Bug: "Fit" algorithm ignores Cut off value

[Blizz 53]

The code that determines whether an object will fit for printing seems to ignore the "cut off bottom" value.

I am trying to print an object that is 210mm high on an UM2, which has 205mm as maximum height. I can cut of whatever I want from the bottom, it still shows as non-printable. It's not exceeding maximum directions in either X or Y.

 

[dirkdirk 5]

hi,

I have exactly the same problem. I want to print a large object in 2 pieces (upper half and bottom half) but I can not generate a gcode although it is not too large within the construction space.

Z=320mm-153mm Cut off = 167mm

(why is the picture so huge?)

 

[Cohen 4]

I worked around this by temporarily setting the Z maximum height at a greater value in Machine settings.

 

[Blizz 53]

Will the machine physically get to 210mm? As in: Is there a safety margin involved?

Or is the extreme limit really 205mm...

I could print the piece at 205, but the full piece would be a lot better obviously

 

[pm_dude 27]

Thats the danger of cnc machines and 3d printers. if you give them instructions they will perform them even if they cant. Thats why you need to be vigilant about it. But if you know you cut off 5 mm then you should be fine.

I cheat the granty height all the time when one piece (the last one being printed) is taller than the normal value.

[aviphysics 9]

I regularly cheat the gantry height as well. Will also sometimes set a very low gantry height and reduce the other dimensions yo just for the print head. Then you can print lots of short stuff one at a time.

[Daid 306]

This is due tot the fact that the "sink into platform" is applied after everything else. It's pretty much a hack in the code, so most code does not handle this properly.

 

[Blizz 53]

Anyhow... just printed the piece at full height (210mm) and I had about a cm of Z to spare.

 

[Daid 306]

Anyhow... just printed the piece at full height (210mm) and I had about a cm of Z to spare.

 

Makes perfect sense. The early UM2s had a 10mm longer print head then the newer UM2s. And Cura is setup so both version work safely.

So yes, you have 10mm MORE Z space then advertised.

 

[pm_dude 27]

Good to know

[dirkdirk 5]

....The early UM2s had a 10mm longer print head then the newer UM2s....

 

how can I tell if I have a new or old model?

 

[Blizz 53]

dirkdirk... Measure it That's what I did to make sure the piece would fit!

From the bottom of the nozzle onto the buildplate at its lowest. Just make sure to have some spare room as - at the end of the print - the plate will always rise about 1cm and go back down before it homes apparently.

 

[pm_dude 27]

I made a change to test. It uses the cut off setting when checking the print one at a time mode and the max height test.

https://github.com/pmsimard/Cura/commit/69d0e568cf64b954f94314b0177ed4969d0080e2