me. For example, I recently acquired some motors which came with flexible couplings. These could fit in very well with the lead screws that I had. But the lengths of these lead screws were quite short, so I had to design my machine travel to be within the capability of the lead screw travel.

I had also a set of fully supported round guide rails that would be ideal for accuracy and precision especially for heavy loads. I intended to use them. Since the machine was going to be small in size, I decided that the moving bed design as opposed to the moving gantry design, would be a better choice.

The main advantage was that the x-axis could be fully supported and the y-axis would be fixed, making it less prone to inaccuracies, which I would expect from working by hand without any precision tools.

Indeed, I did not have a proper drill press. What I had was a homemade drill press made of wood installed with a portable drill. I did not have a table saw for making precision cuts. What I had was a handsaw and a jigsaw, marking out with a try square and measuring tape, and finishing up with a file or sandpaper.

In order to help me work out how the various parts that I had could be assembled, I did some careful measurement of the components and made a detailed drawing of the structure completed with the various components when put in place.

From the drawing, I could also predict how much the moving parts would travel, the location of the center line of the assembly, how much clearance to be made and how to dismantle the machine parts when needed later.

Comparing the measurement on the drawing, I could also know whether it followed good engineering design practices so as to avoid undue vibrations later.

My choice of materials to use was naturally wood or MDF, as I had mentioned before, I did not have any precision tools at hand.

My next obstacle was how to attach the plywood pieces together. That’s when I decided that I need corner clamps. So I found out how to make corner clamps – I made 8 pieces of them – and that took some of my time.

When the plywood pieces had been cut and drilled and the corner clamps where ready to be used, I clamped the 4 sides of the cnc machine and screwed them together.

My next task would be to prepare the bottom base with the supported round rails and fabricate the linear bearing holders for them and attach these to the moving bed. Yes, I did not have the holders for the bearings as they did not come together.