DIY CNC Build in Switzerland - Building the X and Z axis carriage belt mounts and testing motor movements

I started building the belt drive for X and Z axis carriage. The belt drive mount for X and Y axis is very tricky. I needed to come up with a good design so it is easy to mount the belt on the axis and easy to tighten the belt.

Lets start with X Axis. First I needed to measure, the belt location when I mount the X carriage. In the picture below, you see two lines on the MDF. These are the exact belt locations when I mount the X axis to gantry. The Linear bearings just clear from the gantry with 2mm so I need to mount the belt within at most the height of linear bearing.

I decided to use MDF again, but for the simplicity one can use the L shaped aluminum profiles that you can buy anywhere. I marked the area that I needed to cut on the MDF. Then cut the piece...

I used the L shaped joint support brackets for attaching the belt mount to carriage. I just did a test fit without any drilling or screwing.So it looked ok to me.

Now, time to drill the holes. I drilled the holes with drill press and just enlarged the side of screw head so the screw does not stick out of the board.

I used acrylic plate for the mount plate. You can use wood but I wanted to see what is happening to belt:) So I needed something transparent. I cut the exact same size with MDF piece and drilled the holes as well. The final belt mount piece is shown below from different angles.

 

 

The idea of building such a thing is to mount this bracket to gantry first tighten the belt then screw it to X axis. If you have something that cannot be detachable from the X axis plate, then you will have a lot of difficulty to tighten the belt. And if the belt is not tight, then the pulley will skip threat in load condition.

Now time to build even trickier part: Z axis belt mount. All the things should be as precise as possible. So I measured the distance between plates of X and Z axis and calculated the clearance distance. Then, I followed the same procedure, cut the MDF, cut the acrylic plate and drill the holes. BTW, you need to cut a groove on top of the MDF as shown the images below so the belt can be fed by this groove.

In order not to have the belt slipping, I made some shallow cuts on the acrylic plate to hold the belt teeth strongly.

And the most tricky part:) Attaching... First attach the belt to the bracket than place the Y axis on Y axis. I inserted only one of the steel rods so I have at least access to the screws from one side.

Here is a video of the axis movement test. You can also visit my youtube channel
Ozgur Gulderen on Youtube

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PS: I have good news:) I have disassembled the CNC for painting wooden parts. So the next time I will shoot a  looooong video in which I will explain every single piece and assemble it again.