Help me pick the right electronics hardware for a filament printer

[Trakyan]

So how important is orientation for Nylon12 and Nylon12 Carbon Fiber filaments re: woodgrain strength? And how much of a maximum Z height can I push if orientation isn't important?

Your layer bonding does /not/ limit your maximum Z height in any way, shape or form. What it limits is the amount of force the layers can take before they shear or pull apart. This is to do with how the part is loaded when in use, nothing to do with how it prints.

So if you look at a 20T GT2 pinion, that's about what? 1.5" to 1.6" per rev? That's on the edge, but perhaps that's fine. I really need to have a better look at the Nema 17 torque vs speed graphs to give a definitive opinion. Also 3d printers tend to use more microstepping, but microstepping can't always be relied on for accuracy in and of it's self.

Most printers out there, including higher and high end commercial ones use 20 or 16T pulleys with no gear reduction and do fine in terms of torque and accuracy. You don't need anywhere near as much torque for a 3d printer as you do for a mill, the only forces on it are acceleration/deceleration no cutting forces. And you'll never be running your stepper motors on a 3D printer to a speed where you'll lose noticeable amounts of torque, unless you've geared them down significantly. You are entirely correct that anything beyond half stepping isn't really reliable accuracy wise, and printers don't rely on this for accuracy. With a 0.4mm nozzle, the accuracy you get with an ungeared nema 17 running a 20/16T pulley is good enough, and far from your biggest source of error.

Originally I was looking at using a single motor to drive the gantry with a connecting rod to two belts. I was thinking a 12mm rod, so that ruled out 20T and left me with 40T driving the two, and about 3.15" per rev, which is too much IMO, so I was looking at a belt reduction from the connecting rod to the motor, and I still haven't ruled out some belt reduction.

I was watching a vid on Youtube recently of a gentleman refitting a stratasys 3d printer, they definitely had some belt driven gear reduction with Nema 23 motors inside that thing.

Your first idea adds a lot of inertia and mass for the motor to drive (and halves or worse your resolution), which brings me to the part about stratasys systems being geared. If you play spot the difference with a desktop printer and a stratasys (I assume you mean an industrial model?), the stratasys systems are much more heavily built and require the extra torque from some gear reduction to lug around those overgrown axis. Even a 500x500mm print bed can use ungeared nema 17s as long as you build the gantry light enough.

Are you talking about Thomas Sanladerer? I've watched several of his videos. I don't think he knows what he's talking about when it comes to CNC cutting, but in general I like him also. I haven't seen anything to make me think he is more knowledgeable than Angus, he seems to mostly review printers, talk about their features, etc., the same as everyone else. Where are the links for the printers he has built?

I agree that Tom isn't too knowledgeable about CNC, and from what I understand he only has a converted mendelmax to cnc (which was more of an experiment in 'can it be done' not 'this is perfect who needs a proper cnc mill') and a mdf framed cnc he was recently sent to review, which didn't seem to go well. He does however have a manual lathe and mill which he's used in a few videos, and most engineers are at least somewhat trained with those.

He has a bunch of older guides going over every aspect of a printer from extruders to hotends, control boards and motion. Those are very useful but some are a bit outdated at this point.

Some useful guides to look at
https://www.youtube.com/watch?v=pRX_...zECor3EbqF8euw
(mostly the later ones down the playlist)
https://www.youtube.com/watch?v=E5Fq...3G9QSpzsRQCVGG
(series on building a printer, but maybe slightly less relevant for your situation)

Two of his printers he's built
https://www.youtube.com/watch?v=gZU-N3qUbRE
(his own design I think)
https://www.youtube.com/watch?v=M8BlJ_8nD68
(his build of a mendel90)
He's referenced an older mendel he's built in a couple of videos but hasn't made a full video on it.