size accuracy and finish

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airscapes
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size accuracy and finish

Post by airscapes » Mon Mar 19, 2018 11:01 pm

New guy here, not sure what I can expect to achieve with the M2 and PLA, boat loads of stuff to learn..
Printed 20x20x20mm cube using PLA high quality setting of S3d standard M2 profile.
Did some temperature tuning to get the least amount of distortion
Z 20.01+- .02
Y 19.84 +.02-.03
X 19.89 +.02-.03

Then printed a 10mm cube
Z 10.01 +-
Y 9.81
X 9.89

Is this within normal expected tolerances?
Can this be corrected at the machine level, mechanicaly (would think not) or is there a way to compensate within S3D?

I am using the stock 3.5mm, are these gaps at edges normal when printing small items like a 10mm cube? I did not get these when printing the 20mm.
See below
10mm
10cube tops.jpg
20mm
20mm_cube_top.jpg
Thanks in advance
Doug

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ednisley
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Re: size accuracy and finish

Post by ednisley » Mon Mar 19, 2018 11:48 pm

airscapes wrote:not sure what I can expect to achieve with the M2 and PLA
Always remember: a 3D printer produces an object by squeezing molten plastic through a nozzle slightly smaller than a grain of salt and mashing each layer atop a gummy tower of cooling plastic. These pictures may help you see what's going on:

https://softsolder.com/2015/11/12/3d-pr ... alization/

With that in mind, you can expect XY dimensions within 0.2 mm and Z dimensions within 0.1 mm, pretty much day in and day out. Although you can tune any particular model better than that, those settings won't optimize a dissimilar model.

Your results will improve with increasing attention to detail:
  • Measure the actual filament diameter and set it in the slicer
  • Calibrate the Extrusion Multiplier after changing filaments / temperatures / whatever
  • Verify the platform alignment
  • Plastic shrinks as it cools. If that matters, calibrate appropriately.
Treat your M2 with reasonable care, don't beat on it to knock objects off the platform, and it'll crank out surprisingly precise objects like clockwork.

airscapes
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Re: size accuracy and finish

Post by airscapes » Tue Mar 20, 2018 1:01 am

Thanks Ed!
So what you are telling me is this is normal and that is just fine if that is the case.
I thought there were a lot of variables to airbrushing but this is the black hole of variable! :D

One of the assumptions I mistakenly had and am quickly finding was completely incorrect is that S3d Default profile is set up to optimize the M2.. but I think the defaults are just middle of the road.. work well as it but have room for improvement?

How about he gaps in my top layer.. been struggling with what I feel is too much gap between layers but not sure what variable to change.. been over and over the print quality document at S3D but there are always 3 thing that can cause a problem on Tuesday when it is raining and 6 on a sunny Friday! :shock:
Not even sure I have a problem.. which makes it even more frustrating.
Any additional word of wisdom are much appreciated.

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ednisley
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Re: size accuracy and finish

Post by ednisley » Tue Mar 20, 2018 1:07 pm

airscapes wrote:work well as it but have room for improvement
Absolutely! Kinda-sorta by definition, you can tweak the process to optimize any feature you want: speed, surface finish, strength, repeatability, whatever. However, you can't optimize everything at once, so there's no "best" collection of printing parameters for everybody. You get to decide what's important, then adjust the settings to make it happen.
gaps in my top layer
Have you measured and set the actual filament diameter, then calibrated the Extrusion Multiplier?

Until you get those adjusted properly, you're wasting your time doing anything else.

airscapes
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Re: size accuracy and finish

Post by airscapes » Tue Mar 20, 2018 2:41 pm

Well No I have not set the set the actual diameter of filament or messed with the multiplier yet. In preparation for that put my roll of PLA in my new food dehydrator over night at 140F to make sure it is dry.
I just rechecked my starting height and level. I am using a factory plate with the factory applied tape
Nozzle is heated wiped clean and cooled
Hate the app for leveling never get the same results twice. Support gave me the Gcode commands to do it manually.
I send the G28 (believe that homes all)
Then I send G1 F1000 X100 Y125 Z0
Right now the gauge moves under the nozzle with very light resistance
I move the bed back and it is very close to the same as the center.
I move the bed all the to the opposite side and is the same.
Now is when I get confused.. Moving the extrude to the left or right sides, I get no resistance.
As if the glass is bowed up in the center.

In one of the links you provided you mention creating a skirt that covers the entire build surface so one can watch the first layer. How do you do that in S3D or do you need to do that in a CAD program..
My plan is to measure that filament now I know it is dry and attempt to do exactly as you suggest, just wondering about the above height difference between center and sides..

