I want to make a ridiculously large 3D printer… say 1M cubed. I don’t care about print quality at all I just want to print some big damn objects. Here’s what I’m thinking:
2-2.5mm nozzle diameter for somewhere between 1-2mm layers
CNC gantry style config ala Shapeoko and similar machines using V-Slide
PLA cuz its cheap and prints are going to take a couple pounds of plastic anyway
So what should I consider? Should I use 3mm filament on 5lb or more spools or use some kind of filastruder style pellet extruder instead? Do you know of similar (working) projects?
@Shauki Has a bot called quadrap that is about 1m square. It’s very repstrappy, so it might not suit your purposes though.
The bot I’ve been working on should scale that big. It uses an Ultimaker style gantry with spectra instead of gt2. Tslot) frame, works very well with 300mm square build volume. Scaling it would simply require a larger tslot frame and increasing the shaft diameters. I’d go 12mm for the outer shafts, and 10 for the gantry shafts.
Oh and 3mm filament should be fine with a wide extruder nozzle. Maybe a 1mm nozzle with twin heater cartridges. I’d use a direct drive extruder with a Nema 21 to get maximum extrusion speeds.
I am also really curious how a large nozzle diameter (compared to what we normally use) would affect extruder torque and nozzle heating or more to the point what kind of heating will it take to get layers that big to adhere. Can I just use one of +Sanjay Mortimer 's hotends and drill out the nozzle or am I going to have to reinvent the wheel as Tim suggested and use multiple heaters.
@Brian_Evans fair enough, smooth rods that are straight enough over 1m aren’t that cheap I guess :). I wonder if the open builds cnc bot will be accurate enough? I would also try to get it to be as fast as possible. Otherwise, those big prints are going to take days and days. Just go add a further alternative suggestion, how about a vslot machine with core xy mechanics using synchromesh? At least you won’t have to move those big Nemas about then
@Tim_Rastall Yeah I was just starting to think about corexy but then you have to move the bed on the z and I was liking the idea of a stationary bed. Figure moving a gantry and some nemas around would be lighter than a 1M cubed print and platform.
I just have to ask this due to your projected build size and the lack of resolution importance…
Are you sure you want to print in Plastic?
Perhaps some sort of paste extruder would be more appropriate. People do print in ceramic, dough, etc. You could probably set the nozzle size to whatever you want with a paste extruder.
@NathanielStenzel Yeah youre absolutely right and that would be the eventual plan. I would love to go ceramic and have seen some cool pneumatic systems for extruding ceramic slip but that breeds even more complexity that I don’t want to deal with right away. Dr. Behrokh Khoshnevis’s Contour Crafting is awesome on a large scale for example but he had to solve some huge problems to keep those large prints from breaking - think 5th axis troweling. Im hoping there are fewer hurdles to extruding plastic at larger layer heights than normal.
@Brian_Evans I was thinking about suitable hot ends last night and you could conceivably machine a new heater block for an e3d he that accommodates for 2 heater cartridges. I’m not certain if the longer melt zone is necessary if the heater block is able to deliver sufficient power. A long melt zone would mean you’d need to use a PEEK he or perhaps use the (internally) polished stainless tube from the prusa nozzle with an larger block…
Good point about not moving the bed in Z axis if you’ve got quite a few kilos of plastic on it, I’ve had success using gt2 belts on the Z axis for my current project, you could quite happily use the same approach with a belt in each corner and counterweights to offset the gantry’s mass. This would be way cheaper than 2 (or 4) 1m lead screws.
@Tim_Rastall Yeah I saw the modified jhead from Jos - making an extruder for 2mm or so will be interesting because Im not a genius like Sanjay and don’t get the thermal dynamics of such a thing. Even a Printrbot style hotend where the cartridge is placed vertically in a tall heater block (which I hate with a passion BTW) might work to increase the heat zone.
As for the Z… I realized my initial thought of an extended z on the shapeoko with a 3’ long extrusion flying around would be stupid. Im now thinking of a more convention x gantry riding up and down some 40x40 pillars (belts might be good here but a little scary) with the bed sliding on the Y ala Shopbot Buddy/Printrbot style. Need to bust out some Openscad and see what it looks like.
I would advise you to keep the platform on the base and move the nozzle on the x,y,z. I am but a newb (August) to 3D printing and have not designed any, but with future plans of ceramic, I don’t think you want to move aprox 30lb (guessing) of ceramics on a Z axis.
Yeah I can see a heavy y would create lots of backlash (The Shopbot moves slowly) but a heavy z is not without its mechanical challenges. @Tim_Rastall How big is the platform on Ignitus? Are you running that off one stepper? Any problems with leveling?
