Could an expandable 3d printer be considered? I see a lot of 3d printers based on a fixed size. Not sure if you’d want/be able to afford very large scale projects but if you could, you could fit something in a corner of your garage and when you wanted to make something, you move all the stuff out of the way and build something like a coach size. Is it engineering issues/stability/precision or just nobody’s thought of it/wanted it yet?
I asked a similar question before, and I think the general consensus was that “large” print volumes introduce problems with precision, and warping…
how can you make the guide rails expandable?
i can think of a number of ways. offhand, a manual process of screwing the ends together. one would be hollowed out and the other would be a screw.
I can think of a few others but fairly sure that would affect the position/accuracy a bit.
yea … accuracy is a PITA. a stiff rod is a stiff rod but its not so stiff when its in 2 pieces 
Japica !
huh ? japica ?
yeah, please elaborate on that
Yeah, basically, no, you can’t make that.
What you could do is have a system where you can swap out the bars and belts for longer ones over an hourlong rebuild… But there’s no real point.
well i started to make a gantry with 950mm x 700 x 700 approx … i have yet to finish it …
You can make really big gantries – look at the Kamermaker for an example local to me that is in the 2x2x4 range. That’s meters, not feet.
It’s just somewhere between hard to downright impossible to make them adjustable.
@Mark_Cunningham - it seems to me that your example application calls more for a collapsible 3d printer, rather than an “expandable” 3d printer… In other words, a printer that can be easily collapsed when not in use, and then easily set up for use. That seems like a simpler solution than a 3d printer that can expand to have a variable printing volume…
O.O … great idea … collapsible !
I saw a hexapod with a tiny router mounted to the “head”…made an impressively detailed face in some floral foam. Swapping that for an extruder could give you a theoretically unlimited volume.
@Eric_Cha sure that would work as well
Japica was an awful design that tried to fit in a brief case. The idea of portability was nice, but the whole design was nutters, I called them out on that and they disbanded.
@Alex_Kingsbury I’ve been wanting to try that for ages. I was thinking more of a scorpion tail with a nozzle on the end though, because I doubt you could do printer level precision with a hexapod. However, making one that can stand very still while its tail prints sounds doable to me.
Or if it were more of an art project, putting a very small delta system on its underbelly would work too. Although, that would take a pretty big hexapod to accommodate any reasonably sized printing.
ic … i think if in that respect then a single robotic arm with retractable main struts will be the ultimate flexibility … it just sits neatly on one spot 
I think the standing still would be best. The robot would move, lock itself rigidly into position, use some kind of stationary pylons to triangulate its position, and then use an onboard micro-printer. Finish everything the printer can reach, then move on. The software would have to be very heavily modified, or entirely custom. Perhaps each chunk could have bits that stick out for the next chunk to be printed around, locking them together.
Or take the whole idea elsewhere. Imagine a huge, sloppy gantry built fast and cheap from gas pipe or 2 by 4s or whatever. No need for much precision, just able to lock tightly into place. Add a few triangulation pylons, a precise self-adjusting micro-printer, and you have a massive work envelope for cheap, trading time for money. There could even be a micro-printer that a person could manually reposition on stacks of books or whatever to achieve any build volume.
great … send it to the moon now !