I have a 3D printer and it runs really well. I learnt a trick to zero it’s Z-axis which I’ve been applying to my Maslow I think worth sharing.
When replacing stock, or generally trying to stay accurate, I slide a sheet of paper under my sled; you should be able to wiggle it around if the bit is not hitting it. Slowly lower the bit until it bites the paper, then raise .1mm at a time till you get the wiggle back - it’s a feel thing, try it you’ll see.
Are you using a 2 foot sheet of paper? You might want to try the touch method with the electrical contact when the bit hits the metal plate for auto zero.
But I digress. Here we are using a 600cm metal rule, with a wire attached to one end. The wire goes to a battery box containing an LED. Another free wire goes to a crocodile clip that can be attached to the router.
The ruler goes under the sled, in line with the router bit. The crocodile clip is attached to some metal part of the router bit/collet. The Z-axis is run down (in small steps) until the LED lights, then backed off ever-so-slightly.
I do concur that a sheet of paper has a certain elegance.