CNC Mechanicals
Here are some recent modifications I’ve done to my CNC that have expanded its capabilities.
Spindle Mounting Plate
Recently I made a new spindle mounting plate (4th iteration) with m6 threads and holes for pins allowing the spindle holder to be mounted in many orientations and positions. This allows me to push the envelope of what I can machine even further. Also, there are setscrews behind the spindle mounting plate for adjusting the tram of the spindle. This is something that my previous design made extremely hard to finely adjust.
With the next spindle mounting plate, I am able to mount the spindle sideways like a horizontal mill. This allows me to use much larger tools for parts that would have been difficult or impossible without this modification.
Normal vertically mounted spindle.
The part being machined out of steel in the photo above and to the left is a bracket that will hold a brushless motor that can be mounted next to the spindle. This modification allows a connection of the new motor to the spindle with timing belts. The result is I can now optionally utilize much lower rpms than my original spindle is capable of.
Ball Screws
The photo above shows the ball screws on the x-axis and y-axis and their mounting to the frame (top left) and x-axis (bottom) and servo and ball screw mounted to the gantry (top right.)
My original CNC had backlash in excess of 300 microns due to the rack and pinion design. To reduce the backlash, I recently installed ballscrews on the x-axis and y-axis. I designed a custom mount and machined it out of aluminum and spend 3 days getting each ball screw exactly parallel to each axis. I used cheap eBay ballscrews and was extremely surprised when I only had around 8 microns backlash. With the ballscrews, I was able to mill a 40mm by 40mm pocket in aluminum and the dimension was only off only by around 17 microns.
Fixture Plate
I made a fixture plate with m6 threads and 6mm pins. This photo shows the rudder shaft with its two bearing blocks indicated parallel to the x-axis. This arrangement allowed me to machine two grooves for retaining rings on the shaft. I used the servo on the rudder to spin the part during the process creating a fourth machining axis.