Guinea Pigs Required!

Discussion in 'Calibration, Help, and Troubleshooting' started by Greg Holloway, Mar 10, 2016.

  1. PsyVision

    PsyVision Moderator
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    What layer inconsistencies? Not that I'm claiming there aren't any, but interested to understand what aspects, blobs/zits, alignment etc?

    The original experimental profile didn't use z-lift and my resultant prints are comparable except that I'd say my most recent black and red cone doesn't have the scars from my change to the retraction settings (it's better).

    I don't get any oozing at all using the technique in the profile.

    Once I've re-calibrated my offsets/hotend levels then I think the profile (for me..!) is perfect.
     
  2. Spoon Unit

    Spoon Unit Well-Known Member

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    I did see your cone Richard and I thought it looked really superb, hard to fault. There's a difference with Rob's print though, so maybe that's calibration somewhere. That said, printing the dual benchy and the dual cone are quite different propositions.
     
  3. PsyVision

    PsyVision Moderator
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    I wonder if filament itself (and temp) has an effect. I find the E3D Everyday PLA less viscous at 190 then the ColorFabb PLA/PHA for instance. The red I have can be quite oozy.
     
  4. Rob Heinzonly

    Rob Heinzonly Well-Known Member

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    @Greg Holloway: Do you mean this section ?

    ;prime new extruder
    {IF NEWTOOL=0}T0
    {IF NEWTOOL=1}T1,G1 F200,G1 E15 F200,G1 F50,G1 E5 F50,G1 E-1.5 F3000
     
  5. Greg Holloway

    Greg Holloway Administrator
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    @Spoon Unit The Z-Hop is only a test to see how everyone gets on with it. The idea is to help reduce any possible scraping of the extra nozzle on a print if they aren't perfectly aligned. If you have a well levelled machine you can turn off the feature.
     
  6. Greg Holloway

    Greg Holloway Administrator
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    @Rob Heinzonly its an option in S3D under the advanced tab for tool change extra restart distance.
     
  7. Rob Heinzonly

    Rob Heinzonly Well-Known Member

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  8. Paul Seccombe

    Paul Seccombe Well-Known Member

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    Oooh - can we play "guess the news"?
    For those of us not fortunate enough to get to the RepRap Festival, can I assume you will share the news with the original Kickstarter backers or even this whole forum?
     
  9. Spoon Unit

    Spoon Unit Well-Known Member

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    Couldn't resist some dual prints while I was working today to try to really nail the numbers for X and Y diff

    [​IMG]

    Having got that sorted I decided to be really adventurous (yes, even more adventurous than mixing those two colours!)

    [​IMG]

    What an absolute bitch to print. I really recommend you don't try this unless you're going to be able to check on it regularly. The print, combined with the tool change code completely swamps the dump box and it gets messy. Hence you see that I've removed the box here and put a larger cardboard box in underneath. @Greg Holloway you might want to try this just to see how the dump box handles this much purging. The filament sort of stands up, stays right under the extruder when it returns and looks like it could create a real mess. Perhaps the box could actually fill much more of the distance to the back of the BB to allow the filament to fall and go somewhere. Also, once I moved the box out the way, I noticed on more than one occasion the purged heavy filament hit the wiper and fell all the way to the cardboard box, something that didn't happen before, so it feels like you'd want a deeper dump box for this print to be unmanaged.

    There's obvious visible issues with this print, but I'm showing it's best side, so here's the other side:

    [​IMG]

    There's a lot that's gone well here but it's just struggled with the places where it only needs to add a very small dob of filament in one area. By the way, this print was all with zero lift on retraction. Much of the layering is really smooth:

    [​IMG]

    It's given me a good bit of knowledge to watch this build. I'd really think twice now before designing something for dual color printing as you really don't want super small layers. The other noticeable thing was the point where the primed nozzle first gets to the model and restarts:

    Even with an extra restart distance of -0.1 to try to combat it, the small amount that has oozed down the nozzle seems to splurge when it hts. Some of the effect of that is combatted by inside-out outlining, but on the thin area there's no winning and you get those blobs.

    I used this cooling strategy:

    [​IMG]

    I didn't use the extruder steps per mm part of the tool change code, instead tuning the flow per nozzle via the LCD (probably something I could do with GCODE). I did use PID tuning per hotend, but I think that was some flaw in my thinking on that, and I noticed the second extruder go dangerously close to a thermal overrun a couple of times, but it never did.
     
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  10. Rob Heinzonly

    Rob Heinzonly Well-Known Member

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    Allmost there.... Yesterday evening I printed the upper half of the Benchy. And I agree with Spoon Unit it is indeed a bitch to print. I changed the Tool Change extra restart distance from 0.5 mm to -0.3 and lowered the extraction temperature from 220°C to 210°C.

    [​IMG]

    Benchy looks much better now, still not perfect, but better. I may need to lower the restart distance in order to completely get rid of the occasional blobs. All and all this print left me with a huge amount of purged filament.

