My CNC story (part 3)

Please read previous parts first. This is the third part of my CNC story. Click here to find part 2 and here to find part 1. I have started to add images, will add more later on, please revisit the pages.

Restarting and full steam ahead

The project was halted but not really abandoned, and in November 2014 I stumbled across an eBay seller who sold the same type of aluminum profile I actually wanted to use, but originally found too expensive to use for a risky DIY project, like building a DIY, self-designed CNC without prior mechanical design and practical experience.

This seller is selling it at a very reasonable price; he is located in Germany and is very fast in delivering, so I contacted him, gave him all the dimensions and asked for a price for all the listed mechanical parts I wanted. After some conversations I placed my order. Delivery was as expected, very fast, it only took a few days, all pieces cut exactly to the length I wanted, even if not all cuts were exactly at 90°, the parts were fully usable and easily aligned to  90° using the joints I also ordered, and definitely better than what I could have done on my own.

He also sold fixtures, screws, T-nuts and everything else I needed for a better design and quality than my first creation would have allowed.

By December I was back on track. This sudden design change made the mechanical work much simpler and considerably better, so I expected to have the CNC ready and working by the end of December, or at latest beginning of January. I have no milling experience, so I knew I will need some time to learn the entire “how to…” part, but at least for this adapter, the V1-F1A flash adapter, I expected that this practical learning will be quick once I have the CNC up and running.

It turned out that I was a bit optimistic about the time. I was doing good progress, but by the end of December I only had the base, a working X axis and a working Z axis ready. On this picture the Z axis is on the floor to the right of the main frame.

Never the less, I was quite happy about how well the work went on, and since the X axis was really running nice regarding the movement and the accuracy, I was now convinced that I will be able to finish this project one day with success.

Next mistake…

As very common in DIY projects, ideas pop up and design changes are sometimes made suddenly. One such change was generated by an idea to improve my design and to build in the control box and the power supply, so that I could skip two extra boxes. I also had an idea to include the power supply for the spindle motor as well, making the machine a bit larger in height but reducing the total volume and space it needed in the end. This change would reduce the cabling and the number of external boxes, so in theory, it was a very good idea. The only bad thing about it is that it meant I had to spend time and work with moving the electronic parts and place everything on top of the CNC base frame, in the Y beam holding the Y axis.

“If it ain't broke, don't fix it.”

This is as true as it can be. What seemed to be a simple change, yet a huge improvement, created a lot of extra work. It took several weeks to get everything up and working again but it was too late to reverse back the process when I realized this simple truth.

Another mistake was…

...adding new functionality.

I decided that some supervision is needed to be added. Now that I moved the electronics I got a huge front panel with enough real estate to add some instruments to supervise critical currents, voltages and temperatures. While this was also a very useful improvement and was fairly simply to implement, it took some extra time and pushed the start-up further ahead. Never the less, I went for it anyway because I was convinced that either I do it now, or it will never be done and that this design change will definitely add positive improvements.

A new set back

In the end, when the electronics were fixed and everything seemed to work well again I realized that I made yet another mistake.

The Y beam holding and driving the Y axis and carrying the Z axis could not share the same beam which holds the electronics, because the stepper motor driving the Z axis would not have enough free space to move along the Y axis. This could be fixed in two different ways, one by adding some extra spacers to move the Z axis away from the electronics, or another by adding an extra, dedicated Y beam. There was a third option also, which was to move out the control electronics into an external box again, like in the original design, but I did not want to do that, so I went for the second solution because it gave me better options for any future changes. For example replacing the control electronics and relocating it somewhere else is much easier this way than if the Y beam has shared functionality. Anyway, this meant I had to start drilling and sawing again, wasting some more time. If I would have kept the original idea and the control box would have been kept at version 1 as a separate box then these two delays wouldn’t have happened and I’d be almost ready by now.

The timing plans of the project is definitely wrong

The delay is now more than a moth compared to my original hopes about making the first cut already at the end of December 2014. At this stage, it is February 2015, but I am definitely doing progress and the improvements/changes are well motivated.



Please continue with reading Part 4.