What are the steps per mm set for on your Z motor as well as your other motors? Also the only hard limits you should set are the MAX so it won't exceed the bed or travel distance. Let the endstops control the MIN. You also need them connected and properly configured to print.

I've tried both 2560 and 4000 for the steps value via the M92 command, current values as set by M92 and soon to be by firmware defaults:
#define DEFAULT_AXIS_STEPS_PER_UNIT   { 200, 200, 4000, 500 }

I'll kill the MINs.  It was recommend here and there for DaVinci 1.0 Frankenstein machines but not in all places.  I have to tweak the max's anyway and the X/Y steps.

Could this also be caused by the extrusion steps?  e.g. it's overexturding?  Attached a pic for reference

Ok I've tinkered and searched to no avail and I'm sure I'm missing something obvious.

I've built a Frankenvinci using a RAMPS 1.6 board and respective Arduino controller (and a custom built board for endstops and extruder cooling but I digress).  What I'm having an absolute fit is with the Z movement and positioning.  I have this configured for Min/Max.

// The size of the print bed
#define X_BED_SIZE 237
#define Y_BED_SIZE 217

// Travel limits (mm) after homing, corresponding to endstop positions.
#define X_MIN_POS -12
#define Y_MIN_POS -12
#define Z_MIN_POS -2
#define X_MAX_POS X_BED_SIZE
#define Y_MAX_POS Y_BED_SIZE
#define Z_MAX_POS 200

My issue is all of my layers are being squished together and making a blob vaguely resembling a cube (20X20X20 test cube).  As best as I can tell setting M92 Z to either 2560 or 4000 seems to make no difference.

What are the steps per mm set for on your Z motor as well as your other motors? Also the only hard limits you should set are the MAX so it won't exceed the bed or travel distance. Let the endstops control the MIN. You also need them connected and properly configured to print.

I've built a Frankenvinci using a RAMPS 1.6 board and respective Arduino controller (and a custom built board for endstops and extruder cooling but I digress).  What I'm having an absolute fit is with the Z movement and positioning.  I have this configured for Min/Max.

// The size of the print bed
#define X_BED_SIZE 237
#define Y_BED_SIZE 217

// Travel limits (mm) after homing, corresponding to endstop positions.
#define X_MIN_POS -12
#define Y_MIN_POS -12
#define Z_MIN_POS -2
#define X_MAX_POS X_BED_SIZE
#define Y_MAX_POS Y_BED_SIZE
#define Z_MAX_POS 200

My issue is all of my layers are being squished together and making a blob vaguely resembling a cube (20X20X20 test cube).  As best as I can tell setting M92 Z to either 2560 or 4000 seems to make no difference.