Build plate height map

Discussion in 'BigBox General Chat' started by Alex9779, Nov 25, 2016.

  1. Alex9779

    Alex9779 Moderator
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    Oh BTW this is a height map of my print bed after some adjustment... (A lot of adjustment)
    Created with the grid bed compensation feature of RRF beta featuring BLTouch and Excel:
    PrintBedHeightMap1.PNG
     
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  2. dc42

    dc42 Well-Known Member

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    Alex, could you share that spreadsheet?

    Btw you can have up to 441 grid points using the Duet WiFi, so you could do a higher resolution height map if you want. Let me know if you want that number increased, we still have plenty of RAM left.
     
  3. Alex9779

    Alex9779 Moderator
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    Sure but there is a little work to do to get that result. The work in Excel is pretty simple.
    For me a little more because in Germany we use , instead of . to separate decimal numbers.

    First I create a sheet and add the X values from the grid to columns starting from B1. I entered 5, in C1 25 and then pulled them up until the end of the grid.
    Same for Y starting at A2 downwards.
    The I open the heightmap.csv in the WebIF and copy the lines Notpad++, I change every , to ; and then every . to ,
    Then I copy the whole content, paste it to Excel in cell B2, open the paste option and select to use the text importer for the pasted content. I select ; as separator and then I have each value in a cell.
    Selecting everything and adding a 3D plane diagram and you got the result.

    If you would use a semi-colon to seperate the value then you won't have to do the replacement in Notepad before inserting to Excel.
     
  4. dc42

    dc42 Well-Known Member

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    I thought CSV meant comma-separated-variables. I can easily change it to use semicolons, but would that prevent any other programs from being able to import it?
     
  5. Alex9779

    Alex9779 Moderator
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    No idea. Also this may be a location based behaviour. My Excel 2010 doesn't let me choose the import wizard when I paste the comma separated values. That option is only available when I have semi-colons...
     
  6. Alex9779

    Alex9779 Moderator
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    Here is the file....
     

    Attached Files:

  7. dc42

    dc42 Well-Known Member

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    I am just wondering whether Excel lets you set the language of the document, the way that Word did when I used it several years ago? I don't use M$ Office so I can't check this.
     
  8. Pipshag

    Pipshag Active Member

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    For Marlin users, there is Marlin3DPrinterTool which allows you to scan the bed using the IR Sensor. Configurable number of measurement points, in the screenshot it's 2 x 2.

    Also has a guide for adjusting the screws on the bed to get it as leveled as possible before doing MBL or ABL.

    Marlin3DPrinterTool@github

    [​IMG]
     
  9. dc42

    dc42 Well-Known Member

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    Looks nice! We're planning to add visualisation of the bed height map to the Duet's web interface, so we'll include that as a possible visual design for it.
     
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  10. Jasons_BigBox

    Jasons_BigBox Well-Known Member

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    Hi Alex,

    I've had similar problems with delimited files before. On older versions Excel would ask which character delimits the file but the new one doesn't for some reason.

    Looking about on the web, if you go to the 'Data' tab then select 'From Text' you should be able to select the semi-colon as the delimiter. I realise you may well be working in German but on my Excel, it's the third icon in the 'Get external data' panel.

    If it's still being a pain, post a .csv file and I'll see what I can do with it.
     
  11. Alex9779

    Alex9779 Moderator
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    It's ok for now... I think we should not deal with that excel crap. I just wrote up what I did to get the height map.
    I won't do it very often, I just wanted to have a quick overview and Excel was the only tool available to get it quick...
     
  12. Jasons_BigBox

    Jasons_BigBox Well-Known Member

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    Ok, if you get stuck, give me a shout. I used to work on Excel macros a lot including automating import and export of text files.
     
  13. dc42

    dc42 Well-Known Member

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    Coming soon to a web interface near you:

    upload_2016-12-19_19-25-7.png
     
  14. Alex9779

    Alex9779 Moderator
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    Cool... pretty much done with my 100th motor carriage replacement to get the BB printing again...
     
  15. Miasmictruth

    Miasmictruth Well-Known Member

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    Slightly off topic once you have your map, how do you calibrate your nozzle to the map data? (I haven't done the duet upgrade yet but I want to in the nearish future)
     
    #15 Miasmictruth, Jan 4, 2017
    Last edited: Jan 4, 2017
  16. dc42

    dc42 Well-Known Member

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    The corrections from the height map are applied automatically after you run G29 to generate it. If you don't want to repeat the probing every time you turn the printer on, you can load the height map from file using G29 S1. See https://duet3d.com/wiki/Using_mesh_bed_compensation for more.

    Of course, if your height map indicates that the bed is a long way from being level, you should level it mechanically and then probe again.
     
  17. Miasmictruth

    Miasmictruth Well-Known Member

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    Thanks! You answered a question I didn't think to ask lol but very good info. I see now that the M558 command you set the offset between the probe and the nozzle. I typically never rerun manual mesh bed leveling unless there is some sort of issue, is there any particular advantage to allowing it relevel every time? How long does your 42 point mesh take?

    One last side question, considering how accurate this system is, have you given any thought about automatically generating the z offset between the nozzle and the probe with some sort to touch pad to eliminate almost all human error? I was thinking some sort of touch or capacitive sensor where you could touch off the nozzle and the probe to calculated Z? (sorry for my ramblings lol)


    (EDIT) After reading through the wiki a couple times I am curious, during the probing does the nozzle tip touch the bed?

    This line (4. Command the print head down in small steps until the nozzle just touches the bed or just grips a sheet of paper)

    I had imagined that you would set a z offset between the probe and the nozzle of a mm or 2, so that when you probe do don't have to worry about the nozzle catching high spots. Or am I missing something? Also that you would probe the same spot that you would lower the nozzle to, in order to eliminate any unevenness in the bed when setting the offsets.
     
    #17 Miasmictruth, Jan 5, 2017
    Last edited: Jan 5, 2017
  18. Kanedias

    Kanedias Well-Known Member

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    Its not clear which screws its referring to - The standoffs are just threaded at both ends so how can you vary them?
     
  19. dc42

    dc42 Well-Known Member

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    - It's actually the G31 command where you set the probe offsets from the head reference point (which in a single-nozzle printer is the nozzle).

    - If your printer is stable and you don't remove/replace the bed between prints, then you should not need to run mesh levelling very often.

    - Yes it would be possible to devise a system to measure the Z probe trigger height. But if you are looking for a calibration-free system, it's probably simpler to use a nozzle-contact type of Z probe, for which the trigger height is small (around -0.1mm) and reproducible for a given bed material.

    - If you are using a contactless probe such as the IR sensor, then the nozzle doesn't touch the bed during probing.

    HTH David
     
  20. Miasmictruth

    Miasmictruth Well-Known Member

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    Thanks for the reply, been running the Duet wifi with the BLTouch now for a month or so. I haven't remeshed since the initial configuration and its been solid :) love the Duet, I am addicted now lol.
     

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