Now for the calibration stage....

Last night I managed to print my first 20x20x10 mm cube after 2 failed attempts where everything went tits up while laying down the raft due to having oozed the barrel empty that half the raft was printed with no extrudate (is there such a word?)

Third attempt I had the extruder circumvent the table printing a single line before heading in to print the raft. This countered the ooze and the print ran fairly well. I am actually very happy with the cube for a first print

Anyway, I now need to calibrate my printer. It seems the 10mm is in fact 8.4mm on average.

the 20mm sides seem to be around 19.6 - 19.8mm

I have tried measuring my Z axis and it seems as though the first 10mm measures about 9.09mm (sometimes 8.87) and the 40'th or 50'to 10mm measure around 9.5 give or take 0.2mm

Is it possible that the lower 10mm can be so much out from the higher 10mm or is my measuring just useless?

Thanks

Very odd. I just use the thread pitch and the gear ratio and my objects come out the right size. Similarly I use the belt pitch for X & Y. Belts and threaded rods are made very accurately in my experience.

For X & Y you would need to make another object say twice as big. If that comes out 39.6 39.8 then you axes are accurate but your filament width is out, or you have backlash. I.e. a single measurement is a combination of the filament placement, filament width and how much the plastic shrinks. You need to separately calibrate all those to get all objects to come out correct.

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[www.hydraraptor.blogspot.com]

Hey Nop

When you calculate your steps per mm for your axis, what is the formula?

Also, I do notice a bit of a wobble in one of my Z-Axis M8 threaded rods.I guess this woble could be enough for the less than a mm variation?

Cheers

AgeingHippy Wrote:
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> Hey Nop
>
> When you calculate your steps per mm for your
> axis, what is the formula?

See Bob's post here: [forums.reprap.org]

I use 1600 / (1.25 * 8 / 21) for a x8 stepper.

>
> Also, I do notice a bit of a wobble in one of my
> Z-Axis M8 threaded rods.I guess this woble could
> be enough for the less than a mm variation?

It would have to be severe wobble to cause a significant change in height. For example if it wobbled 5mm to the side say 150mm from the bottom bearing the height would be sqrt(150^2 - 5^2) = 149.92. I.e. only 0.08mm error for a 10mm wobble. Maybe your z-axis is loosing steps.

>
> Cheers

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[www.hydraraptor.blogspot.com]