Calibration woes

Hi all,

I'm new here so be gentle with me.

I have a Tevo Tornado and I'm having issues with calibration that I've never seen before.

On a 20 x 20 x 20 calibration cude I'm approx 0.12mm low on x and Y but bang on 20mm on the Z axis. The calibration block I'm using also has three 40mm lets and on X and Y I'm 0.8mm under 40mm on X & Y and 0.5 over on the Z. So how is it that I'm seeing such a difference over a further 20 mm? I'm completely baffled and not new to 3D Printing.

Any help would be appreciated.

Not sure I understand the second 40mm part of you statement but .12 off on x and y could be under extruding or insufficient outline and infill overlap .. On my machine the only thing I can really alter accurately is Z so I take what I get with x and y since there is no mechanical or firmware means to fix them.. I typically us a 2 walled cube to check Z and a single layer model to check Extrusion Multiplier.. No spaces between threads. Also can check thinkness to verify Z. After typing that I reread your post I guess you have something loose or filament that is really fluctuating in diameter or and extruder problem.. but those are guesses

what slicer are you using - could well be the x &y steps need adjusting.

And bear in mind that abs shrinks quite a lt. So always calibrate with good pla. Really cheap pla can have a little shrinkage.
And a tenth of a mill on a cheap machine isn't bad.

Also make sure you're not squeezing too hard on the calipers :-)

Attachment 14286

Thanks for the advice guys.

The attached may be more enlightening with regards to the question regarding the calibration block I'm using.

I'm using Cura and only just getting used to it from using Simplify3d and I've had this printer calibrated to 20mm on all axis previously which is why I'm so confused with what's going on.

As for calipers, I think I'm good in that respect as I'm a Rolls-Royce Propulsion Engineer and just learning the ropes with regards to 3D printing with Cura ;).

If you have bailed out on S3d (i am still using 4.01) try out Prusa slicer.. very much like S3d and free.. Also it is actively being developed..

I've just downloaded Prisa slicer 2.2 and will give it a go. Thanks for the advice.