CNC Jr.

This build is complete, the major elements of the design are:

• Small footprint, approximate 12"x12" cutting area
• Precise movement - currently using 8mm leadscrews, but may consider building custom leadscrews and anti-backlash nuts for finer X/Y control.
  
• Rigid - the machine needs to be very rigid to ensure best X/Y control. The X gantry is fixed and the Y axis sliding table uses 12mm linear shaft. The entire machine is bolted to a 3/4" piece of melamine board.
  
• Quiet - The machine will be enclosed once finished.
  
• Clean - still working on this, but there will be some form of vacuum system to pull dust and clipping downward to a small shop vac.
  
• Control - uses GRBL control and CNC shield. So far GRBL Panel is my preferred software interface.
  
• Spindle - While I purchased a 300W DC spindle, I plan re-sell it on eBay and build a brushless spindle based on the 890KV OX RC Spindle on OB.

Steps of my build are going to be inserted below for basic information on the build layout. Please visit the discussion for periodic updates and design comments.



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4/10/2015 - Build testing is finished. A button panel has been added, but the machine is otherwise complete. Marking this build as done.




3/15/2015 - Build is done and in the testing phase. Here are a few photos. Will be updating details on the machine's final build configuration later on.




2/22/2015 - From the original post, I've ended up nearly rebuilding most of the machine. The changes started with switching to 12mm hardened linear shaft and bearings for the Y axis table. The configuration with the Y-Axis supported by universal gantry plates and wheels on the ends was not working very well, there was a lot of wobble in the table and it was nearly impossible to align it all square.

The hardened shaft approach is extremely rigid and supports the table very well. The shafts, clamps and bearings were a total $40, which is a savings compared to 8 wheels, 2 gantry plates and 4 eccentric spacers. For this application, the shaft is 330mm long and there is no concern of flex. For a larger machine, the I'd suggest OX setup is good since it drives from both sides the plates. If shafts were desired, I'd recommend buying or building a supported shaft.

In addition to changing the Y axis table to use linear shaft, I also changed the layout and orientation of the X axis. I doubled the gantry plate to both sides of the gantry, and moved the leadscrew to the back. I also went to 3 wheels top and bottom to create more support. Unfortunately, the changes I've made have rendered my leadscrew too short for the Y axis and the Z axis. I'll have to order a replacement when they become back in stock.











2/15/15 - The build has reached the point where I can share the general layout of the machine. See discussion regarding the layout of the Y gantry. There are a number of gussets/brackets that still need to be added.