Update: Just had some free time and ran the app, it said my starting height is correct and my bed is level guess there is a first time for everything! :D

Thanks

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ednisley
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Re: size accuracy and finish

Post by ednisley » Tue Mar 20, 2018 6:07 pm

airscapes wrote:As if the glass is bowed up in the center
Most likely, it's the X-axis gantry bowed slightly downward due to belt tension. Opinions on this differ, but, on my M2, it's small enough that I can split the difference across the surface and it's all good.
creating a skirt that covers the entire build surface
Here we go off the deep end.

I confess to working in hard mode, but I don't bother with the automated aids:
https://softsolder.com/2016/06/17/m2-pl ... t-check-2/

Print a calibration square in each corner and get a full-platform skirt for free!

The general idea is to measure the as-printed height of the squares, then adjust the platform to make the actual height match what it should be. This eliminates all the hocus-pocus involved with gauges / shims / paper / cardboard / whatever, measures the platform when it's at operating temperature, and controls the only thing you really care about: the objects on the platform.

Likewise I set the Z axis offset by printing a square in the middle of the platform, measuring the actual height, and storing that value in the printer's EEPROM:
https://softsolder.com/2018/02/13/m2-pl ... confusion/

That post shows me learning something new, as the way I used to set the offset stopped working without my noticing. It's playing in hard mode, but it also eliminates a whole bunch of complexity.
do you need to do that in a CAD program
After you get over the initial learning hump, you'll need specific shapes to solve your very own problems, which means you must produce your very own solid models. I use OpenSCAD, which is very definitely an acquired taste and not for the casual modeler; other folks have favorites more aligned with traditional CAD practices.

airscapes
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Re: size accuracy and finish

Post by airscapes » Tue Mar 20, 2018 7:12 pm

Thanks Ed!! I will work through this, I am using OnShape and have lots to learn but have created a few items already..
https://cad.onshape.com/documents/9d258 ... 79fe4f5b33
As well as the cube and a few other things..

Will ping you if I have any questions about the info you have provide.
BTW last night I ran a bunch of string test adjusting the retraction speed.. got it fairly good... Then today ran again with the PLA after drying .. not a one string to be found..
This is MG brand and has been stored in vacuum bag with descant
Thanks again for all the assistance.. seems like the board is rather quiet compared to my other hobby board.. http://www.avsforum.com/forum/index.php

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ednisley
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Re: size accuracy and finish

Post by ednisley » Tue Mar 20, 2018 8:08 pm

airscapes wrote:stored in vacuum bag with descant
Those little bags get the filament from the OEM to you in good condition, but become worthless when you unseal the bag.

The consensus around here suggests storing filament spools in 6 gallon buckets or sealed tubs with a pound of desiccant and an indicator strip.
ran again with the PLA after drying .. not a one string to be found
The lesson to be learned: any change will affect the results.

When you encounter a problem, ask yourself "What's new and different?" to help pin down the cause. Randomly changing settings will only dig you into a deeper hole, sometimes with no clear way back out.
the board is rather quiet
Folks focus on being helpful, rather than chatting, so the signal-to-noise ratio is extremely high.

After a while, you'll notice the admins do an incredible job of stamping on spammers, too.

Devote some time to reading the vast collection of threads and you'll find a whole bunch of knowledge and useful suggestions, not all of which will be immediately relevant. In a while, though, you'll find yourself thinking "I remember reading about that ...", whereupon aiming a Google search at forum.makergear.com will be productive.

For example:
https://www.google.com/search?q=site%3A ... +desiccant
Last edited by ednisley on Tue Mar 20, 2018 9:16 pm, edited 1 time in total.

mathisyourfriend
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Re: size accuracy and finish

Post by mathisyourfriend » Tue Mar 20, 2018 9:06 pm

"the signal-to-noise ratio is extremely high"

I agree. As a stats nerd I'd like to point out that this heartens me. Usually (especially on the intertubes) it's the other way around.

airscapes
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Joined: Wed Jan 31, 2018 11:36 pm

Re: size accuracy and finish

Post by airscapes » Wed Mar 21, 2018 1:12 am

So I found the other thread on the thin walled boxes while my boxes were printing. I created them 40x40 1.2mm wide and 3mm tall.
I printed them using the S3D options of allow single extrusion walls and allow single extrusion fills and have been and continued working with .1mm height.
All boxes are the same height depending on where I measure them 2.99 to 3.04 H
All thicknesses are between 1.18 - 1.28 on the same cube
The thickness of the MG brand PLA I have go all over the place from 1.68 to 1.80 left it set at 1.75 with a multiplier of .90

I am guessing my bed is level just like the app said it was WOOHOO and my staring height could go up .01. But as soon as I change hot ends I would need to redo the height.
BTW, with the v4 hot end, not sure if older ones are different, you can just go to starting height loosen the lock screw and drop the nozzle onto the feeler gauge and tighten.. that is how I set this height this morning. This is assuming the hot end was not pushed up against the bracket and you have a little room to play.

Nest I guess I have to make a solid cube to tune top layer infill?

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