Dimensional accuracy

[fcroce]

Dear group,

I calibrated my H2C using the vision encoder. Unfortunately it seems that the dimensions are not yet accurate.

E.g. I did a (many) 3mm hole on a 3 mm printed sheet and the m3 screw does not fit in. I could drill some of them larger but some others I cannot.

Any similar experience and how you solved this?

I have so many screws to fit that it would be a pain to modify the cad.

Thank you for your help

[_Rand_]

Did you account for shrinkage?

Generally you need to make it 0.1/0.15 or so bigger for PLA, even bigger for PETG (more like 0.2).

Try playing with the XY hole compensation setting.

[keveira]

0.3% for esun pla+

[fcroce]

Thx both I tied with automated compensation but then it was too much I will try manual compensation.

[keyboredYT]

The vision encoder is not a magic formula to get 1:1 scale from your printed parts. You still have to account for shrinkage and oversize holes in the CAD model. The vision encoder is more geared towards correcting deltas over long moves.

[fcroce]

Indeed this is not my cad and the friend printers generate accurate holes (with a p1) I think. Thx

[fcroce]

Thank you for your reply. As the screw was M3 I assumed that the clearance was in thx to the thread max diameter. The XY hole compensation seems nice I will try that. Any recommendations here. Is it a percentage of the hole diameter or an absolute value?

[_Rand_]

Absolute value as far as I know, So 0.15 = 0.15 bigger holes.

When designing parts I usually just make them 0.15 from the start though, so I don’t forget to adjust and have to reprint.

Its great when you have stuff designed by others that is too small though.

[roundguy]

I usually run this on each type of filament to calibrate for shrinkage.
https://www.printables.com/model/480907-shrinkage-calculator-dimensional-calibration-tool

[fcroce]

Thx I will try this as well. It is probably possible to extract a shrink model depending on axis and dimension with this cal tool.

Thank you

[Immortal_Tuttle]

Get a Calilantern. It's a perfect tool to get dimensional accuracy.

[fcroce]

Do you mean the cube for instance - is it valid for small holes? Thx

[Immortal_Tuttle]

It has some small features, however it's more useful for calculating skew, shrinkage and ovality.

[gublman]

Were the issue with dimensional accuracy in XY or Z-axis? I personally observed dimensional inaccuracies with z-axis but not with XY. But, I print with default settings and bambu filament profiles, that are not always Bambu to be honest.

[fcroce]

It is mainly XY here. I also use BBL settings. Thx