How to print a 1 cm line as 1 cm?

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ido
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Location: Rotterdam - The Netherlands

How to print a 1 cm line as 1 cm?

Post by ido » Tue Aug 15, 2017 9:33 pm

hi,

Watching Tom's video's he is no fan of the xyz calibration cube. I kinda understand why, as there are a lot of factors defining the xyz calibration. Tuning 1 thing could make another thing worse. At least this is what I thought Tom meant.

Now I am designing some things in fusion 360 where dimensions are important. I noticed when printing in one of my PLA's the shape is smaller compared to an ABS print I did. I always thought ABS shrinks more, but that's beside the point.

What is a good approach to make sure that a 1 cm line gets printed as 1 cm? I probably need to do this for each filament.

cheers

Ido

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lowfat
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Re: How to print a 1 cm line as 1 cm?

Post by lowfat » Thu Aug 17, 2017 4:59 am

If you are building a printer yourself you'll need to set the correct steps per mm for the X, Y, and Z. You shouldn't ever need to change these values.
http://www.prusaprinters.org/calculator/

The only one you could ever have to change is the steps per mm for the extruder. This can change based on the diameter of the filament.
https://www.youtube.com/watch?v=YUPfBJz3I6Y

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ido
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Location: Rotterdam - The Netherlands

Re: How to print a 1 cm line as 1 cm?

Post by ido » Thu Aug 17, 2017 7:29 am

thanks for the reply. I forgot to mention, I have a prusa i3 mk2s kit. And I did the extruder calibration.

Still wondering what the best approach would be to calibrate the printing dimensions compared to the dimensions in my CAD model. Perhaps print the xyz cube for each filament and adjust the % size within my slicer to compensate for any differance.

chumm
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Re: How to print a 1 cm line as 1 cm?

Post by chumm » Thu Aug 17, 2017 10:47 pm

Well, the problem is what you're experiencing shouldn't be happening. Yes there are very slight differences between filaments because of them cooling at different rates, but nothing that should be noticeable beyond a few hundredths of a millimeter across a 1 cm span. You probably need to some more testing to see if you're getting these results consistently. This is why the 1cm cube is a bad test: if you make a 2% adjustment because some filament oozed .2mm, you'll then have your prints be off by 2mm when you print something 10cm long.

As noted, filament diameter would be one of the only things that would cause one spool of filament to print at a different size than another. You could take several measurements with calipers of each spool of filament to see if there is any variation in the diameter between the two. If the average diameter of one is different from 1.75mm, you can set that value in your slicer to have it compensate accordingly.

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