MB3D
1
Hello everyone !
I think that the capabilities of 3D printers regarding material variety and product cost are by far not at their limit.
The main reason that comes to my mind and which i want to change is that nearly every 3D printer needs filament instead of cheaper industrial pellets.
Taking a look at Colorfabb you can do some easy math and come to the result, that the XT pellets cost just one third of the same amount when bought as filament !
That’s why i’m currently working on an extruder that uses a screw to push pellets in the hotend.
If you are interested in helping me to make this open source project contact me, i’m sure we can make it!
However the extruder needs a 3D printer to be mounted on, the pellet extruder will have quite some weight and can bearly move when there is a cone of pellets mounted on top. That’s why i am searching an open source printer that has as less Extruder movement as possible (if possible the bed should move in X and Y direction)
I also thought about a unique design in which the printhead is mounted on the very top of the printer (the printer looks like a delta style one).
The bed is a round platform that can rotate on it’s origin with one stepper motor, another steppermotor mounted below the bed let’s the bed move in either X or Y direction. If you understand what i mean then it is possible to reach every point of the bed with very less movement. For further explanation look at the pictures below.
Every kind of help, recommendations, comments etc. is appreciated
-Marius
3 Likes
MB3D
2
Edit :
due to the possibility of 360° rotation of the printbed the linar motion only has to be as long as the radius of the printbed. the rotation of the printbed also is ideal for printing vases etc.
I’d need very much help when doing the code so that slicer software can be used on this printer.
Some basic math for estimation of printer size:
printvolume measurements:
diameter: 30cm
height: 30cm
resulting printer frame measurements:
X or Y direction (depending on placement) : 50-55cm
alternating dimension (so Y or X) : 40cm
(larger when i.e. display mounted on that side)
height: 50-60cm
(depending on the placement of steppermotors and the extruders final size)
Also multi extrusion would be a possiblity with loosing little printvolume
-Marius
Hello again Marius, 
Very interesting ideas. Just one or two points:
1) Print head with built-in extruder.
Without doubt, you’ll need to keep the print head fixed and move the build plate in X, Y and Z dimensions ( AND, let’s call it Z’, for build plate rotation ). This in and of itself need not be a real issue. It’s feasible. In fact, there are a number ( not many ) of printers that do this but, if you are to move the build plate in Z then you’ll probably need two motors just for Z or some way to connect two parallel vertical motions - A toothed belt, perhaps. The main reasons that the print head moves in one dimension on most printers are that it’s small and light, so can change direction quickly without too much power and simplicity. It makes the design by far the least complex. There is a printer that only uses granulated plastic. Can’t remember what it’s called or how it works. Really, the simplest way to work is to extrude filament from granules yourself. There are at least 4 home/workshop filament extruders I know of. The Strooder is a very good one.
2) Z’ movement.
I ask myself “What would be the advantage of a Z’ motion?” If the only advantage is that it allows the print head to get around the build plate faster, it’s probably only helpful for cartesian designs, unless you’re looking to make the fastest delta style in history. I’ve seen 1000mm/s on a delta. Conceivably, one could increase this to 2000 with a Z’ movement but I think the downsides outweigh the advantage. For instance, imagine you have a round plate at the end of a rod and rotate it quickly in your hand. What happens to the plate? It’s hard to accelerate because the outer edges are a long way from the centre and therefore have high moment of inertia. Once it’s moving, the angular momentum with make it want to stay rotating, so you’ll get a pendulum effect when you try to stop it. It’ll wobble, causing an inaccuracy in the print. Also, the error will be inconsistent across the built surface. It’ll be higher towards the edges, where the speed gives the most advantage. It’ll reduce to zero towards the centre, where it’s no advantage. So, you’ll either need to drive it with a super-micro stepper - Like 128 steps per step or more and/or use a worm gear, which would reduce your backlash and vibration.
I hope the above makes sense and I’m certainly not trying to discourage you. I think it’s great that you’re thinking outside the box. keep it up!
Cheers!
AndyL
Pot8oSh3D
MB3D
4
Hi! I’ll now just comment on your first point as I am not at the pic and it would be too much to type on a smartphone. I don’t know if you have understood how I mean the movement of the printer. You talk about X, Y, Z and Z’ but there are only Z (height movement with a very strong motor, then there is X but no Y to move the plate in linear motion (green) as the last and third movement there is R (I call it that but name doesn’t matter much) this causes the plate to rotate (red). With these 3 movements it’s possible for the printer to reach any point on the plate. The X would be with a teethed belt and a gear on the green motor. I know that there could be vibration on the outside of the circular motion but with a powerful steppermotor and maybe even a gearbox this should run smooth. The initial intention for that design is to improve the case-to-printarea relation. When using normal X and Y motion the case has 4x the size of the printed excluding the frame.
MB3D
5
BTW please excuse weird and randomly places words, autocorrection sucks.
OK. I get that you want to increase the case-to print area ratio. Not sure why but I guess that’s up to you.
Far as the direct extruder’s concerned. I think you’d probably be interested in this…
Cheers,
AndyL
Pot8oSh3D
MB3D
7
Hi, making the printer with normal X and Y axis would result in a giant printer. I mean when the nozzle has to reach every part of the bed, the bed has to move the full length of X and Y, plus the bed’s size and the frame, the printer (with 30x30 print area) would measure around 70x70cm which wouldn’t fit on most desktops
MB3D
9
This printer has a moving extruder, this wouldn’t work for a pellet extruder.
My Dad always used to say “There are none so blind as those who will not see”
MB3D
11
Maybe I’m too tired (0:15 here), but I don’t get what you want to tell me with that link
