looking for a general overview of 3d printer software and setup

I have finished assembling my 1st 3D printer, A P3Steel with Ramps 1.4/Marlin/Full Smart LCD

I am well versed in electronics and have acquired a vague understanding of the workings.but am lost of a few things.
I have not found a good clear guide to setting up a 3D printer with my firmware/software/LCD

What is "home" ?? is it when all 3 axis or against the endstops? or is it when the nozzle is at the left front corner of the printable area??
What defines the printable area? after the printer finds the endstops? is this handled in the "Marlin" software?
I have the problem with the nozzle hitting a bed adjust bolt,, I need to find out how the change how the printer goes from "at the end stops" to "on the bed" (my X end stop is way off to the left, 1" off the bed)

It appears the LCD controller has "Limited" control, as in I cant tailor everything through the LCD ?
Is there A good GUI program that I can set up every detail via the usb cable?

Seems as this is some what of a dark art, that is absorbed slowly ??

Thanks for any guidance,
Slack

Not familiar with Marlin but, Home is all axis at endstops. If there is no glass on printbed than you need to chamfer adjuster holes and use "Machine Head" screws so that they are flush with bed. Printable area is the max area that the nozzle can cover. Usually less than your bed size because of lack of heat near the edges. My 8x8 area is only good for 7x7 prints. Thats all I got.

Is the "nozzle" hitting a bed leveling screw? Generally the bed leveling screws are outside of the printing area and they are usually not inside of the actual heated bed (print zone) area. If they are inside your print area currently, then you need to adjust your limit switches and possibly your settings in Marin so that home and the printable area does not include the leveling screws. With some non-standard (unique, non-common) parts this may mean a smaller than planned (200x200) print area. Have you gone through a calibration procedure? I hope this makes sense and good luck!

"What is "home" ?? is it when all 3 axis or against the endstops? or is it when the nozzle is at the left front corner of the printable area??"

Home is the coordinate generated by each axis hitting it's endstop. So if you have your x axis endstop at the minimum position (left) and you home, then the coordinate x=0 is at this position. If the endstop is at the maximum position (right) , the firmware/Marlin in this case takes the printable area or "travel limits" you defined in the configuration.h and works it out. I..e if your x-max endstop is hit and you have defined x as 0-200 then 200mm left of the max endstop is the x=0 point. Since you calibrated the printer so that a set number of stepper motor steps=1mm of movement it can always know where it is once it has defined a starting point or homed (as long as the motor does not skip steps - look this one up).

Most schemes in order to make some sense out of it all have 0,0,0 as the front left position of the print bed with the nozzle 0.1mm above the bed (the paper test - plenty on this on line).

The other parameter in there is "define min software endstops" and "define max software endstops" if both of these are enabled then the nozzle won't be allowed to move outside of this range. Older marlin versions used "define x-min software endstop" and "define y-min software endstop" etc.. but it does the same thing.

However, and this might be of use to you in your situation, you can define "manual home positions" which helps if your printable area is within your print head's actual physical range of movement. So on my corexy my print bed is 7mm right of the x min endstop (left) and 30mm behind the y min endstop (front). So I set manual x home position -7, manual y home position -30. And travel limits to 0-185 for x, 0-185 for y, and 0-170 for z - measure these with a ruler on your printer, from the nozzle. Now when I home x and y it hits the endstops but my 0,0 point is +7,+30 from that position and once I move within the printable area it remains within it as my software endstops are set to enabled.

"It appears the LCD controller has "Limited" control, as in I cant tailor everything through the LCD ?
Is there A good GUI program that I can set up every detail via the usb cable?"

You can change quite a lot of stuff but LCD's are almost always used once a printer is working really well and you are just running off object after object and not tweaking much. Pronterface is the easiest to use IMO, repetier host is popular but a bit less intuitive again IMO, you can use Octoprint running off a Rasberry Pi if you don't want a PC in there.

Make sure you have "eeprom_chitchat" / "enable eeprom" settings in configuration.h so that you can save values to the eeprom which does not get erased when you power off. Do this by sending m500 to save after changing something successfully. But make sure to go back to your configuration.h and change the value or next time you flash a firmware it will be reset. You can display the data in eeprom by sending m503.

