Acceptable dimensional inaccuracy

I am currently printing a model over 3 feet tall. Pieces fit together nicely to print, but I was amazed on how much less tall it was than it should have been, meaning an inch per 20 inches. That seems a lot, right? Since my Prusa i3 MK3S+ extruder drools a bit, I can’t test how much comes out over a given length of filament.

If you print an 100x100x100 cube how much is it off? 1 inch loss in 20 does sound like a lot to me too.

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Yeah, being off by 5% is surprising. Most (all?) bed slingers use lead screws for z, so it’s hard to imagine that they would be off that much, unless the z steps calibration got accidentally corrupted.

I will do that and add to my list of complaints. I will take pics with my caliper. Good idea! Thanks!

Thanks! The first SuperPinda failed as soon as the printer was a few months old. Could the new one be so “off” that it gives these results?

You need to calibrate a printer even when tightening the belts will affect the accuracy.

Many parts on Thingiverse/printables are simply wrong. Designers adjusted the CAD files until they match the result, which causes those things to be wrong sized by default. Hence the comments, which usually are “you need to scale 102% to fit.”

I made a contraption to easy measure the result using calipers as calibrating a printer by using so called calibration cubes is just wrong and stupid.

A printer needs to move 100mm, when told to. With a “calibration print” you calibrate the hardware to filament and slicer settings. As a result a 100mm move is not a 100mm move anymore.

Thanks. Belts are correct, I check those about weekly. By the way, how can horizontal belts affect the Z?

This is my own design. Heights can be checked in the slicer and in MeshMixer.

I did the calibration cube when the printer arrived, but not when it got back from repairs at Prusa. As I said above, I can’t tell the printer to extrude a filament length of 100mm, as the extruder drools and throws blobs as well.

I printed a 100-100mm cube and Z was 1.5 mm off per cube of 100mm, the rest was perfect. Strange, as the calibration cube I printed when the printer arrived had perfect sizes. I did not print one after it came back from Prusa’s repair center.

If I were you I would print @Geit 's calibration tool above, calibrate the Z steps following his directions.

@Geit you tool makes perfect sense to me now that I think about it. Have always used the cube method but will be printing your tool and using it fro now on, Thank You

I think the sensor would only affect the first few layers.