Help me pick the right electronics hardware for a filament printer

[Don McLean]

But you have to bear in mind that it's also material specific. Flexibles - for example - have almost perfect layer bonding no matter what orientation you print them at.

But anyway, the basic gist is that layer bonding is as much material driven as print orientation driven. So don't necessarily let that be a defining factor in your choice.

Nylon 12, and Nylon 12 CF filaments (perhaps also some ABS CF filaments?), I realize these are expensive filaments, but I want to make functional parts for a specific application, and some suppliers of these filaments are less expensive than others. Sure I want to do fun projects also, like a starwars inspired helmet, props for friends and family who would feel at home at comicon, but those are not my main motivation.

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?

And i suspect the reason people don't muck about with gear ratios that often, is simply that most of us have no bloody clue how to rewrite firmware to get custom gearing actually working :-)

I hope you're joking. Are you talking about open source firmware or machine specific closed source firmware? In mach 3 (for CNC routers, mills) for example, this is super easy to set up.

Typically, IMO, for larger CNC machines using Nema 34 steppers you want a gear ratio of 2 to 4 for a rack and pinion system with a pitch circle diameter of 1" on the pinion (alot more for servos) and this is very similar to a belt drive. Not using any gear reduction doesn't work very well. Also using high inductance motors doesn't work well. Also you typically run at 48V as a minimum, with 60V or higher not being uncommon. This gives better speed performance to the stepper motor. 10mm travel per rev to 38mm travel per rev of the motor on X and Y, depending on a number of factors, this is the comfort area for CNC stepper motion, IMO.

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.

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.

If you want 80T and 20T, just get them separate and mount both on the same shaft.

So this method is waaaay more of a PITA than using an idler that already has a built it bearing that you can bolt on somewhere, especially if it is mounted vertically.


I just bought a 22mm carbide tooth hole saw to help with making my own custom mounts for Nema 17's,

*The more scientific explanation behind this is when a layer cools, it contracts. If the print does not cool uniformly, there is differential cooling and contraction. When one side of an object contracts more than another, it causes it to bend and warp (think bimetalic strips) and if the top layers cool quicker and try to curl up, while the bottom layers stay stuck on the bed, the top layers will delaminate from the bottom layers and result in a crack in the print.

Perhaps I should really think about some doors and a lid to make an enclosed space.

As for 3d printing youtubers worth following, thomas is a good one to look at when it comes to the technical side of printers. He has lots of guides on firmware, electronics, mechanics and more and his technical knowledge is spot on and has some backing as he's sourced and built a couple of printers himself of both the delta and cartesian variety. The things Angus says aren't always entirely accurate.

I like watching Angus' videos because he seems like a very honest and kind person. Obviously he is more oriented towards using and reviewing commercially available printers than building them, which is fine.

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?

Don't worry about the long reply, I appreciate the effort you put into it.

On one hand I know a few things from other CNC experience and what I have built / used in the past, on another more relevant hand, I am a total noob in this space. So any help I can get is appreciated.