Dual Head Offset Calibration Tool

Discussion in 'Calibration, Help, and Troubleshooting' started by Spoon Unit, Mar 31, 2016.

  1. Spoon Unit

    Spoon Unit Well-Known Member

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    I just created a tool to help with calibrating the XY offset for the BigBox, though it's equally applicable to all dual head printing.


    I recommend you use Greg's "pin" method to get things close, but for me I wanted to get this super accurate, and the pin method is prone to parallax error. Once you've used the pin method, download the base, 0.2, 0.1, and 0.05 things and, using S3D, composite first 0.2 and base using the dual extrusion wizard. Once printed, selected the best aligned blobs and then figure out from the model shown in S3D how many blobs away from what should have been aligned your aligned blobs are. Nudge your M218 settings in the tool change code in respect of your findings, and then print the 0.1 and again find the closest fit and adjust. Finally do the 0.05. At the end of the process, you should be within 50 microns of accuracy on your XY offset and your dual prints should be bang on.
     
    #1 Spoon Unit, Mar 31, 2016
    Last edited: Mar 31, 2016
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  2. Hans C.

    Hans C. Well-Known Member

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    I like it already, though I'm still waiting for my Godot--I mean my Dual. ;)
     
  3. Alex9779

    Alex9779 Moderator
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    Cool! Thanks for doing this! I thought about such a design too but this seems to be perfect! Will test is as soon as I have my current problem fixed...
     
  4. Spoon Unit

    Spoon Unit Well-Known Member

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    Just reconfigured as dual standard e3d v6, 3 prints from the calibration tool and voila. Certainly close enough for me to complete my next dual print.

    2016-04-01 15.16.10.jpg
     
  5. Sarah Nicholson

    Sarah Nicholson Well-Known Member

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    Seeing that beautifully clean dual print just makes me want my BB even more now! Thanks for sharing the calibration tool.
     
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  6. Spoon Unit

    Spoon Unit Well-Known Member

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    Incidentally, this is printed with a 0.6mm nozzle (black) and a 0.4mm nozzle (green) both printing 0.3mm layers. I did hide the seams in the photo; there are a few because I chose start positions on each layer for speed rather than pretiness. The primary purpose of the test was accuracy of XY calibration.
     
  7. Sarah Nicholson

    Sarah Nicholson Well-Known Member

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    Compared to the blobby oozy mess and painful extracting of the object from the ooze shield that a dual print on my K8400 involves, I'm still impressed :)
     
  8. R Design

    R Design Well-Known Member

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    Beautiful.

    ( Nothing wrong with that top layer ;-) )
     
  9. Spoon Unit

    Spoon Unit Well-Known Member

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    @Sarah Nicholson, can't you employ the same ram-purge technique on the K8400? It's really just a tool-change script that empties the nozzle. It's not secret BB sauce.
     
  10. Sarah Nicholson

    Sarah Nicholson Well-Known Member

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    I might give it a go, although I'd need to tweak it to work with a dual bowden setup, but I got fed up TBH of trying to do dual printing on my K8400 because ever since I had to replace one of the nozzles and the heater block it's virtually impossible to get both the nozzles level so unless the print is very small I either end up with one nozzle scraping the print or curling and lifting because it's too far from the bed :mad:

    It's a shame as I actually got some really nice dual prints out of it when I first had it, admittedly not quite as clean as these oozeless ones but not bad at all, but I've just got frustrated with the hotend design which makes it very very hard to adjust anything.
     
  11. Spoon Unit

    Spoon Unit Well-Known Member

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    Yeh, leveling things is a bit of a bitch. Mine aren't as level as I'd like them, but because they're awkward to move up and down, I've levelled the plane of the print bed with the plane of the line drawn between the bottom of the nozzles. I realise this isn't perfect, but it's workable as long as the difference isn't too massive.

    I've got no experience with Bowden setups.
     
  12. Alex9779

    Alex9779 Moderator
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    Hey @Spoon Unit I thought about this and I think it would be easier if you'd have an indicator where the squares have to match or make the whole thing centered so that in the middle of the cross the squares have to match...
    What do you think?
     
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  13. Syko_Symatic

    Syko_Symatic Well-Known Member

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    image.jpeg
    Effectively that's what the tool does. You can count how many steps out you are. The 5th square down should be centered for the Y and the middle(ish) square along the X. It has worked almost perfectly for me.
     
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  14. Alex9779

    Alex9779 Moderator
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    Ya I know how to use it but obviously I need to know or look in the slicer. It would be nice if I could use the part with most comparing it to something just count and know where the good spot is...
    Anyway leave it as it is...
     
  15. Spoon Unit

    Spoon Unit Well-Known Member

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    I knocked it up pretty quickly, and agree it could be improved by writing some stuff on it. Feel free to remix or i'll sort it out next week when I'm back home. Obvious improvements would be for it to print the offset quantity on the tool together with a number against each blob and a +/- symbol. Other input welcomed!
     
  16. Spoon Unit

    Spoon Unit Well-Known Member

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    I'm redesigning this tool today. Just showing a little progress here. The first two prints work fine, but I've realised I need another adjustment. Here's how it's shaping up:

    2016-04-10 14.24.37.jpg
     
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  17. Spoon Unit

    Spoon Unit Well-Known Member

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    Yep. This overlapping design is definitely easier than that side by side, which doesn't work well due to the mechanics of movement and the reality of a rounded nozzle.

    2016-04-10 16.19.36.jpg
     
  18. Alex9779

    Alex9779 Moderator
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    Sorry I can hit "Like" only one time!
     
  19. Spoon Unit

    Spoon Unit Well-Known Member

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    Just published this at http://www.thingiverse.com/thing:1480365. There's nothing really special in my profile for printing this, however I did notch down the printing speed to 750mm/min for all printing layers as precision is the name of the game in calibration. My prints used a 0.3mm layer height, printing with a 0.6mm left nozzle and a 0.4mm right nozzle, both standard e3d v6 nozzles. In slowing the print down, I also chose first layer height, width, and speed as 100%. No doubt you'll make your own selections in this regard. If there's a demand I'll post my profile, though you'd need to adjust it anyway for your PIDs and offset.
     
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  20. Mike Kelly

    Mike Kelly Volunteer

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    Great work!
     

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