Setting up UBL for the first time on Marlin 2.x on a Prusa i3, how often should I level the bed using G29?

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I used to use the Marlin 1.x software that would level the bed by probing the 4 corners of my print bed (a long time ago, it's been at least 2 years since I used my printer, wasn't able to set it up after I moved).

My slicer had G-code that would kick off a level at the beginning of every print.

I've upgraded to Marlin 2.x and now I'm setting up UBL. It takes quite a bit of time to probe the bed with UBL, like 10 minutes. The steps tell me to save to EEPROM and my firmware is set up to restore after every G28 (Home).

How often should I do a G29 (Bed Leveling)? Should I do it every print? Every 10 prints? 100 Prints? Or when I see that the print isn't sticking to the bed?

EDIT: I went from a Grid-style ABL to UBL because UBL merges the benefits of a few different leveling techniques so theoretically it should be better. I understand I could just go back to grid-style bed leveling but even when it was working, for some reason the z-offset would shift ever so slightly every few prints and I would have to change configure it in my slicer. I'd like to try UBL and see if I can leave my printer for a while without having to fidget with the Z-offset.

PGT

Posted 2019-11-20T01:12:37.963

Reputation: 171

I dont know about UBL, or how long it takes to complete, however if it doesnt take a long time and doesnt requre manual intervention, may as well run it at the beginning of every print. Otherwise just use it when you see problems? – craftxbox – 2019-11-20T04:16:32.503

It takes quite a bit of time, like 10 minutes. With the grid leveling, it was something like 30 seconds, so I did it before every print – PGT – 2019-11-20T04:16:53.683

In that case, just run it any time you change something on the bed or start seeing issues. Going to wait to let someone else post an answer that's more knowledgable here. – craftxbox – 2019-11-20T04:18:32.460

I wonder what made you decide to go from an ABL (Automatic Bed Levelling) sequence (taking 30 seconds before every print) to a UBL (Unified Bed Leveling) that requires 10 minutes of work once in a while? Could you explain that in the question? – 0scar – 2019-11-20T05:57:40.467

@0scar: never really had a setup I was happy with when using a grid-style ABL. The Z-offset would shift over time and I'd have to reflash the firmware or control it in my slicer. I haven't used my printer for a few years so I figured now is the best time to re-configure and use the newest tech. Updated question to include this information. – PGT – 2019-11-20T07:00:46.690

A shifting Z-offset over time (few seconds to fix) would be less work than a 10 minute UBL leveling session! ;-) What makes your Z-offset shift should be addressed, else you will still have the same issue with UBL? – 0scar – 2019-11-20T10:48:39.833

Answers

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This is more of a personal preference type question rather than something with a hard and fast rule.

You should not need to relevel your bed very often unless you have some external force that regularly changes the bed level.

I regularly print objects that take 24+ hours to print, so a 10 minute process prior is not much so it might be worth it to set it up every time if your prints run very long. If you mostly print smaller or quicker to print objects, 10 minutes might matter to you.

I have noticed that my prints fail pretty quickly if I have a leveling issue, and it's not hard to stop the print, clean the plate and relevel at that time.

What should you do?

If 10 minutes doesn't matter that much, go ahead and relevel with every print. If it matters, wait until you start to have issues. See how long it takes for your bed to become unleveled and use that as a guide. E.g. if you can print 10 times before having issues, then try setting it for every 6 or 7 prints.

Verl Humpherys

Posted 2019-11-20T01:12:37.963

Reputation: 91