    [​IMG]
     
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  11. PsyVision

    PsyVision Moderator
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    I've not tried any dual prints recently so I'm a bit behind (working on NinjaFlex at the moment) but have you guys tried adjust the purge script to push less filament through too? The amount of tool changes in things like the benchy and the cool dual colour frog along with the amount of purge waste puts me off a bit.
     
  12. Spoon Unit

    Spoon Unit Well-Known Member

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    Psy, I think wastage goes hand in hand with dual color printing at size. For small models like the Benchy I wonder if we wouldn't be better of simply using an ooze shield, as the second nozzle is never over a part long enough to dribble much, particularly if we catch ink on a shield. I've never tried a shield before, but it does look like the way to go for Benchy. For larger models though, which is what's enabled by the BB after all, an ooze shield will become pointless about a second after the hot spare nozzle crosses the shield.

    Playing with the purge script is an area of interest, but in the absence of any knowledge about why and how it works (I have guessed, but we're still in the dark for now), I suspect that the purge is already tuned by e3d to do its job.

    Rob, the extra restart distance looks to have helped a lot. Looks like you also moved the dump bucket out of the way?

    Finally, I also created a timelapse of the dual Benchy but I think it's probably too sped up to be of any use for analysis, and I think the Pi camera is not really focussed properly. On that score I wonder if anyone has already tried this? - http://www.thingiverse.com/thing:211641
     
  13. Rob Heinzonly

    Rob Heinzonly Well-Known Member

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    @PsyVision Lowering the amount of filament to purge is indeed on my to do list, but only after I know what the psychics are about script.I guess I have to wait till the exhibition in the US.
     
  14. Greg Holloway

    Greg Holloway Administrator
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    Be careful when changing the numbers, things might stop doing what they are supposed to do!

    On the dump issue, if you are doing fancy dual prints take the bucket off, or better still design a new one which takes up the full height available under the bucket. I have been working on an updated wiper that doesn't collect stuck filament. More at the weekend :p
     
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  15. Rob Heinzonly

    Rob Heinzonly Well-Known Member

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    @Spoon Unit The dump bucket is hanging a little bit loose here, I tried to remove it during the print, but the fit was too tight.
     
    #55 Rob Heinzonly, Mar 15, 2016
    Last edited: Mar 15, 2016
  16. Spoon Unit

    Spoon Unit Well-Known Member

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    @Rob Heinzonly the original mount bracket for the dump bucket is too tight. You could always print yourself a less tight fitting design. I already cleared the release of this part with Greg as it's not actually an original part, though it's directly based on STP files used to cut the acrylic.

     
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  17. Alex9779

    Alex9779 Moderator
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    I am doing a few test prints on cold bed in the meantime but I have some concerns about the tool change script.
    I'd propose to make it a bit more failsafe regarding the dock/undock sequences.

    @Greg Holloway is it under an NDA too why the dock sequence at the start does check for NEWTOOL=1 but then uses T0 to dock and vice versa? The other sequences always use the tool they check for...

    IMHO it would be better to do the docking/undocking always with T0 coordinates. That way you are independent from the tool offset set correctly and can position much more exactly. It happened to me a lot of time now crashing the head into the back because of missing tool offset, then I put the offset in the firmware but forgot to change the script that the new X base value is now in the firmware (X=34mm Y=0mm) so that I only have to enter the small correction value calculated with the firmware values as a base.

    I would prefer that because I realised that in a normal print situation you start a print while being at home position. Then the extruder heats up first because S3D does this always first.
    (That could be a feature request to be able to have a script run before everything S3D does generate.)
    The heating up normally generates some ooze.
    Then the head moves back to the ooze bucket leaving the finial ooze at the front of the rubber.
    The extruder is primed and then undocks again at the same position it docked leaving the priming ooze at the back of the rubber but may pick up the initial ooze from the front.

    I see there problems on my tests because of the distance to the bed at the start. That picked up ooze may be dragged with the head, come to the heater or all block and make the nozzle dirty. Sometimes it curled up and got into/under the IR sensor...

    With more exact position we could make the X value when docking different of X when undocking and prevent the problems at the start I described above.
     
  18. Greg Holloway

    Greg Holloway Administrator
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    @Alex9779 The important part of the script is the purge, the rest of it is simply retraction, prime and dock. You can change as you please!

    The order of this is as we developed it. It obviously needs fine tuning and optimising.
     
  19. Alex9779

    Alex9779 Moderator
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    Ok cool... I didn't wanna mess up with things which look simple but I may not fully understand...
     
  20. Spoon Unit

    Spoon Unit Well-Known Member

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    I also wonder about potentially some sort of brush instead of solid rubber as a wipe, though I can see problems with the idea too. Right now it's hard to get the rubber in the perfect spot where it won't also catch the IR Sensor mount and yet still wipe the nozzle. At the back, some sort of screw system to raise and lower the bucket/wiper entity would allow fine tuning that's currently really hard due to the screws and the position of yourself in relation to the nozzle while fiddling.
     

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