Mastering your gantry height

[pm_dude 27]

Hello Makers,

I thought I would share a bit of a trick I've been using for a while now about not limiting yourself to the default gantry height.

For those not aware of what the gantry height is, it's the clearance you have between the bed and the lower axis metal rod driving the print head movement. This is what limit you when doing "Print One At A Time" prints.

Something I have come to like about Cura is to be able to change settings even for a very well defined printer like the UM2. Cura let you change the machine settings to your liking. This is useful when you start customizing your printer with different fan duck or change other things. It's a double edge sword so better be careful otherwise you can seriously damage your printer. I haven't seen those settings in the new Cura.

Today I want to show you how you can get away with no gantry limit in situation that suit your needs. 2 things to keep in mind.

1. If you change your gantry height for one project you better keep in mind to change in back to avoid potential collision on your next prints.

2. Space is limited so plan your object positioning.

Changing your gantry height

In the old Cura.

Go in the Machine Menu -> Machine Settings and change the Printer Gantry height to any higher value. To make sure I don't forget the original setting I usually just add a 0 (ex. 48.0 -> 480.0).

The progressive approach

Sometimes you have a bunch of objects to print and only one of them are over the gantry. One thing you can do here is "try" to position your objects so the tallest objects are printed last. This will avoid any potential collisions and preserve most of the build space available. That can be tricky because Cura decide what pieces to print when and so you need to play around with placement a bit to get it in the order you want.

It would be great if Cura could allow you to select the order in which pieces get printed or sort by height automatically.

The reckless approach

Sometimes you just want to print the same tall thing twice in a row and don't want to be around to wait for bed cool down and start over. If you have enough space you may be able to get away with it. To know if you can do so you need to think in axis.

1. The first thing to think about is to place your first object in the most corner point possible. This way you reduce less build space for other pieces.

2. The deadzone is defined by the axis rods that move the print head. If the respective axis rod get in that zone after the piece is printed it will smash the already printed piece. So you have a X axis dead-zone and a Y axis dead-zone.

It's important to understand and figure out the dead-zone and not place anything in there once the object is printed. This mean objects under the normal gantry height could be printed BEFORE with no issue.

3. Then you can keep adding objects as long as the dead-zone is not an issue. Keep in mind that Cura will also force you to respect the normal print head clearance visible in light gray when selecting objects.

4. Know the print head movements. When the piece is done the build will lower a little, the print head will move above its next object to print and then raise the bed again. Check the layer view to see if the sequence of printed piece is good. The print head could smash a taller than the last printed piece when moving to the next one to print.

5. Beware of pausing and aborting your print. This is not a new issue but is more likely to affect you now with higher pieces (at least on older firmware). When pausing the bed doesn't lower enough to clear every printed object and the printer move to the front left corner right away. This mean it could hit printed pieces. Same with aborting. The print head reach X zero while lowering the bed.

Happy printing everyone.

PM

[bassamanator 1]

I just wanted to make sure I have this right.

 

Let's assume the nozzle is touching the bed right now. The distance between the bed and the bottom of the rod is 32 mm. So my Gantry Height would be 32 mm? If that is the case then the Gantry Height is the vertical distance between the tip of the nozzle and the rod holding the printhead?

 

Thanks!

[GregValiant 1,251]

Yes it is.  When choosing "One at a Time" you will see a plane in Cura at the gantry height.  There should be a popup warning "The build volume height has been reduced...".  It is the Z crash height.  The work-around that pm_dude is describing gets around the limitation, but ya gotta be careful.  The other values in the Machine Settings / Print Head are the dimensions of the print head itself when viewed from above.  The origin for the measurements is the nozzle centerline.  When using "One at a Time" you'll see a gray area around a part in Cura.  That's the XY crash area.

 

When printing "One at a Time" there will be multiple instances of layer numbers as each separate part will have a Layer:0.  That can cause issues with some post-processing plugins that will find the first instance of a layer number and assume that it is the only instance.

 

The image shows the One at a Time build area.  The gray squares are dis-allowed areas in the XY (my print head settings) and the max Z height is at my gantry height of 25.