Comments, Critiques, Ideas Welcome - Revamping Prusa i2 to Allow Full Print Area

Hello everyone!

As the title says, I'm looking to revamp my Prusa i2. The machine is functioning pretty well at this point, so I would like to take the step and make it have an ACTUAL print area of 200 x 200 x 100 (mm).

There's always the chance that I put together my Prusa backwards, but with it already being a smaller printer, I was disappointed to find out that if I want to home the prints during layer changes (to fight against shifting layers at higher speeds), or theoretically print a cube that is the entire print area; I run into multiple issues. I want to at least be able to take advantage of it's capabilities, while maintaining roughly the same overall size.

-The X carriage/extruder is not able to be homed after heights of about 50mm due to the Triangle frame hitting the extruder assembly.
-The top bars of the triangle frame (between Z-motor mounts) interfere with filament feeding at higher heights, as well as limit the total z travel due to the threaded rods being in the way.
-In order to gain more printing on the Y-axis, I flipped the smooth rod clamps to allow the bed to move further in each +/- y directions. As expected, this increased my printable y distance from 106 to 185mm. However, it came with the cost of taking more off of the z direction due to the raised bed height.


So, with the proposed solution. I am sure someone has done this already, or at least thought about it. So, all input, ideas, comments, critiques, design improvements, etc are welcome.

At this point, I have printed the parts and cut the rod, but before actually installing and aligning everything, I'd like to hear your input. The only potential weakness I believe I may experience with this design would be in the overall rigidity of the frame, however, the way I see it, I can always add some braces at the right angles as needed.

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I began by modeling the majority of the printer and design components using CAD.




Now, I have printed parts printed, threaded rod cut, and have it roughly assembled (using eyeball measurements).














After seeing this design, visualizing it, and thinking about it, what do you think?

Thank you for all of your time, efforts, and feedback!
-Pat

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- "Project Locus" - Mostly all printed parts, Corexy, Bowden Setup, 12x12 heatbed, ~1 cubic foot build volume
- SeeMeCNC Rostock Max V2

You have no triangulation in that frame, which means it will flop around (especially with plastic corners!) due to the inertia of the print head and you will get bad prints. Since you have printed corner brackets, it shouldn't be too hard for you to add threaded-rod diagonals to a few of the faces of that cuboid. Your bottom corner brackets are particularly problematic because they have significant separation between the various rods that they join, which means they will flex really badly under the torque from the extruder motion.

I was at a similar stage and decided to go for a new frame. The threaded rod frame is unstable enough and even if you were to apply crossbracing this will be an fine tuning nightmare.

I also was disappointed with the lack of build space as the specs didn't really explain the distances as max travel prior to putting the extruder on which reduced the actually usable area significantly. I also had lots of problems with coldend jams which turned out to be a good thing so decided to lick both problems at the same time. I changed from the direct drive extruder to a Bowden extruder. This ended up removing my heat creap problem but the best part was it gave me another 1.5" travel in the Z axis. The biggest problem with the triangular frame is the servo motor getting in the way on top and hitting the angled supports. I also got another 1" on the right hand side of the Y axis since the servo would run into the Z axis lead screw. A bonus was I also got a all metal hotend for those new filament types that are becoming available.

The basic design of the I2 is good however we need to have some work arounds, this helped me without too much redesign.

When I'm ready for more print area may have to go with a delta design next. Hope this helps.

Hi Pat,

are the files for making this frame available somewhere, or would youshare them please?
Thanks in advance

Marc

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marcething
Hi Pat,

are the files for making this frame available somewhere, or would youshare them please?
Thanks in advance

Marc

Hey Marc, yes I could upload them to thingiverse. I would like to note (and will note) that these parts were designed to match the printing "habits" or "tolerances" if you will, of the i2 that's printing them. Meaning the borders were modified accordingly. (Mainly that holes are 0.7mm oversized in the CAD files). Even if the printer you use to print these parts is spot on, I don't forsee that small of an oversize being an issue.

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- "Project Locus" - Mostly all printed parts, Corexy, Bowden Setup, 12x12 heatbed, ~1 cubic foot build volume
- SeeMeCNC Rostock Max V2

Hi Pat,
That would be perfect; looking forward to it.
I think you are right that that small of an oversize won't be an issue.
Thanks in advance

Marc

Hi Pat ,µ

did you already had time to download them to Thingiverse or somewhere else?

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marcething
Hi Pat ,µ

did you already had time to download them to Thingiverse or somewhere else?

[www.thingiverse.com]

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- "Project Locus" - Mostly all printed parts, Corexy, Bowden Setup, 12x12 heatbed, ~1 cubic foot build volume
- SeeMeCNC Rostock Max V2