size accuracy and finish

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Re: size accuracy and finish

Postby Gwhite » Fri Mar 23, 2018 1:05 pm

That sounds like there may be an offset buried somewhere in the firmware. I want to do a full leveling & zero on my machine, and can see if the shim fits underneath when I command it to Z=0, but it may be a day or two before I can clear enough space to get my laptop next to the printer.
Gwhite
 
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Re: size accuracy and finish

Postby airscapes » Fri Mar 23, 2018 1:23 pm

Gwhite wrote:That sounds like there may be an offset buried somewhere in the firmware. I want to do a full leveling & zero on my machine, and can see if the shim fits underneath when I command it to Z=0, but it may be a day or two before I can clear enough space to get my laptop next to the printer.


Please read the data in bold from my previous post. Z offset is stored in firmware.. you can read it and adjust it via sending gcode that info is there in the post.
The drop on feeler gauge was in response to my thought "I had this correct before I removed this nozzle" why waste 10 minutes doing the complete leveling process when all I did was remove the hot end and change the nozzle.
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Re: size accuracy and finish

Postby airscapes » Fri Mar 23, 2018 1:30 pm

ednisley wrote:
airscapes wrote:What am i missing?


Nothing: you're becoming a careful observer, which is all good!

changed to .02 layer height


If that's really 0.02 mm, then they layers are way too thin for anything other than bragging contests.

If it's 0.02 inch = 0.5 mm, then it's way too thick. Metric units are the default in 3D printing, so always specify inches if you insist on 'Murrican units.

If you're slipped a decimal point and it's really 0.20 mm, that's fine.

bumps along the edges


Remember what's going on: the extruder must exactly fill a sharp angle with a gooey blob of plastic squeezed out of a round hole. Getting a flat surface requires tuning:

  • Diameter & Extrusion Multiplier for exactly the right amount of plastic
  • Infill Overlap, so the round thread fits precisely
  • Infill before perimeter, so a single perimeter thread defines the joint
  • Probably something else I've forgotten

You've already measured & set the diameter & EM, so set the slicer to produce the infill first.

The Retraction distances (1.8 / - 2.0) seem excessive; return those to the defaults. Simple squares don't have much retraction, so they're not good test pieces.

Run off several solid squares with the Infill Overlap set to 0, 5, 10, and 15%, examine their differences, then pick the one you like best.


Ed, you rock!
Decimal point got away from me.. .2 is the height..
Will reset those option and see if I can find the infill before perimeter in S3D, that is not ringing a bell .. but my bell is a bit busted at the moment.
Thanks!
airscapes
 
Posts: 47
Joined: Wed Jan 31, 2018 11:36 pm

Re: size accuracy and finish

Postby Gwhite » Fri Mar 23, 2018 3:05 pm

airscapes wrote:
Gwhite wrote:That sounds like there may be an offset buried somewhere in the firmware. I want to do a full leveling & zero on my machine, and can see if the shim fits underneath when I command it to Z=0, but it may be a day or two before I can clear enough space to get my laptop next to the printer.


Please read the data in bold from my previous post. Z offset is stored in firmware.. you can read it and adjust it via sending gcode that info is there in the post.
The drop on feeler gauge was in response to my thought "I had this correct before I removed this nozzle" why waste 10 minutes doing the complete leveling process when all I did was remove the hot end and change the nozzle.

There are two possible sources of "offset". One is the shim thickness, and one is the setting that tells the machine the mechanical distance from the "home" Z position to the tip of the nozzle. In a simple world, the Z offset saved in the firmware should take care of the difference between "Z = Home", and the tip of the nozzle. If you command the height to Z=0, I would expect the tip to JUST touch the build plate. However, because MakerGear uses a 0.127mm shim to set the height, that has to be accounted for someplace. It may be that sending the machine to Z=0 does actually send it to a height equal to the shim thickness, but I would be surprised. I'm guessing that the leveling/zero-setting software adjusts the firmware offset to compensate for the shim thickness so that when you are done, Z=0 just touches the build plate, and does NOT allow room for the shim.

I really like your approach, but It's all a question of whether you need to drop the extruder down on the shim with the G1 commanded to a height set to Z=0, or Z=shim-thickness. With a 0.2mm layer thickness, it makes a big difference on the first layer, which is critical for good prints.
Gwhite
 
Posts: 149
Joined: Tue Jul 11, 2017 3:38 pm

Re: size accuracy and finish

Postby airscapes » Fri Mar 23, 2018 5:28 pm

Oh one other thing I did read.. Z0 should touch build when the plate and extruder are at operating temp.. So maybe that feeler is the expansion amount?
airscapes
 
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