CNC Router

It was always my dream to have some kind of universal machine to realize my next projects on it. That's why I decided to build a simple CNC router machine. It wouldn't be me, if I just bought a kit and assembly it. I didn't have the nerves to build my own printed circuIt was always my dream to have some kind of universal machine to realize my next projects on it. That's why I decided to build a simple CNC router machine. It wouldn't be me, if I just bought a kit and assembly it. I didn't have the nerves to build my own printed circuit board from scratch, but et least I designed my own mechanics. 

I used SolidWorks CAD software to design each part of the machine separately and also for assembly the 3D parts together to be sure everything would fit and work together. I had contacts to people able to lasercut some sheet metal parts for me and a nearby company imports aluminum profiles so I decided to use combination of these two technologies.

I wanted to have as much working place as possible but, at the same time, the smallest possible machine dimensions. After first design I realized that the motors sticking out would make the machine a lot bigger than it was necessary, therefore in the second design I hide them inside construction - hence the timing belt option instead of straight connection. This has also an advantage to set various gear ratio simply by changing the gear size, and this way control the cutting precision.

Here you can see some pictures of computer and then actual assembly of the machine:

Findings:

Now… the machine works just fine, but I am not going to pretend that everything is as good as it should.

First, the decision to build the machine from sheet metal parts ended up like not very good. I had some concerns about the stability of whole machine, therefor I used a thicker and heavier metal sheets (4mm). At X axis, I used little thinner (3mm) parts. Afterwards, I added bendings wherever it was possible to reinforce it and this way suppress unwanted shaking from side to side. The theoretical, computed precision based also on used screw technology was supposed to be les then 5um (although I knew I would not be able to reach it) but at the end it is not at all that good.

Other reasons, besides the sheet metal part construction, is using low quality suppliers. The ball screw driving the longest – Y axis - was curved. I claimed a new one (two times) but each time it was curved and also each time with different diameter or size. The sheet metal construction, however reinforced, just can’t eliminate these variations and the machine is visibly shaking from side to side. Probably, it would be better, if I used two separate Y axes with two separate motors, which on the other hand, would raise the price of machine and size of the electronics box enclosure (one more stepper motor driver would be needed).

Also, If I was suppose to make the project again, I would design it using only a few types of screws. It is really a huge pain in the ass to dig up exactly the screw currently needed, when you use 15 types of them.

For cutting metal parts I would also like to add at least some air cooling some day.

As for my first machine of this type, however, I am glad it works as it does and although I can’t use it to machine some precise constructions, I can at least use it as a hobby tool for wood, plastic materials or soft metal part.

So thank you for reading this far, hope you like it, and if you have any questions feel free to ask me.