Monday, 28 December 2015

My DIY CNC upgrade project, the Z axis upgrade

I started with a major upgrade of my DIY CNC. The CNC, including the upgrade, is 100% of my own design, there is a long story about it here. 

The first version had its issues, and while it served me well, it is now time for a major upgrade. All axes will be replaced by new, much better designed ones.

One main mechanical upgrade was the changing from unsupported steel rods which made up the horizontal and vertical slides to fully supported and much stronger ones. The Z axis had 10mm rods, the X and Y had 12mm rods. All those are now 16mm fully supported.

The other thing was the lead screws. In my version one I used 12mm stainless steel threaded rods with 1.75mm pitch and the lead nuts were made of acetal (POM), all individually taped by a piece of the threaded rod, which I made a tap of and threaded the lead nuts with to get zero backlash. This worked very well, but the speed was slow, maximum 500mm / minute. These are now replaced with 16mm ball screws and ball nuts. Of course, the speed increased significantly, a quick test bench run shows 1500mm / minute without problems. I could probably get more with higher power supply voltage, but that's for the future.

Even some parts of the electronics will be redesigned when I am done. Already added a USB controller and running with an UC300, which seems to be excellent. I will add some control buttons and jogging wheel also, and will also upgrade the power supply. Maybe I will also change the spindle motor, which is quite weak, but doing what I want it to do.

Anyway, version one of my CNC served me well, but now it is time for a major upgrade. I will post pictures and video as well as more data later on, as I progress, but in the meantime here is a short one showing the Z axis and the differences between old and new.

This video is the first in a series, showing the upgrade of the weakest part in the first version, the Z axis.

Ooops... I am sorry... I have just noticed that I made a slight error in the video. When the new Z axis is shown the caption says "The new X axis" in large red letters. Of course, that's wrong, it is the new Z axis which this video is about. OK, the Z axis is on the X axis, but when I made this video the X axis was not really ready. Sorry about that.

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