Full Bed

Discussion in 'Show off' started by Spoon Unit, May 6, 2016.

  1. gonzalo

    gonzalo Well-Known Member

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    I would place the catch hook on the bottom side so the weight of a tool hanging will help it catch the peg board and compensate for any slack.
     
  2. Miasmictruth

    Miasmictruth Well-Known Member

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    No if its bottom side it will pivot loosening the hook, the tool pulls down in front so the hook will ceatch the top. Then to remove it you pull up and swing out.
     
  3. Kanedias

    Kanedias Well-Known Member

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    I was never able to source pegboard locally (in the UK) I ended up picking up a few sheets of the metal shop display type though.
     
  4. Spoon Unit

    Spoon Unit Well-Known Member

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  5. Spoon Unit

    Spoon Unit Well-Known Member

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    Another full bed print (well, as many as I could stick in quickly and easily. I think this is using slightly more space than I could previously address before the Hybrid. Also, there's a mid-first-layer shot, just for @R Design . Before anyone asks about the shoddy v6 fan guard print, I already re-printed it. I think this one was just a case of over-extrusion combined with a 0.1 layer which just amplifies mistakes.

    This is E3D Silver PLA at 210/70 printed on Kapton+hairspray. Print time - 4 hours. The stick is quite immense and I reckon even small items would have enough stick to print a full bed of tiny items. I just don't need that many cat collar tags though, but it is tempting to see whether Kapton would address the previous problems with tiny items (which might also just have been bad dual head levelling.

    2016-05-20 08.25.20.jpg 2016-05-20 09.14.14.jpg
     
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  6. Kanedias

    Kanedias Well-Known Member

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    Having spent last night tweaking my first layer I'd say you could knock your z offset down by .02 or more to avoid that cresting. Or not, looks like it's working just fine as it is :)
     
  7. Spoon Unit

    Spoon Unit Well-Known Member

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    This is a dual, so there is no z-offset. I think I might be levelling it a touch too close to the bed. To me logically, we're leveling to zero so that when z is set to (in this case) 0.25 for the first layer, you should be at precisely z=0.25. None the less, I do see that cresting and so perhaps I should eyeball is very slightly higher than I am. At the moment I use the eyeball method to go through the levelling process, stopping when I see no more light between the bed and the nozzle. I might just add a further step to knock it back up one notch.
     
  8. Kanedias

    Kanedias Well-Known Member

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    I was getting perfect lines and adhesion but gaps on my first layer. I tried tweaking extrusion multiplier, filament diameter, esteps, extrusion width, extrusion percentage. But none of it was making much difference.

    Left is z offset of 0.76 right is 0.79. At 0.82 I was getting crests like you have there. That's how small the sweet spot is. the main practical difference is I think the gaps were affecting bridging and top layers. But by the third layer, top or bottom, there's no gaps anyway.

    I used feeler gauges and bed levelling screws on my last printer. Being able to dial it in using the jog wheel and the active z motion correction as it prints just feels like luxury to me and was, along with the build volume, was my reason for backing/buying.

    image.jpeg
     
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  9. Spoon Unit

    Spoon Unit Well-Known Member

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    Please expand !
     
  10. Kanedias

    Kanedias Well-Known Member

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    It's nothing too clever; For the single extruder build under main menu > control > motion > Z offset is set during setup when you adjust the IR probe with a piece of gt2 belt. http://wiki.e3d-online.com/wiki/Printer_Commissioning#Calibrating_Z_Offset

    So that sets the _actual_ nozzle height when the IR sensor triggers. By adjusting the z offset you can get the nozzle closer or farther without adjusting the sensor and with a .01mm degree of accuracy.

    What I spent a 1/2 hour doing last night was adjusting the offset value and printing one of those single layer disks, seeing how it looked and adjusting a little more till I had it looking how I wanted. I don't see why you couldn't do the same with a dual.
     
  11. Spoon Unit

    Spoon Unit Well-Known Member

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    Well @Kanedias ,you led me to find something very cool. In the current firmward I'm using (Alex's RC6 MBL), there's an option under Tune to adjust Z Bed on the fly while printing. I began tweaking until my first layer was really sweet. Not quite the same as your solution, but really handy. Also, I see that under Tune, the temps and fans can all be controlled properly now from the LCD. That's also very cool.

    2016-05-20 14.00.17.jpg 2016-05-20 14.26.35.jpg
     
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  12. Kanedias

    Kanedias Well-Known Member

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    Fantastic. So satisfying isn't it?


