I am in the early stages of building a “proper CNC” style Z-axis and spindle sled, ie: I have all the pieces of the puzzle, now I just need to work it out.
I would appreciate any thoughts on this setup.
I am using SBR12 supported linear rails with SFU1204 zero backlash lead screw set and the smallest ER20 air cooled spindle I could find.
I choose a spindle for the speed control offered by VFD to avoid chip loading/bit burning issues. I selected ER20 so that I have a larger range of router bits to choose from as have found ER11 limiting on the desktop 6040 machine I cut my teeth on.
So far it remains to be seen if this is a good idea or not as it’s going to take a bit of engineering to make it work.
What the Ebay listing doesn’t tell you is that the spindle is heavy, ~5kg, and the weight is in the upper 2/3 of the body. I am concerned that by the time you have a bit in the spindle you could be looking at a total length of 250mm with a 5kg lump between 100-250mm away from the sled will causing a tendancy to tip away from the work piece with the cantilevered weight, I suspect i may have to raise the ring height away from the sled to counter for this.
Pieces of the puzzle:
SBR12 rails: https://www.ebay.com.au/itm/302815884241
SFU1204 set: https://www.ebay.com.au/itm/132406400223
Spindle mount: https://www.ebay.com.au/itm/222777650347
I’m also building a uni-strut frame which is another work in progress.