hi, i was looking for something like this. do you happen to have the drawing so i can reproduce it? thanks
So I ended up bailing on this particular upgrade. I wasn’t confident that it was going to be worth the effort, especially since it was kind of a sketchy design to begin with.
Since then I did a bunch of upgrades and made a video about it here:
I have been cutting aluminum very reliably since then. The one time I started to see things degrade, all I needed to do was tighten the router clamps…I guess there was some creep in the petg-cf over time.
I know linear rails are kind of blasphemous here 
, but they seemed like a worthy upgrade at the end (with the extra extrusion).
As noted in some comments here, the z-backlash mod may not have been actually relevant. Yes there is backlash, but it’s not super relevant to this kind of short milling. I later found out that the bit I was using on aluminum had some friction welded aluminum on the tip, preventing it from drilling or digging reliably. After switching bits, most of my z-problems went away. It’s still nice to get rid of the backlash but not sure how much it helps the common use case.
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Your video is what sparked my interest in building my MPCNC. Thank you for that.
It is helpful to hear that the z-backlash mod was not as relevant. I had planned on implementing it and even ordered extra lead screw and nut from Ryan. In the end I built it stock and have just kept them as spares. I have not noticed issues but I am working with wood not aluminum.
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The weight of the router should remove the backlash in Z.
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It doesn’t if you have some aluminum friction-welded to the tip of your endmill . I still ponder how it worked at all. It would still drill, but with a ton of effort and noise, and I guess it would eat up the backlash while it attempted to do so. That’s why I thought it was a problem – Whenever I tried to contour cut something, I had to make toolpaths at least 0.5mm deeper to get through it.
Related: I have now been through a few different endmills from Amazon, and both “Yonico” brand bits I have (1/4", single-flute carbide), get friction-welded aluminum stuck to them immediately. The similar SpeTool, bits have been wonderful . Two of them has like 20 hours milling only aluminum at my feeds and speeds with no lubricant (~22k RPM @ 600mm/min, 0.4mm DOC for contouring, 4mm DOC for adaptive/trochoidal @ 0.6mm stepover).
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