Model sinking below build plate

[TKTrooper 0]

I’ve just completed this print of a head, it was orientated upside down to save on supports needed. As you can see from the screen shots it is barely making contact with the build plate as I wanted. However once the print had finished its as if the model was below the build plate. 

Can anyone explain what has gone wrong, if it’s something I did, and/or how can I fix it please

[gr5 2,099]

I think we need one more screen shot that shows layer view.

 

Is it possible your bed height is way way off?  By maybe 4mm?

[gr5 2,099]

By the way if you only touch a tiny portion of the head to the bed it won't stick well and will eventually fall over.  So you might want to add 3 or 4 supports around the head in cad.  Just 4 towers maybe sticking into those holes in the head?  This is not an easy print to choose an orientation.  

[TKTrooper 0]

The print did have supports just that this view is not showing them. I don’t have a layer view as this picture of the model in Cura are from after the print completed. I re-loaded the printinto Cura to get these pics and show how it looked the first time I sliced it. The print itself cams out fine quality wise just that flat part on top of the head. 

You mention about adding supports around the head, in particular on where to place them. I thought you can’t do that with Cura? I thought you tick the generate supports box and Cura automatically generates supports where it feels they are needed. Can I manually place supports and if so how.

also is there a way to set a print a couple of mm above the build plate

[gr5 2,099]

I meant to add supports in the cad software that you used to create this model.  I usually create my own supports as I'm a little (a lot) smarter than cura is.

 

Well without seeing the part in layer view it's hard to tell what happened.  At the same time I save the gcode file I also do "file" "save project..." so I can go back and see all my settings and the positioning of the part.

 

If you click on the part and have the "move" icon on the top left selected you can set the Z value to negative values which will move the head under the bead.  Or if you simply rotate the head 180 degrees so it's upside down this can happen as well.  But you will SEE the problem in layer view.

 

Always look at your part carefully in layer view before printing.

[peggyb 169]

you can lift the model a bit by disabling 'automatically drop model on the build plate'

and in the move command put in a positive number in the z box

Note: the surface around the red overhang area will not be good, as the support has a little distance to the model and will drop down and leave strings.

You could do some tests with a sphere or your original model to see what the best method is, and stop the print after the bottom slope to reduce time/filament. Play with the x y z distance to get the best support, but not fused to the model.

 

Or turn your model 180 degrees...

[TKTrooper 0]

12 hours ago, gr5 said:

I meant to add supports in the cad software that you used to create this model.  I usually create my own supports as I'm a little (a lot) smarter than cura is.

 

Well without seeing the part in layer view it's hard to tell what happened.  At the same time I save the gcode file I also do "file" "save project..." so I can go back and see all my settings and the positioning of the part.

 

If you click on the part and have the "move" icon on the top left selected you can set the Z value to negative values which will move the head under the bead.  Or if you simply rotate the head 180 degrees so it's upside down this can happen as well.  But you will SEE the problem in layer view.

 

Always look at your part carefully in layer view before printing.

 

I didn’t create the model so I couldn’t add supports. As mentioned I’m a complete novice and just about manage with tinkercad.  I always check the layer view before printing, and when looking this one in layer view prior to print it showed nothing that I could see as a problem. It certainly didn’t show the model below the build plate. When I reloaded the model into Cura again after the print came out like it did, it again just sat barely touch the build plate. I tried to raise it slightly manually but it just dropped back into position. Even when typing in the number i.e Z height at 3mm

Edited June 21, 2018 by TKTrooper

[TKTrooper 0]

2 hours ago, peggyb said:

you can lift the model a bit by disabling 'automatically drop model on the build plate'

and in the move command put in a positive number in the z box

Note: the surface around the red overhang area will not be good, as the support has a little distance to the model and will drop down and leave strings.

You could do some tests with a sphere or your original model to see what the best method is, and stop the print after the bottom slope to reduce time/filament. Play with the x y z distance to get the best support, but not fused to the model.

 

Or turn your model 180 degrees...

 

Thanks I didn’t know that could be done. The only reason I didn’t print it the right way up was to save filament and print time, as it reduced the amount of supports needed

[TKTrooper 0]

O.K so i followed a few tips mentioned. However im noq left more confused than before.
So i disabled the automatically drop the model on the build plate, and even raised it manually by 5mm. But for some reason the same things happens. When viewed in layer view you can see, but when switched to soild view, it is just floating above the build plate as expected.
I even tried slicing in the upright orientation that i didnt want to print it in. But when doing this and then slicing, cura seems to make the model completely solid, despite the model being hollow. I have the infill set to 100% so as to make the walls stronger.

Im not sure why these things are happening as ive never had these problems before with cura. ARRGGHHHHH!!!!!

[gr5 2,099]

Make all the "mesh fixes" vislbe and make sure they are all unchecked.  There's 6 of them.  One of them may be making your head solid again.  It's much easier to have your head model be solid and to set infill to 0% and then you can set your wall width to however thick you want.  It will print much faster this way also.

 

I'm still not sure what is going on with the top of the head.  The head looks like it is raised up off the bed yet there is still something touching the glass.

[TKTrooper 0]

8 hours ago, gr5 said:

Make all the "mesh fixes" vislbe and make sure they are all unchecked.  There's 6 of them.  One of them may be making your head solid again.  It's much easier to have your head model be solid and to set infill to 0% and then you can set your wall width to however thick you want.  It will print much faster this way also.

 

I'm still not sure what is going on with the top of the head.  The head looks like it is raised up off the bed yet there is still something touching the glass.

I thought about doing that with regards to just setting the infill to 0%, but then i thought it will still need to generate supports. And seems as the bottom is sealed, then the supports would be stuck inside rattling around. 

As for the head being raised above the plate, you are correct, it is. yet for some reason it is then creating a growth of some sorts that is extending down to touch the build plate. Again this is solved by printing the right way up, but i want to understand what and why these things are happening in order to better understand. I have in the past contacted ultimaker themselves with another problem i had once, but they just tell people to come to here. They don't seem that interested.

[TKTrooper 0]

EUREKA!!!!!!!!!
Turns out the thing that was causing the extra growth when printing upside down (even if raised above the build plate), was that the "Make Overhang Printable" was ticked. Although i wouldnt of figured it out without gr5 suggesting about unticking "mesh fixes". So although not quite the solution, it was a big help, so thank you

Edited June 24, 2018 by TKTrooper

[gr5 2,099]

>Make Overhang Printable

I wasn't familiar with that feature.  Cura gets new features faster than I can keep track.  Thanks for this - next time I'll know the answer.

[gr5 2,099]

>And seems as the bottom is sealed, then the supports would be stuck inside rattling around. 

Ah.  But if you can make the "bottom" or the *neck* level you can uncheck "print top surface" or something like that (I just made that up).  I've seen people do this with cups all the time.

[kmanstudios 1,120]

1 hour ago, gr5 said:

>And seems as the bottom is sealed, then the supports would be stuck inside rattling around. 

Ah.  But if you can make the "bottom" or the *neck* level you can uncheck "print top surface" or something like that (I just made that up).  I've seen people do this with cups all the time.

Will that cause the chin and nose to not hove top surfaces as well? Best to check your layer view before printing. Also, odd that an experimental feature like make overhang printable would be checked automatically.