It can be easy to overlook the next critical subsystem within mechanical because when you look into the machine, there is nothing but an empty space where the build envelope is to be found. This is, of course, by intention. The build envelope is the work area within the machine that integrates the extrusion system and the mechanical system. This is where it all comes together and where the 3D printed parts are produced layer by layer from the first layers kiss down onto the plate to the topmost layers while the part is cooling. Creating and serving this territory of emptiness is essentially the critical part of desktop 3D printer machine design in the first place. This is where the printed parts are produced after all. It is up to the machine desire to make sure that any sort of part that can be produced within this territory can be produced consistently. In this lecture, we are focusing on the build envelope, the movement envelope, the build platform and the 3D printed part. We'll start with a discussion of the build envelope, the printable area within a 3D printer. We will then expand beyond the build envelope to the movement envelope also known as a mechanical operation envelope with focus on the unprintable areas. This region includes all the areas that the moving parts of the machine must pass through in order to place the tool head in the positions where it needs to go including those that wouldn't work for extruding plastic and fabricating parts. Next, we will discuss the build plate, the stage in which parts are fabricated. And spend time talking about the printed part itself from the perspective of the mechanical system and part orientation and removal. Let's start off with a build envelope. What is the building envelope really? I refer to it as the construction zone for the printer, the work area within the machine. This is the printable area of your machine and determines absolutely the biggest single parts you can print at one time. But a reminder, this doesn't limit the size of the parts and projects you can create in separate pieces and assemble later, just the single parts. Printable area, what does it look like? What does the build envelope look like? It might sound confusing to describe a void as having a shape, but the building envelope for fixed envelope 3D printers, e.i, most of them that you will have access to, has a clearly defined shape and dimension. One that can be more complex than most operators and marketing literature suggests. Most 3D printers have a fixed envelope established by machine design elements such as an XY Gantry that constrains all movement on the X & Y plane to a specific area. And a z-axis that can only move as far up or down as the length of the lead screw less the areas that would drive the plate outside the bounds of the installs and outside of the case. Or they have an XY Gantry called a vertical x-axis and the moving y-axis that can only move so far forward or back. Let's say your part design just barely extends beyond the build envelope along one edge. That's still no good and attempting to use that machine to print the part in that configuration would be a disaster. And unless you have somehow disabled the settings, your slicer will warn you when this happens and gray out your part first. Images of built envelopes, here are some visual examples of a few typical machine types and their bills envelope. Note that these are rough approximations. From model to model and configuration to configuration, there will tend to be certain off-limit areas due to utility tasks within the movement envelope and decisions around where to place the in stops to establish the homing position. Most Cartesian machines have rectanguloid volumes like this. Typically, machine definitions will choke in from the very out most limitations so that there are still some options for tool insertion angle. So if a positions can be consistently hit from any direction of previous travel. Most delta and polar machines have roughly cylindrical build areas. The very top most areas of a delta and machines print area will round off into a complex shape a bit like a cone. Though few machine profiles allow you to print all the way to the very top most area. 3D printer control software options such as Ultimate Karakura typically offer machine profiles for printers that alert you as to whether your part is printable within the build envelope. So you won't easily make mistakes that create issues. These areas that are unprintable are identified by measuring the full build area as well as the size of the tool head and placement of any no travel avoid areas needed for utility actions such as homing and purging. Fixed build envelopes, Soooo, and as I mentioned before, most fixed build envelope printers work this way. What did I mean by fixed and what are the other potential build envelope configurations? We use the term fixed when we are working with machines where the physical constraints of the machine from a kinematic perspective do not change over the course of the machines use. You could produce the shape of the build envelope by moving the tool head to everywhere that it can be driven within the limits of each axis. Everywhere that a nozzle can move is a place where potentially plastic can be deposited exempting the utility position such as priming and switching bay's mentioned before. State defined refers to a configuration element that when adjusted changes the shape of the build envelope. The most common version of this is a multi material printer that has more than one head. Even if you don't have a physical toggle that changes the position of the tool heads, the shape of the space that can be printed by the head in one configuration will by definition be slightly different than a tool had in another position. Expanding or infinite, the third type of build envelope will explore what tends to be called and expanding infinite or continuous build envelope. The most common tweak to allow for the special class of machine design is the addition of a conveyor belt for one axis of the machine. The use of a conveyor belt in fabrication and 3D printing is not new despite