Archive for April 20th, 2017

3D Printer Design Conversation: Part 4

Continued musings about building a large-format 3D printer …

(Continued from yesterday)

taking your challenge and am starting by cloning the M2

That gives you an existence theorem: you know exactly what you want to end up with.

AFAICT, few of the M2’s parts bear standardized numbers you can simply order from a reputable seller. Makergear knows what it’s buying (obviously!), but they’re under no obligation to help out: you must reverse engineer the requirements, find a suitable part, find a supplier, then buy one item.

Let me know how that works out for cost & performance; “cost” should include a nonzero value for your time and “performance” should have numbers you can verify. I (obviously) think the build will be a dead loss on both counts (*), but good data will be interesting.

(*) Albeit useful for educational purposes, which I’ve used to justify many absurd projectst!

How the heck do you read out the current (estimated, obviously) X Y Z position absolute to the machine coordinates?

Perhaps M114 or M117?

My overall list may be helpful, although the RepRap Marlin reference has more detail on their command set:

https://softsolder.com/2013/03/14/g-code-and-m-code-grand-master-list/

The LinuxCNC (and, perhaps, Machinekit) G-Code languages give you access to built-in variables and extend G-Code into a true scripting language. Marlin evolved differently and doesn’t support that sort of thing.

G-Code is pretty much a write-only language, but you can do some interesting things:

https://softsolder.com/2013/07/18/makergear-m2-cnc-platform-corner-clips/

I use the gcmc compiler whenever I can for actual CNC machining:

https://softsolder.com/2014/02/21/can-opener-gear-rebuild/

Works for me, anyhow, although I don’t do much CNC these days.

move my nozzle up .01 at a time

Stiction / microstep errors / command resolution prevent that:

https://softsolder.com/2014/03/06/makergear-m2-z-axis-backlash-numbers/

The only way to measure the nozzle position is to measure a finished part with a known height, because any variation comes from the first layer offset. That’s if you have Z=0 at the platform, of course, rather than whatever offset you get by defining Z=0 at some random height based on jamming business cards / feeler gages / special Japanese rolling papers under the snout. [ptui & similar remarks]

For example:

https://softsolder.com/2015/09/14/makergear-m2-platform-stability/

You need numbers. Lots of numbers. [grin]

strip basic tools out of the control interface

Yet another reason I don’t use S3D: that “Simplify” thing gets in the way of my obsessive need for control.

(Continues tomorrow)

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