Update 1/9/2018 Problem persists was printing perfect at 1.5 for last 2 days then started printing to high had to bump to 1.7 not sure i checked everything from probe to lead screws nothing seams to move and is tight. if wasnt for this one issue i could hit print and walk away when it stays every print is spot on then just changes.

just finished my scratch built printer and finally got marlin working and printing better then i hoped it would almost perfect only one issue left is with the z auto home probe offset i have followed the instructions for setting the z offset brought to 0.0 then temp removed the soft stop and moved the print head down till just snagging a sheet of paper and did a test print and the z was a little high i had to add a additional -.5.. then it was spot on and printing right on but after 5 prints its now every time squashed a little to close so i raised it again and after a few prints its too high again. the auto leveling is working as can see the z leads moving as prints. anyone else had this issue can point me to what might be the cause?

Edit: forgot info XD Marlin latest 1.1.7 main board RamBo 1.3 non mini.

home z with the probe being usually a ziptie thickness higher then hotend tip. if use marlin firmware m211 s0 to disable soft stop and m211 s1 to turn back on when finished. this is the software stop protection to ensure you do not go below z 0.0 then use your display knob to move z down 0.1 at a time till you just grab a standard office paper look at display and check z (EX:-0.5) that is how much you set z offset for you can do that with (m851 z[your offset amount] + thickness of paper for office standard usually 0.1 so if was -0.5 your z offset is 0.6 (Ex: m851 z-0.6) then a m500 to save to eprom m501 to load eprom and reset do a test print if its to close or to far adjust by 0.1 (Ex:m851 z-0.8) then save reload

if using a different firmware im sure it has a similar no -z protection that needs to be temp disabled.

my opinion would be either the ultimaker or the LULZbot Taz 6. as they are more wide spread and alot of info is out there. the taz is open source so you can print spare parts (handy if it will be a work horse) taz dosn't come with a enclosure but when was looking at this one myself i remember seeing lots of simple build enclosures on youtube with plexy and framing.

Edit: Ok spent few hrs digging in info these are the correct setting

Set board #define MOTHERBOARD BOARD_RAMBO

with just this change i got an error

exit status 1

'DIGIPOT_MOTOR_CURRENT' was not declared in this scope

after searching for DIGIPOT in marlin i found in configuration_adv.h (#define DIGIPOT_MOTOR_CURRENT { 135,135,135,135,135 } // Values 0-255 (RAMBO 135 = ~0.75A, 185 = ~1A))

after this the test compile goes without any errors dose anyone know if this is correct? i did not find any info on this error so this was just a guess on my part can anyone confirm this is correct?

in your marlin code is (#define min_software_endstops false) set to true? its above bed leveling section so cant see.

ok right off the bat lets check extrusion caliper or decent ruler manually heat up hotend to current filament temperature then remove the bowden tube pull slowly the tip of filament will be multon. next cut the filament off flush to the end of tube.

with hotend still at temp you should be able to use manual control and extrude a given length. extrude 100m then measure you should have a 100m length of filament stick out the end of the bowden tube let know if under or over and by how much.

if havent altered any settings it should be very close but its one of easy items to check.

finding filament debris is a good sign well in that we can see a cause the extruder grinding threw the filament. as for the z height it is set when the printer z homes and touches the endstop switch giving it Z 0 POS a sheep of standard print paper is best to set the bed to hot end distance.

home printer usual front left corner, this sets it to 0 then adjust bed corner till it is just close enough to add a little friction to the paper sliding under then move hodent to other 4 and repeat adjusting bed till its same height.

(edit)Found this step by step for your ulti 2

thats right forgot about that tho its not using any gui or output like hdmi wander if any info on amp draw when its running in console only mode.... (just looked up ok this isnt going to work tho a pi uses little amps when not running a full gui the usb ports with a wifi dongle will.)

ok looks like a change of plans ill do direct to 12v from psu and use a voltage regulator to step down to 5v.

but to be sure ill have to test the draw and see what the pie is actually using at full tilt printing with Repetier-Server if its 800 or less should be ok to power the pie.

thanks for schematic not sure how i missed that.

will update with what i find out.

(Update: Well that didn't take long to figure out MX1 VCC and GND tho is 5v the rambo won't be able to supply the power so will have to use a voltage regulator just so happens i checked my parts draw and i have a few DC-DC Buck Converters bought a 10 pack on sale some time ago and forgot about them )