a few relatively recent awards of IP for it. Conveyor belts are used elsewhere in automation to allow the machine to advance the build area to the end of the print out of the machine. So if the next piece can be produced either by knocking the piece off the conveyor belt or by extending the base beyond the printable boundaries of the machine. The innovation introduced by build steel for his continuous SLA printer and then explored in his collaborative project with printer Bots Brook Drumm as the printer belt is a set of vertical x axis and an angle to a very very long conveyor belt on the y-axis. By moving the y-axis long distances while the vertical ex stage prints anywhere it can reach along the X Z axis. You can potentially produce massively long objects with stunt projects such as kayaks and multistage rockets to prove the point. Or you can simply keep printing part after part in an endless stream, ready to fall off the front lip of the conveyor belt after cooling in the belt away from the printhead. Another project that hit upon this innovation is the black belt continuous printer. The build envelope for these machines is only theoretically infinite, however. Because as you produce longer and longer objects, the process of extruding and placing the material reaches additional complications and limitations that rarely come up within the body of a typical desktop 3D printer. Issues with uneven cooling warping and the introduction of dust and other particles into an active print job. These printers are pretty exotic designs difficult to accomplish simply because the sizing process to prepare the job files to run these printers required out of the box thinking and troubleshooting. But now the models like this exist, there are other ways to mechanize further movements and extensions two axis mid print. Conceptual printers allow the feeding in of segmented or super long fixed build plates. So a small printer can produce pieces bigger than the main body of the machine and or add additional rotation or actuation for the build plate or elements the machine kinematics. If you enjoy these types of experiments, there are a number of impressive machine builders we share online and attend reprap conferences to demonstrate the new ways of rethinking machine design. So what is the movement envelope? We have discussed the build envelope, the printable area of the machine. What is the movement envelope? If the build envelope is at huge printable chunk of plastic that you can make in the middle of the plate. The movement envelope is the rest of the space between that chunk of plastic and the outer extremities of where the machine can even move. So there isn't room in those areas to really work it printing more elements, but there's some more stuff that you can do. The mechanical operation envelope, movement envelope itself expands beyond the build envelope to include all of the areas that moving parts of the machine may pass through. In order to place the tool head in the positions where it needs to go even the ones that are of no use for actual printing. This is the void where parts cannot be built in both defines the outer borders of the building envelope and conceals within it a number of features that are very useful to the process of printing the object. For example, switching base to toggle between tools. Travel areas where the machine can move the tool head at faster rates without encountering the printed part. Heat cycling areas before and after print where the hotend can't heat cycle without heating the part or dripping filament on to the building envelope. Touch off areas where in stops are triggered at the start of a job sequence. And disallowed areas that establish the placements and positions that the moving parts must not enter, at the risk of colliding with printed parts, the size of a case, or your fingers. One of the most critical roles that the build envelope sub system offers, the printing process is homing. As depending on the machine design, it can be tricky locating the right places to put an in stop on each axis. Take for example, a very very tall Delta machine. The usual place to put the in stops for each tower are at the top of the tower activated by colliding the carriage into the in stops on each of the three towers. However, this is a very very if this is a very very tall Delta printer and the z-axis drive mechanism is not super quick, it can add a long time to the triggering of every print job. So routes to allow toggling at the base of the machine might be more convenient but might cut into the printable areas allowed on the first layer. While there are many reasons that the machine developers will need to block off specific areas for specific configurations. Probably the most important considerations for the movement envelope is making sure that you calculate correctly why an area needs to be disallowed from printing for an action within the movement envelope outside. We've talked about the build platform a little bit from the mechanical standpoint and we're going to talk about it even more when we talk about the extrusion system and what it means. And now we have the build plate itself. So you have the build envelope. You have the movement envelope. There may be may still be areas outside of that that the build platform physically offers that you cannot use. This can be as simple as where you put clips and ways to fasten down the build plate. And it also can be elements that have to do with how its mounted and adjusted in three dimensional space, so it remains at the same distance from the nozzle at every point. We've already talked about this a little bit from the mechanical standpoint and will return to the platform again in the extrusion process. Thanks for joining me on the discussion of the build envelope, platform and related topics. Note that if you really enjoyed hearing about the more exotic types of experiments, with how to conceive of the building envelope and build plate. There are a number of impressive machine builders who share online and attend reprap conferences for the specific purpose to demonstrate new ways to rethink machine design.