    I guess I should look at installing a more recent firmware too.
     
  13. Sarah Nicholson

    Sarah Nicholson Well-Known Member

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    I wonder if there is a way to do the same adjustment via gcode so it could be put in the startup script? Hmm must poke around...
     
  14. Spoon Unit

    Spoon Unit Well-Known Member

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    quite likely, couldn't you just do some hack like this?

    G0 Z0
    G0 Z0.05
    G92 Z0

    I think the thing about this is that's a jog method that lets you iron out the differences between what you think you did in levelling the bed and the actual end result as seen on the print bed. You can knock the bed out of alignment relatively easily if removing a tough print or changing the glass, so you couldn't guarantee the same numbers would always work. Feels to me like this is an operational requirement after each bed level; i.e. print a small square and tweak the Z-Bed.
     
  15. R Design

    R Design Well-Known Member

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    The "gcode" tab in Simplify3d contains "global G code offsets" - boxes to set for all 3 axes. Check see what code it generates.

    I'm slowly getting better with the paper when mesh bed levelling, but nonetheless fine tune using the above when working at lower, more critical, layer heights.

    ps some people may be interested to follow / participate in request thread for Automatic (with IR sensor) Mesh Bed Levelling in Marlin:

    https://github.com/MarlinFirmware/MarlinDev/issues/362#issuecomment-220578340
     
  16. mike01hu

    mike01hu Well-Known Member

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    I find that paper is too thick and have switched to using feeler gauges, in particular the 0.02mm gauge, with substantially better results for the first layer.
     
  17. Spoon Unit

    Spoon Unit Well-Known Member

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    I'm tempted to give this a go. A piece of paper gives also, whereas a feeler guage doesn't. You could lower all the way to the guage and then have a consistent height all the way round. However, it doesn't really sound any different from lowering to the bed and using eyeballs to look for the light disappearing. Are you pushing the gauge around as a test for how much it's caught? If so, how do measure how caught it is, or is this just a "feel" thing. If it's feel-based, it seems that eyes would be just as good.

    It does seem like the IR sensor should be the measure, but I guess that also depends on configuring the height of the sensor trigger from the nozzle point. The benefit there would be that tthe height from nozzle to IR sensor triggering remains constant, so as long as the IR triggered reliably at the same height at all points on the bed, that would be great. I think that's the very nub of the issue though.
     
  18. mike01hu

    mike01hu Well-Known Member

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    I think we'll have Alex telling us off for not carrying on this topic in the right area ;) He's right, but here goes:

    I use feel, as the Mk1 eyeballs are not so good these days! But, feel is OK as it is easy to judge by just gently pulling the feeler gauge against the pressure of the approaching nozzle; if you can pull and feel slight resistance and push and the gauge still moves just as easily, that's it.

    I think the only difficulty with the IR unit is the setting up. You need a fine screw adjustment to achieve a reliable result and that means a redesign of the IR holder. Perhaps @Chase.Wichert will think about this in his new carriage design, as he has done a good job with nozzle height adjustment.
     
    #38 mike01hu, May 21, 2016
    Last edited: May 21, 2016
  19. R Design

    R Design Well-Known Member

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    When I bring the nozzle down on the paper (A4 printer paper, 80gsm) I distinguish 3 click-stages:

    1) paper completely free;

    2) slight contact;

    3) a gritty contact;

    My technique is to lower until I get to "3",

    then back off to "2"

    then go to "1" and back to "2"

    by way of confirmation that I'm really at "2"

    and then hit ENTER.

    My objective is to get consistency over the 9 points.

    Then when printing at a low layer height might notice that it's a bit too close, or a bit too far away.

    Compensation can be made in the Simplify3d Gcode tab and left for all subsequent prints.

    It seems now that the best way to figure out that compensation factor is by using the new RC6 Tune / Z offset feature as the first low layer height first layer is going down. Thereafter you know the number.
     
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  20. Henry feldman

    Henry feldman Well-Known Member

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    @mike01hu I think the other fundamental issue is that the actual hot-end is not rigidly held and screw adjustable. I mean let's be honest, a friction fit, o-ring sealed, 2 grub screw holder is hardly rigid, square or stable. It's not like you can use the grub screws to level the head or square it to the bed (since once the bed is down, almost impossible to get in there and screws in plastic are hardly like tapped metal. This is really the flimsiest part at least to my eyes of trying to get it fine tuned.
     
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