Tweaking your printer's performance is a combination of using the lcd a little, the host program such as pronterface a lot, and eeprom to save, and occasionally altering configuration.h and configuration_adv.h and re-flashing your firmware.

"Seems as this is some what of a dark art, that is absorbed slowly ??"

It is but once you know how it works its second nature. N00b to reasonably competant in 9 months should be doable if you put the hours in and ask questions.

Edited 1 time(s). Last edit at 04/25/2016 11:42AM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

DJ,
Thanks for taking the time to respond, I have been any from small computers for many years (RCA 1802)
I am starting to grasp the layers of control over these small 3D printers (Ramps/Marlin)

My particular P3Steel has its X carriage end stop about 3/4" off the left side of the bed (by design, cant really move it)
The Y end stop does not have adjustment and puts the front edge of the bed about 1/2" behind the printer.
So the problem is when the printer goes from "Home" to the print bed, it collides with the front left bed leveling bolt.
[www.youtube.com]

I thinking the easiest way to fix it is, add adjustment to the y axis and move "home" for the y axis forward about 1/2"?
This kit came with all software pre loaded and configured, so when I choose "bed leveling" in the LCD menu, it finds all the correct corners of the print area.
If I change the y stop, I will need to change a variable in the firmware to let the system know the print area (Y axis) in relation to the y end stop?

Question, these menus and rutienes on the LCD, are they in the LCD hardware? or are they in the Marlin firmware and the LCD is just accessing them ?

Many thanks for the help,
Nick

Ah I see your problem.

One solution would be to remove the levelling screw, countersink the aluminium plate and use a countersunk bolt. These are recommended for this purpose, for the very reason that you don't want to hit them.

As you said, you could physically move x or y or both endstops which would change the trajectory between the home position and the bed, or so that the endstop position was inside the print area and beyond the bolt so it actually homes at 0,0 on the print bed, but this would require you to alter the values needed to perform autolevelling, you would have to change your autolevel grid values in marlin and possibly your travel limits/software endstops too. This isn't that difficult but it is something that's easier to puzzle out when your familiarity with the config and printer is greater. If you have the configuration.h attach it to post here and Ill take a look at how they have it setup.

Another idea would be to add a command to your start gcode to raise the head 5mm before sending g28. So you would add g1 z5 f1000 before g28. This should lift the head above the bolt, send it to x and y endstops (without changing z position) then move the the bed centre and find its z home position. You might need more than 5mm have a play around. Take your nozzle off when experimenting - no use bashing the hell out it.

You can, oddly, move an axis away from its endstop before homing but not towards it, assuming you have endstops at one end of an axis only, the logic of this is beyond me, it would make more sense to only allow movement towards an endstop, or require all printers to have hardware endstops at both ends of an axis so movement would be unrestricted before homing - you'd hit an endstop at some point and the risk of crashing an axis into its physical travel limits would be zero. We have one endstop setups on most printers presumably to save money and complexity. I might ask on Marlin Github why this is, unless anyone here knows offhand?

If printing the lift head code always gets executed automatically, but you would have to remember to do this lift head move manually before homing if controlling the printer from a host such as pronteface, but you can create a custom button with the code which you would press first then hit home. This is a workaround not a solution.

The LCD is a dumb unit on ramps/marlin setup's so its the firmware you are interacting with, if you change the firmware the LCD automatically has the corrected values.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

I ordered 4 countersunk "Metric socket flat head" machine screws, I will countersink the heatbed and swap them out, quickest solution till I come upto speed with firmware end.

My MK3 heat bed was not heating up, it only has .4 ohm across the 12v hookup, new heatbed and mosfet on the way.

Nick

Quote
Slackdaddy
My MK3 heat bed was not heating up, it only has .4 ohm across the 12v hookup

The smaller the resistance, the quicker it heats up ... and measuring such small resistances with cheapo meters is tricky. Measure both pins directly in touch first, then add that to the measured resistance of the board.

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