Darwin based designs + Did anyone buy/recieve a Maxifab?

Howdy,

I've been keeping up with the reprap scene from a sideline point of view for quite some time now and wile I haven't gotten an official reprap, I have been working my way there from a lesser technical instillation. After having some good success with a ToM I have come across the Maxifab project, which seems like a half priced version of the Ultimaker, which in turn is an alternative version of the Darwin (its good to know your family lineage in this right?) I figured since the maxifab was Sanguiloulou based and I could put some prussia platforms on it , it was generaly a good midway point between having a fully modifiable Reprap model, and a makerbot. Not quite here nor there as it were.

I thought that wile people here are almost deffinately owners of a more official RepRap/RepStrap, there was still the chance that one or serveral would own a maxifab, or at least be associated with others who had and had opinions on it.

And in general, what are the likely pitfalls of a Darwin based design? Considering its position in the tree, I assume there was a reason for dropping it, but I'm wondering if any flaws at that time have been mitigated by newer updates to the framing, like the ultimaker, makerbot, and Replicator (though i dont recall MakerBot ever pointing out its near exact origin for that design as being the darwin in any news releases.)

I hadn't seen the Maxifab before, but it looks like an interesting design.

Considering the Darwin vs Mendel, I think that is an interesting question. One of the design flaws of Reprap machines is that the are designed to have some of their parts printed by the machine. You might say that is not a flaw, because the very purpose of the machine is to self-replicate! The problem is that because the printer can't print large structural elements, it is relegated to printing small plastic joints. This means the design puts reliance for strength and size on parts that probably will never be printable, e.g. smooth steel rods.

I think that the Mendel is an attempt to reduce the number of non-printable parts by using a triangular frame over a square frame, but in the long run is still a dead end as far as self-replication goes. The actual volume of printed parts is quite low, in order to make Reprap more self-replicating it needs a ground up redesign, which is a lot harder than revising the design to use cheaper vitamins, so people focus on the latter.

The Darwin style may have fallen out of favour in Reprap circles, but it is the Darwin style that is the choice of commercial designs. One advantage of Mendel is that the moving mass of the Y axis is reduced, but there are ways to mitigate that.

If you are not so bothered about full self-replication, then a square frame is a lot easier to design and build, and has the advantage that it can be easily enclosed. The enclosure can also provide the structural support as in Maxifab.

Edited 1 time(s). Last edit at 10/14/2012 06:42AM by bobc.

Replicatability is about the most improtant reason why the RepRap community exists. The less replicatable a design is, the smaller the number of tinkerers.

The design flaw of the Darwin is its square design in conjunction with vertex connectors. Connectors can also be considered to be hinges and doing this consideration quickly shows where the problems are. Its wobbly.

Another shortcoming of the Darwin is its DC extruder.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Traumflug Wrote:
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> Replicatability is about the most improtant reason
> why the RepRap community exists. The less
> replicatable a design is, the smaller the number
> of tinkerers.

That is true. The challenge would be to build a printer from whatever you can find in a local hardware store.

> The design flaw of the Darwin is its square design
> in conjunction with vertex connectors. Connectors
> can also be considered to be hinges and doing this
> consideration quickly shows where the problems
> are. Its wobbly.

The vast majority of objects are built on a square frame. Squareness itself is not necessarily a problem. Using inadequate printed parts for pieces of the structure is a problem, which is a problem I identified in all Repraps. If you use decent quality connectors then stability is not a problem, but of course that little bit of self-replication may be eliminated.

The design of the Mendel is a compromise, and it is due to the desire to have parts self-printed, which is really my point.

> Another shortcoming of the Darwin is its DC
> extruder.

Yes, that is a trivial modification.