Mark One users??

[MARKFORGED]

Hey All,Apologies for being late to this thread... I can certainly help answer some of these questions.

Why the one square inch rule? Is there some hard limit on either the material or the extrusion mechanism that makes it impossible or problematic to lay fiber in smaller areas?

The Mark One requires a minimum solid area of 1 square inch to place fiber. The area has to be continous (in most cases holes are not allowed to place fiber). Note as well the fiber is a continous strand for each layer (no fiber cuttings are allowed at one layer).

There isn't exactly a 1 square inch rule, but there is a minimum fiber length per layer that basically equals 1 sq inch if doing something like a disc or rectangle (with no holes). The min fiber length per layer is actually about 612mm, which is the distance from the fiber cutting assembly and the printhead (since we effectively use a bowden system). Smaller parts can be tricky, but we are actively working on ways to mitigate the constraints and optimize printing. As I'm sure you've noticed, our software team is constantly updating Eiger with new features and optimizations. We hope to have more info soon.

This is limiting for many more complex geometries. Also there is a minimum width required to place at least one fiber ring, from my estimation it requires at least a 3mm thick wall. You have to take all that in consideration for designing your part.

The minimum wall thickness can vary, and sometimes be optimized by the FFF nylon settings (check out the support articles next time you have a minute). Basically the wall thickness is defined by the walls (shells) and fiber. Each nylon wall is equal to .4mm, and the fiber is about 1mm when printed., so you can effectively print ~2mm wall thickness (.4mm + 1mm + .4mm) so long as you meet the min. fiber requirement of ~612mm. We have 2 walls as the default (for better overall printing/quality), which is why you correctly pointed out the default ~3mm thickness ((2x.4mm) + 1mm + (2x .4mm)).

We just ordered one. I had a sample part printed with CF. The part has .275 tabs that are .312 long and it filled them pretty well. I think the trick was to make sure the ends were rounded so the CF can make the corner.

This can be correct in some cases. Carbon is super stiff and brittle, so it can't always make certain bends. If you have parts that require hard corners, Kevlar or Fiberglass works very well.

If the part is designed for these constraints, you can actually print rings of fiber around holes to reinforce – which is actually much better than drilling through and terminating the fibers like you would with traditional composites.




Big thanks to you all for contributing to this community, and please keep the feedback coming. Feel free to PM me or file a support request for specific feedback, so we can get it on our roadmap.


Thank you,
Jeff