I'm planning on moving into a smaller place soon, which will be quite limited on space. I have also been contemplating how I may maintain this hobby as my current printer a Prusa i2 takes up too much space. I mean you've got the printer itself, power supply (not mounted to the frame), all the cables, spools of filament. It takes up a lot horizontal space. Plus it's not really a good design. I figure this would be an opportunity to build something that fits my "needs". Which are rigidity of frame, accuracy, speed, noise, ability to be enclosed, and footprint, trans-portability. I do understand that there will be trade off's between all of these. For example I know that I won't be trying trying to obtain some crazy speeds, without giving up accuracy or obtain a small footprint without giving up build volume. I do think however noise, ability to enclose, footprint, and rigidity of frame can all be kept with no compromise. Now when I say trans-portability, I mean that I may have to store it in my car when it's not being used.
I've looked at existing designs (folding/portable types, cartesian, hbot, corexy), I've created my own CAD drawings for custom designs for pretty much all the printer types out there. Each have had their problems with one or more of the above "needs". Sometimes the rigidity, but usually the the footprint to build volume ratio. I'm not looking for much, only a 150x150x150 build volume. Of all the machine types, all had a footprint that was quite larger than the build volume. Except the delta. Since everything is under the build plate, it's quite compact on the footprint.
My questions are with the frame. Say I built something along the size of a Kossel Mini, using RobotDigg's metal corners for the XXL version (20x40 extrusion). That should be quite rigid and able to stand transport/storage without the frame skewing right? I do worry about the horizontal extrusions sliding as they're only connected via the slots on the sides. If the design also included that they were also attached to the corners by being screwed into the tapped ends, I wouldn't think twice about it. Should that even be a consideration or do they hold super solid?
They hold very well. My 1m high Kossel was transported on the back seat of my car several times when it was still using 2020 extrusion. The base triangle of my printer uses 2060 extrusions on two sides for extra rigidity. See link in my signature for details.
IMO 2040 extrusion is overkill for a Kossel Mini, 2020 would be adequate. OTOH the 2040 corners would be a good investment if you might want to enlarge the printer some day.
Small deltas normally use a separate power supply due to limited space under the bed.
Delta printer calibration calculator, mini IR Z probe, and colour touch screen control panel: [escher3d.com]
Now that I think about it, the way the design works would prevent the horizontal extrusions from sliding wouldn't they. Because the corner pieces maintain that angle pretty far out, for it to slide at all, the extrusions would have to be super loose on 2/3 of the lower frame to allow enough room for it to move. Plus I just though about top/bottom panels if installed and also bolted down to the tapped ends of the vertical extrusions, plus some type of stop blocks installed on the other side of the corner pieces would effectively sandwich them in place.
I do think I'm going with a Delta. Probably gonna stick with the 2040 corner pieces. Even though I may not upgrade the footprint, I may later increase the height. I just noticed that about the power supply, I'm thinking of building a base base for all that stuff. It'd be nice to have the Duet Wifi, to just plug in the one power cord, add filament and go.
Though magnetic rod ends would be nice, i think I'd like something that mechanically will hold everything when I pack it.
Edited 1 time(s). Last edit at 06/06/2017 02:40PM by FA-MAS.
I've built a mini Kossel and printed a pedestal for it with 12mm mdf base is you look at the thread Kossel k800 overall height of it is 720mm, I would definatly go with aluminium corners and goof thing i like about deltas is the actual movement of them, and I built mine so I can take it places
Edited 1 time(s). Last edit at 06/06/2017 07:27PM by chris33. Check my rubbish blog for my prusa i3
I think corexy with vertical X axis would actually be as fast and and small when compared to delta (150mm cube build volume is about 212mm inscribed circle with delta design). Small corexy would not need anything larger than 2020 profile and would be extra fast and rigid with minature,15mm linear guides for Y and Z axis (I would go with carbon fiber rods for X like in original HyperCube).
Oh yeah, I guess I forgot to mention that I'm not looking for a design unsupported smooth rod so Linear Rails it is. Oh yeah, none of the core parts could be plastic either. My Prusa is cracking and failing because the ABS has gotten brittle. Also in every CoreXY design that I came across or came up with myself, it was the motors and the Y Ends that took up the most room. Either the motors were outside the frame (which kind of kills the enclose-ability for me, or they were inside and took up quite a bit of space. Cause then the motors are inside (sure you can offset it under the extrusions a little like the Hypercube), but then the belts and pulleys are also inside and it all seemed fairly inefficient use of space to me. All the plastic Y Ends look to be designed to take up as little space as possible, but I'll not be using plastic parts. So designing something that is easily machined (say like DD's printer) or even something I could print then cast was an option. Yet all pre-made solutions as well as my own designs of which there were multiple iterations just took up too much space, thus the need to extend the frame to get the build volume I wanted.
One of my designs started out exactly like that. Swapping to linear rails (i'm never using smooth rods again) would decrease build height by about 13mm (not much), it would break the ability to enclose the machine as the carriages protrude outside the extrusion by 3.5 mm. You could mount the rails on the inside, then you break the envelope on the top of the printer, and 26mm is taken up, plus Y ends, motor mounts, and idler mounts would have to extend further inwards. A Y end design with a slot that the belt would route through would be needed. More complicated. The pulleys on the Y Ends could be stacked which would be nice. But mounting vertically would mean the idlers would either be mounted individually on either side of the rail or stacked on one side. In one scenario the Y End would have to be wider in Y direction to allow the idlers to be on either side but not in X. On the other scenario, it would have to be wider in X direction but not Y as if the idlers were both on the same side of the rail, there would have to be a hole big enough for both passes of the belt to fit through. Or somehow mount it vertically so the rail is above or below the belts. Same in the case of horizontal mounts. Plus the Y End would have to be wide enough in the X direction to allow use of 2 screws on the linear rail, using 1 on each side wouldn't be very rigid. Then of course there also needs to be a solution to support the tops of those idlers/pulleys. And then, depending on how you mount the carriage and your hotend mounting, it may take up even more space. There's lots of combinations, I've found that the requirement of linear rail complicates them all.