What is gantry height?
Let's start off by explaining a little about gantries. Unless you work within architecture or engineering (honestly, if you work with a 3D printer on a regular basis, you might actually work in these fields!), you might not recognize the word because it isn't used often. The gantry is the frame structure that holds up something else -this can include a platform used to transfer a mobile crane or the vertical towers that hold the space shuttle until it is launched. Gantries work as support structures, like the columns that support a bridge.
In the case of 3D printing, the gantry height is the vertical distance between the plate you are printing on and the bottom of the nozzle as it touches the plate. The setting is only used when printing one item at a time and isn't typically used for printing multiple items or printing in sequence.
How do I use gantry height?
Gantry height is based on the size of the printhead. Along with several other x and y axis settings, these heights determine how much your printer moves during printing a single item.
You'll find gantry height important because if you do want to print multiple things at the same time without cooling down the bed, having the right height is critical. Otherwise, the printhead can collide with other printed objects on the bed and potentially wreck them right after printing – and either headed to the next print stop or going “back home” with a complete job.
Let's give an example: You are printing a series of small towers of varying heights. You'll want to design these towers so that they are below the gantry height to avoid being clipped by the printhead going over – and keep in mind what sequence the printhead intends to go in, all while avoiding putting a short tower near where the printhead returns to base. This sounds difficult, but in reality most software products will warn you if something is off about your plans and are likely to result in having your printhead and something already printed collide.
Can I change the gantry height?
Yes, you can change the gantry height within the software with your 3D printer, like Cura. The gantry height might need to be raised to print larger objects so that the printhead doesn't hit anything. You'll also find that if you replace your printhead, you'll almost certainly have to change the default gantry height to avoid accidentally knocking over your own prints or printing the wrong heights entirely with a new printhead.
When should I change the gantry height?
Your software will probably help you with this, but you'll want to change the gantry height when creating prints that have multiple heights in place and if the resulting prints cause an obstacle for the printhead to move around or go back.
Can I print tall objects without changing the gantry height?
Yes, you can! With some planning, you can set up your prints to have the tallest object finish last. This way, your printhead will have to be a little higher when finishing and lower as its on its way home. You might also want to set this tall object as close to “the end” as possible to avoid having the printhead swing over the finished objects.
How do I measure gantry height?
If you are printing similar-sized objects, you might not have to worry about this at all. If you do want to know your gantry height and how to measure it, start by getting a gauge that measures in millimeters or smaller – or for that matter, the measurement your software accepts. You can then measure vertically from the base of your build plate up to the very bottom of your printhead. This will be especially applicable if you do print multiple pieces with varying heights. You'll know how much distance you really have and be able to plan your printhead route for the purpose without crushing anything like Godzilla.
Pausing with gantry height
Not all print software is the same. You'll want to be careful to not pause your print if you have changed the gantry height. Why? The printhead could readily go as low as necessary to “get home” without going on the established route and accidentally destroy prints on its path there. Either find a way to tell the printhead how to get home, or don't pause when adjusting gantry height or printing multiple heights.
Can I print multiple items with gantry height on?
You can in some software, but it's not easy. Gantry height is meant to limit you to a “One at a time” print, which also includes printing off a few things, then stopping. The biggest limitation here is that some printers don't let you choose which order to print in, and you might have to find a way to get around software telling you not to because you aren't supposed to use specific gantry heights while printing multiples.