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  1. #141
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    Just for fun, I thought I would print a Marvin and put all the nuggets of wisdom I've learned on this forum since my last dismal failure (http://www.print3dforum.com/showthre...ll=1#post43910).

    This time it came out pretty good!

    IMG_5317.JPG

    IMG_5318.JPG

    What I did differently:
    - used the Cube 3 slicer. Before I used the Ekocycle slicer and got a pretty clean loop, but the Cube 3 slicer with PLA and ABS were terrible.
    - added a cooling post/tower. That's what made the loop work this time. The Cube 3 slicer didn't do badly after all.
    - used a different filament = MatterHackers PLA.
    - changed the M227 P450 S450 G450 F600 to M227 P400 S400 G450 F600, because I'm using a B2B bowden setup which is less stretchy than the stock one. I don't think this made any difference in the Marvin, but it did result in some very fine stringing between the cooling post and the Marvin. My conclusion is that the normal retraction amount (P450 S450) is probably ok.

    =================
    My take on the M227 command is this:
    Pxxx is the retract distance
    Sxxx is the prime distance
    Gxxx is the retract speed
    Fxxx is the prime speed

    The P & S could be the reverse, ie P is prime and S is retract -- that would take some experimentation to determine. But they are always the same value, so who cares? ;o)

    Ditto for G & F - could be the reverse. F is always higher than G -- would you want to retract fast and prime slower, or vice versa?

    I'm mentioning this because I've been tinkering with these values, related to modding the bowden tube.
    Last edited by JohnTee; 12-18-2018 at 06:09 AM.

  2. #142
    3D Printer God(dess)
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    Go wilder... I dropped down to 225 225 for the MakeShaper filament. Fixed it! Ekocycle kicks out 375 IIRC. So something in the 300 range should work nicely. That blob on the cooling tower there, that's your canary.

    But yes, excellent Marvin! Is his butt drooping? That was the hardest thing to manage.

    Here's what is at issue, John. If you see what retract really does in the nozzle, you would understand immediately why it drools. The melt remains in the tip, it just has the pressure release because a section above the melt is stretch thin... in the neighborbood of 1-1.2mm thin. So nothing really retracted according the business end, it just wasn't pushing for a brief moment. Then the problem comes in. That stretched piece of filament has zero control of actual pressure and it not has to purge the air through whatever vent it find (same place it came from), so you have pressure differentials within the tube at the very end that you are also fighting. This was my foray into the "...why MakeShaper filement wouldn't print" episode. The motion was too violent and the filament temp was too high. Made an air-entrained mess!

    Dialing in temperatures is less fun. Every filement will behave slightly different. But 3DS really spikes on their own filament. That 235*C for the start of PLA is darn hot for PLA.

    Oh, keep an eye on your fan with all that stringing. I saw that was a PETG anomaly. It likes the intake in the black housing on the left side. Just wipe it every so often.
    Come to think of it, stringing is one way to dial in temps. Do you watch CNC Kitchen? Some crazy stuff!

  3. #143
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    I finally learned how to make macro's in Notepad++.

    Now there's one to modify the print temps and another to change the M227 retract/prime values.

    This cuts the print file creation time down to only 10 simple steps!

  4. #144
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    You're also doing the M228's right?

    - - - - - - - - - -

    I did a lot of checking in M$ Excel.
    Sometimes you have M22n P/S450's but sometimes P/S 400 sneaks in there.
    They're easy to overlook.

    I was going to say that the config files have all 4 of these values defined. I need to look again.
    I'm pretty sure you are correct. I've played with them to see what happens.
    All I know is that the last 2 values tend to change the behavior when the print commences after the retract/purge.

    - - - - - - - - - -

    HA! 3D Hubs inactivated my account and trashed all my data! I submitted a 'perfect' Marvin in PLA to get approved.
    Seems I was one of the last to get a 3D printing spot there. Now they're cleaning house for non-active accounts.

    <sigh>

    - - - - - - - - - -

    And John! Definitely remove that extra G1 that pauses the head just outside the waste bin (X-95... or something like that)! It doesn't belong there.

    - - - - - - - - - -

    John, these are the calls I found in the build config for Cube3 related to retraction.

    Context:
    Ekocycle: M227 P375 S375 G400 F800 Cube3: M227 P450 S450 G600 F800
    Ekocycle: M228 P0 S375 Cube3: M228 P0 S450

    prime_descriptions.PNG
    Last edited by TommyDee; 12-21-2018 at 06:03 AM.

  5. #145
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    Very interesting info!

    Which file is that config info in, and where is it located? Is it in the CubePrint program directory?

    What does Prime Holdoff and Reverse Holdoff mean? I.e., what does the M228 command actually do? Is it a retraction operation for longer movements?

    You were right - I did not modify the M228's in my Marvin test - was that the reason for the stringiness? However, his butt was quite buff - no drooping there!

  6. #146
    3D Printer God(dess)
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    LOLOL I don't know what they really mean and more importantly how the slicer uses the data.

    This is from the Build_Config.something.cube3.xml in the x86 programs folder structure.

    These are global commands so they hold true until changed. They are often simply repeated per loop or layer.

    Until I get back into really mapping the commands to the slicer parameters that are in the config files, I really cannot comment reliably, on in what I saw in print behavior.
    And that kind of anecdotal evaluation is pretty weak evidence.

    But do notice that obscure PrimeHoldOff thingy. Is that the P0 of the M228? Is it useful for drool control? Is it just a useful definition?

    Look at the routine the slicer uses between objects and layers. This will give you a hint of what you've been staring at for the last 3 months.

    Merry Christmas!

  7. #147
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    Shoot! I thought you knew the answer to Everything, TD!!

    Merry Christmas to you and yours!

  8. #148
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    Workin' on it.

  9. #149
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    One of my printers decided to go rogue...

    I started to print some pieces for a spool holder with my new polylite PETG, and after I did the normal Manual Z-gap setting (.180 gap), it did this:

    P1080316.JPG The first piece started fairly ok, but it got thinner and thinner as it went on.

    The same file printed perfectly on my other printer.

    After trying again with the same result, I drilled the plastic nozzle shield opening to 3.0mm so the nozzle will seat in the heater block instead of against the shield. Then I did the Calibration procedure (again). This time it did better.

    P1080315crop.jpg (I stopped after the first few layers were looking good.)

    I supposed I didn't do the calibration correctly the last time. I find the instructions somewhat confusing.

  10. #150
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    There is very little difference between the shield hole and the full seating of the nozzle in the heater block. Normally I find plastic interfering with one or the other so make for poor seating. This inevitably leads to gap-drift as well. When the interfering plastic oozes out of the way, the gap is reduced. But it sounds like yours is off for a different reason. I've had the heat-shield pop off from an extruder expanding without the play to counter it, but I figured that was the heater block flexing as well.

    Recent aggressive tip cleaning changed my gap for some odd reason. I hadn't adjusted that in months. Somehow the gap was greatly reduced. Re-gap'd and all has been well but I never quite got the reason for this. Remember that this is the Cube3 that I had to repair a broken plastic flange with a flanged screw. The fix is stronger than the original.

    Oh, you did see that Cube for parts on eBay, right? $49? Shipping was reasonable. Could well be fully functional.

    Happy New Year!

 

 

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